Reverse forwarding information base enforcement

Patent metadata

Field	Value
Publication number	US-11075836-B2
Application number	US-201615169003-A
Country	US
Kind code	B2
Filing date	May 31, 2016
Priority date	May 31, 2016
Publication date	Jul 27, 2021
Grant date	Jul 27, 2021

Abstract

In exemplary embodiments of the present invention, a router determines whether or not to establish a stateful routing session based on the suitability of one or more candidate return path interfaces. This determination is typically made at the time a first packet for a new session arrives at the router on a given ingress interface. In some cases, the router may be configured to require that the ingress interface be used for the return path of the session, in which case the router may evaluate whether the ingress interface is suitable for the return path and may drop the session if the ingress interface is deemed by the router to be unsuitable for the return path. In other cases, the router may be configured to not require that the ingress interface be used for the return path, in which case the router may evaluate whether at least one interface is suitable for the return path and drop the session if no interface is deemed by the router to be suitable for the return path.

First claim

What is claimed is:

1. A method of managing stateful routing sessions by a router, the method comprising:
receiving, by the router, a first packet for a forward path of a new stateful routing session on an ingress port of the router;
analyzing, by the router, in response to the first packet for the forward path of the new stateful routing session received on the ingress port of the router, at least one candidate egress port to determine if at least one candidate egress port is a suitable candidate egress port for a return path for the session that is associated with a valid route for the return path and can provide a predetermined level of performance required for the return path including at least one of bandwidth, error rate, or latency;
when said analyzing determines that at least one candidate egress port is a suitable candidate egress port for the return path for the session, establishing, by the router, the stateful routing session using a suitable candidate egress port for the return path for the session, wherein establishing the stateful routing session comprises determining a next node for the stateful routing session and forwarding a modified first packet containing session metadata toward the next node; and
when said analyzing determines that no candidate egress port is a suitable candidate egress port for the return path for the session, dropping the session by the router without forwarding the modified first packet containing session metadata toward the next node.

2. A method according to claim 1 , wherein the at least one candidate egress port consists of the ingress port.

3. A method according to claim 1 , wherein analyzing at least one candidate egress port for suitability for a return path for the session comprises:
determining whether a valid route exists for the return path; and
when a valid route exists for the return path, determining whether the return path is associated with a given candidate egress port.

4. A method according to claim 1 , wherein determining whether a given candidate egress port can provide a predetermined level of performance required for the return path comprises exchange link monitoring protocol messages over the given candidate egress port including packet loss detection metadata.

5. A method according to claim 1 , further comprising:
when a plurality of candidate egress ports are suitable candidate egress ports, selecting one of the suitable candidate egress ports for the return path for the session.

6. A method according to claim 1 , wherein analyzing at least one candidate egress port for suitability for a return path for the session comprises:
maintaining a reverse forwarding information data base that stores performance information for each router port; and
referencing the reverse forwarding information database to determine suitability.

7. A method according to claim 6 , wherein the at least one candidate egress port includes a plurality of candidate egress ports, and wherein analyzing at least one candidate egress port for suitability for a return path for the session further comprises:
referencing the reverse forwarding information database to determine a best suitable candidate egress port from among the plurality of candidate egress ports.

8. A router comprising:
a plurality of communication interfaces;
a computer storage; and
a packet router configured to implement method of managing stateful routing sessions, the method comprising:
receiving, by the packet router, a first packet for a forward path of a new stateful routing session on an ingress port of the router;
analyzing, by the packet router, in response to the first packet for the forward path of the new stateful routing session received on the ingress port of the router, at least one candidate egress port to determine if at least one candidate egress port is a suitable candidate egress port for a return path for the session that is associated with a valid route for the return path and can provide a predetermined level of performance required for the return path including at least one of bandwidth, error rate, or latency;
when said analyzing determines that at least one candidate egress port is a suitable candidate egress port for the return path for the session, establishing, by the packet router, the stateful routing session using a suitable candidate egress port for the return path for the session, wherein establishing the stateful routing session comprises determining a next node for the stateful routing session and forwarding a modified first packet containing session metadata toward the next node; and
when said analyzing determines that no candidate egress port is a suitable candidate egress port for the return path for the session, dropping the session by the packet router without forwarding the modified first packet containing session metadata toward the next node.

9. A router according to claim 8 , wherein the at least one candidate egress port consists of the ingress port.

10. A router according to claim 8 , wherein analyzing at least one candidate egress port for suitability for a return path for the session comprises:
determining whether a valid route exists for the return path; and
when a valid route exists for the return path, determining whether the return path is associated with a given candidate egress port.

11. A router according to claim 8 , wherein determining whether a given candidate egress port can provide a predetermined level of performance required for the return path comprises exchange link monitoring protocol messages over the given candidate egress port including packet loss detection metadata.

12. A router according to claim 8 , wherein the method further comprises:
when a plurality of candidate egress ports are suitable candidate egress ports, selecting one of the suitable candidate egress ports for the return path for the session.

13. A router according to claim 8 , wherein analyzing at least one candidate egress port for suitability for a return path for the session comprises:
maintaining, by the packet router, a reverse forwarding information database in the computer storage, the reverse forwarding information base storing performance information for each router port; and
referencing, by the packet router, the reverse forwarding information database to determine suitability.

14. A router according to claim 13 , wherein the at least one candidate egress port includes a plurality of candidate egress ports, and wherein analyzing at least one candidate egress port for suitability for a return path for the session further comprises:
referencing, by the packet router, the reverse forwarding information database to determine a best suitable candidate egress port from among the plurality of candidate egress ports.

15. A computer program product comprising a tangible, non-transitory computer readable medium having embodied therein a computer program that, when run on at least one computer processor, implements a packet router for a router, the packet router implementing a method of managing stateful routing sessions by a router, the method comprising:
receiving a first packet for a forward path of a new stateful routing session on an ingress port of the router;
analyzing, in response to the first packet for the forward path of the new stateful routing session received on the ingress port of the router, at least one candidate egress port to determine if at least one candidate egress port is a suitable candidate egress port for a return path for the session that is associated with a valid route for the return path and can provide a predetermined level of pe

Assignees

• 128 Tech Inc

Inventors

• Menon Abilash
• Penfield Robert
• Kaplan Hadriel S

Classifications

• H04L45/36 Primary

  Backward learning · CPC title

• H04L45/745 Primary

  Address table lookup; Address filtering · CPC title

• H04L47/32

  by discarding or delaying data units, e.g. packets or frames · CPC title

• H04L45/38

  Flow based routing · CPC title

• H04L49/309

  Header conversion, routing tables or routing tags · CPC title