Patent ID: 6337861
Filing Date: 2002-01-08
Classification: H04L

Abstract:
A tag-switching router comprising:A) circuitry for receiving an input packet, said input packet including an input IP datagram containing an input IP payload and prepended with a tag stack containing a top tag stack entry that includes a top tag, said input IP datagram including an input source IP address and an input destination IP address; B) memory circuitry containing a forwarding table, said top tag pointing to a forwarding entry in the forwarding table, said forwarding entry containing a replacement tag and the identity of a link over which the input IP datagram is to be forwarded; C) circuitry for replacing the top tag in the tag stack with the replacement tag; D) circuitry for generating at least one output packet, said output packet: i) including, if the input IP datagram has any one of a set of at least one predetermined fault condition, an output IP datagram containing an ICMP message and prepended with the tag stack that includes the replacement tag, said output IP datagram having the input source IP address as its destination address; ii) otherwise including at least a fragment of the input IP payload and prepended with the tag stack that includes the replacement tag, said at least one output packet having the input destination IP address as its destination address; and E) circuitry for forwarding each output packet over the link identified in the forwarding entry.