Method and apparatus for applying once-only processing in a data network

A method for avoiding duplicate processing at a data network node comprising the steps of:

• determining whether said network node is adjacent to a host;
• receiving a data packet associated with said host;
• and
• applying a once-only operation to said data packet only if said network node is adjacent to said host;
• wherein said step of determining comprises the steps of:
• transmitting a ping packet to said host;
• receiving a ping response and determining, in response to receipt of said ping response, that said network node is adjacent to said host, wherein said adjacency between said network node and said host is found only when there is a path between said network node and said host containing no other data network node capable of applying said once-only operation to said data packet other than said network node;
• and
• dropping ping packets received from other network nodes.

A network node comprising:

• means for determining whether said network node is adjacent to a host;
• means for receiving a data packet associated with said host;
• and
• means for applying a once-only operation to said data packet only if said network node is adjacent to said host;
• wherein said means for determining comprises:
• means for receiving a broadcast data packet which is seperate from said data packet and determining, in response to receipt of said broadcast data packet, that said network node is adjacent to said host, wherein said adjacency between said network node and said host is found only when there is a path between said network node and said host containing no other data network node capable of applying said once-only operation to said data packet other than said network node;
• and
• means for dropping said broadcast data packet.

A network node comprising:

• means for determining whether said network node is adjacent to a host;
• means for receiving a data packet associated with said host;
• and
• means for applying a once-only operation to said data packet only if said network node is adjacent to said host;
• wherein said means for determining comprises:
• means for transmitting a ping packet to said host;
• means for receiving a ping response and determining, in response to receipt of said ping response, that said network node is adjacent to said host, wherein said adjacency between said network node and said host is found only when there is a path between said network node and said host containing no other data network node capable of applying said once-only operation to said data packet other than said network node;
• and
• means for dropping ping packets received from other network nodes.