In the enclosure failure scenario we assume that the IPFE is colocated with the application servers in its Target Set. In this case, IPFE-A1 is in an enclosure with Server1, Server2, and Server3.
When the enclosure containing IPFE-A1, Server1, Server2, and Server3 fails:
- All connections to all servers in the enclosure will fail.
- IPFE-A2 will detect that IPFE-A1 is down and start servicing TSA1.
- Clients with existing connections to TSA1 will detect that TSA1 is unavailable and send traffic to TSA2.
- Depending on configuration, IPFE-A2 will send optionally send a TCP RST (for TCP connections) or a configured ICMP message in response to client connection requests to TSA1.
When the enclosure recovers:
- IPFE-A2 will detect that IPFE-A1 has recovered and relinquish control of TSA1.
- IPFE-A1 will take over control of TSA1.
- Since TSA1 did not have any existing connections during the failure, no special handling of existing connections is required.
- Over a period of time, clients are expected to route new connections to TSA1, resulting in connections to recovered servers in the associated Target Set.
- In the interim, there will be a substantial imbalance between the two IPFEs as well as between the servers in the two TSAs. The IPFEs will monitor the traffic for imbalances and distribute new connections to reduce the imbalance.