Source Alive Route Injection

• US 20130033978A1
• Filed: 08/01/2011
• Published: 02/07/2013
• Est. Priority Date: 08/01/2011
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Eckert, Toerless, Venaas, Stig
• Granted Patent: US 9,019,815 B2
• Time in Patent Office: Days
• US Class Current: 370/216
• CPC Class Codes: G06F 11/2035 without idle spare hardware
• CPC Class Codes: G06F 11/2048 where the redundant components share neither address space nor persistent storage
• CPC Class Codes: H04L 45/123 Evaluation of link metrics techniques for monitoring network metrics H04L43/08
• CPC Class Codes: H04L 45/16 Multipoint routing
• CPC Class Codes: H04L 45/22 Alternate routing
• CPC Class Codes: H04L 45/28 using route fault recovery

Abstract

Multiple redundant sources for a datastream can be established in a network, where the redundant sources are configured with the same source address. One of the redundant sources provides the datastream to a receiver of a multicast group. If the redundant source fails, another redundant source can be used in its place, ensuring the receiver continues to receive the datastream. A routing element coupled to a redundant source monitors the redundant source for failure and informs the rest of the network of the status of the coupled redundant source. The routing element can inform other routing elements of the status by advertising or withdrawing a route that reaches the coupled redundant source, which the other routing elements can use to update their routing tables.

Claims

1. A method comprising:

monitoring whether datastream packets are received from a first redundant source;

determining that the first redundant source is active, based on the datastream packets; and

advertising a first route, in response to the determining that the first redundant source is active, wherein

the first redundant source is reachable by the first route.

2. The method of claim 1, further comprising:

subsequent to the determining the first redundant source is active, determining that the first redundant source becomes inactive, based on the datastream packets; and

withdrawing the first route, in response to the determining that the first redundant source becomes inactive.

3. The method of claim 2, wherein the determining that the first redundant source is active further comprises

detecting that the datastream packets are received from the first redundant source for a duration of a threshold active time.

4. The method of claim 3, wherein the determining that the first redundant source becomes inactive further comprises

detecting that the datastream packets are not received from the first redundant source for a duration of a threshold inactive time.

5. The method of claim 2, wherein the determining that the first redundant source is active further comprises:

evaluating that the datastream packets satisfy a performance metric.

6. The method of claim 5, wherein the determining that the first redundant source becomes inactive further comprises:

evaluating that the datastream packets fail to satisfy a performance metric.

7. The method of claim 6, wherein the performance metric comprises one of a minimum transmit time, a minimum packet loss metric, a minimum error rate, and a minimum bandwidth.

8. The method of claim 1, further comprising:

receiving a route update for a second route to a second redundant source, wherein

a packet transport tree for a downstream receiver currently uses the second route;

updating a routing table with the route update for the second route; and

determining a best route, wherein

the best route is selected from the routing table according to a selection policy.

9. The method of claim 8, wherein

the selection policy indicates that a route to a preferred redundant source is the best route,

preference of redundant sources is indicated by a prefix length associated with a route of a redundant source, and

a longest prefix length indicates the route to the preferred redundant source.

10. The method of claim 8, wherein

the selection policy indicates that a route to a closest redundant source to a receiver is the best route,

distance is indicated by a route weighting metric associated with a route of a redundant source, and

a least route weighting metric indicates the route to the closest redundant source.

11. The method of claim 8, further comprising

maintaining the packet transport tree on the best route.

12. The method of 1, further comprising:

receiving a join message for a downstream receiver;

selecting a best route to a redundant source from a routing table according to a selection policy, wherein

the best route comprises one of the first route to the first redundant source and a second route to a second redundant source, and

the best route is selected in support of building a packet transport tree between one of the first and second redundant sources and the downstream receiver.

13. An apparatus comprising:

a port configured to receive datastream packets from a first redundant source;

a monitoring module configured to detect whether the datastream packets are received on the port; and

a state module configured to

determine that the first redundant source is active, based on the datastream packets, and

trigger generation of a route advertising message comprising a first route, in response to the determination that the first redundant source is active, wherein

the first redundant source is reachable by the first route.

14. The apparatus of claim 13, wherein

the state module is further configured to, subsequent to the determination that the first redundant source is active,

determine that the first redundant source becomes inactive, and

trigger generation of a route withdrawal for the first route, in response to the determination that the first redundant source becomes inactive.

15. The apparatus of claim 14, wherein

the state module is configured to determine that the first redundant source is active by being further configured to

determine that the datastream packets are received from the first redundant source for a threshold active time, and

the state module is configured to determine that the first redundant source becomes inactive by being further configured to

determine that the datastream packets are not received from the first redundant source for a threshold inactive time.

16. The apparatus of claim 14, wherein

the monitoring module is further configured to

evaluate whether the datastream packets received from the first redundant source satisfy a performance metric,

the state module is configured to determine the first redundant source is active by being further configured to

determine the datastream packets satisfy the performance metric for a threshold active time, and

the state module is configured to determine the first redundant source becomes inactive by being further configured to

determine the datastream packets fail to satisfy the performance metric for a threshold inactive time.

17. The apparatus of claim 14, further comprising:

a routing module configured to

receive a route update for a second route to a second redundant source, wherein

a packet transport tree for a downstream receiver currently uses the second route,

update a routing table with the route update for the second route,

determine a best route, wherein

the best route is selected from the routing table according to a selection policy.

18. The apparatus of claim 14, further comprising:

a routing module configured to

receive a join message for a downstream receiver,

select a best route to a redundant source from a routing table according to a selection policy, wherein

the best route comprises one of the first route to the first redundant source and a second route to a second redundant source, and

the best route is selected in support of building a packet transport tree between one of the first and second redundant sources and the downstream receiver.

19. A system comprising:

means for monitoring whether datastream packets are received from a redundant source;

means for determining that the redundant source is active, based on the datastream packets; and

means for advertising a first route, in response to the determination that the redundant source is active.

20. The system of claim 19 further comprising:

means for determining that the redundant source becomes inactive, based on the datastream packets; and

means for withdrawing the first route, in response to the determination that the redundant source becomes inactive.