Crossbar Switch Fabric - Lucent Technologies Cajun P220 Operation Manual

Cajun P550 Switch Overview

Crossbar Switch Fabric

The crossbar switch matrix provides low latency, high throughput packet switching using
a crossbar architecture (Figure 1-3).
Crossbars are more scalable than shared memory architectures. Architecturally, you can
add more capacity simply by adding more switch elements. By comparison, shared
memory switches have an inherent maximum upper boundary in throughput that
makes high-density, single-backplane gigabit switches impractical. With a crossbar
architecture you increase the number of gigabit ports in your network and the
architecture scales to meet your needs.
The crossbar supports:
13 fabric ports (two per I/O module slot, plus one for the Supervisor Module).
1.76 Gbps (in and out) on each fabric port.
22.88 Gbps total capacity, 45.76 Gbps total backplane capacity.
Under-subscribed switching fabric in most configurations (two connections per I/O
module slot, plus one for the supervisor module).
Single copy replication - When possible, input frames destined for output multiple
switch ports pass through the crossbar only once and are copied by the crossbar to
each destination.
Hardware-assisted multicast pruning - The switch only forwards to appropriate
destination switch ports.
1-6
Figure 1-3. Crossbar Architecture
Port 1
1.76 Gb/s
Port 2
Port 13
22.88 Gb/s
1.76 Gb/s
Cajun P550/P220 Switch Operation Guide
Port 1
Port 2
Crossbar
Port 13