SCTPfx: A fast failover mechanism based on cross-layer architecture in SCTP multihoming

This paper proposes SCTPfx, a fast failover mechanism in SCTP multihoming. For data communication, SCTP uses a single path among multiple available paths in an association. This path is called the primary path. If the primary path fails, failover procedure is carried out, i.e., one of the secondary path is engaged as the new primary. However, it takes more than 30 sec for failover because SCTP detects primary path failure by timeouts of several data chunks. To solve this problem, SCTPfx employs a cross-layer architecture called CEAL. CEAL can quickly notify SCTP of primary path failure caused by an event in the link layer or the network layer, e.g., the Ethernet cable was unplugged by accident, the IP address of the interface became unavailable due to timeout, or an ICMP unreach message was received. SCTPfx also supports fast recovery, i.e., when the original primary path recovers after failover, it is quickly engaged as the new primary again. SCTPfx was implemented on FreeBSD. As a result of measurements in our test network, SCTPfx achieves failover in 40 msec.