A two-stage failover mechanism for high availability in service function chaining

Service function chaining (SFC) enables specific network flows to be processed through an ordered set of service functions. In this paper, we propose a two-stage failover mechanism to provide high availability (HA) in SFC. In the proposed mechanism, a secondary service function path (SFP) is pre-computed, which is maximally disjointed with the primary SFP, and a backup service function instance (SFI) is prepared for each service function. For a failure event, the first local repair stage is examined by means of the preconfigured backup SFI. If the backup SFI is not available and/or any link is failed, the second end-to-end repair stage is triggered by replacing the primary SFP with the secondary SFP. Simulation results demonstrate that the proposed failover mechanism can reduce the recovery time by 50%-75% compared to the conventional approach.