Cisco Catalyst 4500 Series Software Configuration Manual page 821

Chapter 27 Configuring EtherChannel and Link State Tracking
As an example of a connectivity change from link-state group 1 to link-state group 2 on switch A,
see
ports 1 and 2 do not change. However, if the link for upstream port 5 is also lost, the link state of the
downstream ports changes to the link-down state. Connectivity to server 1 and server 2 is then
changed from link-state group1 to link-state group 2. The downstream ports 3 and 4 do not change
state because they are in link-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.
You can recover a downstream interface link-down condition by removing the failed downstream port
from the link-state group. To recover multiple downstream interfaces, disable the link-state group.
Figure 27-3
Distribution
switch 1
Link-state
Switch A
Link-
state
group 2
Link-
state
group 1
Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
Figure 27-3 on page 27-25. If the upstream link for port 6 is lost, the link states of downstream
Typical Link-State Tracking Configuration
Link-state
group 1
group 1
Port Port
Port
5 6
7
Port
8
Port Port Port Port
1 2 3 4
Server 1 Server 2
Primary link
Secondary link
Network
Layer 3 link
Link-state
group 2
Port
Server 3
Understanding Link-State Tracking
Distribution
switch 2
Link-state
group 2
Port Port
Port
6 5
7
Switch B
8
Port Port Port Port
1 2 3 4
Link-
state
group 1
Link-
state
group 2
Server 4
27-25