Session Continuity in the Presence of Network Address Translation

• US 20170346787A1
• Filed: 05/31/2016
• Published: 11/30/2017
• Est. Priority Date: 05/31/2016
• Status: Active Grant

• Current Assignee: 128 Technology, Inc. (Juniper Networks Incorporated)
• Original Assignee: 128 Technology, Inc. (Juniper Networks Incorporated)
• Inventors: Menon, Abilash, Yungelson, Anna, McCulley, Scott A., Penfield, Robert, Mendez Cirera, Francisco Jose, Sullivan, Thomas E.
• Granted Patent: US 10,091,099 B2
• Time in Patent Office: Days
• CPC Class Codes: H04L 45/38 Flow based routing
• CPC Class Codes: H04L 61/2514 between local and global IP addresses
• CPC Class Codes: H04L 67/142 Managing session states for stateless protocols; Signalling session states; State transitions; Keeping-state mechanisms

Abstract

Embodiments of the present invention provide for continuity of “stateful” routing sessions in the presence of source network address translation (NAT). Specifically, a stateful routing session may be moved from one routing path to another routing path, e.g., due to a routing change in the communication network, where the routing paths have different source NAT status. For example, the stateful routing session may be moved from a path having no source NAT to a path having source NAT, from a path having source NAT to a path having no source NAT, or from paths having different source network address translations. When a stateful routing session is moved from an existing routing path to a new routing path, the routers detect the routing change based on the change in source NAT status using a special link monitoring protocol. Upon detecting the change in source NAT status, session metadata is included in at least the first packet forwarded following detection of the change in source NAT status so that the stateful routing session can continue without interruption.

Claims

1. A method of providing session continuity by a router in the presence of source network address translation (NAT), the method comprising:

establishing, by the router, a stateful routing session with a remote router;

running, by the router, a link monitoring protocol with the remote router to detect a change in source NAT status associated with the stateful routing session; and

sending, by the router, session metadata in at least a first session packet forwarded to the remote router following detection of the change in source NAT status.

2. A method according to claim 1, wherein the link monitoring protocol is an augmented Bidirectional Forwarding Detection (BFD) protocol.

3. A method according to claim 1, further comprising:

modifying, by the router, a flow associated with the stateful routing session based on the change in source NAT status.

4. A method according to claim 3, wherein modifying the flow comprises:

deactivating the flow;

establishing a new flow based on the change in source NAT status; and

activating the new flow.

5. A method according to claim 4, wherein:

the flow includes an action chain having a chain descriptor linked to a series of functional blocks;

deactivating the flow comprises deactivating the action chain;

establishing a new flow comprises establishing a new series of functional blocks and linking the new series of functional blocks to the chain descriptor; and

activating the new flow comprises activating the action chain.

6. A method according to claim 4, wherein modifying the flow further comprises:

storing context information associated with the flow;

linking the new flow to the stored context information; and

using the stored context information to forward packets using the new flow.

7. A method according to claim 1, wherein sending session metadata in at least a first session packet forwarded to the remote router following detection of the change in source NAT status comprises:

activating a metadata action mechanism associated with the stateful routing session to cause the router to send session metadata in at least a first session packet forwarded to the remote router following detection of the change in source NAT status.

8. A router comprising:

a plurality of communication interfaces;

a computer storage; and

a packet router configured to implement method of providing session continuity in the presence of source network address translation (NAT), the method comprising;

establishing, by the packet router, a stateful routing session with a remote router;

running, by the packet router, a link monitoring protocol with the remote router to detect a change in source NAT status associated with the stateful routing session; and

sending, by packet the router, session metadata in at least a first session packet forwarded to the remote router following detection of the change in source NAT status.

9. A router according to claim 8, wherein the link monitoring protocol is an augmented Bidirectional Forwarding Detection (BFD) protocol.

10. A router according to claim 8, wherein the method further comprises:

modifying, by the packet router, a flow associated with the stateful routing session based on the change in source NAT status.

11. A router according to claim 10, wherein modifying the flow comprises:

deactivating the flow;

establishing a new flow based on the change in source NAT status; and

activating the new flow.

12. A router according to claim 11, wherein:

the flow includes an action chain having a chain descriptor linked to a series of functional blocks;

deactivating the flow comprises deactivating the action chain;

establishing a new flow comprises establishing a new series of functional blocks and linking the new series of functional blocks to the chain descriptor; and

activating the new flow comprises activating the action chain.

13. A router according to claim 11, wherein modifying the flow further comprises:

storing context information associated with the flow;

linking the new flow to the stored context information; and

using the stored context information to forward packets using the new flow.

14. A router according to claim 8, wherein sending session metadata in at least a first session packet forwarded to the remote router following detection of the change in source NAT status comprises:

activating a metadata action mechanism associated with the stateful routing session to cause the router to send session metadata in at least a first session packet forwarded to the remote router following detection of the change in source NAT status.

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 providing session continuity in the presence of source network address translation (NAT), the method comprising:

establishing, by the packet router, a stateful routing session with a remote router;

running, by the packet router, a link monitoring protocol with the remote router to detect a change in source NAT status associated with the stateful routing session; and

sending, by the packet router, session metadata in at least a first session packet forwarded to the remote router following detection of the change in source NAT status.

16. A computer program product according to claim 15, wherein the link monitoring protocol is an augmented Bidirectional Forwarding Detection (BFD) protocol.

17. A computer program product according to claim 15, wherein the method further comprises:

modifying, by the packet router, a flow associated with the stateful routing session based on the change in source NAT status.

18. A computer program product according to claim 17, wherein modifying the flow comprises:

deactivating the flow;

establishing a new flow to associate the second ingress interface with the first egress interface; and

activating the new flow.

20. A computer program product according to claim 18, wherein modifying the flow further comprises:

storing context information associated with the flow;

linking the new flow to the stored context information; and

using the stored context information to forward packets using the new flow.

21. A computer program product according to claim 15, wherein sending session metadata in at least a first session packet forwarded to the remote router following detection of the change in source NAT status comprises:

activating a metadata action mechanism associated with the stateful routing session to cause the router to send session metadata in at least a first session packet forwarded to the remote router following detection of the change in source NAT status.

19. A computer program product according to claim 19, wherein:

the flow includes an action chain having a chain descriptor linked to a series of functional blocks;

deactivating the flow comprises deactivating the action chain;

establishing a new flow comprises establishing a new series of functional blocks and linking the new series of functional blocks to the chain descriptor; and

activating the new flow comprises activating the action chain.

22. A system comprising:

a first router; and

a second router, wherein;

the first router is configured to establish a stateful routing session with a remote router, run a link monitoring protocol with the remote router to detect a change in source NAT status associated with the stateful routing session, and send session metadata in at least a first session packet forwarded to the remote router following detection of the change in source NAT status; and

the second router is configured to receive a packet containing session metadata for a session associated with a change in source NAT status, identify the stateful routing session based on the session metadata, and update session-related information and affected flows based on header information in the packet.