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 will go 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 2 TSAs, and in fact when both IPv4 and IPv6 are supported, the IPFE will usually be configured with at least 4. 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 multihomed SCTP connections, the Target Set is represented by both a Primary Address and a Secondary Address. Each application server in the Target Set must also be configured for multihomed SCTP.