Cisco Systems 3560 Manual De Usuario

Link-state tracking, also known as trunk failover, is a feature that binds the link state of multiple 
interfaces. For example, link-state tracking provides redundancy in the network when used with server 
NIC adapter teaming. When the server network adapters are configured in a primary or secondary 
relationship known as teaming, if the link is lost on the primary interface, connectivity is transparently 
changed to the secondary interface.

 shows a network configured with link-state tracking. To enable link-state 

tracking, create a link-state group, and specify the interfaces that are assigned to the link-state group. An 
interface can be an aggregation of ports (an EtherChannel), a single physical port in access or trunk 
mode, or a routed port. In a link-state group, these interfaces are bundled together. The downstream 
interfaces are bound to the upstream interfaces. Interfaces connected to servers are referred to as 
downstream interfaces, and interfaces connected to distribution switches and network devices are 
referred to as upstream interfaces. 

The configuration in 

 ensures that the network traffic flow is balanced as follows:

For links to switches and other network devices

Server 1 and server 2 use switch A for primary links and switch B for secondary links.

Server 3 and server 4 use switch B for primary links and switch A for secondary links. 

Link-state group 1 on switch A

Switch A provides primary links to server 1 and server 2 through link-state group 1. Port 1 is 
connected to server 1, and port 2 is connected to server 2. Port 1 and port 2 are the downstream 
interfaces in link-state group 1.

Port 5 and port 6 are connected to distribution switch 1 through link-state group 1. Port 5 and 
port 6 are the upstream interfaces in link-state group 1.

Link-state group 2 on switch A

Switch A provides secondary links to server 3 and server 4 through link-state group 2. Port 3 is 
connected to server 3, and port 4 is connected to server 4. Port 3 and port 4 are the downstream 
interfaces in link-state group 2.

Port 7 and port 8 are connected to distribution switch 2 through link-state group 2. Port 7 and 
port 8 are the upstream interfaces in link-state group 2.

Link-state group 2 on switch B

Switch B provides primary links to server 3 and server 4 through link-state group 2. Port 3 is 
connected to server 3, and port 4 is connected to server 4. Port 3 and port 4 are the downstream 
interfaces in link-state group 2.

Port 5 and port 6 are connected to distribution switch 2 through link-state group 2. Port 5 and 
port 6 are the upstream interfaces in link-state group 2.

Link-state group 1 on switch B

Switch B provides secondary links to server 1 and server 2 through link-state group 1. Port 1 is 
connected to server 1, and port 2 is connected to server 2. Port 1 and port 2 are the downstream 
interfaces in link-state group 1.

Port 7 and port 8 are connected to distribution switch 1 through link-state group 1. Port 7 and 
port 8 are the upstream interfaces in link-state group 1.

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: