The M20 Internet router is a complete routing system that provides SONET/SDH, ATM, Ethernet, and channelized interfaces for large networks and network applications, such as those supported by Internet service providers (ISPs). Application-specific integrated circuits (ASICs), a definitive part of the router design, enable the router to forward data at the high speeds demanded by current network media.
The router accommodates up to four Flexible PIC Concentrators (FPCs), which can each be configured with a variety of network media types, altogether providing up to 64 physical interface ports per system. The router height of 14 in. (36 cm) enables stacked installation of five M20 systems in a single floor-to-ceiling rack, for increased port density per unit of floor space.
The router’s maximum aggregate throughput is 3.2 gigabits per second (Gbps) per FPC. Inserting a combination of PICs with an aggregate higher than the maximum throughput is supported, but constitutes oversubscription of the FPC.
The router architecture cleanly separates control operations from packet forwarding operations, which helps to eliminate processing and traffic bottlenecks. Control operations in the router are performed by the Routing Engine, which runs JUNOS software to handle routing protocols, traffic engineering, policy, policing, monitoring, and configuration management. Forwarding operations in the router are performed by the Packet Forwarding Engine, which consists of hardware, including ASICs, designed by Juniper Networks.