Spanning Tree; Problems With Apparent Network Loops - 3Com 3C15500 - Network Director User Manual

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HAPTER LAN ANAGEMENT
Figure 312 Network Topology Example (2)
Note that the links from the layer 2 switches to the 4007 layer 3 switch
have been lost and each end-station is shown connected to both a layer 2
switch and the 4007. This is a known limitation of 3Com Network
Director. The work around is to discover all subnets within the one
discovery operation.

Spanning Tree

3Com Network Director does not support networks where there is a
separate Spanning Tree domain for each VLAN. 3Com Network Director
may not represent the topology of such networks correctly. In general,
3Com switches only support one Spanning Tree domain.
Problems with In order for 3Com Network Director to construct its map of the network,
apparent network it reads the Bridge Forwarding Table from each of the switches on the
loops network. This table tells 3Com Network Director which ports on a switch
have learned which MAC addresses. After gathering this information
from all switches, 3Com Network Director can work out how the various
devices on the network are connected together.
Switches with VLANs configured typically have a Bridge Forwarding Table
per VLAN. 3Com Network Director reads these per-VLAN Bridge
Forwarding Tables. However, in some circumstances, a MAC address can