Overview of the P220 Gigabit Switch Family

Figure 2-3.Trunking Translation

Trunking Translation:

Frame Format:

•“Clear”

•IEEE

802.1Q

•Multilayer

•3Com

Translation Function

Frame Format: “Normal” - Ethernet or 802.3 with valid

CRC

Translation Function

Frame Format:

•“Clear”

•IEEE

802.1Q

•Multilayer

•3Com

Dual Layer Spanning Trees

Spanning trees are an IEEE 802.1 standard which provides distributed routing over multiple LANs connected by bridges.

There are three spanning tree models:

❒Single IEEE 802.1D spanning tree

❒Spanning tree per VLAN

❒Optimized “per-VLAN” spanning trees using a scalable, two-layer spanning tree approach

Note: All models interoperate with legacy IEEE 802.1D bridges and switches.

Dual layer spanning trees provide two very important capabilities:

❒Smaller spanning tree domains means much faster convergence during spanning tree reconfiguration.

❒Per-VLAN operation enables you to use more of the available bandwidth when you have redundant links. A particular link can be blocked on one VLAN, but still forward packets on another.

Cajun P550/P220 Switch Operation Guide

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