Routing Table Manager (RTM)


DC-RTM is a source code implementation of an IP Routing Table Manager for use with Metaswitch's IP Routing Protocol products. It combines routing information from multiple routing protocols (and optionally multiple instances of each protocol) to generate an integrated master routing table for IPv4 or IPv6 addresses, and populates the corresponding forwarding tables with active routes. It also exports external routes into the routing protocols, as required. This design provides a simple way to integrate different routing protocols, while maintaining a separate forwarding table for high-performance routing lookups.

DC-RTM can be used with Metaswitch's routing products (DC-ISIS, DC-OSPF, DC-BGP, DC-RIP, and as an MRIB with DC-PIM) and also third-party routing products. Statically defined routes can also be configured through the MIB interface.

Multiple instances of DC-RTM can be used to provide

  • distribution of routing function for highly scaled and fault-tolerant systems
  • Virtual Router Forwarding Tables for VPN services
  • simultaneous IPv4 and IPv6 support.

DC-RTM shares Metaswitch's unicast IP routing architecture. 

DC-RTM stores the received routes and selects a single "active" route for each destination (because it may be provided with multiple routes to the same destination). The active route is selected based on policy information configured through the DC-RTM MIB. This includes information such as the weighting to give routes from each routing protocol. Active routes are then passed to the Forwarding Table through the Active Routes Interface.

DC-RTM can also be configured to export routes that have been received from one IP routing protocol to another. Static routes can also be exported. For example, routing information from DC-BGP could be exported into DC-ISIS or DC-OSPF, which would then distribute the information throughout the IS-IS network as external routes or throughout the OSPF network in AS-external LSAs. The choice of which routes to export is configurable through the DC-RTM MIB.