Released
Datasheet
PM73487 QRT
PMC-Sierra, Inc.
PMC-980618
Issue 3
622 Mbps ATM Traffic Management Device
1.6 5 Gbps to 160 Gbps Application Example – LAN-to-WAN
A powerful application of the QRT and the QSE devices is the creation of modules that can be
used in a range of switches with only the interconnection changing between different sizes. ATM
switches from 5 Gbps to 160 Gbps can be realized with only two unique cards. A port card has
one QRT, and a switch card has two QSEs. The switch fabric consists of three stages, each with
32 QSEs (or 16 switch cards). To plan for future scalability, the middle stage must be built-in
upfront. This is a one-time cost. Then, in order to scale in 5 Gbps increments, one switch card and
its accompanying eight port cards should be added. Finer bandwidth scaling is possible by popu-
lating the additional switch card with port cards as needed (in increments of 622 Mbps). With this
switch fabric topology, scaling is possible up to 160 Gbps. Once the initial middle stage cost has
been incurred, the per-port cost for 5 Gbps through 160 Gbps systems remains almost constant
Switch Card - Two QSEs
Port Card - One QRT
x32
x32
One UTOPIA
Level 2 Interface
QSE
(PM73488
x32
x32
QRT
(PM73487
QSE
(PM73488
Figure 9. 5 Gbps to 160 Gbps Switches Modeled Using Only Two Cards
9
PMC [ PMC-SIERRA, INC ]
