Multiplex communications – Network configuration determination – Using a particular learning algorithm or technique
Reexamination Certificate
1999-01-12
2003-02-11
Kizou, Hassan (Department: 2662)
Multiplex communications
Network configuration determination
Using a particular learning algorithm or technique
C370S254000, C370S255000, C370S400000, C709S220000, C709S228000
Reexamination Certificate
active
06519231
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to data communications networks and, more specifically, the present invention relates to multi-link trunk data communications networks using the spanning tree protocol.
2. Background Information
Data communications networks may be used to interconnect many computing resources, such as for example computers, workstations, servers, printers, modems, storage devices, etc. For example, two or more computers may be connected together through a network. Network users are able to, among other things, share files, printers and other resources, send messages and run applications on remote computers. An important part of any data communications network includes the physical components, boxes or network communications devices used to interconnect the computing resources.
FIG. 1
is an illustration of data communications network
101
including a box A
103
, a box B
105
and a box C
107
. Boxes A
103
, B
105
and C
107
are network communication devices such as for example, bridges, switches, etc. As shown in
FIG. 1
, a physical link
109
is used to connect box A
103
to box B
105
. Physical link
109
is coupled between port
1
of box A
103
and port
3
of box B
105
. Physical link
111
is used to connect box B
105
to box C
107
. Physical link
111
is coupled between port
4
of box B
105
and port
5
of box C
107
. A physical link
113
is used to connect box A
103
to box C
107
. Physical link
113
is coupled between port
2
of box A
103
and port
6
of box C
107
.
During operation of data communications network
101
, packets are broadcast and forwarded among boxes A
103
, B
105
and C
107
through the physical links
109
,
111
and
113
. For example, box A
103
may transmit a packet to box B
105
through physical link
109
. After box B
105
receives the broadcast packet from box A
103
, box B
105
forwards the received packet through the other ports of box B
105
. Therefore, box B
105
forwards the broadcast packet from port
4
through physical link
111
to box C
107
. Similarly, after box C
107
receives the broadcast packet from box B
105
, box C
107
forwards the received packet through the other ports of box C
107
. Therefore, box C
107
forwards the broadcast packet from port
6
through physical link
113
back to box A
107
.
Even though box A
103
originated the packet received from box C
107
through physical link
113
, box A
103
will nevertheless reforward the received packet back out of port
1
through physical link
109
to box B
105
. Consequently, broadcast packets that are forwarded throughout a network may be replicated and rebroadcast by each box and loop continuously throughout the network and cause an undesired avalanche.
To remedy this situation, the loop in data communications network
101
may be identified and removed to prevent broadcast packets from being continuously rebroadcast. For example, assume box A
103
is determined to be a root node and that boxes B and C
105
and
107
are leaf nodes in data communications network
101
. Thus, the loop in data communications network may be removed by preventing packets from being forwarded between box B
105
and box C
107
. As result, broadcast packets are no longer continuously rebroadcast throughout data communications network
101
. One known protocol for identifying and removing loops in a data communications network is the spanning tree protocol as described in ANSI/IEEE Standard 802.1D.
Another important factor in data communications network is the bandwidth of the connections between the boxes of the network. Bandwidth is defined to be the amount of data that can be transmitted over a link in a given period of time. As the usage of a data communications network increases, the amount of traffic that is carried by the links between the boxes of the data communications network increases. If the bandwidth of the connections between the boxes of the network is not adequate to carry all of the network traffic, network performance is compromised.
One known method of increasing the bandwidth of connections between boxes in data communications networks is the utilization of a multi-link trunk.
FIG. 2
provides an illustration of a data communications network
201
including a multi-link trunk
209
coupling a box A
203
to a box B
205
.
FIG. 2
also shows data communications network
201
including a box C
207
coupled to box A
203
through a physical link
215
. Multi-link trunk
209
includes two physical links shown as physical link
211
and physical link
213
. Together, physical links
211
and
213
form the single logical link of multi-link trunk
209
.
The multi-link trunk
209
coupling together boxes A
203
and B
205
includes two physical links
211
and
213
in comparison to the single physical link
215
coupling together boxes A
203
and C
207
. Assuming the bandwidth of physical links
211
,
213
and
215
are all equal, the bandwidth of the multi-link trunk
209
connection between boxes A
203
and B
205
is twice that of the connection between boxes A
203
and C
207
. Therefore, network performance of communications between box A
203
and box B
205
is improved with multi-link trunk
209
.
A problem arises when using the spanning tree protocol to remove loops in data communications networks that utilize multi-link trunks. To illustrate,
FIG. 3
shows a data communications network
301
that suffers from a loop condition. Data communications network
301
includes a multi-link trunk
309
that couples a box A
303
to a box B
305
. Multi-link trunk
309
includes two physical links shown as physical link
311
and physical link
313
. Together, physical links
311
and
313
form the single logical link of multi-link trunk
309
. Data communications network
301
also includes a box C
307
coupled to box A
303
through a physical link
317
. Box C
307
is also coupled to box B
305
through a physical link
315
.
During operation of data communications network
301
, box A
303
may transmit a packet to box B
305
through multi-link trunk
309
. After box B
305
receives the broadcast packet from box A
303
, box B
305
forwards the received packet through other ports of box B
305
. Therefore, box B
305
forwards the broadcast packet from port
6
through physical link
315
to box C
307
. Similarly, after box C
307
receives the broadcast packet from box B
305
, box C
307
forwards the received packet through other ports of box C
307
. Thus, box C
307
forwards the broadcast packet from port
8
through physical link
317
back to box A
303
, which is where the packet originated. Therefore, there is a loop condition in data communications network
301
.
As discussed earlier, the known spanning tree protocol may be used to identify and remove loops in data communications networks. Assuming that box A
303
is determined to be a root node, the spanning tree protocol would remove the loop by preventing packets from being forwarded across physical link
315
between box B
305
and box C
307
. However, the known spanning tree protocol would also detect a loop condition existing between box A
303
and box B
305
because of the multiple physical links of multi-link trunk
309
. In particular, physical links
311
and
313
form a loop between box A
303
and box B
305
. Consequently, the known spanning tree protocol would prevent packets from being forwarded across either physical link
311
or physical link
313
, thereby transforming the high bandwidth connection of multi-link trunk
309
into an ordinary single physical link.
SUMMARY OF THE INVENTION
A method and an apparatus for interconnecting a plurality of boxes in data communications network is disclosed. In one embodiment, the first and second ports of a first box are coupled to first and second ports of a second box, respectively, to form first and second physical links between the first and second boxes. The first and second physical links form a logical
Ding Da-Hai
Ilyadis Nicholas
Kong Nelson
Blakely , Sokoloff, Taylor & Zafman LLP
Logsdon Joe
Nortel Networks Limited
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