U.S. patent application number 11/683246 was filed with the patent office on 2007-07-05 for interface link layer device for long delay connections.
This patent application is currently assigned to Sony Deutschland GmbH. Invention is credited to Peter Buchner, Gralf Gaedeken, Gerd SPALINK.
Application Number | 20070153700 11/683246 |
Document ID | / |
Family ID | 8168046 |
Filed Date | 2007-07-05 |
United States Patent
Application |
20070153700 |
Kind Code |
A1 |
SPALINK; Gerd ; et
al. |
July 5, 2007 |
INTERFACE LINK LAYER DEVICE FOR LONG DELAY CONNECTIONS
Abstract
An interface link layer device (1) to be connected in-between a
first sub net-work (5) and a long delay link (3) to which at least
one second sub network (4) is connected via another interface link
layer device (2) is able to simulate or replace time critical
messages of the at least one second sub network (4). To set-up a
network with such interface link layer devices information about
the configuration of the sub network (5; 4) connected to an
interface link layer device (1; 2) is transmitted from said
respective interface link layer device (1; 2) to all other
interface link layer devices (2; 1) connected to said respective
interface link layer device (1; 2) via the long delay link (3),
whereafter a respective interface link layer device (2; 1)
connected thereto which received information about the
configuration of at least one other sub network (5; 4) is able to
perform the necessary simulation.
Inventors: |
SPALINK; Gerd; (Stuttgart,
DE) ; Gaedeken; Gralf; (Weinsberg, DE) ;
Buchner; Peter; (Kirchheim, DE) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
Sony Deutschland GmbH
Berlin
DE
|
Family ID: |
8168046 |
Appl. No.: |
11/683246 |
Filed: |
March 7, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09799748 |
Mar 6, 2001 |
|
|
|
11683246 |
Mar 7, 2007 |
|
|
|
Current U.S.
Class: |
370/238 |
Current CPC
Class: |
H04L 12/64 20130101;
G06F 13/4072 20130101; H04L 12/462 20130101 |
Class at
Publication: |
370/238 |
International
Class: |
H04J 3/14 20060101
H04J003/14 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 7, 2000 |
EP |
00 104 844.6 |
Claims
1. A portal connected as a local node to a first bus and configured
to exchange data between the first bus, and a second portal
connected as a local node to a second bus, wherein said portal,
comprises: an interface configured to receive, from said second
portal, node information comprising node ID information pertaining
to nodes remote to said first bus; a memory configured to store
node ID translation information based on said node ID information;
and a module configured to translate, on the basis of said node ID
translation information, a node ID of packets sent via said portal
from a local node of said first bus to a local node of said second
bus.
2. A portal connected as a local node to a first bus and configured
to exchange data between the first bus and a second portal that is
connected as a local node to a second bus, wherein said portal,
comprises: an interface configured to receive, from said second
portal, node information comprising node ID information pertaining
to nodes remote to said first bus; a memory configured to store
node ID translation information based on said node ID information;
and a module configured to translate, on the basis of said node ID
translation information, a node ID of packets received at said
portal from a local node of said second bus destined for a local
node of said first bus.
3. A portal connected as a local node to a first bus and configured
to exchange data between the first bus and a second portal that is
connected as a local node to a second bus, wherein said portal,
comprises: an interface configured to send, to said second portal,
node information comprising node ID information pertaining to nodes
local to said first bus; a memory configured to store node ID
translation information based on node ID information received from
said second portal; and a module configured to translate, on the
basis of said node ID translation information, a node ID of packets
sent via said portal from a local node of said first bus to a local
node of said second bus.
4. A portal connected as a local node to a first bus and configured
to exchange data between the first bus and a second portal that is
connected as a local node to a second bus, wherein said portal,
comprises: an interface configured to send, to said second portal,
node information comprising node ID information pertaining to nodes
local to said first bus; a memory configured to store node ID
translation information based on node ID information received from
said second portal; and a module configured to translate, on the
basis of said node ID translation information, a node ID of packets
received at said portal from a local node of said second bus
destined for a local node of said first bus.
5. A portal for interfacing data packets between a first bus and a
bridge over a network in which said portal interconnects said first
bus and said bridge and a second portal interconnects said bridge
and a second bus, wherein said portal, comprises: a memory
configured to store node ID information for each node local to a
bus other than said first bus, said node ID information comprising
a virtual node ID assigned to the respective node in correlation
with a physical node ID of said respective node; and a module
configured to selectively transform, when said bus receives/sends
data packets from/over said network, addressing information of said
data packets on the basis of said node ID information from a
virtual node ID to a corresponding physical node ID or from a
physical node ID to a corresponding virtual node ID.
6. A portal for routing data packets between a first bus and a
second bus in a network, wherein in said network said portal
interconnects said first bus and a bridge and a second portal
interconnects said bridge and said second bus, wherein said portal,
comprises: a first interface configured to perform serial data
communication with a node of said first bus via said first bus; the
interface configured to forward data packets received via said
bridge from said second bus to said node; and a first module
configured to transform a destination ID of said data packets to be
forwarded to said node from a node ID assigned by said second
portal into a node ID locally assigned to said node at said first
bus.
7. The portal of claim 6, further comprising: a second interface
configured to transmit data packets received from said node to said
second bus via said communication path; and a second module
configured to transform a source ID of said data packets to be
transmitted to said second bus from a node ID locally assigned to
said node in said first bus into a node ID used by said second
portal.
8. The portal of claim 7, wherein said first module and said second
module are the same module.
9. The portal of claim 7, wherein said first interface and said
second interface are the same interface.
10. A portal for routing data packets between a first bus and a
second bus in a network, wherein in said network said portal
interconnects said first bus and a bridge and a second portal
interconnects said bridge and said second bus, wherein said portal,
comprises: an interface configured to transmit data packets
received from a node connected to said first bus to said second bus
via said bridge; and a module configured to transform a source ID
of said data packets to be transmitted to said second bus from a
node ID locally assigned to said node in said first bus into a node
ID used by said second portal.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 09/799,748 filed Mar. 6, 2001, and claims the benefit of
priority under 35 U.S.C. .sctn. 119 from European Patent
Application No. 00 104 844.6, filed Mar. 7, 2000, the entire
contents which is incorporated herein by reference.
DESCRIPTION
[0002] The present invention relates to an interface link layer
device for a network comprising a long delay link and a method of
setting up such a network which comprises at least two sub networks
each of which is connected via an inter-face link layer device
according to the present invention to said long delay link. In
particular, the present invention relates to a transparent long
delay IEEE 1394 network.
[0003] The EP 0 848 568 A1 and the European Patent Application with
the Application No. 99 126 221.3 which is filed by the Applicant of
the present invention and herewith incorporated into this
specification describe e. g. coaxial interfaces between two IEEE
1394 serial bus systems, i. e. sub networks, to build a distributed
IEEE 1394 network.
[0004] Generally, networks according to the IEEE 1394 standard work
only with nodes with short, direct interconnections, since very
strict timing requirements, e. g. during the self identification
phase (in the following self ID phase), have to be fulfilled. For
example, standard wired IEEE1394 networks are limited to 4, 5
meters length for every cable.
[0005] To build networks which are e. g. not only set up in one
room, but inside the whole home plastic optic fiber (POF)
implementations are known to ensure longer transmission paths.
However, these POF implementations have the disadvantage of
requiring a new plastic optic fiber cabling inside the home.
[0006] On the other hand, coaxial cable is available in many homes,
since such cables build the basis for current radio and television
reception, but the channel encoding/decoding required when setting
up a network with coaxial cable according to the IEEE 1394 standard
produces a significant delay. Therefore, a transparent
self-configuration according to which every node within the network
knows which other node is connected as used for a POF
implementation is not possible. Wireless transmission is even more
convenient, but the transmission technology also produces
significant delays for which reason a special adaptation is
necessary which is not included within the IEEE 1394 standard.
[0007] An extension to the IEEE 1394 standard, namely the DRAFT
IEEE 1394.1 standard tries to enable connections of IEEE 1394
networks through a bridge, but inherits two main disadvantages,
namely that (1) this standard is not 1009'0 backwards compatible,
and (2) the controllers within the IEEE 1394.1 network must be
aware that bridge devices exist, i. e. the IEEE 1394.1 network is
not fully transparent in both communication directions between two
sub networks.
[0008] Therefore, it is the object underlying the present invention
to provide a solution for distributed networks including at least
two sub networks which are connected by a long delay link, which is
backwards compatible and fully trans-parent in both directions of
communication in-between two sub networks.
[0009] This object is solved by an interface link layer device
which is to be connected in-between a first sub network and a long
delay link to which at least one second sub network is connected
via another interface link layer device according to the present
invention.
[0010] A method to set-up such a network and a preferred embodiment
thereof is described in the present invention.
[0011] According to the present invention the main problem of the
prior art described above to meet the severe timing requirements,
e. g. during the self ID phase in which each network device, i. e.
node, identifies itself to the network, i. e. to all other nodes,
are met within a distributed network in which at least two sub
networks exists which are interconnected by a long delay link,
since according to the present invention the interface link layer
device which is allocated to one sub network via which this sub
network is connected to the long delay link simulates all other sub
networks in that at least the timing requirements of nodes
connected to said other sub networks are fulfilled. Therefore, in
case of a self ID phase when every connected node has to present
certain information, e. g. its presence within a certain time
frame, the interface link layer device according to the present
invention outputs this information of the sub network which it
simulates to the sub network to which it is allocated within the
given time. Similar in case of requests to nodes connected to other
sub networks a request pending message can be sent to the
requesting device in advance from the interface link layer device
according to the present invention before the "real" answer comes
from the device to which the request was addressed.
[0012] To initialize or set up such a distributed network all
interface link layer de-vices according to the present invention
behave initially like a single node which is connected to the
respective sub network. After an initial self ID phase after which
all interface link layer devices according to the present invention
know the number of nodes and their respective information of the
connected sub network to which they are respectively allocated this
information is transmitted via the long delay link to all other
interface link layer devices according to the present invention. In
case a link layer device according to the present invention
receives such information it initiates a second self ID phase
within the respective connected sub network, e. g. with a bus
reset, and behaves during this phase like the number of nodes with
the respective information received according to the IEEE 1394
standard. Since preferably the nodes within each sub network need
not to be configured to have different node IDs, i.e. a node within
a first sub network can have the same node ID as another node
within a second sub network but the real and virtual nodes within
one sub network must have and get automatically assigned different
node IDs, the interface link layer device according to the present
invention translates in this case node IDs of the addressed
virtual, i. e. simulated devices to node IDs that are used in the
respective physical sub network which is simulated and vice
versa.
[0013] After such an initialization and apart from the simulations
necessary to full-fill the given timing requirements the interface
link layer devices according to the present invention perform an
operation of a link layer device, i.e. to for ward data packets
from the link in-between at least two sub networks to a sub network
and vice versa as it is e. g. described in the above referenced
documents.
[0014] The present invention and its embodiments will be better
understood from a detailed description of an exemplary embodiment
thereof taken in conjunction with the accompanying drawing,
wherein
[0015] FIG. 1 shows a distributed network including two sub
networks connected by a long delay bi-directional connection via a
respective interface link layer device according to the present
invention.
[0016] FIG. 1 shows an IEEE 1394 network comprising a first sub
network 5 and a second sub network 4 which are connected with each
other by a long delay bi-directional connection 3. In-between the
first sub network 5 and the long delay bi-directional connection 3
a first interface link layer device 1 is arranged which is
allocated to and therefore regarded to belong to the first sub
network 5, i. e. which behaves like a network device or node within
the first sub network 5. Similar, a second interface link layer
device 2 is connected in-between the second sub network 4 and the
long delay bi-directional connection 3 which is allocated to and
therefore regarded to belong to the second sub network 4.
[0017] In the shown example the first sub network 5 comprises 3
nodes, namely a first node 5A which is named device C and has a
node ID 4, a second node 5B which is named device D and has a node
ID 3, and a third node 5C which is named device E and has a node ID
2. Further, the second sub network 4 comprises a fourth node 4A
which is named device A and has a node ID 2 and a fifth node 4B
which is named device B and has a node ID 3.
[0018] As described in the introductory part of this specification
such networks as de-scribed above which comprise two or more sub
networks connected with each other by a long delay bi-directional
connection are known in the prior art, but inherit the drawbacks
also mentioned above to be not 100% backwards compatible and fully
transparent in both directions of communication, or requiring an
expensive fiber optic cabling.
[0019] According to the present invention, on the other hand, each
of the first inter-face link layer device 1 and the second
interface link layer device 2 has the feature to transmit
information about its own sub network 5, 4 to the respective other
interface link layer device 2, 1, and based on information received
from the respective other interface link layer device 2, 1 simulate
the respective sub network 4, 5 the respective other interface link
layer device 2, 1 is connected to. Such a simulation is performed
by a respective interface link layer device 1, 2 according to the
present invention at least during phases with severe timing
requirements, such as the self ID phase during which each node of a
sub network identifies itself to the sub network.
[0020] Therefore, in the shown example the first interface link
layer device 1 which is named interface 1 "comprises" the virtual
fourth node 4A' which is a simulation of the fourth node 4A, namely
of the device A, and the virtual fifth node 4B' which is a
simulation of the node 4B, namely of the device B. The second
interface link layer device 2 which is named interface 2
"comprises" the virtual first node 5A' which is a simulation of the
first node 5A, namely of the device C, the virtual second node 513'
which is a simulation of the second node 5B, namely of the device
D, and the virtual third node 5C' which is a simulation of the
third node 5C. namely of the device E.
[0021] The respective interface link layer device 1, 2 according to
the present invention behaves like the number of nodes about which
it received information so that new node identifiers are
automatically assigned during a self ID phase to the virtual nodes
according to the IEEE 1394 standard to secure that within each of
the sub networks 5, 4 no conflicts occur. Therefore, within the
first sub network 5, e. g. the node identifiers 2 to 4 are assigned
to the physical nodes 5A to 5C and node identifiers different to 2
to 4 to the virtual fourth and fifth node 4A' and 413' within the
interface link layer device 1, in the shown example the node ID 0
for the virtual fourth node 4A' and the node ID 1 for the virtual
fifth node 4B'. Similar, within the second sub network 4 the node
identifiers 2 and 3 are assigned to the physical fourth and fifth
nodes 4A and 4B and node identifiers different thereto are assigned
to the virtual first to third nodes 5A', 5B' and 5C' within the
second interface link layer device 2, for example as shown in FIG.
1, the node ID 4 for the virtual first node 5A', the node ID 1 for
the virtual second node B', and the node ID 0 for the virtual third
node 5C'.
[0022] To be able to properly simulate the respective other sub
network, i. e. the respective sub network a respective interface
link layer device is connected to not directly, but only via the
long delay link, the following initialization procedure is
performed:
[0023] Initially, the first sub network 5 and the second sub
network 4 behave and act as independent networks respectively
comprising the network devices and an interface link layer device
which acts as a normal network device or network controller.
Therefore, in the initial phase during which both interface link
layer devices 1, 2 behave like a single node the first sub network
5 knows after a self ID phase that it comprises four nodes, namely
the first to third nodes 5A to 5C and the first interface link
layer device 1. Since this information is distributed within the
whole first sub network 5 also the first interface link layer
device 1 is able to collect the necessary information about the
network topology of the first sub network 5. Similar, after the
initial self ID phase of the second sub network 4 the interface
link layer device 2 knows that the second sub network 14 comprises
the fourth node 4A, the fifth node 4B, and the second interface
link layer device 2.
[0024] After such a self ID phase within one of the sub networks 5,
4 during which a respective interface link layer device 1, 2
collected new information such information is distributed via the
long delay bi-directional connection 3 to the respective other
interface link layer device 2, 1. In the shown example, for
per-forming the self ID phase, this information might comprise the
number of nodes connected to a respective sub network and their
name. In this way the first interface link layer device 1 gets the
information that the second sub network 4 comprises two network
devices apart from the second interface link layer device 2, namely
the fourth node 4A, i. e. the device A and the fifth node 413,
namely the device B, and the second interface link layer device 2
gets the information that the first sub network 5 comprises three
devices apart from the first interface link layer device 1, namely
the first node 5A, i. e. the device C, the second node 513, namely
the device D, and the third node 5C, namely the device E.
[0025] Preferably, both interface link layer devices 1, 2 should
also know the whole network topology, i. e. the topology of each
sub network 5, 4.
[0026] Finally, after receiving such an information via the long
delay bi-directional connection 3 each of the interface link layer
devices 1, 2 according to the present invention initiates a second
self ID phase within the own connected sub network, e. g. with a
bus reset. During this second self ID phase which is initiated
since the respective interface link layer device according to the
present invention received information about another sub network,
the interface link layer device 1, 2 which received such
information simulates a certain number of nodes according to the
information received. Therefore, the first interface link layer
device 1 simulates the second sub network, namely the fourth device
4A and the fifth device 4B, and the second interface link layer
device 2 simulates the first sub network, namely the first to third
nodes 5A to 5C. This simulation is performed strictly according to
the IEEE 1394 standard, e. g. the first interface link layer device
1 sends two self ID packets to the first sub net-work 5 and
represents two node IDs after the self ID phase. Likewise, the
second interface link layer device 2 sends three self ID packets
and represents three node IDs after the self ID phase. During this
second self ID phase the 1 node identifiers within a sub network
are newly assigned according to the IEEE 1394 standard. Therefore.
to properly set-up a node ID translation table within each of the
interface link layer devices 1, 2 an information about the new node
IDs is exchanged in-between all connected interface link layer
devices 1. 2.
[0027] A bus reset to initiate a new self ID phase is always
carried out in case a device is newly connected to an IEEE 1394
bus, removed therefrom or a device requests it. Therefore, based on
this automatic self configuration mechanism de-fined within the
IEEE 1394 standard, also the network set-up according to the
present invention is always kept in a transparent self configured
state, since an interface link layer device 1, 2 according to the
present invention collects the information of the connected sub
network 5, 4 in case of a not self initiated self ID phase and
transmits it to another interface link layer device 2. 1 connected
to the long delay link 3 which in turn initiates a new self ID
phase within the respective own connected sub network as described
above.
[0028] Preferably, if an interface link layer device according to
the present invention already comprises information about another
sub network, this information is also used during a not self
initiated self ID phase to simulate this other sub network for the
purpose of speeding up the whole self ID phase within the whole
network. Further preferably, in case an interface link layer device
ac-cording to the present invention receives an information from
another interface link layer device which is not different to the
information already received, no self initiated self ID phase is
initiated by said interface link layer device.
[0029] Since the node identifiers of the virtual nodes simulated
within the interface link layer device according to the present
invention are changed in respect to the nodes which are simulated
the interface link layer device according to the present invention
also translates the node IDs in packets that are sent to the other
side of the long delay link 3 on basis of the node ID translation
table which is set up after the second above-described self ID
phase as described above.
[0030] To properly simulate a respective sub network 4, 5 a
respective interface link layer device 1, 2 preferably simulates
not only the number of nodes within the respective other sub
network 4, 5, but also the topology, i. e. the connection scheme of
the respective nodes. Therewith, within each of the sub networks 4,
5 the whole network is build up by physical and virtual nodes
according to the same topology as if a normal link would be present
instead of the interface link layer devices 1, 2 according to the
present invention and the long delay link 3. This scheme is also
shown in FIG. 1 in which the device C, i. e. the first node 5A,
builds the root of the first sub network 5 to which the devices D
and E, namely the second and third nodes 5B and 5C, are
respectively directly connected, and in which the device B, namely
the fifth node 4B, builds the root of the second sub network 4 to
which the device A, namely the fourth node 4A, is directly
connected, and in which the link in-between said both sub networks
5, 4 is set up in-between both roots, i. e. in-between the first
node 5A and the fifth node 4B.
[0031] Since the above example is based on the IEEE 1394 standard
and the number of nodes should be addressed with node IDs only, i.
e. the bus ID of the IEEE 1394 physical layer is not used, the
number of nodes connected to the interface link layer devices is
limited to 63, i. e. the whole network can have a maximum of 63
connected devices which each represent an own node.
[0032] According to the present invention the long delay
bi-directional connection 3 might have a delay larger than timeouts
defined according to the IEEE 1394 standard, e. g. in the order of
100 .mu.s . . . 10 ms, since for larger delays asynchronous IEEE
1394 transactions may fail, because timing requirements are not
met. However, in case the appropriate information is transmitted
after the initial self ID phase from one interface link layer
device to another interface link layer device this other interface
link layer device can not only simulate the respective other sub
network during the self ID phase to meet the timing requirements,
but also during normal operation, e. g. by distributing commands or
answers to the connected sub network which indicate that the
respective addressed device which is simulated by the interface
link layer device needs some time to process the answer, or by
locally storing all or some registers of a device to be simulated
within the interface link layer device, since a command to a device
can always be seen as a read request to a respective device
according to the IEEE 1212 standard which defines the control and
status register architecture as a higher layer of the IEEE1394
standard. For example, the respective bus info block defining the
capabilities of a device/node can be stored within the interface
link layer device according to the present invention.
[0033] The long delay link 3 through which the interface link layer
devices according to the present invention communicate might be a
coaxial cable, a wireless, an infra-red, an asynchronous transfer
mode (ATM) which is used for professional long distance, high speed
data connections, an unshielded twisted pair (UTP), a plastic optic
fibre (POF) and/or another appropriate connection, e. g. a
combination of the aforesaid types of connections. Such a
connection is assumed to be static. If the network topology on one
side, i. e. within one sub network, changes, the sub network on
this side reconfigures itself by the standard IEEE 1394 mechanism
and the new network topology information or further information
required to properly simulate this sub network is transmitted to
the other interface link layer device whereafter this other
interface link layer device performs a new self ID phase within the
connected sub network.
[0034] Since the interface link layer devices according to the
present invention only require an own node identifier during a self
ID phase during which they do not simulate another sub network no
node identifiers are "wasted" during operation, since in this case
only node identifiers for the simulated devices are needed.
[0035] Of course, the present invention is not limited to a network
consisting of two sub networks, but can also comprise three or more
sub networks connected to the same long delay bi-directional link
3. In this case the communication on the long delay link 3 may be
organized in packets or in channels as described in the
above-referenced European Patent Application 99 126 221.3 and each
interface link layer device simulates two or more sub networks.
[0036] In case no node at all is connected to one sub network, i.
e. only the interface link layer device according to the present
invention is present within this sub network it is possible that
the link in-between this interface link layer device and the other
interface link layer devices connected through the long delay link
3 has not to be established and therefore the respective other
interface link layer devices will not simulate nodes of this
particular sub network. In case the whole network would only
comprise two interface link layer devices the interface link layer
device connected to the "existing" sub network might behave like a
simple IEEE 1394 repeater.
[0037] According to the invention a distributed network including a
long delay link can be built up compatible with existing IEEE1394
devices. These devices need not to know that a long delay
connection exists when they communicate with a device simulated
inside one of the interface link layer devices. Therefore,
ac-cording to the present invention a distributed IEEE 1394 network
including a 5 long delay link is built up which is completely
transparent and retaning all the advantages of the IEEE 1394
standard.
[0038] Of course, the invention can also be applied to other
communication standards to set-up long delay links while fulfilling
timing requirements.
* * * * *