PM8621 datasheet(163/184 Pages) PMC

163 / 184 page

NSE-8G™ Standard Product Data Sheet

Preliminary

Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use

162

Document ID: PMC-2010850, Issue 1

Figure 33 Relabeled Graph

12.13.5 Experimental Results

The performance of PMC-Sierra’s Open Path Algorithm has been studied by implementing it in

C++ and running extensive random connection tests. Tests for NSE/SBS applications of this

algorithm used a single NSE-8G connected to 12 SBSs, each carrying a full complement of DS0

connection. Many runs were completed in which an initially unloaded switch is presented with a

sequence of random call establishment requests up to the point of 100% switching loads. These

runs were carried out on a 600 MHz Alpha running Linux. In all of these runs, no otctet open path

search took longer than 10

µs, thus supporting up to 100,000

1 DS0 call establishments per second.

T1s and other aggregates require the establishment of multiple octet open paths; complete T1s

can be established at about 3,700 T1/sec. The reasons for this surprisingly good performance are

explained in the separate open path algorithm document. It is our opinion that these rates are

sufficiently high that the call establishment algorithm should not be a bottleneck in any

application of the NSE/SBS, and that this rate is sufficiently high to permit the NSE/SBS to be

used for PSTN call establishment rates (up to 100,000 calls/sec in a switch supporting 96,768

full-duplex calls, with the switching core implemented in 1 NSE-8G and 12 SBS chips).

12.13.6 Multicast

Scheduling general multicast connections is an entirely different class of problem. With

unrestricted multicast, the underlying architecture is non-blocking up to capacity dictated by the

number of slots in a frame, but finding the non-blocking schedule is NP-hard. There is no

polynomial time running algorithm known to solve this class of problem.

There are two approaches to solving the multicast problem:

• Heuristic algorithms that have statistical probability of success for simple versions of the

problem; (and)

• Restricted multicast, where the form of restriction provides a means to solve the scheduling

problem.

1 This ignores inband or uP to NSE limitations.

PM8621 Datasheet(PDF) 163 Page - PMC-Sierra, Inc