Multihoming

What is Multihoming?

In the IP terminology, a host is called multi-homed if it can be addressed by multiple IP addresses. Multihoming is used only for recovering from network failures  and is not used, for example, for load balancing.

SCTP Association explaining multihoming
SCTP Association explaining multihoming

How multihoming is used in SCTP?

To make full use of the SCTP multi-homing, the host also needs to support multiple network interfaces,each of which has to be configured to work in a different sub-network.The SCTP implementation supports two paths per association. Normally data is sent through the primary path. If a network failure occurs in the primary network, SCTP resends unacknowledged data through the secondary path automatically. The application cannot see which path is used and it does not affect sending of data traffic in application level either. In this case, the SCTP stack takes care of all the details.The SCTP association works normally so that data runs through the primary path and SCTP heart beat runs through the secondary path . If something unexpected happens in the primary path, the SCTP usually has an alternative path available. The SCTP monitors a condition of the secondary
path all the time by using a heartbeat message. The following figure describes how the SCTP re-transmission works when both the primary and the secondary paths failed. The retransmission procedure starts always the same way; the first retransmission is done through the secondary path. The example above is based on the following SCTP parameters