Method and apparatus for wire speed IP multicast forwarding

A switch comprising:

• a memory storing a multicast data packet received from a port connected to the switch;
• egress port forwarding logic, the egress port forwarding logic comprising:
• a table of modification entries including a modification entry for each member of a multicast group associated with the multicast data packet, an index to the table of modification entries for the multicast group stored with the data packet in the memory;
• and
• editing logic which modifies a copy of the multicast data packet received from the memory dependent on the modification entry;
• ingress port forwarding logic which generates a multicast forward vector for the multicast data packet, the multicast forward vector indicating to which ports the stored multicast data packet is to be forwarded;
• and
• port queue logic which stores a pointer to the multicast data packet stored in the memory in at least one port queue dependent on the multicast forward vector, the port queue logic removes the pointer to the multicast data packet stored in the port queue after the stored multicast data packet has been forwarded to all members of the multicast group connected to the port associated with the port queue.

A switch comprising:

• a memory storing a multicast data packet received from a port connected to the switch;
• egress port forwarding logic, the egress port forwarding logic comprising:
• a table of modification entries including a modification entry for each member of a multicast group associated with the multicast data packet, an index to the table of modification entries for the multicast group stored with the data packet in the memory, the modification entry comprises:
• a virtual LAN identification;
• a pointer to a next modification entry;
• a tag indicator;
• and
• a forward type indicator;
• and
• editing logic which modifies a copy of the multicast data packet received from the memory dependent on the modification entry.

A switch comprising:

• a memory storing a multicast data packet received from a port connected to the switch;
• egress port forwarding logic, the egress port forwarding logic comprising:
• table of modification entries including a modification entry for each member of a multicast group associated with the multicast data packet an index to the table of modification entries for the multicast group stored with the data packet in the memory the modification entry comprises:
• a virtual LAN entry stored in a virtual LAN identification table;
• and
• an intermediate entry stored in an intermediate LAN identification table wherein the intermediate entry includes an index to the virtual LAN entry;
• and
• editing logic which modifies a copy of the multicast data packet received from the memory dependent on the modification entry.

A method for forwarding a multicast data packet in a switch comprising the steps of:

• storing in a memory, the multicast data packet received from an ingress port;
• storing table of modification entries including a modification entry for each member of a multicast group associated with the multicast data packet, a plurality of members of the multicast group coupled to a same egress port;
• modifying a copy of the multicast data packet received from the memory dependent on the modification entry associated with the member;
• and
• forwarding the modified copy of the multicast data packet to the egress port in a next available egress port cycle time.

A method for forwarding multicast data packets in a switch comprising the steps of:

• storing in a memory, a multicast data packet received from an ingress port;
• providing egress port forwarding logic, the egress port forwarding logic including a table of modification entries including a modification entry for each member of a multicast group associated with the multicast data packet an index to the table of modification entries for the multicast group stored with the data packet in the memory and editing logic for modifying the multicast data packet;
• modifying in the egress port forwarding logic a copy of the multicast data packet received from the memory dependent on the modification entry;
• forwarding by the egress port forwarding logic the modified copy of the multicast data packet to an egress port in a next available egress port cycle time;
• selecting a multicast forward vector for the multicast data packet dependent on parameters included in the multicast data packet, the multicast forward vector indicating to which egress ports the multicast data packet is to be forwarded;
• and
• storing, by the packet manager a pointer to the multicast data packet stored in the memory in a port queue associated with the egress port dependent on the multicast forward vector.

A method for forwarding multicast data packets in a switch comprising the steps of:

• storing in a memory, a multicast data packet received from an ingress port;
• providing egress port forwarding logic, the egress port forwarding logic including a table of modification entries including a modification entry for each member of a multicast group associated with the multicast data packet an index to the table of modification entries for the multicast group stored with the data packet in the memory and editing logic for modifying the multicast data packet, the modification entry including a virtual LAN identification, a pointer to next entry, a tag indicator and a forward type indicator;
• modifying in the egress port forwarding logic a copy of the multicast data packet received from the memory dependent on the modification entry;
• and
• forwarding by the egress port forwarding logic the modified copy of the multicast data packet to an egress port in a next available egress port cycle time.

A method for forwarding multicast data packets in a switch comprising the steps of:

• storing in a memory, a multicast data packet received from an ingress port;
• providing egress port forwarding logic, the egress port forwarding logic including a table of modification entries including a modification entry for each member of a multicast group associated with the multicast data packet, an index to the table of modification entries for the multicast group stored with the data packet in the memory editing logic for modifying the multicast data packet, the egress port forwarding logic including a virtual LAN identification table and an intermediate LAN identification table for storing the multicast entry, the multicast entry includes an index to a location in the virtual LAN identification table including a virtual LAN identification;
• modifying in the egress port forwarding logic a copy of the multicast data packet received from the memory dependent on the modification entry;
• and
• forwarding by the egress port forwarding logic the modified copy of the multicast data packet to an egress port in a next available egress port cycle time.

A switch comprising:

• a memory storing a multicast data packet received from an ingress port connected to the switch;
• egress port forwarding logic, the egress port forwarding logic comprising:
• a table of modification entries including a modification entry for each member of a multicast group associated with the multicast data packet, a plurality of members of the multicast group coupled to a same egress port, an index to the table of modification entries for the multicast group stored with the data packet in the memory;
• and
• means for modifying a copy of the multicast data packet received from the memory dependent on the modification entry associated with the member.

A switch comprising:

• a memory storing a multicast data packet received from an ingress port connected to the switch;
• egress port forwarding logic, the egress port forwarding logic comprising:
• a table of modification entries including a modification entry for each member of a multicast group associated with the multicast data packet an index to the table of modification entries for the multicast group stored with the data packet in the memory;
• and
• means for modifying a copy of the multicast data packet received from the memory dependent on the modification entry;
• means for generating a multicast forward vector for the multicast data packet, the multicast forward vector indicating to which ports the stored multicast data packet is to be forwarded;
• and
• means for storing a pointer to the multicast data packet stored in the memory in at least one port queue dependent on the multicast forward vector, the means for storing removes the pointer to the multicast data packet stored in the port queue after the multicast data packet has been transmitted to each member of the multicast group connected to the egress port associated with the port queue.

A switch comprising:

• a memory storing a multicast data packet received from an ingress port connected to the switch;
• egress port forwarding logic, the egress port forwarding logic comprising:
• a table of modification entries including a modification entry for each member of a multicast group associated with the multicast data packet, an index to the table of modification entries for the multicast group stored with the data packet in the memory, the modification entry comprises:
• a virtual LAN identification;
• a pointer to next entry;
• a tag indicator;
• and
• a forward type indicator;
• and
• means for modifying a copy of the multicast data packet received from the memory dependent on the modification entry.

A switch comprising:

• a memory storing a multicast data packet received from an ingress port connected to the switch;
• egress port forwarding logic, the egress port forwarding logic comprising:
• a table of modification entries including a modification entry for each member of a multicast group associated with the multicast data packet, an index to the table of modification entries for the multicast group stored with the data packet in the memory, the modification entry comprises:
• a virtual LAN entry stored in a virtual LAN identification table;
• and
• an intermediate entry stored in an intermediate entry stored in an intermediate LAN identification table wherein the intermediate entry includes an index to the virtual LAN entry;
• and
• means for modifying a copy of the multicast data packet received from the memory dependent on the modification entry.