High Availability

The IPFE supports active-standby or active-active high availability (HA) when paired with a second IPFE instance. The mated pair of IPFEs expose typically one or two TSAs per configured IP version.

Each TSA can operate in an active-standby mode, where all traffic to a given TSA goes to the active (for that TSA) IPFE, if it is available. If the active IPFE fails or if its mate is explicitly selected as Active, traffic to the TSA goes to the mate IPFE. For active-active HA, the addresses must be configured in pairs, where one IPFE is active for one address in a pair, and the mate is active for the other.

Note that the IPFE supports more than two TSAs, and in fact when both IPv4 and IPv6 are supported, the IPFE is usually configured with at least four TSAs. An IPFE and its mate are numbered 1 and 2, whereas an IPFE pair is numbered A and B. The four IPFEs are numbered A1, A2, B1, and B2.

For multi-homed SCTP connections, the Target Set is represented by both a public address and an alternate address. Each application server in the Target Set must also be configured for multihomed SCTP.