TX Matrix Routing Engine Functions

The TX Matrix Routing Engine handles all routing protocols, as well as the software processes that control the TX Matrix interfaces and user access to the TX Matrix router. All Routing Engines in the routing matrix run software processes that control chassis components and system management. For more information about the processes, see Routing Engine Software Components.

• Processing of routing protocol packets—The Routing Engine handles all packets that concern routing protocols, freeing the Packet Forwarding Engine to handle only packets that represent Internet traffic.
• Software modularity—Because each software process is devoted to a different function and uses a separate process space, the failure of one process has little or no effect on the others.
• In-depth Internet functionality—Each routing protocol is implemented with a complete set of Internet features and provides full flexibility for advertising, filtering, and modifying routes. Routing policies are set according to route parameters (for example, prefix, prefix lengths, and Border Gateway Protocol [BGP] attributes).
• Scalability—The Junos routing tables have been designed to hold all the routes in current networks with ample capacity for expansion. Additionally, the Junos OS can efficiently support large numbers of interfaces and virtual circuits.
• Management interface—Different levels of system management tools are provided, including the Junos OS command-line interface (CLI), the Junos XML management protocol, the craft interface, and SNMP.
• Storage and change management—Configuration files, system images, and microcode can be held and maintained in primary and secondary storage systems, permitting local or remote upgrades.
• Monitoring efficiency and flexibility—The TX Matrix router supports functions such as alarm handling and packet counting on every port, without degrading packet-forwarding performance.

The TX Matrix Routing Engine constructs and maintains one or more routing tables. From the routing tables, the Routing Engine derives a table of active routes, called the forwarding table, which is then copied to the T640 routers (see Figure 1). The Junos kernel running on each T640 router's Routing Engine copies its forwarding table to all Packet Forwarding Engines in the router. The design of the ASICs allow the forwarding table in the Packet Forwarding Engine to be updated without interrupting forwarding performance.

Figure 1: Control Packet Handling for Routing and Forwarding Table Updates