System and method for performing cascaded lookups to forward packets

A system comprising:

• a network device, wherein the network device comprises:
• a first lookup table comprising a plurality of first lookup table entries;
• a second lookup table comprising a plurality of second lookup table entries;
• and
• a lookup restriction unit wherein
• the first lookup table is configured to identify first information in response to receiving a first key generated from a first portion of a packet header,
• the first portion of the packet header comprises at least a first part of a multicast group destination address,
• the first information identifies a subset of the second lookup table,
• the subset of the second lookup table comprises at least one of the second lookup table entries;
• and
• the lookup restriction unit is configured to prevent a second key generated from a second portion of the packet header from matching any second lookup table entry that is not comprised in the subset of the second lookup table identified by the first information, wherein
• the second portion of the packet header comprises at least a second part of the multicast group destination address.

A computer readable non-transitory storage medium storing program instructions executable by a processor to:

• allocate at least one entry in a first lookup table and at least one first entry in a subset of a second lookup table for each multicast tree, wherein
• the subset of the second lookup table comprises at least one entry;
• and
• configure a lookup restriction unit to prevent a lookup in the second lookup table from matching entries not included in the subset of the second lookup table if a corresponding lookup in the first lookup table matches the at least one entry in the first lookup table.

A system comprising:

• network interface means for receiving a packet header via a network link;
• means for accessing a first lookup table based on a first portion of the packet header, wherein
• the first portion of the packet header comprises at least a first part of a multicast group destination address,
• the first lookup table identifies a subset of a second lookup table,
• the subset of the second lookup table comprises at least one entry;
• and
• means for accessing the subset of the second lookup table based on a second portion of the packet header, wherein
• the second portion of the packet header comprises at least a second part of the multicast group destination address.