High-Speed Router Design

Content Classes of Routers Components of a Router High-Speed Router Lookup Advances in Switching Fabrics Speeding Up Output Queues Input-Queued Switches Scheduling

Classes of Routers Backbone Routers  Reliability and speed Enterprise Routers  Different service qualities, cheap Access Routers  Diversity

Components of A Router

High-Speed Router Lookup The speed of a route lookup algorithm is determined by the number of memory accesses and the speed of the memory. Access time Data structures of Routing Table  Changes relatively slowly, every 2 min

Advances in Switching Fabrics Crossbar  scheduler Shared memory  Memory access speeds Bus  Bus capacitance and arbitration overhead Advance in Bus speed

Speeding Up Output Queues The major problem is the speed at which the output queue can be accessed To build very wide memories that can load an entire packet in a single memory cycle  Memory prices continue to drop

Input-Queued Switches A significant bottleneck, to avoid packet loss, output queues must run much faster than the input links. Head-of-line blocking problem Access to the switch fabric

Scheduling FCFS  Malicious source Fair Queuing

References [1] S. keshav, Issues and Trends in Router Design [2]University of California Berkeley, Router Design: Table Lookups and Packet Scheduling [3]Shivkumar Kalyanaraman, High Speed Router Design Overview

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