U.S. patent application number 12/397811 was filed with the patent office on 2010-09-09 for routing frames in a trill network using service vlan identifiers.
This patent application is currently assigned to JUNIPER NETWORKS, INC.. Invention is credited to Sanjiv Doshi, Apurva Mehta, Kumar Mehta, Ramasamy Ramanathan, Sunesh Rustagi, Shiva Shenoy.
Application Number | 20100226381 12/397811 |
Document ID | / |
Family ID | 41226223 |
Filed Date | 2010-09-09 |
United States Patent
Application |
20100226381 |
Kind Code |
A1 |
Mehta; Apurva ; et
al. |
September 9, 2010 |
ROUTING FRAMES IN A TRILL NETWORK USING SERVICE VLAN
IDENTIFIERS
Abstract
Methods, apparatus, and products are disclosed for routing
frames in a TRILL network using service VLAN identifiers by:
receiving a frame from an ingress bridge node for transmission
through the TRILL network to a destination node that connects to
the TRILL network through an egress node, the received frame
including a customer VLAN identifier, a service VLAN identifier
uniquely assigned to the ingress bridge node, and a destination
node address for the destination node, the received frame not
having mac-in-mac encapsulation; adding, in dependence upon the
service VLAN identifier and the destination node address, a TRILL
header conforming to the TRILL protocol, the TRILL header including
an ingress bridge nickname and an egress bridge nickname; and
routing, to the egress bridge node through which the destination
node connects to the network, the frame in dependence upon the
ingress bridge nickname and the egress bridge nickname.
Inventors: |
Mehta; Apurva; (Cupertino,
CA) ; Ramanathan; Ramasamy; (Santa Clara, CA)
; Mehta; Kumar; (Cupertino, CA) ; Rustagi;
Sunesh; (Cupertino, CA) ; Doshi; Sanjiv; (San
Jose, CA) ; Shenoy; Shiva; (Los Altos, CA) |
Correspondence
Address: |
AKIN GUMP STRAUSS HAUER & FELD, LLP
P.O. BOX 130688
DALLAS
TX
75313-0688
US
|
Assignee: |
JUNIPER NETWORKS, INC.
Sunnyvale
CA
|
Family ID: |
41226223 |
Appl. No.: |
12/397811 |
Filed: |
March 4, 2009 |
Current U.S.
Class: |
370/401 |
Current CPC
Class: |
H04L 45/72 20130101;
H04L 45/66 20130101; H04L 12/465 20130101; H04L 45/00 20130101 |
Class at
Publication: |
370/401 |
International
Class: |
H04L 12/56 20060101
H04L012/56 |
Claims
1. A method of routing frames in a Transparent Interconnection of
Lots of Links (`TRILL`) network using service virtual local area
network (`VLAN`) identifiers, the TRILL network including a
plurality of bridge nodes, at least one of the plurality of bridge
nodes operating as an ingress bridge node through which the frames
are received into the TRILL network, and at least one of the
plurality of bridge nodes operating as an egress bridge node
through which the frames are transmitted out of the TRILL network,
at least one ingress bridge node and at least one egress bridge
node assigned a unique service VLAN identifier, the method
comprising the steps of: receiving, by one of the plurality of
bridge nodes from the ingress bridge node, a frame for transmission
to a destination node, the destination node connected to the TRILL
network through the egress bridge node, the received frame
including a customer VLAN identifier, a service VLAN identifier for
the ingress bridge node, and a destination node address for the
destination node, the received frame not having mac-in-mac
encapsulation; adding, by the one bridge node to the received frame
in dependence upon the service VLAN identifier for the ingress
bridge node and the destination node address for the destination
node, a TRILL header conforming to the TRILL protocol, the TRILL
header including an ingress bridge nickname and an egress bridge
nickname; and routing, by the one bridge node to the egress bridge
node through which the destination node connects to the network,
the received frame in dependence upon the ingress bridge nickname
and the egress bridge nickname.
2. The method of claim 1 wherein the received frame further
comprises a vender header specified by a vender of the ingress
bridge node, the vender header including the service VLAN
identifier.
3. The method of claim 1 wherein the step of routing the received
frame further comprises the steps of: encapsulating the received
frame with an Ethernet header in dependence upon the ingress bridge
nickname and the egress bridge nickname, the Ethernet header
including a media access control (`MAC`) address for a next bridge
in the TRILL network that is on a path from the one bridge node to
the egress bridge node; and routing the received frame to the next
bridge node in dependence upon the MAC address.
4. The method of claim 1 further comprising the step of adding, by
the ingress bridge node, the service VLAN identifier for the
ingress bridge node to the received frame.
5. The method of claim 1 wherein hardware of the ingress bridge
node and hardware of the egress bridge node are incapable of
mac-in-mac encapsulation.
6. The method of claim 1 wherein the service VLAN identifier
conforms to the Institute of Electrical and Electronics Engineers
(`IEEE`) 802.1ad standard.
7. A method of routing frames in a Transparent Interconnection of
Lots of Links (`TRILL`) network using service virtual local area
network (`VLAN`) identifiers, the TRILL network including a
plurality of bridge nodes, at least one of the plurality of bridge
nodes operating as an ingress bridge node through which the frames
are received into the TRILL network, and at least one of the
plurality of bridge nodes operating as an egress bridge node
through which the frames are transmitted out of the TRILL network,
at least one ingress bridge node and at least one egress bridge
node assigned a unique service VLAN identifier, the method
comprising the steps of: receiving, by one of the plurality of
bridge nodes connected to the egress bridge node by a single hop, a
frame for transmission to a destination node, the destination node
connected to the network through the egress bridge node, the
received frame originating from a source node connected to the
network through the ingress bridge node, the received frame
including a destination node address for the destination node and a
TRILL header, the TRILL header including an ingress bridge nickname
for the ingress bridge node and an egress bridge nickname for the
egress bridge node; determining, by the one bridge node, that the
received frame traverses the egress bridge node on the next hop
toward the destination node; replacing, by the one bridge node in
response to the determination, the TRILL header with the service
VLAN identifier for the ingress bridge node; and routing, by the
one bridge node, the received frame to the egress bridge node.
8. The method of claim 7 wherein the step of replacing the TRILL
header further comprises the step of replacing the TRILL header
with a vender header specified by a vender of the egress bridge
node, the vender header including the service VLAN identifier.
9. The method of claim 7 wherein hardware of the ingress bridge
node and hardware of the egress bridge node are incapable of
mac-in-mac encapsulation.
10. The method of claim 7 wherein the service VLAN identifier
conforms to the Institute of Electrical and Electronics Engineers
(`IEEE`) 802.1ad standard.
11. A method of routing frames in a Transparent Interconnection of
Lots of Links (`TRILL`) network using service virtual local area
network (`VLAN`) identifiers, the TRILL network including a
plurality of bridge nodes, at least one of the plurality of bridge
nodes operating as an ingress bridge node through which the frames
are received into the TRILL network, and at least one of the
plurality of bridge nodes operating as an egress bridge node
through which the frames are transmitted out of the TRILL network,
at least one ingress bridge node and at least one egress bridge
node assigned a unique service VLAN identifier, the method
comprising the steps of: receiving, by one of the plurality of
bridge nodes from the ingress bridge node, a frame for transmission
to a destination node, the destination node connected to the TRILL
network through the egress bridge node, the received frame
including a customer VLAN identifier, a service VLAN identifier for
the egress bridge node, and a destination node address for the
destination node, the received frame not having mac-in-mac
encapsulation; adding, by the one bridge node to the received frame
in dependence upon the service VLAN identifier for the egress
bridge node and a port on which the one bridge node received the
received frame, a TRILL header conforming to the TRILL protocol,
the TRILL header including an ingress bridge nickname and an egress
bridge nickname, the port associated with the ingress bridge
nickname, the service VLAN identifier for the egress bridge node
associated with the egress bridge nickname; and routing, by the one
bridge node to the egress bridge node through which the destination
node connects to the network, the received frame in dependence upon
the TRILL header.
12. An apparatus for routing frames in a Transparent
Interconnection of Lots of Links (`TRILL`) network using service
virtual local area network (`VLAN`) identifiers, the TRILL network
including a plurality of bridge nodes, the apparatus operating as
one of the plurality of bridge nodes, at least one of the plurality
of bridge nodes operating as an ingress bridge node through which
the frames are received into the TRILL network, and at least one of
the plurality of bridge nodes operating as an egress bridge node
through which the frames are transmitted out of the TRILL network,
at least one ingress bridge node and at least one egress bridge
node assigned a unique service VLAN identifier, the apparatus
comprising: a computer memory storing a computer program, the
computer program comprising instructions when executed cause the
apparatus to: receive, from the ingress bridge node, a frame for
transmission to a destination node, the destination node connected
to the TRILL network through the egress bridge node, the received
frame including a customer VLAN identifier, a service VLAN
identifier for the ingress bridge node, and a destination node
address for the destination node, the received frame not having
mac-in-mac encapsulation, add, to the received frame in dependence
upon the service VLAN identifier for the ingress bridge node and
the destination node address for the destination node, a TRILL
header conforming to the TRILL protocol, the TRILL header including
an ingress bridge nickname and an egress bridge nickname, and
route, to the egress bridge node through which the destination node
connects to the network, the received frame in dependence upon the
ingress bridge nickname and the egress bridge nickname; and a
processor that is operatively coupled to the computer memory and
executes the instructions.
13. The apparatus of claim 12 wherein the received frame further
comprises a vender header specified by a vender of the ingress
bridge node, the vender header including the service VLAN
identifier.
14. The apparatus of claim 12 wherein the instructions that when
executed cause the apparatus to route the received frame further
comprise additional instructions that when executed cause the
apparatus to: encapsulate the received frame with an Ethernet
header in dependence upon the ingress bridge nickname and the
egress bridge nickname, the Ethernet header including a media
access control (`MAC`) address for a next bridge in the TRILL
network that is on a path from the one bridge node to the egress
bridge node; and route the received frame to the next bridge node
in dependence upon the MAC address.
15. The apparatus of claim 12 wherein the ingress bridge node adds
the service VLAN identifier for the ingress bridge node to the
received frame.
16. The apparatus of claim 12 wherein hardware of the ingress
bridge node and hardware of the egress bridge node are incapable of
mac-in-mac encapsulation.
17. The apparatus of claim 12 wherein the service VLAN identifier
conforms to the Institute of Electrical and Electronics Engineers
(`IEEE`) 802.1ad standard.
18. An apparatus for routing frames in a Transparent
Interconnection of Lots of Links (`TRILL`) network using service
virtual local area network (`VLAN`) identifiers, the TRILL network
including a plurality of bridge nodes, at least one of the
plurality of bridge nodes operating as an ingress bridge node
through which the frames are received into the TRILL network, and
at least one of the plurality of bridge nodes operating as an
egress bridge node through which the frames are transmitted out of
the TRILL network, at least one ingress bridge node and at least
one egress bridge node assigned a unique service VLAN identifier,
the apparatus operating as one of the plurality of bridge nodes
connected to the egress bridge node by a single network hop, the
apparatus comprising: a computer memory storing a computer program,
the computer program comprising instructions that when executed
cause the apparatus to: receive a frame for transmission to a
destination node, the destination node connected to the network
through the egress bridge node, the received frame originating from
a source node connected to the network through the ingress bridge
node, the received frame including a destination node address for
the destination node and a TRILL header, the TRILL header including
an ingress bridge nickname for the ingress bridge node and an
egress bridge nickname for the egress bridge node, determine that
the received frame traverses the egress bridge node on the next hop
toward the destination node, replace, in response to the
determination, the TRILL header with the service VLAN identifier
for the ingress bridge node, and route the received frame to the
egress bridge node; and a processor that is operatively coupled to
the computer memory and executes the instructions.
19. The apparatus of claim 18 wherein the instructions that when
executed cause the apparatus to replace the TRILL header further
comprise additional instructions that replace the TRILL header with
a vender header specified by a vender of the egress bridge node,
the vender header including the service VLAN identifier.
20. The apparatus of claim 18 wherein hardware of the ingress
bridge node and hardware of the egress bridge node are incapable of
mac-in-mac encapsulation.
21. The apparatus of claim 18 wherein the service VLAN identifier
conforms to the Institute of Electrical and Electronics Engineers
(`IEEE`) 802.1ad standard.
22. A computer-readable medium for routing frames in a Transparent
Interconnection of Lots of Links (`TRILL`) network using service
virtual local area network (`VLAN`) identifiers, the TRILL network
including a plurality of bridge nodes, at least one of the
plurality of bridge nodes operating as an ingress bridge node
through which the frames are received into the TRILL network, and
at least one of the plurality of bridge nodes operating as an
egress bridge node through which the frames are transmitted out of
the TRILL network, at least one ingress bridge node and at least
one egress bridge node assigned a unique service VLAN identifier,
the computer-readable medium encoded with instructions that are
executed by a processor in a data processing system to perform the
steps of: receiving, by one of the plurality of bridge nodes from
the ingress bridge node, a frame for transmission to a destination
node, the destination node connected to the TRILL network through
the egress bridge node, the received frame including a customer
VLAN identifier, a service VLAN identifier for the ingress bridge
node, and a destination node address for the destination node, the
received frame not having mac-in-mac encapsulation; adding, by the
one bridge node to the received frame in dependence upon the
service VLAN identifier for the ingress bridge node and the
destination node address for the destination node, a TRILL header
conforming to the TRILL protocol, the TRILL header including an
ingress bridge nickname and an egress bridge nickname; and routing,
by the one bridge node to the egress bridge node through which the
destination node connects to the network, the received frame in
dependence upon the ingress bridge nickname and the egress bridge
nickname.
23. The computer-readable medium of claim 22 wherein the received
frame further comprises a vender header specified by a vender of
the ingress bridge node, the vender header including the service
VLAN identifier.
24. The computer-readable medium of claim 22 wherein the step of
routing the received frame further comprises the steps of:
encapsulating the received frame with an Ethernet header in
dependence upon the ingress bridge nickname and the egress bridge
nickname, the Ethernet header including a media access control
(`MAC`) address for a next bridge in the TRILL network that is on a
path from the one bridge node to the egress bridge node; and
routing the received frame to the next bridge node in dependence
upon the MAC address.
25. The computer-readable medium of claim 22 wherein the method
further comprises the step of adding, by the ingress bridge node,
the service VLAN identifier for the ingress bridge node to the
received frame.
26. The computer-readable medium of claim 22 wherein hardware of
the ingress bridge node and hardware of the egress bridge node are
incapable of mac-in-mac encapsulation.
27. The computer-readable medium of claim 22 wherein the service
VLAN identifier conforms to the Institute of Electrical and
Electronics Engineers (`IEEE`) 802.1ad standard.
28. A computer-readable medium for routing frames in a Transparent
Interconnection of Lots of Links (`TRILL`) network using service
virtual local area network (`VLAN`) identifiers, the TRILL network
including a plurality of bridge nodes, at least one of the
plurality of bridge nodes operating as an ingress bridge node
through which the frames are received into the TRILL network, and
at least one of the plurality of bridge nodes operating as an
egress bridge node through which the frames are transmitted out of
the TRILL network, at least one ingress bridge node and at least
one egress bridge node assigned a unique service VLAN identifier,
the computer-readable medium encoded with instructions that are
executed by a processor in a data processing system to perform the
steps of: receiving, by one of the plurality of bridge nodes
connected to the egress bridge node by a single hop, a frame for
transmission to a destination node, the destination node connected
to the network through the egress bridge node, the received frame
originating from a source node connected to the network through the
ingress bridge node, the received frame including a destination
node address for the destination node and a TRILL header, the TRILL
header including an ingress bridge nickname for the ingress bridge
node and an egress bridge nickname for the egress bridge node;
determining, by the one bridge node, that the received frame
traverses the egress bridge node on the next hop toward the
destination node; replacing, by the one bridge node in response to
the determination, the TRILL header with the service VLAN
identifier for the ingress bridge node; and routing, by the one
bridge node, the received frame to the egress bridge node.
29. The computer-readable medium of claim 28 wherein the step of
replacing the TRILL header further comprises the step of replacing
the TRILL header with a vender header specified by a vender of the
egress bridge node, the vender header including the service VLAN
identifier.
30. The computer-readable medium of claim 28 wherein hardware of
the ingress bridge node and hardware of the egress bridge node are
not capable of mac-in-mac encapsulation.
31. The computer-readable medium of claim 28 wherein the service
VLAN identifier conforms to the Institute of Electrical and
Electronics Engineers (`IEEE`) 802.1ad standard.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is related to U.S. patent application Ser.
No. 12/344,644 filed Dec. 29, 2008, which Applicants hereby
incorporate by reference in its entirety.
TECHNICAL FIELD
[0002] The present invention relates to the field of computer
networking, and in particular to a technique for routing frames in
a Transparent Interconnection of Lots of Links (TRILL) network
using service virtual local area network (VLAN) identifiers.
BACKGROUND OF THE INVENTION
[0003] Early computer networks consisted of a small number of
devices attached together using a single cable. Computer networks
have since evolved, however, beyond a simple collection of attached
devices. Current computer networks may connect thousands of devices
spread across large local areas, and these local area networks may
in turn be connected together to form still larger networks such
as, for example, the Internet.
[0004] Today's computer networks often interconnect
widely-disparate devices distributed throughout multiple local
networks into a single virtual network. Virtual networking
technology allows devices located on a single physical network to
operate as part of multiple virtual networks. Such virtual networks
provide flexibility not available in early computer networks and
allow network administrators to create layers of abstraction to
simply complex network topologies. For example, using a virtual
network, an enterprise may have a virtual blade server chassis with
routers spread across multiple physical locations that effectively
acts as a single router, allowing a data center split across
multiple sites to act as if the data center is a single site.
[0005] The predominate standard used to construct and access
today's computer networks is Ethernet. Ethernet is a family of
frame-based computer networking technologies for local area
networks. Ethernet is promulgated by Institute of Electrical and
Electronics Engineers (IEEE) in various standards specifications as
part of the IEEE 802 family of standards. Ethernet defines a number
of wiring and signaling standards for the Physical Layer of the
Open Systems Interconnection (OSI) Networking Model, the means for
network access at the Media Access Control (MAC) and Data Link
Layer, and a common addressing format. At the physical layer,
Ethernet networks are ubiquitous, carrying all kinds of traffic
over multiple types of physical connections (wired or wireless),
including 10 Mbps, 100 Mbps, 1 Gbps, 10 Gbps, 100 Gbps connections.
The Ethernet service layer, generally referred to as Layer-2
because it is the MAC and Data Link Layer in the OSI networking
model, provides the services generally required by a network. These
network services typically include filtering, replication,
forwarding broadcast, unicast, and multicast (BUM) traffic, and
following a serviced topology, which may include virtual local area
networks (VLANs), ATM segments of VLANs based on the ATM Lane
Standard (ELANs), Ethernet Private Lines (ELINEs), and rooted
multipoint Ethernet virtual connections (ETREEs).
[0006] VLAN services are specified in the IEEE 802.1Q standard and
allow enterprise customers to configure various computing devices
to communicate as if those devices were attached to the same
broadcast domain, regardless of their physical locations. VLANs
provide segmentation services traditionally provided by routers in
local area network (LAN) configurations and address issues such as
scalability, security, and network management. Bridges in VLAN
topologies enforce the integrity of VLAN broadcast domains because
such bridges are not permitted to bridge network traffic between
VLANs. In this way, VLANs may provide broadcast filtering,
security, address summarization, and traffic flow management.
Network administrators may use VLANs to create multiple Layer 3
networks on the same Layer-2 bridge. For example if a Dynamic Host
Configuration Protocol (DHCP) server, which broadcasts its
presence, were plugged into a bridge, the DHCP server would serve
any host device connected to the bridge. By using VLANs, however, a
network administrator may easily split up the devices on the
network so that some hosts will not use that DHCP server and will
default to link-local addresses.
[0007] Because enterprise customers often have multiple networks
distributed across multiple physical sites, customer's typically
connected these physically separate networks together through the
network of a network provider. For example, a company may connect
its network at site A to its network at site B through a network
provided by a telecommunications company. Despite the customer
networks being connected through a provider network, devices on the
different customer networks may still use VLAN services to
communicate through the provider's network as though the devices
were all located on the same LAN.
[0008] For the same reasons that enterprise customers take
advantage of the VLAN services described in the IEEE 802.1Q
specification, network providers also take advantage of VLAN
services to provide flexibility, security, traffic flow management,
and reduce their network administration burden. The drawback,
however, is that under the IEEE 802.1Q specification, there are
only 4096 identifiers available to specify different VLANs. Thus, a
network provider and all the customers that provider serves must
share the 4096 VLAN identifiers.
[0009] Because industry participants deemed such a limited number
of VLAN identifiers inadequate to meet the needs of both customers
and providers, the IEEE 802.1Q standard was amended by the IEEE
802.ad standard, often referred to as "Q-in-Q" or "stacked VLANs."
The IEEE 802.ad standard sets forth an architecture and bridge
protocol to provide separate instances of MAC network services to
multiple independent users of a provider network in a manner that
does not require cooperation among the customers, and requires a
minimum of cooperation between the customers and the provider of
the MAC network service. Q-in-Q provides customers with the ability
to configure their own VLANs inside the VLAN provided to the
customer by a service provider. In such a manner, the service
provider may configure one service VLAN for the customer, and the
customer can utilize that service VLAN to establish multiple
customer VLANs.
[0010] In a manner similar to enterprise customers, network service
providers often maintain multiple provider network domains, which
are bridged together using a provider backbone bridging network.
IEEE promulgates specifications for such a provider backbone
bridging network in the IEEE 802.1ah standard. IEEE 802.1ah
compliant networks provide complete separation of customer and
service provider domains by encapsulating Ethernet frames with a
service provider MAC header. Because the Ethernet frames are
originally encapsulated in the customer network with a customer MAC
header, this subsequent encapsulation with a service provider MAC
header is often referred to as `MAC-in-MAC encapsulation.` Using
MAC-in-MAC encapsulation, Ethernet frames being sent in a
customer's network from one domain to another through multiple
service provider network domains contain two MAC headers. The
customer MAC header provides routing information to the bridges in
the customer's networks, while the service provider MAC header
provides routing information to the bridges in the service
provider's backbone bridging network.
[0011] To provide an overview of Ethernet header stacking of
encapsulation, FIG. 1 sets forth a line drawing that illustrates
exemplary Ethernet frame structures compliant with the IEEE 802.1
family of standards. FIG. 1 illustrates a traditional Ethernet
frame 100 implemented in a customer's network according to the IEEE
802.1D standard. The customer frame 100 consists of a payload 101,
a header type (EthType) 102 indicating that frame 100 is an 802.1D
frame, a customer network source MAC address (C-SA) 103, and a
customer network destination MAC address (C-DA) 104. The customer
network source MAC address 103 specifies the source node in the
customer network that originates the frame 100, while the customer
network destination MAC address 104 specifies the destination node
in the customer network to which the frame is bound for
delivery.
[0012] As mentioned above, a customer may organize the nodes into
varies VLANs to provide traffic flow management, security, ease
network administration, and the like. VLANs established by a
customer for use within the customer's networks are generally
referred to a `customer VLANs.` In a network using customer VLANs,
frame 100 is encapsulated as frame 110 to include a customer VLAN
identifier (C-VID) 115 and a new header type (EthType) 116,
indicating that the frame 110 is an 802.1Q frame. As used in this
application, encapsulation may allow additional fields to be placed
in any position relative to the encapsulated object, including
interior to the original object, and does not require the
additional fields be placed surrounding or at either end of the
encapsulated object.
[0013] In a provider bridge (PB) network that bridges two customer
networks, the frame 110 is further encapsulated as shown by frame
120, adding new fields for: a service VLAN identifier (S-VID) 127,
and a new header type (EthType) 128 indicating the frame 120 is
IEEE 802.1ad compliant. In a provider backbone bridging (PBB)
network that bridges multiple PB networks, the frame 120 is further
encapsulated to add additional fields for: a service identifier
(I-SID) 131, a new header type (EthType) 132 corresponding to the
service identifier 131, a backbone VLAN identifier 133, an
additional header type (EthType) 134 indicating that the frame 130
is IEEE 802.1ah compliant, a backbone source MAC address (B-SA) 135
specifying the bridge through which the frame ingresses into the
PBB network, and a backbone destination MAC address (B-DA) 136
specifying the bridge through which the frame egresses the PBB
network.
[0014] For further explanation of header stacking or encapsulation
in a IEEE 802.1ad provider bridge network, FIGS. 2 and 3 set forth
network diagrams that illustrate an exemplary provider bridge
network 200 interconnecting exemplary networks for customers A and
B (201 and 202, respectively). In FIGS. 2 and 3, customer A 201
maintains three networks 203, 205, 207, while customer B 202
maintains two networks 204, 206. The provider bridge network 200
consists of six bridges, four provider edge bridges (PEB) 1-4 and
two provider core bridges (PCB) 1-2. An edge bridge is a bridge
through which frames ingress and egress the network 200--that is,
an edge bridge is positioned at the `edge` of the network topology.
A core bridge is a bridge used to interconnect one or more edge
bridges.
[0015] FIG. 2 illustrates a frame 220 at several stages as the
frame 220 traverses the networks of FIG. 2 from customer equipment
(CE)-11 210 in network 203 of customer A 201 to CE-31 212 in
network 205 of customer A 201. In FIG. 2, the communications
between CE-11 210 and CE-31 212 are implemented using a customer
VLAN, and so the frame 220a from CE-11 210 is encapsulated with a
customer VLAN header 230 that includes a customer VLAN identifier
(C-VID) and a header type (EthType) specifying that the frame 220a
is an IEEE 802.1Q compliant frame. The frame 220 includes a source
MAC address (CE-11-SA) for CE-11 210, which indicates that CE-11
210 originated the frame 220a, and a destination MAC address
(CE-31-DA) for CE-31 212, which indicates that the frame 220 is
destined for CE-31 212.
[0016] When provider edge bridge (PEB)-1 240 receives the frame
220a, PEB-1 240 encapsulates the frame 220a into an 802.1ad frame
220b by adding a service VLAN header 231 to the frame 220. The
service VLAN header 231 includes a service VLAN identifier
(S-VID-A) assigned by the provider to customer A 201 and a header
type (EthType) specifying that the frame is IEEE 802.1ad compliant.
Using the service VLAN identifier to identify devices in the
networks 203, 205, 207 of customer A 201, the provider bridges
learn information about the MAC addresses of the computing devices
in customer A's networks. From the learned MAC information, the
provider bridges route the frame 220 through the provider network
200 from the PEB-1 240 through which the frame 220 ingresses the
network 200 to the PEB-3 242 through which the frame 220 egresses
the network 200. PEB-3 242 then de-encapsulates the frame 220b by
removing to service VLAN header 231, leaving IEEE 802.1Q compliant
frame 220a for delivery to CE-31 212.
[0017] Similarly, in FIG. 3, computing device CE-15 310 in network
204 of customer B 202 sends an IEEE 802.1Q compliant frame 320a to
device CE-25 312 customer B's network 206. At PEB-1 240, frame 320a
is encapsulated with a service VLAN header 331. The service VLAN
header 331 includes a service VLAN identifier (S-VID-B) assigned by
the service provider to customer B 202 and a header type (EthType)
specifying that the frame is IEEE 802.1ad compliant. The ingress
bridge 240 of the provider network 200 forwards the frame 320b to
the egress bridge 342 of the provider network 200, which in turn
de-encapsulates the frame 320b by removing the service VLAN header
331, leaving IEEE 802.1Q compliant frame 320a for delivery to CE-35
312. As the provider bridges receive various frames on their ports,
the bridges learn the MAC addresses of the devices in customer B
network by monitoring the MAC addresses associated with each
service VLAN identifier assigned to customer B 202 by the network
provider.
[0018] From the description above, one of ordinary skill in the art
will note that in a provider bridge network, the service provider
uses one or more SVLANs to transport frames for a customer's VLANs
between multiple customer networks. To determine the forwarding
path for each service VLAN through the provider's bridge network,
the provider bridges often use the Generic VLAN registration
protocol (GVRP) or the Multiple VLAN Registration Protocol (MVRP).
For multicast traffic containment, provider bridges may use the
Generic Attribute Registration Protocol Multicast Registration
Protocol (GMRP) or the Multiple Multicast Registration Protocol
(MMRP). For purposes of forwarding traffic, provider edge bridges
learn all customer equipment MAC addresses and forward customer
frames based on service VLAN identifier and customer VLAN
identifier pairs, while provider core bridges learn all customer
equipment MAC addresses, but forward customer frames based only on
the service VLAN identifiers. Within a particular provider bridge
network, a given customer equipment MAC address is at the same site
for all service VLANs.
[0019] Even with the stacked VLAN protocols, provider bridge
networks have scaling problems. Because only 4,096 service VLAN
identifiers are available under current protocols, provider bridge
networks are limited in the number of customer networks they can
serve effectively and efficiently. Further, because provider
bridges learn the MAC addresses for all customer devices, scaling
issues often arise when a provider serves one or more customers
with large virtual networks. In addition, there is a potential for
interaction between customer and service provider control
protocols.
[0020] Provider Backbone Bridge (PBB) Networks are one attempt to
alleviate these issues because PBB networks allow a service
provider to partition a large provider bridge network into several
smaller provider bridge networks that are interconnected by the PBB
network. For further explanation, FIG. 4 sets forth a network
diagram that illustrates an exemplary provider backbone bridge
network 400 interconnecting exemplary provider bridge networks 410,
420, 430. The PBB network 400 of FIG. 4 consists of four provider
backbone edge bridges (BEB)--that is, BEB-11 416, BEB-12 418,
BEB-21 434, and BEB-22 436--and two provider backbone core bridges
(BCB)--that is, BCB-1 401 and BCB-2 402.
[0021] FIG. 4 illustrates a frame 412 at several stages as the
frame 412 traverses the networks of FIG. 4 from customer equipment
(CE)-11 411 to CE-34 431. The customer utilizing the PB networks
410, 430 and the PBB network 400 has grouped CE-11 411 and CE-34
431 in the same customer VLAN. Thus, frame 412a from CE-11 411
includes a customer VLAN header 415. The customer VLAN header 415
includes the customer VLAN identifier (C-VID) assigned by the
customer for the customer VLAN and a header type (EthType) that
specifies that the frame 412a is IEEE 802.1Q compliant.
[0022] When the frame 412a reaches the provider edge bridge
(PEB)-11 413, PEB-11 413 encapsulates the frame with a service VLAN
header 417. The service VLAN header 417 includes the service VLAN
identifier (S-VID) assigned to the customer by the network provider
and a header type (EthType) that specifies that the frame 412a is
IEEE 802.1ad compliant.
[0023] When the frame 412b reaches the provider backbone edge
bridge (BEB)-11 416, BEB-11 416 encapsulates the frame with a
backbone header 419. The backbone header 419 includes a service
identifier (I-SID), a new header type (EthType) corresponding to
the service identifier, a backbone VLAN identifier, an additional
header type (EthType) indicating that the frame 412c is IEEE
802.1ah compliant, a backbone source MAC address (BEB-11-SA)
specifying the backbone edge bridge through which the frame
ingresses into the PBB network 400, and a backbone destination MAC
address (BEB-22-DA) specifying the backbone edge bridge 436 through
which the frame egresses the PBB network 400.
[0024] The frame 412c is routed through the provider backbone
bridge network 400 from the ingress bridge, BEB-11 416, to the
egress bridge, BEB-22 436. BEB-22 436 de-encapsulates the frame
412c by removing the backbone header 419, leaving the frame 412
IEEE 802.1ad compliant. BEB-22 436 then sends the frame 412 along
to PEB-31 433 in the IEEE 802.1ad compliant provider bridge network
430. PEB-31 433 further de-encapsulates the frame 412 by removing
the service VLAN header 417, leaving the frame 412 IEEE 802.1Q
compliant. PEB-31 433 then forwards the frame 412 along to CE-34
431 for delivery.
[0025] In a provider backbone bridge network, there is clear
demarcation between customer and service provider domains. MAC
address learning for customer equipment is limited to the provider
edge bridge, and the I-SID field allows separation of Ethernet as a
service from Ethernet as infrastructure.
[0026] As mentioned above, the networking architectures described
by the IEEE 802.1Q, 802.1ad, and 802.1ah standards allow enterprise
customers to establish multiple networks that are geographically
dispersed, yet operate as a single virtual network. These
physically separate LANs communicate through PB and PBB networks
using forwarding trees established using a spanning tree protocol.
The spanning tree protocol is an OSI Layer-2 protocol that ensures
a loop-free topology for any bridged LAN. This protocol allows a
network design to include spare (redundant) links to provide
automatic backup paths if an active link fails, without the danger
of bridge loops, or the need for manual enabling or disabling of
these backup links. Bridge loops must be avoided because such loops
result in traffic that floods the network. The spanning tree
protocol is defined in the IEEE 802.1D standard, and, as the name
suggests, it creates a spanning tree within a mesh network of
connected Layer-2 bridges, and disables those links that are not
part of the tree, leaving a single active path between any two
network nodes.
[0027] There are certain disadvantages to the spanning tree
protocol used in the networks described above with reference to
FIGS. 1-4. Because the spanning tree protocol disables links that
are not part of the forwarding tree, bottlenecks are often created
by concentrating traffic onto selected links. Also, due to the
nature of the spanning tree protocol temporary loops may develop if
spanning tree messages are lost or as the network topology changes
because nodes are brought on-line or taken off-line or moved in the
network. During periods when temporary loops exists, frames may
flood the network because the standard Ethernet header does not
contain a time-to-live field or hop count that specifies when a
frame has become stale and should be discarded. Further, the paths
developed between nodes of the network are not necessarily the
pair-wise shortest path, but rather are the paths that remain after
the spanning tree protocol eliminates redundant paths.
[0028] In an attempt to create a network solution without the
disadvantages of the spanning tree protocol, the Internet
Engineering Task Force (IETF) has sought developed additional
protocols. One such protocol is the "Transparent Interconnection of
Lots of Links" (TRILL) protocol. The TRILL protocol and other
similar specifications require the use of router-bridges
(R-Bridges) to routes frames hop-by-hop through the network along
the shortest path to the frames destination in the network, e.g.,
the network's edge bridge. For further explanation, FIG. 5 sets
forth a network diagram that illustrates an exemplary TRILL network
500, also known as a router-bridge network, because the devices
behave as both a router and a bridge at the ISO Layer-2 level. The
TRILL network 500 includes three core router-bridges (CRB)--that
is, CRB-4 540, CRB-5 542, and CRB-6 544--as well as five edge
router-bridges (ERB)--that is, ERB-1 530, ERB-2 532, ERB-8 534,
ERB-9 536, and ERB-7 538. The TRILL network 500 is provided to
customers by a network provider. The edges of the TRILL network 500
typically extend into the datacenter where the customer equipment
is housed. In fact, often each equipment rack includes a bridge
that operates as an edge of the TRILL network 500. These TRILL
networks can extend throughout one or more datacenters to
interconnect various networks.
[0029] The TRILL network 500 of FIG. 5 interconnects two IEEE
802.1Q networks 510, 520. 802.1Q network 510 is connected to the
TRILL network 500 through ERB-1 530 and ERB-2 532. 802.1Q network
520 is connected to the TRILL network 500 through ERB-8 534 and
ERB-536. 802.1Q network 510 includes a legacy bridge (LB)-55 514
and a enterprise bridge (EB)-16 516, neither of which are TRILL
compliant. 802.1Q network 520 includes EB-85 524 and EB-96 526. End
point devices include customer equipment (CE)-11 512 connected to
LB-55 514, CE-31 522 connected to EB-85 524, and CE-77 539
connected to ERB-7 538. End point devices CE-11 512, CE-31 522, and
CE-77 539 can be any type of computing device, including
workstations, servers, network devices, and so on.
[0030] FIG. 5 illustrates a frame 518 at several stages as the
frame 518 traverses the networks of FIG. 5 from CE-11 512 to CE-31
522. The customer utilizing the TRILL network 500 to bridge
multiple 802.1Q networks has grouped CE-11 512 and CE-31 522 in the
same customer VLAN. Thus, frame 518a sent by LB-55 514 for CE-11
512 includes a customer VLAN header 519. The customer VLAN header
519 includes the customer VLAN identifier (C-VID) assigned by the
customer for the customer VLAN and a header type (EthType) that
specifies that the frame 518a is IEEE 802.1Q compliant.
[0031] When the frame 518a reaches the ERB-1 530, ERB-1 530
encapsulates the frame 518 with a TRILL header 551. The TRILL
header 551 includes a TRILL source nickname (ERB-1-SN) specifying
ERB-1 as the ingress edge router-bridge for the frame 518, a TRILL
destination nickname (ERB-8-DN) specifying ERB-8 534 as the egress
edge router-bridge for the frame 518, various TRILL flags, a hop
count, and a header type (EthType) indicating that frame 518b is a
TRILL frame. TRILL nicknames are assigned to every router-bridge in
a TRILL network using a dynamic nickname acquisition protocol or
other protocols as will occur to those of skill in the art.
[0032] To provide the hop-by-hop routing in accordance with the
TRILL protocol, ERB-1 530 uses MAC-in-MAC encapsulation to add an
Ethernet MAC header 552 to frame 518. The MAC header 552 includes a
outer transport VLAN identifier (OT-VLAN-ID), a header type
(EthType), a source MAC address (ERB-1-SA) specifying ERB-1 530 as
the node transmitting the frame 518b on the next network hop
through the network 500, and a destination MAC address (CRB-5-DA)
specifying CRB-5 542 as the node receiving the frame 518b on the
next network hop through the network 500. ERB-1 530 then sends the
frame 518 to CRB-5 542, which routes the frame through the TRILL
network 500 to CRB-4 540 based on a shortest path to ERB-8 534. As
the frame traverses the TRILL network 500, the MAC header 552 is
changed at each hop to update the source and destination MAC
addresses for the next network hop. Accordingly, when the frame
518c passes from CRB-4 540 to ERB-8 534, the frame 518 includes MAC
header 562. The MAC header 562 of FIG. 5 includes a source MAC
address (CRB-4-SA) specifying CRB-4 540 as the node transmitting
the frame 518c on the next network hop through the network 500 and
a destination MAC address (ERB-8-DA) specifying ERB-8 534 as the
node receiving the frame 518c on the next network hop through the
network 500. Upon receiving the frame 518c, ERB-8 534
de-encapsulates the frame 518 by removing the MAC header 562 and
the TRILL header 551, leaving frame 518a for delivery to CE-31 522
through EB-85 524.
[0033] The TRILL network 500 of FIG. 5 operates as a massive switch
fabric from the perspective of the customer network. Frames enter
the TRILL network at an ingress bridge and are routed along the
shortest path hop-by-hop through the TRILL network to an egress
bridge for delivery to a customer network. As the bridges in the
TRILL network learn the MAC address of the customer equipment in
the customer networks to which the TRILL bridges connect, the TRILL
bridges share information among one another about which customer
MAC addresses related to which TRILL bridge nickname. ISO Layer-2
frames with known unicast addresses are routed hop-by-hop based on
TRILL nicknames of the ingress and egress edge router-bridges by
the transit or core router-bridges. ISO Layer-2 multicast traffic
can also be routed hop-by-hop based on multicast distribution
trees.
[0034] In addition to TRILL, there are other provider bridging
protocols such as Shortest Path Provider Backbone Bridging (SPPBB)
described in IEEE 802.1aq that represent attempts by industry
participants to utilize the shortest path through the network to
forward frames between edge bridges. One feature common to all of
these solutions however, whether TRILL, SPPBB, or any other, is the
use of MAC-in-MAC encapsulation. Unfortunately, current generation
hardware for typical rack-mounted bridges, that form the edge of
these networks, do not support MAC-in-MAC encapsulation, thereby
limiting the use of TRILL, SPPBB, and similar solutions that
provide shortest path routing at Layer-2 level.
BRIEF SUMMARY OF THE INVENTION
[0035] Methods, apparatus, and products are disclosed for routing
frames in a TRILL network using service VLAN identifiers. Routing
frames in a TRILL network using service VLAN identifiers according
to embodiments of the present invention advantageously does not
require edge bridges that support MAC-in-MAC encapsulation to
overcome the 4096 VLAN identifier limitation across multiple,
interconnected IEEE 802.1 Q networks. Rather, such edge bridges
need only be updated with software improved for routing frames
using bridge identifiers according to embodiments of the present
invention. In this manner, existing rack-mounted bridges may be
utilized as edge bridges in networks that require MAC-in-MAC
encapsulation to provide shortest path forwarding services such as,
for example, TRILL networks or SPB networks.
[0036] In accordance with embodiments of the present invention, the
TRILL network in which frames are routed using service VLAN
identifiers includes a plurality of bridge nodes. At least one of
the bridge nodes operates as an ingress bridge node through which
frames are received into the network. At least one of the bridge
nodes operates as an egress bridge node through which frames are
transmitted out of the network. A bridge node in the network
receives a frame from the ingress bridge node for transmission to a
destination node. The destination node is connected to the TRILL
network through the egress bridge node, and the source node
originating the frame is connected to the TRILL network through the
ingress bridge node. The received frame includes a customer VLAN
identifier, a service VLAN identifier for the ingress bridge node,
and a destination node address for the destination node. As
received, the frame does not utilize MAC-in-MAC encapsulation at
this point. Rather, the bridge node uses the service VLAN
identifier for the ingress bridge node and the destination node
address for the destination node to add a TRILL header to the frame
that conforms with the TRILL protocol. The TRILL header includes an
ingress bridge nickname and an egress bridge nickname. The bridge
node then routes the frame to the egress bridge node through which
the destination node connects to the network in dependence upon the
ingress bridge nickname and the egress bridge nickname.
[0037] In accordance with embodiments of the present invention, the
frame eventually traverses through the TRILL network to reach a
bridge node connected to the egress bridge node by a single hop.
The bridge node connected to the egress bridge node by a single hop
receives the frame for transmission to a destination node. The
frame includes a destination node address for the destination node
and a TRILL header, which in turn includes an ingress bridge
nickname for the ingress bridge node and an egress bridge nickname
for the egress bridge node. The bridge node determines that the
frame traverses the egress bridge node on the next hop toward the
destination node. Based on this determination, the bridge node
replaces the TRILL header with the service VLAN identifier for the
ingress bridge node and routes the frame to the egress bridge node.
The egress bridge node may then route the frame to the destination
node.
[0038] The foregoing and other objects, features and advantages of
the invention will be apparent from the following more particular
descriptions of exemplary embodiments of the invention as
illustrated in the accompanying drawings wherein like reference
numbers generally represent like parts of exemplary embodiments of
the invention.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0039] The accompanying drawings, which are incorporated in and
constitute a part of this specification, illustrate implementations
consistent with the present invention and, together with the
detailed description, serve to explain advantages and principles
consistent with the invention.
[0040] FIG. 1 sets forth a line drawing that illustrates exemplary
Ethernet frame structures compliant with the IEEE 802.1 family of
standards.
[0041] FIG. 2 sets forth a network diagram that illustrates an
exemplary provider bridge network interconnecting exemplary
customer networks.
[0042] FIG. 3 sets forth a network diagram that illustrates an
exemplary provider bridge network interconnecting exemplary
customer networks.
[0043] FIG. 4 sets forth a network diagram that illustrates an
exemplary provider backbone bridge network interconnecting
exemplary provider bridge networks.
[0044] FIG. 5 sets forth a network diagram that illustrates an
exemplary TRILL network.
[0045] FIG. 6 sets forth a network diagram that illustrates a TRILL
network having bridges that support routing frames in a TRILL
network using service VLAN identifiers according to embodiments of
the present invention.
[0046] FIG. 7 sets forth a block diagram of automated computing
machinery comprising an exemplary bridge useful in routing frames
in a TRILL network using service VLAN identifiers according to
embodiments of the present invention.
[0047] FIG. 8 sets forth a diagram illustrating an exemplary method
of routing frames in a TRILL network using service VLAN identifiers
according to embodiments of the present invention.
[0048] FIG. 9 sets forth a diagram illustrating a further exemplary
method of routing frames in a TRILL network using service VLAN
identifiers according to embodiments of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0049] While certain exemplary embodiments are described in detail
and shown in the accompanying drawings, it is to be understood that
such embodiments are merely illustrative of and not devised without
departing from the basic scope thereof, which is determined by the
claims that follow.
[0050] Although the following disclosure is discussed using
terminology related to Ethernet links, various IEEE 802 standards
and TRILL, these are merely by way of example and illustration, and
the scope of the present invention is not so limited, but extends
to the fullest scope defined by the claims herein.
[0051] Typical edge bridges used in conjunction with rack-mounted
equipment do not support the MAC-in-MAC encapsulation required in
current shortest path backbone bridging network solutions, such as
for example TRILL network solutions. When various bridges in a
TRILL network, however, are modified for routing frames in a TRILL
network using service VLAN identifiers according to embodiments of
the present invention, edge bridges having hardware that does not
support MAC-in-MAC encapsulation can be used as part of a TRILL
network solution.
[0052] For further explanation, FIG. 6 sets forth a network diagram
that illustrates a TRILL network having bridges that support
routing frames in a TRILL network using service VLAN identifiers
according to embodiments of the present invention. The TRILL
network of FIG. 6 includes four core router-bridges (CRB)--that is,
CRB-4 602, CRB-5 604, CRB-6 606, and CRB-7 608--and four edge
router-bridges implemented as top-of-rack devices (T-ERB)--that is,
T-ERB-1 610, T-ERB-2 612, T-ERB-8 614, and T-ERB-9 616. In the
example of FIG. 6, the TRILL network 600 interconnects customer
equipment (CE)-11 620 and CE-31 630. CE-11 620 connects to the
TRILL network 600 through T-ERB-1 610, while CE-31 630 connects to
the TRILL network 600 through T-ERB-8 614. The network 600 of FIG.
6 is referred to as a `TRILL` network in the sense that at least
the core routing bridges have hardware that supports frame routing
in accordance with the TRILL protocol.
[0053] FIG. 6 illustrates frame 640 in various stages as the frame
640 traverses the networks of FIG. 6. In FIG. 6, the network
administrator managing CE-11 620 and CE-31 630 has grouped CE-11
620 and CE-31 630 into a customer VLAN for data communications.
Accordingly, frame 640 of FIG. 6 includes a customer VLAN header
642 that includes a customer VLAN identifier (C-VID) identifying
the particular customer VLAN to which the CE-11 620 and CE-31 630
are assigned. The VLAN header 642 also includes a header type
(EthType) specifying that the frame is an IEEE 802.1Q compliant
frame. The frame 640a also includes a source MAC address (CE-11-SA)
designating CE-11 620 as the originator of the frame 640a and a
destination MAC address (CE-31-DA) designating CE-31 630 as the
destination node to which the frame 640 is transmitted.
[0054] In the example of FIG. 6, T-ERB-1 610 receives the frame
640a from CE-11 620 through customer network 611. T-ERB-1 610,
along with other edge bridges in the TRILL network 600, utilizes
service VLAN identifiers to route the frame 640 through the network
600. This service VLAN identifier is similar to service VLAN
identifiers used in 802.1ad networks for identifying a service.
Within an 802.1ad network, a service VLAN identifier distinguishes
frames for customer networks of two or more customers that use the
same customer VLAN identifier. The service VLAN identifier often
conforms to the IEEE 802.1ad standard, but is not required to do
so.
[0055] In the example of FIG. 6, each edge bridge 610, 612, 614,
and 616 is assigned a unique service VLAN identifier with which
that edge bridge stores in each frame entering, or ingressing, into
the network 600 from another computer network. The service VLAN
identifiers may be assigned to each edge bridge by the service
provider supplying the TRILL network 600. Often, however, the
service VLAN identifier may be assigned to each edge bridge as part
of negotiations among the bridges in the network 600 using any
dynamic acquisition control protocol as will occur to those of
skill in the art--much in the same way each bridge in the TRILL
network 800 acquires its TRILL nickname. In fact, the value of the
service VLAN identifier assigned to each edge bridge may be the
same as the value of the TRILL nickname for that edge bridge as
discussed in more detail below.
[0056] T-ERB-1 610 of FIG. 6 has a service VLAN identifier of
"T-ERB-1-SVLAN." The T-ERB-1 610 of FIG. 6 adds a service VLAN
identifier (T-ERB-1-SVLAN) for the ingress bridge node to the frame
640b by adding a vender header 652 to the frame 640b that includes
the service VLAN identifier (T-ERB-1-SVLAN). The vender header 652
is a customized header having a format defined by the vender of
T-ERB-1 610. One of skill in the art will note, however, that many
different header format may be used, including header formats that
are not vender-specific.
[0057] In the example of FIG. 6, T-ERB-1 610 routes the frame 640b
to a next bridge in the TRILL network 600 that is on a path from
the ingress bridge node 610 to the egress bridge node 614 through
which the destination node 630 connects to the network 600--that
is, CRB-5 604. T-ERB-1 610 of FIG. 6 routes the frame 640b based on
the destination node address (CE-31-DA) for the destination node,
CE-31 630. T-ERB-1 610 of FIG. 6 uses the destination address to
identify the egress bridge 614 through which the destination node
connects to the network 600. T-ERB-1 610 learns the edge bridges
through which various nodes connect to the network 600 by recording
the ingress node identifier-origin node address pairs for the
frames that T-ERB-1 610 receives for processing when it operates as
an egress node. After identifying the egress bridge through which
the destination node connects to the network 600, then T-ERB-1 610
identifies the next node--CRB-5 604--along the shortest path to the
egress bridge node 614. T-ERB-1 610 then transmits the frame 640b
to CRB-5 604 through the port connecting T-ERB-1 610 to CRB-5
604.
[0058] CRB-5 604 of FIG. 6 receives the frame 640b from the ingress
bridge T-ERB-1 610 and adds a TRILL header 654 to the frame 640 in
dependence upon the service VLAN identifier (T-ERB-1-SVLAN) and the
destination node address (CE-31-DA) for the destination node, CE-31
630. The TRILL header 654 is a standard header conforming to the
TRILL protocol and includes an ingress bridge nickname and an
egress bridge nickname.
[0059] As mentioned above, the value that a bridge uses for its
service VLAN identifier may be the same value that the bridge uses
for its TRILL nickname. However, one of ordinary skill in the art
will understand that the same value need not be used because the
service VLAN identifier is distinct, or separate, from the TRILL
nickname for any particular edge bridge. That is, the service VLAN
identifier is generally part of a customized vender header that
does not conform to the TRILL protocol, while the TRILL nickname is
part of the TRILL header used to route frames according to the
TRILL protocol. The bridges in a network generally obtain their
TRILL nicknames using a dynamic nickname acquisition protocol
described in the "Rbridges: Base Protocol Specification"
promulgated by the TRILL Working Group, which is affiliated with
the Internet Engineering Task Force.
[0060] Having a bridge identifier in a vender header distinct from
the TRILL nickname in the TRILL header allows bridges to be
utilized as edge bridges in the TRILL network 600 that are not
capable of encapsulating a frame with a standard TRILL header such
as, for example, TRILL header 551 in FIG. 5. For example, in FIG.
6, the hardware of edge router-bridges 610, 612, 614, 616 in FIG. 6
do not support the TRILL protocol. That is, the hardware of edge
router-bridges 610, 612, 614, 616 in FIG. 6 are not capable of
encapsulating a frame with a standard TRILL header such as, for
example, TRILL header 551 in FIG. 5, and utilizing MAC-in-MAC
encapsulation required under the TRILL protocol to route the frame
from one hop to another through the TRILL network 800. Rather than
use the TRILL nicknames for the ingress and egress router-bridges,
the edge router-bridges add service VLAN identifiers that are
unique for each edge router bridge in the TRILL network 600 of FIG.
6 and are supported by the hardware of those bridges. The ingress
bridge has the ability to add these service VLAN identifiers to the
frame because, although hardware of edge router-bridges 610, 612,
614, 616 in FIG. 6 cannot add a TRILL header to a frame, the edge
router-bridge hardware does support certain stacked headers or
customized headers that allows these router-bridges to add the
service VLAN identifier for the ingress bridge to the frame
640.
[0061] To add the ingress bridge nickname to the TRILL header 654,
therefore, CRB-5 604 need only add the value of the service VLAN
identifier for the ingress bridge node 610 as the ingress bridge
nickname in the TRILL header 654. To add the egress bridge nickname
to the TRILL header 654, CRB-5 604 may lookup the service VLAN
identifier for the egress bridge node associated with the
destination node address in a table that stores such values. The
contents of this table may be updated periodically using network
control protocol and may be implemented in any manner as will occur
to those of ordinary skill in the art. After obtaining the SVLAN
identifier for the egress bridge node, CRB-5 604 may then add the
value of the SVLAN identifier for the egress bridge node as the
egress bridge nickname in the TRILL header 654.
[0062] When CRB-5 604 adds the TRILL header 654 in the example of
FIG. 6, CRB-5 604 generally removes the vender header 652 that
contains the service SVLAN identifier (T-ERB-1-SVLAN) because such
a customized vender header 652 is not part of the standard TRILL
protocol. One of ordinary skill in the art will note, however, that
in some embodiments, the vender header may remain part of the frame
as it travels through the core bridges in the TRILL network
(600).
[0063] In the example of FIG. 6, CRB-5 604 routes the frame 640c to
the egress bridge node through which the destination node 630
connects to the network 600 based on the ingress bridge nickname
and the egress bridge nickname in the TRILL header 654. Using the
ingress bridge nickname and the egress bridge nickname, CRB-5 604
may identify the next bridge in the TRILL network 600 that is on a
path from the bridge node to the egress bridge node according to
the TRILL protocol. In the example of FIG. 6, the next bridge in
the TRILL network 600 that is on a path from the bridge node to the
egress bridge node is CRB-4 602. CRB-5 604 may then route the frame
640c to the egress bridge node by encapsulating the frame with an
Ethernet header 656 that includes the MAC address for CRB-4 602.
CRB-5 604 then routes the frame 640c to the next bridge node, CRB-4
602 in dependence upon the MAC address in the MAC header 656.
[0064] In the example of FIG. 6, CRB-4 602 receives the frame 640b
from the CRB-5 604 for transmission to CE-31 630. Upon examining
the information in the frame 640c, CRB-4 602 determines that the
frame 640 traverses the egress bridge node T-ERB-8 614 on the next
network hop. Because T-ERB-8 614 does not have the hardware to
support TRILL header 654, CRB-4 602 replaces the TRILL header 654
with a customized vender header that includes the service VLAN
identifier (ERB-1-SVLAN) for the ingress bridge 610. CRB-4 602 then
routes the frame 640d to the egress bridge node T-ERB-8 614. CRB-4
602 knows that egress bridge node T-ERB-8 614 lacks MAC-in-MAC
encapsulation capabilities because those capabilities are generally
broadcast to other nodes on the network 600 when egress bridge node
T-ERB-8 614 initially joins the network 600.
[0065] The egress bridge node T-ERB-8 614 in FIG. 6 receives the
frame 640d from CRB-4 602 for transmission to the destination node
CE-31 630. Because customer networks 611, 613 of FIG. 6 are IEEE
802.1Q networks, T-ERB-8 614 removes the service VLAN identifier
(T-ERB-1-SVLAN) from the frame 640d, leaving frame 640a. T-ERB-8
614 then routes the frame 640 for delivery to the destination node
CE-31 630 through customer network 613.
[0066] When T-ERB-8 614 first receives the frame 640, T-ERB-8 614
records the ingress node identifier-origin node address pair.
Recording this value pair allows T-ERB-8 614 to learn that the
origin node 620 is connected to the network 600 through edge bridge
610 and utilize the information in the future when T-ERB-8 614
operates as an ingress bridge node. T-ERB-8 614 utilizes such
information as an ingress bridge node because T-ERB-8 614 needs to
know which edge bridge is the egress bridge node to determine the
shortest path through the network 600.
[0067] One of ordinary skill in the art will note that in the
example of FIG. 6, the first core router-bridge that received the
frame from the ingress bridge added a TRILL header to the frame.
The core router-bridges then utilized the TRILL nicknames in the
TRILL header to route the frame through the network to core bridge
directly connected to the egress bridge by a single network hop. In
such a manner, once the TRILL header has been added to the frame,
the other core bridge-routers that route the frame using the TRILL
header need not be configured for routing frames in a TRILL network
using service VLAN identifiers according to embodiments of the
present invention. Rather, these router-bridges may route the frame
in the standard fashion provided by the TRILL protocol. Depending
on the topology of the network, therefore, standard router-bridges
may be utilized along with router-bridges modified to operate in
accordance with embodiments of the present invention.
[0068] Routing frames in a TRILL network using service VLAN
identifiers according to embodiments of the present invention is
implemented generally with computers, that is, automated computing
machinery. For further explanation, therefore, FIG. 7 sets forth a
block diagram of automated computing machinery comprising an
exemplary bridge 150 useful in routing frames in a TRILL network
using service VLAN identifiers according to embodiments of the
present invention. The bridge 150 of FIG. 7 is one of a plurality
of bridge nodes included in the computer network. At least one of
the bridge nodes in the network operates as an ingress bridge node
through which the frames are received into the computer network.
Also, at least one of the bridge nodes in the network operates as
an egress bridge node through which the frames are transmitted out
of the computer network.
[0069] In the example of FIG. 7, the exemplary bridge 150 includes
at least one processor 156 or `CPU` as well as random access memory
168 (RAM) which is connected through a high speed memory bus 166
and bus adapter 158 to the processor 156 and to other components of
the exemplary bridge 150.
[0070] Stored in RAM 168 of FIG. 7 is a routing module 190. The
routing module 190 of FIG. 7 is computer program instructions for
routing frames in a TRILL network using service VLAN identifiers
according to embodiments of the present invention. The TRILL
network includes a plurality of bridge nodes. At least one of the
plurality of bridge nodes operates as an ingress bridge node
through which the frames are received into the TRILL network. At
least one of the plurality of bridge nodes operates as an egress
bridge node through which the frames are transmitted out of the
TRILL network. In the TRILL network, each ingress bridge node and
each egress bridge node is assigned a unique service VLAN
identifier. As mentioned above, often the value for the service
VLAN identifier assigned to each bridge node is the same value as
the TRILL nickname acquired by each bridge using a dynamic nickname
acquisition protocol described in the "Rbridges: Base Protocol
Specification" promulgated by the TRILL Working Group, which is
affiliated with the Internet Engineering Task Force.
[0071] The routing module 190 of FIG. 7 operates generally for
routing frames in a TRILL network using service VLAN identifiers
according to embodiments of the present invention by: receiving,
from the ingress bridge node, a frame for transmission to a
destination node, the destination node connected to the TRILL
network through the egress bridge node, the received frame
including a customer VLAN identifier, a service VLAN identifier for
the ingress bridge node, and a destination node address for the
destination node, the received frame not having MAC-in-MAC
encapsulation; adding, to the frame in dependence upon the service
VLAN identifier for the ingress bridge node and the destination
node address for the destination node, a TRILL header conforming to
the TRILL protocol, the TRILL header including an ingress bridge
nickname and an egress bridge nickname; and routing, to the egress
bridge node through which the destination node connects to the
network, the frame in dependence upon the ingress bridge nickname
and the egress bridge nickname.
[0072] The routing module 190 of FIG. 7 also operates generally for
routing frames in a TRILL network using service VLAN identifiers
according to embodiments of the present invention by: receiving a
frame for transmission to a destination node, the destination node
connected to the network through the egress bridge node, the frame
originating from a source node connected to the network through the
ingress bridge node, the frame including a destination node address
for the destination node and a TRILL header, the TRILL header
including an ingress bridge nickname for the ingress bridge node
and an egress bridge nickname for the egress bridge node;
determining that the frame traverses the egress bridge node on the
next hop toward the destination node; in response to the
determination, replacing the TRILL header with the service VLAN
identifier for the ingress bridge node; and routing, by the bridge
node, the frame to the egress bridge node.
[0073] Also stored in RAM 168 is an operating system 154. Operating
systems useful in bridges according to embodiments of the present
invention may include Juniper Networks' JUNOS.RTM. and JUNOSe.RTM.,
Cisco's IOS.RTM., or Extreme Networks' ExtremeXOS.RTM.. Other
operating systems that may be useful in bridges according to
embodiments of the present invention may include lightweight
versions of UNIX.TM., Linux.TM., Microsoft XP.TM., and others as
will occur to those of skill in the art. Operating system 154 and
routing module 190 in the example of FIG. 7 are shown in RAM 168,
but many components of such software typically are stored in
non-volatile memory 172 also, for example, Electrically Erasable
Programmable Read-Only Memory (EEPROM) or in memory of the
application-specific integrated circuits (ASICs) 186.
[0074] The bridge 150 of FIG. 7 includes a bridge interface 180
connected to the other component of the bridge 150 through the bus
adapter 158. The bridge interface 180 provides ports 182 through
which nodes 184 connected to the bridge 150. The nodes 184 may be
implemented as servers, workstations, network devices, or any other
computing device as will occur to those of skill in the art. The
bridge interface 180 of FIG. 7 includes switching circuitry
controlled by the processor 156 or ASICs 186. The switching
circuitry of the bridge interface 180 provides high-speed switching
services to rapidly receive frames on one port and forward those
frames on to their ultimate destination through another port. The
switching circuitry may also provided limited processing
capabilities off-loaded from the ASICs 186 or the processor
156.
[0075] In the example of FIG. 7, the ASICs 186 connected to the
bridge interface 180 provide certain frame processing services in
an effort to offload processing from the main processor 156. For
example, the ASICs 186 may be used to provide filtering,
replication, forwarding, encapsulation, or de-encapsulation
services. Even still, the ASICs 186 may contain and execute the
routing module 190 as described above.
[0076] The exemplary bridge 150 of FIG. 7 includes a bus adapter
158, a computer hardware component that contains drive electronics
for the high speed buses, the front side bus 162 and the memory bus
166, as well as drive electronics for the interface bus 169 and the
slower expansion bus 160. Through the expansion bus 160 of FIG. 7,
the communications adapter 167, non-volatile memory 172, and I/O
adapter 178 are connected to the other components of the exemplary
bridge 150.
[0077] The exemplary bridge 150 of FIG. 7 includes one or more
input/output (`I/O`) adapters 178. I/O adapters 178 provide
components that allow the processor 156 to interface with various
I/O components of the bridge. Exemplary I/O components may include,
for example, light-emitting diodes (LEDs), liquid-crystal displays
(LCDs), physical switches and buttons, or other interface
components as will occur to those of skill in the art.
[0078] The exemplary bridge 150 of FIG. 7 also includes a
communications adapter 167 for data communications with other
computing devices out of band from the network communications
through ports 182. The communications adapter 167 may provide the
processor 156 with an interface according to the Universal Serial
Bus (USB) specification, Small Computer System Interface (SCSI)
specification, RS-232 specification, Inter-Integrated Circuit
(I.sup.2C) bus protocol, a System Management Bus (SMBus) protocol,
an Intelligent Platform Management Bus (IPMB) protocol, or the
like.
[0079] One of ordinary skill in the art will note that the
exemplary implementation of the bridge 150 of FIG. 7 is for
explanation only and not for limitation. Other computing
architectures as will occur to those of skill in the art may also
be useful for routing frames in a TRILL network using service VLAN
identifiers according to embodiments of the present invention. For
example, the bridge may be implemented using a general-purpose
computer or a specialized computing device dedicated for network
frame processing, or other hybrid architectures.
[0080] FIGS. 8-9 provide further explanation of various embodiments
of the present invention as different bridges operating according
to embodiments of the present invention route a frame through a
TRILL network. FIG. 8 sets forth a flow chart illustrating an
exemplary method of routing frames in a TRILL network 800 using
service VLAN identifiers according to embodiments of the present
invention. The TRILL network 800 of FIG. 8 includes a plurality of
bridge nodes 810, 812, 814, 816, 818. In FIG. 8, bridge node 810
operates as an ingress bridge node through which the frames are
received into the TRILL network 800, and bridge node 818 operates
as an egress bridge node through which the frames are transmitted
out of the TRILL network 800. In the example of FIG. 8, the
hardware of the ingress bridge node 810 and hardware of the egress
bridge node 818 do not support MAC-in-MAC encapsulation, and thus
are unable to support the TRILL protocol at the hardware level.
[0081] The bridge node 812 of FIG. 8 includes twelve ports 900a-l
through which other nodes may connect to the bridge node 812. In
the example of FIG. 8, the ingress bridge node 810 connects to the
bridge node 812 through port 900b. Core bridge node 816 connects to
the bridge node 812 through port 900k.
[0082] The method of FIG. 8 includes receiving 902, by the bridge
node 812 from the ingress bridge node 810, a frame 822 for
transmission to a destination node 808. In the example of FIG. 8,
the destination node 808 connects to the TRILL network 800 through
customer network 805 and the egress bridge node 818. The bridge
node 812 may receive 902 the frame 822 from the ingress bridge node
810 according to the method of FIG. 8 by retrieving the frame 822a
from a reception stack for port 900b and advancing the stack
pointer for the reception stack.
[0083] The frame 822a of FIG. 8 specifies a source node address 826
for the source node (not shown) originating the frame 822a and a
destination node address 824 for a destination node 808 to which
the frame 822 is transmitted. The source and destination node
addresses 826, 824 may be implemented as MAC addresses. The frame
822a also includes a customer VLAN identifier 823 that the
equipment on the customer network uses to assign the frame 822 to a
particular VLAN established across one or more customer networks.
The frame 822a further includes a vender header 830 that specifies
a service VLAN identifier 831. The service VLAN identifier 831 of
FIG. 8 and the frame 822a generally conform to the IEEE 802.1ad
standard, but one of ordinary skill in the art will recognize that
such conformance is not a required feature in embodiments of the
present invention.
[0084] The method of FIG. 8 also includes adding 904, by the bridge
node 812 to the frame 822 in dependence upon the service VLAN
identifier 831 for the ingress bridge node 810 and the destination
node address 824 for the destination node 808, a TRILL header 1003
conforming to the TRILL protocol. The TRILL header 1003 includes an
ingress bridge nickname 1004 and an egress bridge nickname 1006. As
mentioned above, the values for the ingress bridge nickname 1004
and the egress bridge nickname 1006 may be the same as the values
of the service VLAN identifiers for the ingress bridge 810 and the
egress bridge 818, respectively. Thus, the bridge node 812 may add
904 the ingress bridge nickname 1004 according to the method of
FIG. 8 by storing the value of the service VLAN identifier 831 in
the frame 822a in the TRILL header 1003 as the ingress bridge
nickname 1004. The bridge node 812 may add 904 the egress bridge
nickname 1006 according to the method of FIG. 8 by looking up in
the network topology 1105 the nickname for the edge bridge through
which the destination node 808 connects to the network 800 and
storing that value as the egress bridge nickname 1006 in the TRILL
header 1003.
[0085] The network topology 1105 of FIG. 8 is a table that
maintains the network topology for network 800 which defines the
data communications connections among the nodes in the network 800.
The bridge nodes determines the data communications connections
among the nodes based on the control frames exchanged among the
nodes according to a control protocol such as, for example, the
Intermediate System to Intermediate System ("IS-IS") protocol. The
network topology 1105 also associates the edge bridges with the
nodes outside of the network 800 that send or receive frames
through the network 800. Such a network topology may be implemented
and periodically updated in any manner as will occur to those of
ordinary skill.
[0086] The method of FIG. 8 includes routing 906, by the bridge
node 812 to the egress bridge node 818 through which the
destination node 808 connects to the network 800, the frame 822b in
dependence upon the ingress bridge nickname 1004 and the egress
bridge nickname 1006. The bridge node 812 may route 906 the frame
822b based on the ingress bridge nickname 1004 and the egress
bridge nickname 1006 according to the method of FIG. 8 by
encapsulating the frame 822b with an Ethernet header 908. One of
ordinary skill in the art will note at this point the frame 822 now
utilizes MAC-in-MAC encapsulation, which is generally supported by
the core bridges 812 and 816 in the TRILL network 800, but not the
edge bridges 810 and 818. The Ethernet header 908 includes a MAC
address for a next bridge in the network 800 that is on a path from
the bridge node 812 to the egress bridge node 818--that is, bridge
816.
[0087] In the example of FIG. 8, the bridge node 812 uses the
forwarding tables 1005 established in accordance with the TRILL
specification to identify the next bridge in the network 800 that
is on the shortest path from the ingress bridge node 810 to the
egress bridge node 818. Each bridge has a set of forwarding tables
customized for that bridge's location in the topology of the
network 800 for routing frames between different pairs of edge
bridges. In this manner, the bridge node 812 can use the ingress
bridge nickname 1004 and the egress bridge nickname 1006 to locate
the next node along the path between any pair of ingress and egress
nodes.
[0088] After the Ethernet header 908 is added to the frame 822b,
then the bridge node 812 may route the frame 822b to the next
bridge node using the MAC address 910 of that next node by placing
the frame 822b in the transmission stack for the port 900k
corresponding to MAC address 910. Once the frame 822 is placed in
the transmission stack for a port 900k, the bridge interface, such
as the bridge interface described with reference to FIG. 7, sends
the frame 822 out from the appropriate port 900k to the next
bridge--that is, bridge 816.
[0089] In the example of FIG. 8, even though bridge 812 receives
the frame 822a from edge bridge 810 in the TRILL network 800, one
of ordinary skill in the art will note that the received frame 822a
does not already have a TRILL header or an additional MAC address
for TRILL network equipment based on the TRILL header. In such a
manner, the frame 822 does not utilize MAC-in-MAC encapsulation as
the frame 822 traverse the first hop in the TRILL network 800. This
allows the TRILL network 800 to use bridges with hardware that does
not support MAC-in-MAC encapsulation as edge bridges. Because the
current generation of bridges does not support MAC-in-MAC
encapsulation, the ability to use existing bridges as edges bridges
in a TRILL network reduces the financial costs of implementing a
TRILL network solution.
[0090] When using bridges that do not support MAC-in-MAC
encapsulation as edge bridges in a TRILL network, the MAC addresses
for the bridges in the TRILL network and the supporting TRILL
header must be stripped from the frame before the frame reaches the
egress bridge node--namely, when the frame reaches bridge 816. For
further explanation of the frame processing that takes place at
core bridge 816, FIG. 9 sets forth a flow chart illustrating a
further exemplary method of routing frames in a TRILL network 800
using service VLAN identifiers according to embodiments of the
present invention.
[0091] The network topology of FIG. 9 is similar to the topology in
FIG. 8. The TRILL network 800 of FIG. 9 includes a plurality of
bridge nodes 810, 812, 816, 818. In FIG. 9, bridge node 810
operates as an ingress bridge node through which the frames are
received into the TRILL network 800, and bridge node 818 operates
as an egress bridge node through which the frames are transmitted
out of the TRILL network 800. Each ingress bridge node and each
egress bridge node is assigned a unique service VLAN identifier.
The bridge nodes 812, 816 of FIG. 9 operate as core bridges. In the
example of FIG. 9, the hardware of the ingress bridge node 810 and
hardware of the egress bridge node 818 do not support MAC-in-MAC
encapsulation, and thus are unable to support the TRILL
protocol.
[0092] The bridge node 816 of FIG. 9 includes twelve ports 1100a-1
through which other nodes may connect to the bridge node 816. In
the example of FIG. 9, the core bridge node 812 connects to the
bridge node 816 through port 1100c. Egress bridge node 818 connects
to the bridge node 816 through port 1100i.
[0093] The method of FIG. 9 includes receiving 1102, by bridge node
816, a frame 822 for transmission to a destination node 808. The
destination node 808 of FIG. 9 connects to the network 800 through
the egress bridge node 818 and customer network 805. The frame 822
specifies the source node address 826 of the source node
originating the frame 822 and the destination node address 824 of
the destination node 808. The frame 822 has a TRILL header 1003
that includes an ingress bridge nickname 1004 and an egress bridge
nickname 1006. The frame 822 also includes an Ethernet header 908
that includes a MAC address 910 of the bridge node 816--all similar
to those described above with reference to FIG. 8. The bridge node
816 may receive 1102 the frame 822b according to the method of FIG.
9 by retrieving the frame 822d from a reception stack for port
1100c and advancing the stack pointer for the reception stack. The
reception stack may be implemented as a buffer into which frames
received from a port 1100 are placed until those frames are
processed by the bridge 816.
[0094] The method of FIG. 9 includes determining 1104, by the
bridge node 816, that the frame 822 traverses the egress bridge
node 816 on the next network hop. In the method of FIG. 9, the
bridge node 816 may determine 1104 that the frame 822 traverses the
egress bridge node 816 on the next network hop using network
topology 1105, which may be obtained and implemented in a manner as
will occur to those of skill in the art, particularly through a
dynamic control protocol that periodically detects changes in the
network topology.
[0095] As previously mentioned, egress bridge 818 does not support
MAC-in-MAC encapsulation. Thus, the method of FIG. 9 includes
replacing 1108, by the bridge node 816 in response to the
determination, the TRILL header 1003 with the service VLAN
identifier 831. Because the TRILL nicknames and the service VLAN
identifiers may be implemented using the same values, the bridge
node 816 may replace 1108 the TRILL header 1003 with service VLAN
identifier 831 according to the method of FIG. 9 by removing the
TRILL header 1003 and the Ethernet header 908 and adding a vender
header 830 to the frame 822c that includes the value of the ingress
bridge nickname 1004 as the service VLAN identifier 831. In some
other embodiments in which the service VLAN identifiers for the
edge bridges and the TRILL nicknames are not the same, then the
bridge 816 may use a lookup table that associates service VLAN
identifiers for edge nodes with their corresponding TRILL
nicknames. The lookup table may be implemented in any manner as
will occur to those of skill in the art and periodically updated
using a network control protocol or other such mechanism as will
occur to those of skill in the art.
[0096] The method of FIG. 9 includes routing 1110, by the bridge
node 816, the frame 822 to the egress bridge node 816. The bridge
node 816 may route 1110 the frame 822 to the egress bridge node 816
according to the method of FIG. 9 by storing the frame 822 in the
transmission stack for the port 1100i corresponding the next bridge
818. Once the frame 822 is placed in the transmission stack for a
port 1100i, the bridge interface, such as the bridge interface
described with reference to FIG. 7, sends the frame 822 out from
the appropriate port 1100i to the egress bridge 818.
[0097] One of ordinary skill in the art will recall from above that
the service VLAN identifier 831 is part of a customized or stacked
vender header that does not conform with IEEE 802.1Q. Because the
customer network of FIG. 8 is a IEEE 802.1Q compliant network, the
egress bridge node 818 removes the vender header 830 from the frame
822 before sending the frame 822 to the destination node 808.
[0098] By removing the TRILL header 1003 and the additional MAC
address 910 for TRILL network equipment that is based on the TRILL
header, the frame 822 is essentially transformed from a TRILL frame
with MAC-in-MAC encapsulation into a frame with stack headers that
does not utilize MAC-in-MAC encapsulation, typically an IEEE802.1ad
compliant frame. This allows the TRILL network 800 to use bridges
with hardware that does not support MAC-in-MAC encapsulation as
edge bridges. Because the current generation of bridges does not
support MAC-in-MAC encapsulation, the ability to use existing
bridges as edges bridges in a TRILL network reduces the financial
costs of implementing a TRILL network solution.
[0099] When egress bridge 818 receives the frame 822, egress bridge
818 records the ingress node identifier (Customer VLAN ID
823)-origin node address (Source Address 826) pair. Recording this
value pair allows egress bridge 818 to learn that the origin node
(not shown) is connected to the network 800 through edge bridge 810
and utilize the information in the future when egress bridge 818
operates as an ingress bridge node. Egress bridge 818 utilizes such
information as an ingress bridge node because edge bridge 818 needs
to know which edge bridge is the egress bridge node to determine
the shortest path through the network 800.
[0100] Exemplary embodiments of the present invention are described
largely in the context of a fully functional network bridges
configured for routing frames in a TRILL network using service VLAN
identifiers. One of skill in the art will recognize, however, that
the present invention also may be embodied in a computer program
product disposed on computer readable media for use with any
suitable data processing system. Such computer readable media may
be transmission media or recordable media for machine-readable
information, including magnetic media, optical media, or other
suitable media. Examples of recordable media include magnetic disks
in hard drives or diskettes, compact disks for optical drives,
magnetic tape, and others as will occur to those of skill in the
art. Examples of transmission media include telephone networks for
voice communications and digital data communications networks such
as, for example, Ethernets.TM. and networks that communicate with
the Internet Protocol and the World Wide Web as well as wireless
transmission media such as, for example, networks implemented
according to the IEEE 802.11 family of specifications. Persons
skilled in the art will immediately recognize that any computer
system having suitable programming means will be capable of
executing the steps of the method of the invention as embodied in a
program product. Persons skilled in the art will recognize
immediately that, although some of the exemplary embodiments
described in this specification are oriented to software installed
and executing on computer hardware, nevertheless, alternative
embodiments implemented as firmware or as hardware are well within
the scope of the present invention.
[0101] It will be understood from the foregoing description that
modifications and changes may be made in various embodiments of the
present invention without departing from its true spirit. The
descriptions in this specification are for purposes of illustration
only and are not to be construed in a limiting sense. The scope of
the present invention is limited only by the language of the
following claims.
* * * * *