Link Failure Response (LFR) Configuration

The LFR protocol determines which chassis will be brought down should all VSB interconnect links between the VSB chassis go down, and it is determined that both VSB chassis are operational. Both chassis in an operational VSB system use the same IP address and function as a single system with the GbE interconnect links acting as a virtual backplane for the system. Should all VSB interconnect links go down and both chassis remain operational, the two physical chassis would function as independent network devices with the same IP address.

The LFR protocol allows GbE ports to be designated as VSB monitor links that operate in a standby mode to the primary GbE VSB bond ports. The VSB monitor link provides dedicated redundant control plane connectivity and is used only as a backup communication path between two bonded chassis in the unlikely event that all of the primary VSB interconnect links fail or become unavailable. When the primary GbE VSB bond ports are down, the VSB monitor links facilitate a communications path to allow the physical chassis with highest LFR priority in the bonded pair to remain active while placing the chassis with the lower priority into a dormant state, except for all bonded links which maintain current state.

The LFR protocol must be globally enabled on each VSB chassis in the VSB system for LFR monitoring to occur. Use the set bonding lfr enable command to globally enable LFR on each physical chassis.

The LFR monitor port is configured using the set bonding port enable command, the same as a VSB interconnect port. What distinguishes the port types in a VSB context is the port speed. On the S-Series, all 1GbE software ports enabled for VSB are LFR ports. On the K-Series, 1 and 10GbE ports enabled for VSB on non-fabric modules are LFR ports.

The VSB feature supports a combined total of 32 VSB GbE interconnect and LFR GbE monitor links on a VSB system (32 VSB ports per chassis).

The physical chassis to be placed in dormant state is determined by the LFR priority. A chassis‘ LFR priority defaults to 10 times the VSB chassis ID. For example, if the VSB chassis ID is 1, the LFR priority is 10. The LFR priority can be manually set using the set bonding chassis command lfr-priority parameter with a valid range of 1 - 255. Setting a duplicate LFR priority is not allowed.

Use the show bonding command to review LFR state and port configuration details.