IBM 12.1(22)EA6 User Manual

The link state of the downstream interfaces depend on the link state of the upstream interfaces in the 
associated link-state group. If all of the upstream interfaces in a link-state group are in a link-down state, 
then the associated downstream interfaces are forced into a link-down state. If any one of the upstream 
interfaces in the link-state group is in a link-up state, the associated downstream interfaces are allowed 
to change to, or remain in, a link-up state.

In 

, downstream interfaces 1, 2, and 3 are in link-state group 1 with upstream interfaces 17 

and 18. Similarly, downstream interfaces 4, 5, and 6 are in link-state group 2 with upstream interfaces 
19 and 20.

If link is lost on upstream interface 17, the link state of downstream interfaces 1 to 3 do not change. If 
upstream interface 18 also loses link, downstream interfaces 1 to 3 go into a link-down state. 
Downstream interfaces 4 to 6 do not change state.

You can recover a downstream interface link-down condition by removing the failed downstream port 
from the link-state group. You can also enable one of the upstream interfaces in the group to change to 
the link-up state. To recover multiple downstream interfaces, disable the link-state group.

These sections describe how to configure trunk failover ports:

There are no link-state groups defined, and trunk failover is not enabled for any group.

BladeCenter

For example

Catalyst 3550 Switch

92356

Downstream interface 1

Link-state group 1
  Upstream interface 17
  Upstream interface 18

Link-state group 2
  Upstream interface 19
  Upstream interface 20

Cisco

ESM

Downstream interface 2
Downstream interface 3
Downstream interface 4
Downstream interface 5
Downstream interface 6

Network