HP ProCurve 9304M Installation And Configuration Manual page 195

Figure 7.8 Trunk port mismatch
Four ports on each device are eligible for
link aggregation. The device negotiates
a four-port trunk using the ports.
One device reloads, after which only
two of its ports are eligible for link
aggregation.
However, the first device is still configured
with the four-port trunk group. The trunks
are mismatched.
This type of mismatch does not occur
in release 06.7.01 and later.
Flexible Trunk Eligibility
Software release 07.6.01b also increases the tolerance for down ports during link negotiation. In previous
releases, all the ports in a valid trunk configuration (2-port, 4-port, or 8-port trunk starting on a valid primary port
number) need to be up. Thus, in previous releases, if you enable link aggregation on four ports but one of the
ports is down, the device will negotiate based only on a valid two-port trunk group consisting of two of the up ports.
For example, if you enable link aggregation on ports 1/1 - 1/4 and port 1/3 is down, 802.3ad will negotiate only for
a two-port link consisting of ports 1/1 and 1/2.
In release 07.6.01b and later, the device groups the device's ports into 2-port groups consisting of an odd-
numbered port and the next even-numbered port. For example, ports 1/1 and 1/2 are a two-port group, as are
ports 1/3 and 1/4, 9/1 and 9/10, and do on. If either of the ports in a two-port group is up, the device considers
both ports to be eligible to be in an aggregate link.
Configuring Trunk Groups and Dynamic Link Aggregation
Port 1/1
Port 1/2
Port 1/3
Port 1/4
Port 1/1
Port 1/2
Port 1/3
Port 1/4
Port 1/1
Port 1/2
Port 1/3
Port 1/4
Port 1/1
Port 1/2
X
X
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