3. Router Architecture for M-series Routers and T-series
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
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).