Network switch wherein egress port specified by ingress interface is overwritten with standby port before switch fabric for failed ports

摘要

A network switch comprises ingress cards 50a, switch unit 40 and egress cards 50x,y. The ingress card processes incoming signals, attaches egress card/port information 56 to them and forwards them to switch 40. Monitor 30 and update 43 units track failed/faulty egress ports and maintain translation table 48 which specifies back-up ports for failed ports. Switch 40 uses the egress card/port information received from ingress card 50a to reference table 48 in the translation unit 42 and rewrites card/port information as necessary. Switch fabric 46 then transfers the signals to the appropriate egress card and port for onward transmission. The invention avoids having to update routing tables in multiple ingress cards in the event of a fault, thereby reducing control traffic and delays. The translation table 48 may be implemented as content addressable memory containing only entries for faulty ports. The invention may be used with link aggregation schemes.