Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
2001-05-10
2003-08-19
Kizou, Hassan (Department: 2662)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S244000, C370S374000
Reexamination Certificate
active
06608836
ABSTRACT:
FIELD OF THE INVENTION
The field of invention relates generally to communication; and more specifically, to a method and apparatus for an egress channel architecture that supports protection within SONET/SDH based networks.
BACKGROUND
Protection within SONET Networks
Synchronous Optical NETwork (SONET) and Synchronous Digital Hierarchy (SDH) based networks typically emphasize redundancy. That is for example, should a particular network line that couples a pair of nodes within the network fail (or degrade), the network is designed to “switch over” to another network line so that traffic flow is not substantially interrupted. Various types of redundancy may be designed into a SONET network. Some examples are illustrated in the discussion that follows.
FIG. 1
shows a point-to-point perspective. Point to point redundancy focuses on the behavior of a pair of nodes
131
,
132
that are coupled together by a plurality of SONET lines
104
1
,
104
2
, . . .
104
x−1
,
104
x
. Although other point-to-point schemes may be possible, common point-to-point schemes typically include 1+1 and 1:N. Both schemes classify a network line as either a working line or a protection line. A working line is deemed as the “active” line that carries the information transported by the network. A protection line serves as a “back-up” for a working line. That is, if a working line fails (or degrades), the protection line is used to carry the working line's traffic.
In a 1+1 scheme, both the working and protection lines simultaneously carry the same traffic. For example, referring to
FIG. 1
, if line
104
1
is the working line and line
104
2
is the protection line; the transmitting node
131
simultaneously transmits the same information on both the working line
104
1
and the protection line
104
2
. The receiving node
132
, during normal operation, “looks to” the working line
104
1
for incoming traffic and ignores the incoming traffic on the protection line
104
2
. If a failure or degradation of the working line
104
1
is detected, the receiving node
132
simply “looks to” the protection line
104
2
for the incoming traffic (rather than the working line
104
1
).
In a 1:N scheme one protection line backs up N working lines (where N is an integer greater than or equal to 1). For example, referring to
FIG. 1
, lines
104
1
through
104
x−1
may be established as the working lines while line
104
x
may be established as the protection line. If any of the working lines
104
1
through
104
x−1
fail or degrade, the transmitting node
132
sends the traffic of the failed/degraded working line over the protection line
104
x
. The receiving node
132
also “looks to” the protection line
104
x
for the traffic that would have been sent over the failed/degraded working line prior to its failure/degradation.
FIG. 2
shows a ring perspective. Ring redundancy schemes focus on the behavior of a plurality of nodes
231
through
234
coupled together in a ring. Redundancy is handled by sending identical streams of traffic in opposite directions. A first direction may be referred to as the working direction while a second direction may be referred to as the protection direction. In a Unidirectional Line Switched Ring (ULSR) approach, working traffic is sent in a first direction around the ring (e.g., clockwise) and protection traffic is sent in a second direction around the ring (e.g., counter-clockwise).
In a Bi-directional Path Switched Ring (BPSR), the working traffic flows in the “fastest” direction. That is, of the two directions around the ring from a transmitting node to a receiving node, a first direction will have a shorter propagation delay than a second direction. For each transmitting/receiving node pair, the working traffic corresponds to the direction having the shorter propagation delay and the protection traffic corresponds to the direction having the longer propagation delay. In either the ULSR or BPSR approaches, if failure or degradation occurs in the working direction, active traffic is looked for in the protection direction.
More sophisticated SONET networks may also be designed that provide protection at higher degrees of resolution. That is, each SONET line (such as line
104
1
of
FIG. 1
or line
204
of
FIG. 2
) may be viewed as transporting a number of STS-1 signals. For example, if lines
104
1
and
204
each correspond to an STS-n line, each of these lines may be viewed as carrying n STS-1 signals (e.g., an STS-48 line may be viewed as carrying 48 STS-1 signals).
Furthermore, in other environments, each STS-1 signal is used as a resource for carrying a plurality of lower speed signals. Protection may be provided for STS-1 signals individually or for their constituent lower speed signals individually. Either of these forms of protection are commonly referred to as “path protection. For example, in one type of 1+1 path protection scheme, an individual “working” STS-1 signal within an STS-n line (rather than all the STS-1 signals on the STS-n line) is backed up by a “protection” STS-1 signal transported on another STS-n line.
Automatic Protection Switching (APS) is a protocol that may be executed by the nodes within a SONET network. APS allows SONET nodes to communicate and organize the switching over from their working configuration to a protection configuration in light of a failure or degradation event. For example, in a typical approach, K1 and K2 bytes are embedded within the SONET frame that is communicated between a pair of nodes in order to communicate failure/degradation events, requests for a switch over, etc.
Distributed Switch Architecture
FIG. 3
shows a distributed “full mesh” switch architecture
331
. The architecture
331
of
FIG. 3
may be utilized to implement a SONET node such as nodes
131
,
132
of
FIG. 1
or nodes
231
through
234
of FIG.
2
. An ingress channel receives incoming data from a networking line.
FIG. 3
shows ingress channels
301
1
through
301
x
that each receive incoming data on a respective network line
303
1
through
303
x
.
An egress channel transmits outgoing data onto a networking line.
FIG. 3
shows egress channels
312
1
through
312
x
that each transmit outgoing data on a respective network line
304
1
through
304
x
. In a full mesh architecture, each ingress channel
301
1
through
301
x
transmits all of its ingress traffic to each egress channel
312
1
through
312
x
. For example, referring to
FIG. 3
, ingress channel
301
1
receives n STS-1 signals from its corresponding network line
303
1
(e.g., if network line
303
1
is an OC-48 line; n=48 and the ingress line channel receives 48 STS-1 signals).
All n of the STS-1 signals received by the ingress channel
301
1
are transmitted across the node's backplane
305
over each of its output lines
306
,
310
,
311
,
312
. As a result, each egress channel
312
1
through
312
x
receives all n STS-1 signals received by ingress channel
303
1
. In one approach, each STS-1 signal is provided its own signal line to each egress channel. As a result, each output
306
,
310
,
311
,
312
corresponds to a n-wide bus.
As each ingress channel is similarly designed, each egress channel
312
1
through
312
x
receives all the incoming traffic received by the node. For example, in the particular example of
FIG. 3
, there are x ingress channels
301
1
through
301
x
that each receive n STS-1 signal. As such, each egress channel
312
1
through
312
x
receives xn STS-1 signals (which correspond to the total amount of traffic received by the node
331
).
For example, note that egress channel
312
1
receives inputs
306
through
309
where each of these inputs correspond to the n STS-1 signals received by their corresponding ingress channel (i.e., input
306
for ingress channel
301
1
, input
307
for ingress channel
301
2
, input
308
for ingress channel
301
3
, . . . and input
309
for ingress channel
301
x
). In order to implement the switching fabric of the node, each egress channel
312
1
through
Mao Jim
Wu Wei
Blakely , Sokoloff, Taylor & Zafman LLP
Kizou Hassan
Nguyen Hanh
Turin Networks
LandOfFree
Method and apparatus for egress channel architecture that... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for egress channel architecture that..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for egress channel architecture that... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3106289