Abstract: An apparatus and method for a frequency based integrated circuit that selectively filters out unwanted bands or regions of interfering frequencies utilizing one or more tunable notch or bandpass filters or tunable low or high pass filters capable of operating across multiple frequencies and multiple bands in noisy RF environments. The tunable filters are fabricated within the same integrated circuit package as the associated frequency based circuitry, thus minimizing R, L, and C parasitic values, and also allowing residual and other parasitic impedance in the associated circuitry and IC package to be absorbed and compensated.

Abstract: In a router, externally received messages addressed to an active line card are bridged to a protection line card. Each line card in the router is programmed to respond to such externally received messages by directing them to the protection line card associated with the active line card as well as to the active line card. The protection line card is configured with inbound and outbound path tables that are the clones of the inbound and outbound path tables of its corresponding active line card. Bridging is accomplished by revising descriptors stored in a plurality of line cards to indicate an association between an active one of the line cards and its protection line card. Received messages are addressed using the revised descriptors to the active line card and also to its protection line card. Upon failure of an active line card, its physical interface can be disabled once its protection line card has clones of the inbound and outbound path tables and bridging has been set up.