Lucent Technologies P550 - Manual (Page 32)

Cajun P550 Switch Overview
1-12 Cajun P550/P220 Switch Operation Guide
Figure 1-7. Trunking Translation
Spanning Tree Models
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.
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