3Com 4007, Implementation Manual, Page: 226 / 684

226 C
HAPTER
12: T
RUNKING
It is important to understand the relationships between Ethernet, bridge,
and VLAN port-related information:
■
Ethernet port information — Each physical port is always listed
individually, regardless of whether it is part of a trunk.
■
Bridge port information — This information uses the concept of
bridge ports. When you perform bridge port operations, you specify
the trunk’s anchor port, not the other ports in the trunk, as the
representative bridge port. In the bridge port displays, each selectable
bridge port has a port field that contains multiple port numbers if the
bridge port represents a trunk (for example,
3,5
or
6-8
).
■
VLAN information — When you define VLANs (as described in
Chapter 14), you must specify the bridge ports that you want to be
part of the VLAN. If you have a trunk, you specify its anchor port as
the bridge port. The VLAN that you create then includes all of the
physical ports in the trunk.
If you plan to use trunks (aggregated links), define the appropriate
trunks
before you define your VLANs. (If you define a VLAN with
certain ports and subsequently configure some of those ports to be
part of a trunk, the module removes those ports from the VLAN and
places them in the default VLAN.) When you define a VLAN that
includes trunk ports, you must specify the trunk’s anchor port
(lowest-numbered port).
Trunk Control
Message Protocol
(TCMP)
The Trunk Control Message Protocol (TCMP) performs the following
functions:
■
Detects and corrects trunks that violate trunk configuration rules
■
Ensures orderly activation and deactivation of trunk ports
The module runs a separate TCMP agent for each trunk. If TCMP detects
an invalid configuration, the protocol restricts the trunk to the largest
subset of ports that is a valid configuration.
By default, TCMP is enabled. Keeping TCMP enabled is optional, but
recommended. If you disable TCMP, the network still functions, but
without automatic trunk validation and reconfiguration. By default,
TCMP is enabled.