Data structure identifying for multiple addresses the reverse path forwarding information for a common intermediate node and its use

A method for determining reverse path forwarding information, the method comprising:

• performing a lookup operation on an address lookup data structure based on a particular address of a particular packet to identify a leaf node of a plurality of leaf nodes corresponding to the particular address, the leaf node including a reverse path forwarding indirection link;
• and
• traversing the reverse path forwarding indirection link to a particular reverse path sub-data structure identifying whether or not an interface on which the particular packet was received was allowable or not;
• wherein each of a particular plurality of the plurality of leaf nodes having a same intermediate reachability node in a network includes a particular indirection link to the particular sub-data structure, and the particular plurality of the plurality of leaf nodes includes the leaf node.

An apparatus for determining reverse path forwarding information, the apparatus comprising:

• means for performing a lookup operation on an address lookup data structure based on a particular address of a particular packet to identify a leaf node of a plurality of leaf nodes corresponding to the particular address, the leaf node including a reverse path forwarding indirection link;
• and
• means for traversing the reverse path forwarding indirection link to a particular reverse path sub-data structure identifying whether or not an interface on which the particular packet was received was allowable or not;
• wherein each of a particular plurality of the plurality of leaf nodes having a same intermediate reachability node in a network includes a particular indirection link to the particular sub-data structure, and the particular plurality of the plurality of leaf nodes includes the leaf node.

An apparatus for performing lookup operations to identify reverse path forwarding information, the apparatus comprising:

• one or more computer-readable media configured to store an address lookup data structure for identifying leaf nodes of a plurality of leaf nodes corresponding to matching addresses;
• and
• one or more lookup engines for performing lookup operations on the address lookup data structure;
• wherein each of the plurality of leaf nodes in the data structure includes a reverse path forwarding indirection link to a corresponding sub-data structure indicating reverse path forwarding information, and each of a particular plurality of the plurality of leaf nodes having a same intermediate reachability node in a network includes a particular indirection link to a same particular sub-data structure indicating reverse path forwarding information.