U.S. patent application number 12/482741 was filed with the patent office on 2010-06-17 for interworking oam between ethernet and atm/frame relay networks.
This patent application is currently assigned to AT&T Corp.. Invention is credited to Stephen Holmgren, David Kinsky.
Application Number | 20100150160 12/482741 |
Document ID | / |
Family ID | 40811062 |
Filed Date | 2010-06-17 |
United States Patent
Application |
20100150160 |
Kind Code |
A1 |
Kinsky; David ; et
al. |
June 17, 2010 |
INTERWORKING OAM BETWEEN ETHERNET AND ATM/FRAME RELAY NETWORKS
Abstract
The present invention provides a network system that interworks
OA&M (Operations, Administration and Maintenance) failure
notification data from the ATM Domain to the Ethernet Domain and
vice versa. Failure indications or notifications are typically
routed from one domain to another within 1-2 seconds; providing
service providers and customers the ability to react quickly to
network faults. This enhances the overall quality of the
Ethernet-to-ATM Interworking service and provides a similar level
of reliability across the Ethernet/ATM/FR domains.
Inventors: |
Kinsky; David; (High Bridge,
NJ) ; Holmgren; Stephen; (Little Silver, NJ) |
Correspondence
Address: |
AT&T Legal Department - HB;Patent Docketing
One AT&T Way, Room 2A-207
Bedminster
NJ
07921
US
|
Assignee: |
AT&T Corp.
New York
NY
|
Family ID: |
40811062 |
Appl. No.: |
12/482741 |
Filed: |
June 11, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10740269 |
Dec 18, 2003 |
7558274 |
|
|
12482741 |
|
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|
60489716 |
Jul 21, 2003 |
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Current U.S.
Class: |
370/395.53 |
Current CPC
Class: |
H04L 69/18 20130101;
H04L 69/40 20130101; H04L 12/4675 20130101; H04L 12/46
20130101 |
Class at
Publication: |
370/395.53 |
International
Class: |
H04L 12/28 20060101
H04L012/28 |
Claims
1. A network system for notifying/communicating at least one
failure message from at least one source to at least one
destination, said system comprising: a first network associated
with the source, generates a first frame, said first frame includes
a failure notification message and a first destination address in a
first format compatible with the first network; a second network
associated with the destination having a second destination
address; and an interworking facility for receiving the first
frame, forming a second frame of a second format compatible with
the second network, and mapping the first destination address to a
second destination address specifying in the second format the
destination address in the second network, so that the second
network upon receipt of the second destination address routes the
second frame to the destination, wherein the second frame includes
the failure notification message; wherein the first frame has an
Ethernet format; wherein the first destination address includes a
Virtual Local Area Network (VLAN) tag with the Ethernet formatted
first frame; wherein the second frame has an Asynchronous Transport
(ATM) format; wherein said second destination address comprises an
ATM Permanent Virtual Circuit (PVC) tag; wherein said failure
notification message includes a Remote Defect Indication for
sending a message back to a transmitting terminal that a failure
has been indicated; and wherein the interworking facility
interworks the ATM format frames with the Ethernet format frames by
the steps of receiving at the interworking facility an Ethernet
formatted first frame with the corresponding VLAN tags; matching
the VLAN tag of the first destination with the corresponding PVC
values of the second destination address using a mapping table;
converting the Ethernet format frame to the ATM format frame; and
sending the ATM format frame with the corresponding PVC tag to the
destination served by the second network.
2. The system according to claim 1, wherein said failure
notification message includes automated Operations, Administration
and Management traffic.
3. The system according to claim 1 wherein the second frame has an
Asynchronous Transport (ATM) format and wherein the second
destination address comprises an ATM Permanent Virtual Circuit
(PVC) VPI/VCI value.
4. The system according to claim 1 wherein the first frame has an
Asynchronous Transport (ATM) format and wherein the first
destination address comprises an ATM PVC VPI/VCI value.
5. The system according to claim 4 wherein the second frame has an
Ethernet format and wherein the second destination address
comprises a VLAN tag within the Ethernet formatted first frame.
6. The system according to claim 1, wherein said source includes at
least one Ethernet router.
7. The system according to claim 1, wherein said destination
includes at least one ATM router.
8. The system according to claim 1, wherein said destination
includes at least one frame relay router.
9. The system according to claim 1, wherein said interworking
facility includes Ethernet Interworking Switch.
10. The system according to claim 1, wherein said second network
includes Frame Relay Edge Switch.
11. The system according to claim 1 wherein said failure
notification message includes failure in a link between the source
and the first network.
12. The system of claim 11 wherein said link failure is detected by
the source.
13. The system of claim 11, wherein said link failure is detected
by the first network.
14. The system of claim 11 wherein said source is an Ethernet
router and said first network is an Ethernet network.
15. The system of claim 1 wherein said failure notification message
includes multiple failures in links between the sources and the
first network.
16. The system of claim 1, wherein said source is an ATM router and
first network is an ATM network.
17. The system of claim 16, wherein said multiple link failures are
detected by the first network.
18. The system of claim 17, wherein said first network is an
Ethernet network.
19. The system of claim 17, wherein said first network is an ATM
network
20. A network system for notifying/communicating at least one
failure message from at least one source to at least one
destination, said system comprising: a first network associated
with the source, generates a first frame, said first frame includes
a failure notification message and a first destination address in a
first format compatible with the first network; a second network
associated with the destination having a second destination
address; and an interworking facility for receiving the first
frame, forming a second frame of a second format compatible with
the second network, and mapping the first destination address to a
second destination address specifying in the second format the
destination address in the second network, so that the second
network upon receipt of the second destination address routes the
second frame to the destination, wherein the second frame includes
the failure notification message; wherein the first frame has an
Asynchronous Transport (ATM) format; wherein the first destination
address includes an ATM PVC Virtual Local Area Network (VLAN) tag
with the Ethernet formatted first frame; wherein the second frame
has an Ethernet format; wherein said second destination address
comprises a (VLAN) tag with the Ethernet formatted first frame;
wherein the mapping of the first destination address to the second
destination address comprises the step of mapping the ATM PVC
VPI/VCI to the VLAN tag; and wherein the interworking facility
interworks the ATM formal frames with the Ethernet format frames by
the steps of: receiving at the interworking facility an ATM
formatted first frame with the corresponding PVC VPI/VCI value;
matching the VPI/VCI of the first destination with the
corresponding VLAN values of the second destination address using a
mapping table; converting the ATM format frame to the Ethernet
format frame; and sending the Ethernet format frame with the
corresponding VLAN tag to the destination served by the second
network.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Non-Provisional
application Ser. No. 10/740,269 filed on Dec. 18, 2003 and U.S.
Provisional Application No. 60/489,716 filed Jul. 21, 2003.
[0002] The present application is related to U.S. utility patent
applications, "ETHERNET TO ATM SERVICE INTERWORKING TECHNIQUE,"
Ser. No. 10/016,019, filed on Dec. 12, 2001; "FAILURE NOTIFICATION
METHOD AND SYSTEM IN AN ETHERNET DOMAIN," Ser. No. 10/248,761,
filed on Feb. 14, 2003; and "DISCOVERY AND INTEGRITY TESTING METHOD
IN AN ETHERNET DOMAIN," Ser. No. 10/248,858, filed on Feb. 25,
2003, the contents of which are incorporated by reference
herein.
FIELD OF THE INVENTION
[0003] The present invention relates to interworking data between
Ethernet domains and ATM/Frame Relay domains and, more
particularly, to integrating operations, administration, management
(OAM) traffic failure data.
BACKGROUND OF THE INVENTION
[0004] Traditionally, for customers running IP networks, they
typically rely on routing protocols such as Border Gateway Protocol
(BGP), Open Shortest Path First (OSPF), Routing Information
Protocol (RIP) also known as layer 3 IP Routing Protocols, to
detect a failure in the network and route around the problem. These
routing protocols send systematic "hello" messages to their remote
end points and when one isn't observed after a period of time, they
assume there's a problem and route around it. So, these Layer 3 IP
Routing Protocols are needed to re-route around failures, such as
between two separate networks like Ethernet and ATM. Using these
Layer 3 techniques takes about 30-60 seconds to detect and respond
to a failure. This is inefficient and too slow but that is a
limitation of the Layer 3 routing protocols.
[0005] Customers who rely on Frame Relay/ATM networks are used to
failure notification response times of 1-2 seconds (or less). The
FR/ATM network independently generates a failure notification
towards customer premises equipment at the onset of failure.
Customers of this new Ethernet to FR/ATM Interworking service
require similar failure notification behavior from the network.
Therefore, it is required to integrate automated Operations,
Administration and Management traffic which can propagate failure
indications end-to-end much faster, and does not require either a
Layer 3 IP Routing Protocol or any type of "hello" or integration
timer messages.
[0006] It is known that regular traffic can be interworked between
Ethernet and ATM, e.g. using the technique described in the patent
application Ser. No. 10/016,019. It is also known that there is a
native OAM in the Ethernet domain, e.g. see the patent application
Ser. No. 10/248,761 and Ser. No. 10/248,858. The difficulty
involves implementing Ethernet OAM first, then bridging EOAM with
ATM OAM.
[0007] So, besides integrating (interworking) regular traffic data
between Ethernet and ATM, it is also advantageous to integrate OAM
failure notification between the two separate networks. Moreover,
it is also advantageous to provide failure indications by a much
faster and more reliable means.
SUMMARY OF THE INVENTION
[0008] The present invention provides a method for
notifying/communicating at least one failure message from at least
one source to at least one destination, the source served by a
first network and the destination served by a second network. The
method includes receiving at an interworking facility a first frame
which includes a failure notification message and a first
destination address in a first format compatible with said first
network, forming a second frame of a second format compatible with
the second network, the second frame including the failure
notification message and mapping the first destination address to a
second destination address specifying in the second format the
address of the destination in the second network so that the second
network, upon receipt of the second destination address, can route
the second frame to the destination.
[0009] The present invention also provides a network system for
notifying/communicating at least one failure message from at least
one source to at least one destination. The system includes a first
network associated with the source, generates a first frame
includes a failure notification message and a first destination
address in a first format compatible with the first network. Also
included is a second network associated with the destination having
a destination address and an interworking facility. The
interworking facility receives the first frame, forms a second
frame of a second format compatible with the second network, and
maps the first destination address to a second destination address
specifying in the second format the destination address in the
second network, so that the second network upon receipt of the
second destination address routes the second frame to the
destination, wherein the second frame includes the failure
notification message.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 shows a block schematic diagram of a prior art
network architecture for interworking regular traffic data between
two networks.
[0011] FIG. 2 shows a block schematic diagram comprising part of
the network architecture of FIG. 1 and the manner in which the link
failure notification is transmitted from a source to a
destination.
[0012] FIG. 3 shows a block schematic diagram comprising part of
the network architecture of FIG. 1 and the manner in which the link
failure notification is transmitted from a source to a
destination.
[0013] FIG. 4 shows a block schematic diagram comprising part of
the network architectures of FIG. 1 and the manner in which the
trunk failure detected in the Ethernet domain 14 is
transmitted.
[0014] FIG. 5 shows a block schematic diagram comprising part of
the network architecture of FIG. 2 and the manner in which the link
failure notification is transmitted from a source to a
destination.
[0015] FIG. 6 shows a block schematic diagram comprising part of
the network architecture of FIG. 3 and the manner in which the link
failure notification is transmitted from a source to a
destination.
[0016] FIG. 7 shows a block schematic diagram comprising part of
the network architecture of FIG. 4 and the manner in which the
trunk failure detected in the Ethernet domain 14 is
transmitted.
[0017] FIG. 8 shows a block schematic diagram comprising part of
the network architecture of FIG. 1 and the manner in which the link
failure notification is transmitted from a destination to a
source.
[0018] FIG. 9 shows a block schematic diagram comprising part of
the network architecture of FIG. 1 and the manner in which the link
failure notification is transmitted from a destination to a
source.
[0019] FIG. 10 shows a block schematic diagram comprising part of
the network architecture of FIG. 1 and the mariner in which the
trunk failure detected in the ATM domain 18 is transmitted.
[0020] FIG. 11 shows a block schematic diagram comprising part of
the network architecture of FIG. 1 and the mariner in which the
link failing notification is transmitted from a destination to the
source.
[0021] FIG. 12 shows a block schematic diagram comprising part of
the network architecture of FIG. 1 and the manner in which the
trunk failure detected in the ATM domain 18 is transmitted.
DETAILED DESCRIPTION
[0022] The present invention provides a service that interworks two
networking OAM protocols (Ethernet OAM and ATM OAM). It allows for
failure notification of OAM packets observed in one domain (e.g.
Ethernet) to be carried into the other domain (e.g. ATM) and vice
versa. Specifically if a failure is detected in the Ethernet
domain, OAM packets are forwarded on the failed VLAN in the
Ethernet domain to the applicable PVC in the ATM domain. The
Failure Notification scheme works essentially the same in the
Ethernet-to-ATM direction. Customer equipment in either domain
would get near Real Time notification of a failure independent of
the domain.
[0023] FIG. 1 depicts a block schematic diagram of a prior art
network architecture 10 as shown in U.S. patent application Ser.
No. 10/016,019 for interworking a source and destination that lie
in first and second networks having different protocols to allow
the source to send data using its own protocol by first
establishing for the source a set of addresses in a format
compatible with the destinations that lie in second network, and
thereafter having an interworking facility act as a proxy between
networks. In the embodiment of FIG. 1, the source 10 comprises a
first router 10a and a second router 10b and the destination 12
comprises one of routers 12a and 12b. Broadly stated, in the
illustrated embodiment, either the first router 10a or the second
router 10b routes data in the form of Ethernet formatted
information frames onto an Ethernet-based Metropolitan Area Network
(MAN) or Ethernet Domain 14 which comprises a first network, the
router 12a routes data in the form of ATM formatted information
frames onto an ATM domain 18, which comprises a second network, and
router 12b routes data in the form of Frame Relay formatted
information frames which are converted [to ATM] at the edge of the
ATM domain 18. The Ethernet domain 14 as shown provides network
services to a plurality of customers and/or customer sites. For
illustration purposes, FIG. 1 only shows two source routers 10a and
10b and two destination routers 12a and 12b, although any number of
sources and destination sites may be shown connected to the
Ethernet domain 14 and the ATM domain 18 respectively.
[0024] To enable transmission of the data to one of the destination
routers 12a and 12b that lie outside the first network, the
Ethernet network 14 transmits each Ethernet formatted information
frame destined for one of the routers 12a and 12b to an Ethernet
InterWorking Switch (EIWS) 16 for transmission to the Wide Area ATM
core network 18 (a second) network that serves the routers 12a and
12b as discussed below. The EIWS 16 functions as an interworking
facility typically comprising an Ethernet switch that serves as a
proxy between the Ethernet network 14 and the ATM network 18 which
services a plurality of edge devices that utilize one of a
plurality of protocols, such as ATM or Frame Relay.
[0025] In practice, the interworking facility establishes a set of
pseudo addresses in a format compatible with the first network that
correspond to destinations in the second network so that the source
can address an information frame using its own protocol for a
destination that actually lies in the second network without
concerning itself with the protocol employed in the second network.
In the case where the first information frame comes from a source
in an Ethernet-based network, the first information frame will have
a Virtual Local Area Network (VLAN) tag associated with the address
of the destination. On the other hand, if the information frame
comes from a source in an ATM Virtual Private network (VPN), the
frame will include a Virtual Path Identifier (VPI)/Virtual Channel
Identifier (VCI), herein after referred to as a Permanent Virtual
Circuit (PVC) that corresponds to the address of (e.g., the network
path to) the destination in a format compatible with the ATM
network, even though the destination lies in another network having
a different protocol.
[0026] Upon receipt of the first traffic failure frame at the
interworking facility, the facility forms a second frame compatible
with the second network, the second frame including the traffic
failure. The destination address of the first frame is mapped to a
second destination address compatible with the second network.
Thus, for example, the VLAN tag in an originating Ethernet frame is
mapped to a VPN PVC for an ATM frame and vice versa. Mapping the
destination address from a format compatible with the first traffic
failure frame to a format compatible with the second traffic
failure frame allows propagation of the second frame, including the
information embodied in its traffic failure, to the
destination.
[0027] Generally, two types of alarms are sent when error or
failure is detected in the flow of traffic from one domain to the
other domain. An alarm indication signal (AIS) is generated which
sends a message in the same, i.e. forward direction as that of the
signal to the effect that an error or failure has been detected. A
Remote Defect Indication (RDI) is generated which sends a message
back to a transmitting terminal that a failure (AIS) has been
indicated, i.e. received.
[0028] FIGS. 2-12 show transmission of traffic failure
notifications upon detection of traffic failures in different areas
of the network architecture of FIG. 1.
[0029] Referring to FIG. 2 of the present invention, there is shown
a block schematic diagram comprising part of the network
architecture of FIG. 1 and the manner in which the link failure
notification is transmitted from a source to a destination. Link
failure I.sub.1 occurs on a link in the Ethernet domain 14. In this
case, the failure is detected on a R.sub.x port of Ethernet Edge
Switch 20 facing the Ethernet router 10a. The Ethernet edge switch
20 recognizes that this failure is on the Green VLAN, and generates
an Ethernet OAM AIS (EOAM.AIS) message and forwards it towards the
EIWS 16 on the Green VLAN. Upon receipt of the EOAM.AIS message,
EIWS 16 performs two functions. One, EIWS 16 sends an EOAM.RDI
message on the Green VLAN back towards the Ethernet router 10a
notifying the router 10a of the link failure I.sub.I detection.
Two, EIWS converts the EOAM.AIS message on the Green VLAN into an
ATM.AIS message on the Green PVC as described below. AIS is in the
same `forward direction` as the traffic flow direction where the
error was detected, it signals the detection of an outage
condition. Whereas, the RDI is a response in the reverse direction
to receiving the AIS error message (i.e. "I have received a message
about an error condition") rather than the actual error
detection.
[0030] EIWS 16 operates to interwork the Ethernet frames with the
ATM frames to facilitate the actual transmission of failure
notification as described herein below. When EIWS 16 receives
traffic failure message from the Ethernet Network 14, it opens the
message/packet to determine the VLAN tag embodied in the packet for
the purpose of matching the VLAN tag to a PVC path of the ATM
network 18. To match the VLAN tag to an ATM PVC, the EIWS 16 uses a
PVC-VLAN mapping table (not shown) that cross references VLAN tags
to corresponding ATM PVC VPI/VCI values. By mapping the VLAN tag to
the corresponding ATM PVC, the EIWS 16 effectively converts the
Ethernet address into an ATM address.
[0031] Referring back to FIG. 2, when EIWS 16 receives the EOAM.AIS
message on Green VLAN from Ethernet network 14, it maps the Green
VLAN to Green PVC of the ATM network 18, using the PVC-VLAN mapping
table. It recognizes this packet as an EOAM.AIS message, and
converts it to an ATM.AIS message on the appropriate PVC. EIWS 16
then forwards the ATM.AIS message to the ATM network 18. The ATM
network 18 then forwards the ATM.AIS message towards the ATM router
12a on the Green PVC. The ATM router 12a receives the ATM.AIS
message, processes the failure notification, and takes the
subinterface corresponding to the Green PVC out of service. In
other words, the IP address associated with Green PVC is no longer
available for data transmission. Also, Cust 1 ATM Router 12a, per
ATM protocol, responds with an ATM.RDI packet on the Green PVC.
This ATM.RDI packet is an acknowledgement by Cust 1 ATM Router 12a
that it has successfully received the failure notification message.
The ATM.RDI packet on the Green PVC is transmitted through the ATM
domain 18 to the EIWS 16. The EIWS 16 receives the ATM.RDI message
for the Green PVC and converts into EOAM.RDI message for the Green
VLAN and forwards it to the Ethernet router 10a. Note that the
EOAM.RDI message is a redundant message reiterating the link
failure detection. The Ethernet domain 14 is not limited to a
single Ethernet service provider and, for purposes of the present
invention, may consist of multiple Ethernet service providers
(ESPs). In such a case, the layer two device "facing" the edge
router 10a, namely switch 20 in FIG. 2, would aggregate traffic
from multiple Ethernet service providers.
[0032] Referring to FIG. 3 of the present invention, there is shown
a block schematic diagram comprising part of the network
architecture of FIG. 1 and the manner in which the link failure
notification is transmitted from a source to a destination. Link
failure I.sub.2 occurs on a link in the Ethernet domain 14 between
router 10b and edge switch 20 (Red VLAN). In this case, the failure
is also detected on the R.sub.x port Ethernet Edge Switch 20 facing
the Ethernet router 10b. An Ethernet OAM AIS (EOAM.AIS) message is
generated by the Ethernet edge switch 20 and sent towards the EIWS
16 on the Red VLAN. Again, EIWS 16 performs two functions. One,
EIWS 16 sends an EOAM.RDI message on the Red VLAN back towards the
Ethernet router 10b notifying the router 10b of the link failure
I.sub.2 detection. Second, EIWS 16 maps the EOAM.AIS message into
an ATM.AIS message, and forwards the ATM.AIS message to the ATM
domain 18 on to the applicable PVC (Red PVC) based on the PVC-VLAN
mapping table. Since, in this case the network path is on the Red
PVC, the ATM network 18 then forwards the ATM.AIS message towards
the frame relay (FR) edge switch 22. The FR edge switch 22 receives
the ATM.AIS message and converts it into the equivalent frame relay
(F.R.) OAM (a/k/a LMI-Link Management Interface) message indicating
the Red PVC has gone into an inactive state. This state change is
signaled in a message called an Asynchronous Status message, with
the Activity bit (A-bit) set to 0. The Cust2 F.R. router 12b
receives this F.R. OAM message, and takes the subinterface
associated with the Red PVC out of service. In other words the IP
address of the Red PVC is no longer available for data
transmission. The FR edge switch 22 also generates an ATM.RDI
message on the Red PVC back towards the EIWS 16. The EIWS 16
receives the ATM.RDI message for the Red PVC. It converts it into
an EOAM.RDI message for the Red VLAN and forwards it to the
Ethernet router 10b.
[0033] Referring to FIG. 4 of the present invention, there is shown
a block schematic diagram comprising part of the network
architectures of FIG. 1 and the manner in which the trunk failure
detected in the Ethernet domain 14 is transmitted. Trunk failure
T.sub.1 occurs in the Ethernet domain 14 that carries multiple
VLANs as discussed above. T.sub.1 indicates multiple customer
traffic failures have occurred, since more than one customer
circuit is carried on the trunk. In this case, the failure is
detected on the R.sub.x port of a switch in the Ethernet domain for
traffic data being transmitted from the source, routers 10a and 10b
to the destination, routers 12a and 12b. An EOAM.AIS message is
generated in the Ethernet domain 14 towards the EIWS 16 on both the
Green and Red VLANs. The behavior of the network for Green VLANs is
similar to the one described in FIG. 2 and for the Red VLANs is
similar to the one described in FIG. 3.
[0034] Referring to FIG. 5 of the present invention, there is shown
a block schematic diagram comprising part of the network
architecture of FIG. 2 and the manner in which the link failure
notification is transmitted from a source to a destination. Link
failure I.sub.3 occurs in the Ethernet domain 14 for router 10a
(Green VLAN) similar to the one in FIG. 2, however, in this case
the failure is detected on an Rx port of the Ethernet router 10a.
The Ethernet Cust1 Router 10a generates an EOAM.RDI message and
transmits the same from the Ethernet Domain 14 towards the EIWS 16
on the Green VLAN. The EIWS 16 maps the EOAM.RDI message into an
ATM.RDI message, and forwards the ATM.RDI message to ATM network 18
on Green PVC based on the PVC-VLAN mapping table. The ATM network
18 then forwards the ATM.RDI message towards the ATM router 12a.
Upon receipt of the ATM.RDI message, the ATM router 12a processes
the failure notification, and may take the subinterface associated
with the Green PVC out of service. It is to be noted that because
the link failure I.sub.3 was detected by the Cust1 Ethernet Router
10a itself, an AIS message was not generated simply because the
function of the AIS message is to notify the Cust1 Ethernet Routers
of the link failure.
[0035] Referring to FIG. 6 of the present invention, there is shown
a block schematic diagram comprising part of the network
architecture of FIG. 3 and the manner in which the link failure
notification is transmitted from a source to a destination. Link
Failure I.sub.4 occurs on a link in the Ethernet domain 14 for
router 10b (Red VLAN) similar to the one in FIG. 3, however, in
this case, the failure is detected on the Rx port of the Ethernet
Router 10b. An EOAM.RDI message is generated by the Ethernet Cust2
Router 10b and transmitted towards the EIWS 16 on the Red VLAN.
EIWS 16 maps the EOAM.RDI message into an ATM.RDI message, and
forwards the ATM.RDI message on to the applicable PVC (Red PVC)
based on the PVC-VLAN mapping table. The ATM network 18 then
forwards the ATM.RDI message towards the Frame Relay Edge Switch
22. The F.R. Edge Switch 22 receives the ATM.RDI message. It may
create a Frame Relay LMI update on the Red PVC indicating Abit=FAIL
as indicated in FIG. 2 and forward the same to the F.R. router 12b
notifying of the link failure I.sub.4 detection. Again, note that
since the link failure I.sub.4 was detected by the Cust2 Ethernet
Router 10b, the AIS message is not generated.
[0036] Referring to FIG. 7 of the present invention, there is shown
a block schematic diagram comprising part of the network
architecture of FIG. 4 and the manner in which the trunk failure
detected in the Ethernet domain 14 is transmitted. A Trunk Failure
(T.sub.2) occurs in the Ethernet domain 14 that carries multiple
VLANs. In this case, the failure is detected on the Rx port of the
switch in the Ethernet domain 14 for traffic data being transmitted
from the destination, routers 12a and 12b to the source routers 10a
and 10b. An EOAM.AIS message is generated in the Ethernet domain 14
both on the Green and Red VLANs towards the Ethernet Customer
Routers 10a and 10b respectively. Both Customer Routers 10a and 10b
receive the EOAM.AIS messages and in turn generate their own
EOAM.RDI messages towards the EIWS domain 14. The behavior of the
network for Green VLAN is similar to the one described in FIG. 5
and for the Red VLAN is similar to the one described in FIG. 6.
[0037] Referring to FIG. 8 of the present invention, there is shown
a block schematic diagram comprising part of the network
architecture of FIG. 1 and the manner in which the link failure
notification is transmitted from a destination to a source. Link
Failure (I.sub.5) occurs on a link in the ATM domain 18 for ATM
Router 12a (Green PVC). In this case, the failure is detected on
the Rx port of the ATM Router 12a. An ATM.RDI packet is generated
by the ATM router 12a towards the EIWS 16 on the Green PVC. In this
case, EIWS 16 interworks ATM frames to Ethernet frames. When EIWS
16 receives the ATM.RDI message on Green PVC from the ATM network
18, it maps the Green PVC to Green VLAN of the Ethernet Domain 14
using the PVC-VLAN mapping table and converts the ATM.RDI message
to EOAM.RDI message, thereby essentially reversing the process
described previously with reference to FIG. 3. EIWS 16 then
forwards the EOAM.RDI message to the Ethernet network 14 which is
then forwarded to the Ethernet router 10a.
[0038] Referring to FIG. 9 of the present invention, there is shown
a block schematic diagram comprising part of the network
architecture of FIG. 1 and the manner in which the link failure
notification is transmitted from a destination to a source. Link
Failure (I.sub.6) occurs on the Frame Relay link for FR router 12b
(Red PVC). The failure is detected at both the FR Edge Switch 22
and the FR Router 12b. The ER Edge Switch 22 generates an ATM.AIS
message on the Red PVC towards the EIWS 14. The EIWS 14 performs
two functions. One, it generates an ATM.RDI message and sends it
back to the ATM domain 18 which in turn forwards the ATM.RDI
message towards the FR Router 12b on the Red PVC. Since the link
failure occurred on both the FR edge switch and router 12b, the
router never receives this second LMI failure update. The ATM.RDI
message is an acknowledgement by the EIWS 14 that it has
successfully received the failure notification message. Second, the
EIWS 16 receives the ATM.AIS message and maps it into an EOAM.AIS
message. It then forwards the EOAM.AIS message on to the applicable
VLAN (Red VLAN) based on the PVC-VLAN mapping table. The EOAM.AIS
message is received at the Ethernet Router 10b via the Ethernet
Domain 14. The Ethernet router 10b receives the EOAM.AIS message,
processes the failure, and takes the subinterface associated with
the Red VLAN out of service. In other words, the IP address
associated with Red VLAN is no longer available for data
transmission. Also, the Ethernet Router 10b per Ethernet protocol
responds with an EOAM.RDI message and sends the same into the
Ethernet domain 14 on the Red VLAN. The Ethernet domain 14 forwards
the message to the EIWS 16. The EIWS 16 receives the EOAM.RDI
message for the Red VLAN and generates an ATM.RDI message for the
Red PVC and forwards it to the F.R. Edge Switch 22. The F.R. Edge
Switch 22 receives the ATM.RDI message. However, since the link
between the FR Edge Switch 22 and the ATM router 10b has been
disconnected, it does nothing with the RDI message.
[0039] Referring to FIG. 10 of the present invention, there is
shown block schematic diagram comprising part of the network
architecture of FIG. 1 and the manner in which the trunk failure
detected in the ATM domain 18 is transmitted. A Trunk Failure
(T.sub.3) occurs in the ATM domain 18 that carries multiple PVCs.
In this case, the failure is detected on the Rx port of an ATM
switch in the ATM domain 18 for traffic data being submitted from
the source routers 10a and 10b to the destination routers 12a and
12b. The ATM Network 18 immediately generates ATM.AIS messages on
both Green and Red PVCs towards the ATM/FR routers 12a and 12b
respectively. The ATM router 12a receives the ATM.AIS message,
processes the failure, and takes the subinterface associated with
the Green PVC out of service. When the F.R. Edge Switch 22 (Red
PVC) receives the ATM.AIS message, it converts it into an LMI
message with Abit=Fail. It then forwards the LMI message to the
F.R. router 12b. The F.R. Router 12b receives the message,
processes the failure, and takes the subinterface associated with
the RED PVC out of service. The ATM router 12a responds with an
ATM.RDI message for the Green PVC. Likewise, the F.R. Edge Switch
22 responds with an ATM.RDI message for the Red PVC. Both RDI
messages are forwarded to the EIWS 16 via the ATM Domain 18 on
their respective PVCs. The EIWS 16 maps the ATM.RDI messages into
EOAM.RDI messages and forwards the EOAM.RDI messages on to the
applicable VLANs based on the PVC-VLAN mapping table. The EOAM
messages of the trunk failure notification are received at the
applicable Ethernet Routers 10a and 10b on the Green and Red VLANs
respectively.
[0040] Referring to FIG. 11 of the present invention, there is
shown block schematic diagram comprising part of the network
architecture of FIG. 1 and the manner in which the link failure
notification is transmitted from a destination to the source. Link
Failure (I.sub.7) occurs in the ATM domain 18 between ATM edge
switch 24 and ATM router 12a (Green PVC). In this case, the failure
is detected on the Rx port of an ATM Switch 24. The ATM Domain 18
generates an ATM.AIS message on the Green PVC towards the EIWS 16.
The EIWS 16 performs two functions. One, it generates an ATM.RDI
message back into the ATM domain 18 towards the ATM Router 12a.
Second, the EIWS 16 maps the ATM.AIS message into an EOAM.AIS
message. It then forwards the EOAM.AIS message on to the applicable
VLAN (Green VLAN) based on the PVC-VLAN mapping table. The EOAM.AIS
message is received at the Ethernet Router 10a. The Ethernet router
10a receives the EOAM message, processes the failure, and takes the
subinterface associated with the Green VLAN out of service. The
Ethernet Router 10a responds with an EOAM.RDI message on the Green
VLAN. This EOAM.RDI message is an acknowledgement by Cust1 Ethernet
Router 10a that it has successfully received the failure
notification message. The EOAM.RDI message on the Green VLAN is
transmitted through the Ethernet domain 14 towards the EIWS 16. The
EIWS 16 receives the EOAM.RDI message and generates a ATM.RDI
message into the ATM domain 18. The ATM domain 18 then forwards the
message to the ATM Router 12a. Note that the ATM.RDI message is a
redundant message reiterating the link failure detection.
[0041] Referring to FIG. 12 of the present invention, there is
shown a block schematic diagram comprising part of the network
architecture of FIG. 1 and the manner in which the trunk failure
detected in the ATM domain 18 is transmitted. A Trunk Failure
(T.sub.4) occurs in the ATM domain 18 that carries multiple PVCs.
In this case, the failure is detected on the Rx port of the ATM
switch for traffic data flowing towards the EIWS. The ATM Network
18 generates ATM.AIS messages towards the EIWS 16 for both Green
and Red PVCS. EIWS 16 converts the ATM.AIS messages into EOAM.AIS
messages and transmits EOAM.AIS messages on both Green and Red
VLANs. EIWS 16 also sends ATM.RDI messages back toward routers 12a
and 12b (see FIGS. 9 & 11).
[0042] It will be apparent that the present invention has been
described herein with reference to certain preferred or exemplary
embodiments. The preferred or exemplary embodiments described
herein may be modified, changed, added to, or deviated from without
departing from the intent, spirit and scope of the present
invention, and it is intended that all such additions,
modifications, amendments and/or deviations be included within the
scope of the following claims.
* * * * *