Link State Tracking

A group of links may contain upstream links and downstream links. When all upstream links in a group are down, Link State Tracking (LST) shuts all the downstream links down. In order to let the peer on the other side know that it needs to stop sending traffic on the downstream links. When the upstream link recovers, LST brings up the downstream links, letting the peers know that they may resume forwarding traffic on those links.

A link can be a member of several groups. A downstream interface is shut down if at least one of the groups requests a shutdown and is brought back up if all groups request it to be up.

In situations with only downstream links in a group (no upstream links), the downstream links will stay up.

The following is a basic example of how to configure link state tracking group and tracking VLAN.

Link_State_Tracking.png

To configure Link State Tracking group:

  1. Create tracking group. Run:

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    switch-1 (config) # link state tracking group group1

  2. Configure link type on the interface. Run:

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    switch-1 (config) # interface ethernet 1/2 link type upstream switch-1 (config) # interface ethernet 1/1 link type downstream

  3. Add interfaces into the group. Run:

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    switch-1 (config) # interface ethernet 1/1 link state tracking group group1 switch-1 (config) # interface ethernet 1/2 link state tracking group group1

To configure Link State Tracking VLAN:

  1. Create VLAN. Run:

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    switch-2 (config) # vlan 100

  2. Configure VLAN members. Run:

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    switch-2 (config) # interface ethernet 1/1 switchport access vlan 100 switch-2 (config) # interface ethernet 1/2 switchport access vlan 100

  3. Configure link type on the interface. Run:

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    switch-2 (config) # interface ethernet 1/2 link type upstream switch-2 (config) # interface ethernet 1/1 link type downstream

  4. Create link state tracking VLAN. Run:

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    switch-2 (config) # link state tracking vlan 100

To verify Link State Tracking configuration, run:

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switch-1 (config) # show link state tracking group group1   --------------------------------------------------------------------------------------- Group Port Type Interface Admin Status Operational Status --------------------------------------------------------------------------------------- group1 Upstream Eth1/2 Enabled Up

link type

link type {downstream | upstream}
no link type

Configures an interface’s link direction.
The no form of the command deletes the interface’s link direction configuration.

Syntax Description

downstream

Configures interface as downstream

upstream

Configures interface as upstream

Default

N/A

Configuration Mode

config interface ethernet

History

3.7.1000

Example

switch (config interface ethernet 1/1)# link type downstream

Related Commands

show link state tracking

Notes

  • IPL, loopback, and VLAN interfaces are not supported.

  • An interface can be either upstream or downstream but not both.

link state tracking group

link state tracking group <group-name>
no link state tracking group <group-name>

Creates a link state tracking group if one does not exist, and if applied to a specific interface, then it adds that interface to the group.
The no form of the command deletes a link state tracking group, and if applied to a specific interface, then it removes that interface from the group.

Syntax Description

group-name

Name for link state tracking group

Default

N/A

Configuration Mode

config config interface ethernet config interface port-channel config interface mlag-port-channel

History

3.7.1000

Example

switch (config interface ethernet 1/1)# link state tracking group group1

Related Commands

show link state tracking

Notes

  • The maximum number of tracking groups/VLANs is 64

  • Link state tracking group name should not contain any of the following characters: [*/\"\\ ;,.?<>:@#$%^&()=] and should consist of no more than 255 characters

  • Tracking the link state of member ports in a LAG or MLAG is not supported

link state tracking vlan

link state tracking vlan <vlan-id>
no link state tracking vlan <vlan-id>

Creates a VLAN link state tracking group. All VLAN members are automatically added into this group.
The no form of the command deletes a VLAN link state tracking group.

Syntax Description

vlan-id

ID of VLAN whose link state to track

Default

N/A

Configuration Mode

config

History

3.7.1000

Example

switch (config)# link state tracking vlan 100

Related Commands

show link state tracking

Notes

The maximum number of tracking groups/VLANs is 64

show link state tracking

show link state tracking [group <group-name> | vlan <vlan-id>]

Displays link state tracking configuration.

Syntax Description

group

Displays link state tracking per tracking group

vlan

Displays link state tracking per VLAN

Default

N/A

Configuration Mode

Any command mode

History

3.7.1000

Example

switch (config)# show link state tracking

---------------------------------------------------------------------------------------
Group Port Type Interface Admin Status Operational Status
---------------------------------------------------------------------------------------
Vlan 100 Upstream Eth1/54 Enabled Down
Vlan 100 Downstream Eth1/1 Enabled Down (by tracking)
Vlan 100 Unassigned Eth1/2 Enabled Up
Vlan 101 Upstream Eth1/54 Enabled Down
Vlan 101 Downstream Eth1/1 Enabled Down (by tracking)
Vlan 101 Unassigned Eth1/2 Enabled Up
group1 Downstream Eth1/1 Enabled Down (by tracking)

Related Commands

link type
link state tracking group
link state tracking vlan

Notes

The maximum number of tracking groups/VLANs is 64

© Copyright 2023, NVIDIA. Last updated on Sep 8, 2023.