DSC SWe Multihoming

SCTP, part of the Signaling Transport (SIGTRAN) suite of protocols, is an IP transport protocol that allows carriers to use IP infrastructure to transport SS7 telephony traffic over an IP network. This protocol functions at an equivalent level and replaces the Transmission Control Protocol (TCP). SCTP has been approved by the International Engineering Task Force (IETF) as specified in RFC 2960 and RFC 4960.

Multihoming, one of the key features of SCTP, is the ability of an association (that is a connection) to support multiple IP addresses or interfaces at a given end point in your network. In case of a network failure, using more than one IP address allows rerouting of packets and provides an alternate path for retransmission. Therefore, the network address redundancy provides a certain level of network-level fault tolerance. Within an SCTP association, one of the IP addresses assigned to receive data is the primary address of the peer endpoint. During normal operation, the traffic is sent on this (primary) IP path (see the following figure).

 DSC Multihomed Configuration (Example)

If one of the routes fails, SCTP manages the lost packets according to SCTP specifications. SCTP recognizes that the IP path is unavailable, and all traffic is transmitted using the other (secondary) IP path. SCTP sends a message to the Management layer, but the link typically does not fail. This process is not visible using the Menu UI, but can be detected by reviewing the log records.

Plan to have two IP paths for each remote device, ensuring that each IP path is routed through a different Ethernet interface for failover.

Topics

Note: The terms Static Route and IP Route can be used interchangeably in this documentation.