Adding static routes (referred to in this document as IP routes) to the routing table associates destination IPs to a specific Ethernet interface on the SP2000. With multihoming scenarios, when the Stream Control Transmission Protocol (SCTP) establishes an association, this protocol selects one destination IP address and one outbound interface to that destination IP address. The choice is made according to the lowest cost route. Traffic over one IP route can be redirected to another IP route.
When there is a timeout error on a path to a destination IP address, SCTP tries to choose another outbound interface. The choice is made in a round-robin fashion. SCTP keeps using the same outbound interface until a timeout error occurs. You can achieve failover by providing multiple paths to the same destination IP address, thus allowing SCTP to manage the routing.
SP2000 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, use of 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).
SP2000 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 at two IP paths for each remote device, ensuring that each IP path is routed through a different Ethernet interface for failover.
Note
The SP2000 supports Network Address Translation (NAT) for single-homed but not for multi-homed SCTP associations.
Topics
Note: The terms Static Route and IP Route can be used interchangeably in this documentation.
| Task | Procedure |
|---|---|
Add an IP route | |
| Modify the source IP for a route | |
| Delete a static route | |
| Review multihoming examples |
Virtual SP2000 (vSP2000) Multihoming with NAT Support
Note
This feature is only available for the DSC SWe/VSP2000 platforms using IPv4 and IPv4-mapped IPv6 address.
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 a network. In case of a network failure, use of more than one IP address allows re-routing of packets and provides an alternate path for retransmission. Therefore, the network address redundancy provides a certain level of network-level fault tolerance.
Topics
| Task | Procedure |
|---|---|
| For an overview of multihoming with NAT support, refer to | DSC SWe/vSP2000 Multihoming with NAT Support |
To provision the SCTP NAT egress and ingress mappings, refer to The SCTP NAT section of the DSC Web UI allows for all management operations for the SCTP NAT mapping. | |
| To delete an egress or ingress entry, refer to | |
| For examples of SCTP NAT multihoming configuration with multiple customers, refer to | DSC SWe/vSP2000 Multihoming with NAT Support Configuration Example |
Overview
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