Method to setup protocol independent multicast trees in the presence of unidirectional tunnels

Patent metadata

Field	Value
Publication number	US-9401859-B2
Application number	US-201313747956-A
Country	US
Kind code	B2
Filing date	Jan 23, 2013
Priority date	Jan 23, 2013
Publication date	Jul 26, 2016
Grant date	Jul 26, 2016

Abstract

Embodiments of the invention are directed to establishing a PIM tree to a source that is reachable over a unicast tunnel in a packet switched network. Advantageously, a Reverse Path Forwarding (RPF) Vector TLV to establish a PIM tree may be used in cases where there is an absence of source reachability in the core of a network.

First claim

What is claimed is:

1. A method of establishing a protocol independent multicast tree in a packet switched network, the method comprising:
at a first node in the network,
receiving a join message that indicates a source node of a multicast group;
looking up a route to the source node;
determining if the first node has an adjacency with a first next hop node along the route;
forwarding the join message to the first next hop node responsive to the first node having an adjacency with the first next hop node;

responsive to the first node not having an adjacency with the first next hop node:
performing a recursive next hop resolution of the first next hop node to find a second next hop on an alternate route to the source node through the first next hop node;
responsive to not finding the alternate route:
dropping the join message; and

responsive to finding the alternate route and having an adjacency with the second next hop:
forwarding the join message to the second next hop node.

2. The method of claim 1 further comprising based on the first node configuration and responsive to action of performing recursive next hop resolutions:
altering the join message to include a reverse path forwarding vector that indicates the first next hop node; and
forwarding the altered join message to the second next hop node that was found when performing the recursive next hop resolution of the first next hop node.

3. The method of claim 2 further comprising:
at the second next hop node,
receiving the altered join message;
performing a next hop resolution of the reverse path forwarding vector; and
forwarding the altered join message to a third next hop node that was found when performing the next hop resolution.

4. The method of claim 1 wherein performing further comprises finding an alternate route that does not use a tunnel.

5. The method of claim 1 wherein receiving a join message further comprises receiving a source specific multicast join message.

6. The method of claim 1 further comprising:
at the source node,
receiving the join message and adding an originating node of the join message to the multicast group.

7. A network node comprising;
an interface for receiving and transmitting data packet traffic;
a processor coupled to the interface;
a memory coupled to the processor, the memory including routing information;
a program of computer readable instructions stored in the memory that when executed by the processor cause the network node be operable to:
receive via the interface a on message that indicates a source node of a multicast group;
look up in the memory a route to the source node;
determine if the network node has an adjacency with a first next hop node along the route; and
forward the join message to the first next hop node responsive to the network node having an adjacency with the first next hop node;
responsive to the network node not having an adjacency with the first next hop node:
perform a recursive next hop resolution of the first next hop node to find a second next hop on an alternate route to the source node through the first next hop node;
responsive to not finding the alternate route:
drop the join message; and
responsive to finding the alternate route and having an adjacency with the second next hop:
forward the join message to the second next hop node.

8. The network node of claim 7 wherein the program when executed by the processor further causes the network node be operable to:
based on node configuration or responsive to the action of performing recursive next hop resolution,
alter the join message to include a reverse path forwarding vector that indicates the first next hop node; and
forward the altered join message to the second next hop node that was found when performing the recursive next hop resolution of the first next hop node.

Assignees

• Kotalwar Jayant
• Kollipara Siva
• Alcatel Lucent

Inventors

• Kotalwar Jayant
• Kollipara Siva

Classifications

• H04L45/48 Primary

  Routing tree calculation · CPC title

• H04L45/22 Primary

  Alternate routing · CPC title

• H04L45/16

  Multipoint routing · CPC title

• H04L45/34

  Source routing · CPC title

• H04L12/185

  with management of multicast group membership · CPC title