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NMC DOiT Vol.2 Scenario 7 Day 4-2 – Catalyst 3560 Link State Tracking

586 Words. Plan about 3 minute(s) to read this.

The Catalyst 3560 has the ability to error-disable interfaces you define, if another interface has gone down. This is known as link state tracking. The feature is straightforward. You define an interface to track as an “upstream” interface. If that upstream interface goes down, you can then err-disable ports you’ve defined as “downstream” interfaces.

Take a look at the following IOS code to see link state tracking in action. Here I define etherchannel 1 to be my upstream interface (Po1 contains Gi1/0/13 – 15). If Po1 goes down, I want Gi1/0/23 to be disabled.

CAT3#conf t
Enter configuration commands, one per line. End with CNTL/Z.
CAT3(config)#link state track 1
CAT3(config)#interface po1
CAT3(config-if)#link state group 1 upstream
CAT3(config-if)#interf gi1/0/23
CAT3(config-if)#link state group 1 downstream
CAT3(config-if)#^Z
CAT3#show link state group 1 detail

Link State Group: 1 Status: Enabled, Up
Upstream Interfaces : Po1(Up)
Downstream Interfaces : Gi1/0/23(Up)

(Up):Interface up (Dwn):Interface Down (Dis):Interface disabled

CAT3#conf t
Enter configuration commands, one per line. End with CNTL/Z.
CAT3(config)#interf po 1
CAT3(config-if)#shut
CAT3(config-if)#^Z
CAT3#
6d18h: %PM-4-ERR_DISABLE: lsgroup error detected on Gi1/0/23, putting Gi1/0/23 in err-disable state
6d18h: %LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel1, changed state to down
6d18h: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/23, changed state to down
6d18h: %LINK-5-CHANGED: Interface GigabitEthernet1/0/13, changed state to administratively down
6d18h: %LINK-5-CHANGED: Interface GigabitEthernet1/0/14, changed state to administratively down
6d18h: %LINK-5-CHANGED: Interface GigabitEthernet1/0/15, chan
6d18h: %LINK-5-CHANGED: Interface Port-channel1, changed state to administratively down
6d18h: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/23, changed state to down
6d18h: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/13, changed state to down
6d18h: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/14, changed state to down
6d18h: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/15, changed state to down
CAT3#show link state group 1 detail

Link State Group: 1 Status: Enabled, Down
Upstream Interfaces : Po1(Dwn)
Downstream Interfaces : Gi1/0/23(Dis)

(Up):Interface up (Dwn):Interface Down (Dis):Interface disabled

CAT3#conf t
Enter configuration commands, one per line. End with CNTL/Z.
CAT3(config)#interf po1
CAT3(config-if)#no shut
CAT3(config-if)#exi
CAT3(config)#exi
6d18h: %SYS-5-CONFIG_I: Configured from console by console
6d18h: %LINK-3-UPDOWN: Interface Port-channel1, changed state to down
6d18h: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/13, changed state to down
6d18h: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/14, changed state to down
6d18h: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/15, changed state to down
6d18h: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/13, changed state to up
6d18h: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/14, changed state to up
6d18h: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/15, changed state to up
6d18h: %PM-4-ERR_RECOVER: Attempting to recover from lsgroup err-disable state on Gi1/0/23
6d18h: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/13, changed state to up
6d18h: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/14, changed state to up
6d18h: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/15, changed state to up
6d18h: %LINK-3-UPDOWN: Interface Port-channel1, changed state to up
6d18h: %LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel1, changed state to up
6d18h: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/23, changed state to up
6d18h: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/23, changed state to up
CAT3#show link state group 1 detail

Link State Group: 1 Status: Enabled, Up
Upstream Interfaces : Po1(Up)
Downstream Interfaces : Gi1/0/23(Up)

(Up):Interface up (Dwn):Interface Down (Dis):Interface disabled

Read more about Catalyst 3560 link state tracking.