PM8610-BIAP PMC [PMC-Sierra, Inc], PM8610-BIAP Datasheet - Page 298

• Manufacturer Part Number: PM8610-BIAP
• Description: SBS Telecom Standard Product Data Sheet Preliminary
• Manufacturer: PMC [PMC-Sierra, Inc]

13.3.1
13.3.2
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-2000168, Issue 3
There are several aspects of this problem:
The basic scheduling problem is to find the switch settings to properly route a set of connections.
This is more formally described using the definitions in the following paragraphs.
Port: An STS-12 input/output data stream. The serial ports on the SBS devices and the NSE-20G
devices operate at STS-12 rates and utilize STS-12 frames. Since the intention of the NSE-20G is
to serve as a DS0-granularity switch, these STS-12 frames must be treated as repeating on a cycle
of 12*9*90 = 9720 octets. All connections considered by this algorithm are octet connections.
Higher aggregations of traffic are handled as collections of octets, and are ignored for the
purposes of describing this algorithm.
Timeslot: A specific octet location in the 9720 octet cyclic structure.
Spacetimeslot: A timeslot on a specific port, identified by a space component and a time
component: for example, octet 9 on port 3 of SBS device 2
Connection: A mapping of an input spacetimeslot to an output spacetimeslot. Connections come
in two varieties, multicast and unicast. Unicast connections are a mapping of a single input
spacetimeslot to a single output spacetimeslot. Multicast connections are a mapping of a single
spacetimeslot to multiple output spacetimeslots. This algorithm is only concerned with the
unicast problem.
We begin by describing a simplified version of the algorithm, applied to a specific SBS/NSE-20G
configuration. Figure 24 illustrates the application. Four SBS devices are connected by one port
each to an NSE, which is likewise connected by one port to the egress side of each SBS device.
Only four ingress/egress ports of 32 on the NSE-20G are in use in this application, but the ideas
generalize easily to larger fabrics.
Problem Description
Naïve Algorithm
The algorithm must succeed for arbitrary permutation requests (i.e., neither the fabric nor the
algorithm can fail to connect any one-to-one connection request).
The algorithm must permit connection of 2-cast requests (port replication for either snooping
or for advanced redundancy fabrics). In fabrics with spare capacity and multicast/broadcast
servers, the algorithm must permit mapping of multicast/broadcast requests, up to the
capacity of the fabric and the servers.
This algorithm must be fast enough to satisfy requirements for response to operator requests
for connection changes.
This algorithm must be fast enough to satisfy requirements for protection responses to
equipment failures.
Reconnection requests may be made individually in which case an incremental connection-
setting algorithm is desired, or as complete batches in which case a batch algorithm may be
desirable.
Reconnection requests may be pre-computed for fast protection fall-over mechanisms.
SBS Telecom Standard Product Data Sheet
Preliminary
298