3Com 4007, Implementation Manual, Page: 225 / 684

Trunking Overview
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Trunks also enhance network availability because the Trunk Control
Message Protocol (TCMP) detects and handles physical configuration
errors in the point-to-point configuration. The interface module
automatically distributes traffic across the ports that are associated with
the trunk. If any of the trunk’s ports go down or up, the module
automatically redistributes traffic across the new arrangement of
Key Concepts Before you configure trunking on your module, become familiar with the
key concepts in this section.
Port Numbering in a Trunk
When you combine ports on a trunk, the module logically groups the
physical ports that you specify into a single bridge port, identified by a
single bridge port number in bridge statistics. For example, Figure 11
shows that Ethernet ports 2, 3, and 4 are represented by bridge port 2
after trunking. The lowest numbered port in the trunk, called the
anchor
port , represents the entire trunk. After trunking, you can select bridge
port 2 when you specify bridge port or virtual LAN (VLAN) information,
but you cannot select bridge ports 3 or 4 since they are part of the trunk.
Figure 11 Bridge Port Numbering After Trunking
Regardless of whether you define trunking, the physical port numbering
on your module remains the same.
Physical port: 1 2 3 4 5 6
1 2 3 4 5 6
Bridge port number:
Trunked MACs
Ethernet port number:
1 2 3 4