Method for maintaining differentiated services data flow at a network device implementing redundant packet discard security techniques

摘要

An improved method is described for providing Differentiated Services (Diffserv) traffic to a node in a network that implements a security method that discards duplicate packets received at the node. The method includes the step of identifying at least two service levels to be provided to received traffic and assigning different size look-back window counts to each of the service levels. The look-back window count indicates a number of packets that have been previously received at the node that should be compared against a received packet to determine whether a duplicate packet has been received. In one embodiment, a service level that has higher priority is assigned a lower look-back window count and thus examines fewer previously received packets than a service level having a lower priority. Such an arrangement reduces the possibility that traffic having higher priority is dropped as a security measure.

主权项

1. A method of determining whether to discard a received packet at a node, the method comprising the steps of:
responsive to a service level associated with the received packet, selecting a number from at least two available numbers, wherein the number identifies a number of previously received packets and wherein the at least two available numbers are different; comparing a sequence number associated with the received packet against sequence numbers associated with the selected number of previously received packets; and discarding the received packet in the event of a match between any one of the sequence numbers associated with the selected number of previously received packets and the sequence number associated with the received packet.