Configuring Link-State Tracking; Default Link-State Tracking Configuration; Link-State Tracking Configuration Guidelines - Cisco Catalyst 3120 Software Manual

Configuring Link-State Tracking

In a link-state group, the upstream ports can become unavailable or lose connectivity because the
distribution switch or router fails, the cables are disconnected, or the link is lost. These are the
interactions between the downstream and upstream interfaces when link-state tracking is enabled:
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You can recover a downstream interface link-down condition by removing the failed downstream port
from the link-state group. To recover from multiple downstream interfaces, disable the link-state group.
Configuring Link-State Tracking
These sections describe how to configure link-state tracking ports:
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Default Link-State Tracking Configuration

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

Link-State Tracking Configuration Guidelines

Follow these guidelines to avoid configuration problems:
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Cisco Catalyst Blade Switch 3120 for HP Software Configuration Guide
37-24
If any of the upstream interfaces are in the link-up state, the downstream interfaces can change to or
remain in the link-up state.
If all of the upstream interfaces become unavailable, link-state tracking automatically puts the
downstream interfaces in the error-disabled state. Connectivity to and from the servers is
automatically changed from the primary server interface to the secondary server interface.
As an example of a connectivity change from link-state group 1 to link-state group 2, when the
primary link from blade switch 1 to distribution switch 1 is lost, blade server 1 connects through its
secondary Ethernet server interface to blade switch 2 in link-state group 2.
If the link-state group is configured, link-state tracking is disabled, and the upstream interfaces lose
connectivity, the link states of the downstream interfaces remain unchanged. The server does not
recognize that upstream connectivity has been lost and does not failover to the secondary interface.
Default Link-State Tracking Configuration, page 37-24
Link-State Tracking Configuration Guidelines, page 37-24
Configuring Link-State Tracking, page 37-25
Displaying Link-State Tracking Status, page 37-26
An interface that is defined as an upstream interface cannot also be defined as a downstream
interface in the same or a different link-state group. The reverse is also true.
An interface cannot be a member of more than one link-state group.
You can configure only ten link-state groups per switch.
Do not configure a cross-connect interface (gigabitethernetn/0/17 or gigabitethernetn/0/18, where n
is the stack member number from 1 to 9) as a member of a link-state group.
Chapter 37 Configuring EtherChannels and Link-State Tracking
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