Virtual bridging functions, Vlan functions – Lucent Technologies P550 User Manual
Page 40
Overview of the P220 Gigabit Switch Family
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Cajun P550/P220 Switch Operation Guide
❒ 17.6 Gbps total capacity.
❒ 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.
Virtual Bridging Functions
The switch design supports:
❒ Over 24,000 Media Access Control (MAC) addresses in the switch address
forwarding table. This feature allows the switch to store forwarding information for
hosts in very large networks.
❒ Segmented address tables qualified by address and Virtual LAN (VLAN)
membership. This feature allows the same host to appear on different VLANs on
different ports.
❒ Optional per-VLAN spanning tree. This isolates loop control to smaller domains, so
spanning trees converge faster during reconfiguration.
VLAN Functions
A VLAN (Virtual LAN) is a software defined group(s) of hosts on a local area network
(LAN) that communicate as if they were on the same wire, even though they are
physically on different LAN segments throughout a site.
VLANs provide network managers with two significant capabilities:
❒ The ability to segment traffic in a “flat” switched network. This helps prevent traffic
from being forwarded to stations where it is not needed.
❒ The ability to ignore physical switch locations when creating workgroups. VLANs
are logical constructions and can traverse physical switch boundaries.
The P220 switch supports Layer 1, port-based VLANs, which have the following
characteristics:
❒ Frames classified as they enter the switch using Layer 1 (Port-based).
❒ Explicitly tagged VLAN packets are forwarded based on the information in the
packet. (See OpenTrunk Technology on page 2-5 for more information.)
❒ Up to 1000 VLANs. VLANs define a set of ports in a flooding domain. Packets that
need to be flooded are sent only to ports participating in that VLAN.