Lucent Technologies P550 - Manual (Page 39)

Overview of the P220 Gigabit Switch Family
Cajun P550/P220 Switch Operation Guide 2 -3
Figure 2-1. Crossbar Architecture
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 P220G crossbar supports:
❒ Nine fabric ports running at full line rate.
❒ 1.76 Gbps (in and out) on each fabric port.
❒ 31.68 Gbps total capacity.
❒ Under-subscribed switching fabric.
❒ Single copy replication. When possible, input frames destined for output on
multiple switch ports pass through the crossbar only once and are copied by the
crossbar to each destination.
❒ Hardware-assisted multicast pruning. The switch forwards only to appropriate
destination switch ports.
The P220FE crossbar supports:
❒ Five fabric ports running at full line rate.
❒ 1.76 Gbps (in and out) on each fabric port.
Crossbar
Port 1
Port 2
Port 13
1.76 Gb/s
22.88 Gb/s
Port 1
Port 2
Port 13
1.76 Gb/s