SCTP Programmer's Guide

Figure 1-5 A Single-Homed Connection
In Figure 1-5, Host A contains a single network interface (NI
A1
) and Host B contains a
single network interface (NI
B1
). NI
A1
is the only interface for Host A to interact with
Host B.
When a network or path failure occurs, the endpoint is completely isolated from the
network. Multihoming in SCTP ensures better chances of survival if a network failure
occurs, when compared to TCP. The built-in support for multi-homed hosts in SCTP
enables a single SCTP association to run across multiple links or paths, to achieve link
or path redundancy. This enables an SCTP association to achieve faster failover from
one link or path to another, with minimum interruption in the data transfer service.
Figure 1-6 illustrates the mutli-homed connection in SCTP.
Figure 1-6 A Multihomed Connection
In this figure, Host A contains multiple network interfaces to interact with Host B,
which also has multiple interfaces.
SCTP selects a single address as the "primary" address and uses it as the destination
for all DATA chunks for normal transmission. All the other addresses are considered
as alternate IP addresses. SCTP uses these alternate IP addresses to retransmit DATA
chunks and to improve the probability of reaching the remote endpoint. Retransmission
SCTP Features 29