Multicast routing using core based trees
DCFirst Claim
1. A method for enabling a particular node to join a particular multicast group of nodes in a network comprising a plurality of nodes, said method comprising the steps of:
- transmitting from said particular node a join request control packet indicating a multicast address of a core node on a multicast tree corresponding to said multicast group,receiving said join request control packet at another node,writing an address of the node from which said join request control packet was received in an entry of a forwarding table maintained at said other node, which entry is indexed by said multicast address of said core node, andif said other node is not already on said multicast tree of said particular multicast group, writing an address of a next node on a path to said core node in said forwarding table entry indexed by said multicast address of said core node and retransmitting said packet from said other node to said next node.
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Abstract
A method for routing multicast packets in a network is disclosed. A node s101 wishing to join a particular multicast group transmits a packet via a sequence of nodes (r101, r102, r104, r107) including a core node r107 on the multicast tree corresponding to the particular multicast group which the node wishes to join. The packet contains a request to join the particular multicast group and the multicast address of the core node r107 of the multicast tree corresponding to the particular multicast group. The packet is received at each node r101, r102, r104, r107 of the sequence of nodes. Each node r101, r102, r104, r107 which receives the packet writes an address of the node s101, r101, r102, r104 from which the packet was received in an entry of a multicast forwarding table maintained thereat which entry is indexed by the multicast address of the core node r107. If the node r101, r102, r 104 which received the packet is not on the multicast tree of the particular multicast group, the node r101, r102, r104 writes an address of the next node r102, r104, r107 of the sequence of nodes in the multicast forwarding table entry indexed by the multicast address of the core node r107. The packet is then retransmitted to the next node r102, r104, r107 of the sequence of nodes.
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Citations
16 Claims
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1. A method for enabling a particular node to join a particular multicast group of nodes in a network comprising a plurality of nodes, said method comprising the steps of:
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transmitting from said particular node a join request control packet indicating a multicast address of a core node on a multicast tree corresponding to said multicast group, receiving said join request control packet at another node, writing an address of the node from which said join request control packet was received in an entry of a forwarding table maintained at said other node, which entry is indexed by said multicast address of said core node, and if said other node is not already on said multicast tree of said particular multicast group, writing an address of a next node on a path to said core node in said forwarding table entry indexed by said multicast address of said core node and retransmitting said packet from said other node to said next node. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for enabling a particular node to join a particular multicast group of nodes in a network, said multicast group having a multicast tree including a core node, said method comprising the steps of:
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transmitting a join request control packet containing a multicast address of said core node from said particular node to a node already on said multicast tree using unicast routing, at said node already on said multicast tree, writing an address of the node from which said join request control packet was received in an entry of a forwarding table maintained at said node already on said multicast tree, which entry is indexed by said multicast address of said core node, and transmitting a join acknowledgement control packet to said particular node. - View Dependent Claims (13, 14)
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15. A method for transmitting a data packet to a multicast group of nodes in a network using a multicast tree of nodes associated with said group comprising the steps of:
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at each node on a multicast tree corresponding to said multicast group, retrieving an entry from a forwarding table maintained at each node and indexed by a multicast address of a core node indicated by said data packet, and transmitting a copy of said data packet to each node indicated by said retrieved entry except a node from which said packet was received., said multicast tree having been constructed by the steps of; transmitting from a particular node wishing to join said particular multicast group a join request control packet indicating a multicast address of said core node, receiving said join request control packet at another node, writing an address of the node from which said join request was received in an entry of a forwarding table maintained at said other node, which entry is indexed by said multicast address of said core node, and if said other node is not already on said multicast tree of said particular multicast group, writing an address of a next node on a path to said core node in said forwarding table entry indexed by said multicast address of said core node and retransmitting said packet form said other node to said next node.
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16. A method for transmitting a data packet from a source node which is not a member of a multicast group of nodes to a multicast group of nodes in a network using a multicast tree of nodes associated with said group comprising the steps of:
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transmitting said data packet containing a multicast address of a core node on said multicast tree from said source node to a node on said multicast tree using unicast routing, said packet being transmitted on said multicast tree by the steps of; at each node on a multicast tree corresponding to said multicast group, retrieving an entry from a forwarding table maintained at each node and indexed by a multicast address of a core node indicated by said data packet, and transmitting a copy of said data packet to each node indicated by said retrieved entry except a node from which said packet was received.
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Specification