3. Router Architecture for M-series Routers and T-series Platforms:
The router architecture separates routing and control functions from packet forwarding operations, which results in increase in the performance of the router.
Each router consists of two major architectural components:
The Routing Engine, which provides Layer-3 routing services and network management.
The Packet Forwarding Engine, which provides all operations required for transit packet forwarding.
Figure 1: Simplified Router Architecture:
The routing engine constructs one or more routing tables, from these routing tables routing engine generates a table of active routes called forwarding table,
this table is then copied into packet forwarding engine.
Routing Engine is the logical location to store the JUNOS software. The Routing Engine operates all routing protocols and makes all routing table decisions,
herby building a master routing table with the best path to each destination. The router then places these best paths into the forwarding table on the Routing
Engine and copies that same data into the forwarding table on the Packet Forwarding Engine.
The important features of M-Series and T-Series routers include the following:
IPv4 and IPv6 unicast and multicast support
Routing: Supports IS-IS, RIP ng, BGP, OSPF v3, and Static
L2 VPNs, L3 VPNs
Supports ICMP v6
Offers CLI, and JUNIScript API
The routers support a variety of high-speed interfaces (including SONET/SDH, Ethernet, and ATM) for large networks and network applications.
High Availablility Options such as Graceful RE Switchover (GRES), and Bidirectional Forwarding Detection (BFD).