Label distribution protocol graceful restart on existing sessions
Systems and methods include operating a label distribution protocol (LDP) session with a peer node in a network; responsive to a change in graceful restart of the LDP session, sending a notification message to the peer node with a graceful restart capability change indication; responsive to receiving a second notification message from the peer node with graceful restart capability change indication, updating the graceful restart capability for the LDP session; and, responsive to failing to receive the second notification message, leaving the graceful restart capability as it was prior to the change.
1 . A node in a network comprising:
one or more modules and a plurality of ports; and
circuitry configured to
operate a label distribution protocol (LDP) session with a peer node in a network;
responsive to a change in graceful restart of the LDP session, send a notification message to the peer node with a graceful restart capability change indication;
responsive to receiving a second notification message from the peer node with graceful restart capability change indication, update the graceful restart capability for the LDP session, wherein the notification message and second notification messages each include a fault tolerant (FT) type-length-value (TLV) that signals a runtime change in graceful restart capability and a status TLV carrying a status code, distinct from existing LDP status codes, to indicate that capability change, wherein the runtime change occurs during the LDP session after session establishment without tearing down the LDP session, and wherein the ET TLV includes a FT flags field comprising a graceful restart enable/disable bit that indicates whether graceful restart is enabled or disabled for the LDP session; and
responsive to failing to receive the second notification message, leave the graceful restart capability as it was prior to the change.
2 . The node of claim 1 , wherein the LDP session is initially created with an initialization message not having graceful restart; and wherein the change is to enable graceful restart dynamically at runtime without requiring a session teardown disrupting the LDP session.
3 . The node of claim 1 , wherein the LDP session is initially created with an initialization message having graceful restart; and wherein the change is to disable graceful restart dynamically at runtime without disrupting the LDP session.
4 . The node of claim 1 , wherein the notification message and the second notification message are advisory notification messages.
5 . The node of claim 1 , wherein the FT TLV is a vendor-private type-length value (TLV) having an unknown bit set such that the ET TLV is silently discarded by a peer node that does not support the FT TLV.
6 . The node of claim 5 , wherein the status code in the status TLV indicates a graceful restart capability change.
7 . The node of claim 6 , wherein the status code is different from other status codes in LDP.
8 . The node of claim 6 , wherein the FT TLV includes FT flags for graceful restart configuration.
9 . A method comprising steps of:
operating a label distribution protocol (LDP) session with a peer node in a network;
responsive to a change in graceful restart of the LDP session, sending a notification message to the peer node with a graceful restart capability change indication;
responsive to receiving a second notification message from the peer node with graceful restart capability change indication, update the graceful restart capability for the LDP session, wherein the notification message and second notification messages each include a fault tolerant (FT) type-length-value (TLV) that signals a runtime change in graceful restart capability and a status TLV carrying a status code, distinct from existing LDP status codes, to indicate that capability change, wherein the runtime change occurs during the LDP session after session establishment without tearing down the LDP session, and wherein the FTV TLV includes a FT flags field comprising a graceful restart enable/disable bit that indicates whether graceful restart is enabled or disabled for the LDP session; and
responsive to failing to receive the second notification message, leaving the graceful restart capability as it was prior to the change.
10 . The method of claim 9 , wherein the LDP session is initially created with an initialization message not having graceful restart; and wherein the change is to enable graceful restart dynamically at runtime without requiring a session teardown disrupting the LDP session.
11 . The method of claim 9 , wherein the LDP session is initially created with an initialization message having graceful restart; and wherein the change is to disable graceful restart dynamically at runtime without disrupting the LDP session.
12 . The method of claim 9 , wherein the notification message and the second notification message are advisory notification messages.
13 . The method of claim 9 , wherein the FT TLV is a vendor-private type-length-value (TLV) having an unknown bit set such that the ET TLV is silently discarded by a peer node that does not support the FT TLV.
14 . The method of claim 13 , wherein the status code in the status TLV indicates a graceful restart capability change.
15 . The method of claim 14 , wherein the status code is different from other status codes in LDP.
16 . The method of claim 14 , wherein the FT TLV includes FT flags for graceful restart configuration.
17 . A non-transitory computer-readable medium comprising instructions that, when executed, cause a node in a network to perform steps of:
operating a label distribution protocol (LDP) session with a peer node in a network;
responsive to a change in graceful restart of the LDP session, sending a notification message to the peer node with a graceful restart capability change indication;
responsive to receiving a second notification message from the peer node with graceful restart capability change indication, update the graceful restart capability for the LDP session, wherein the notification message and second notification messages each include a fault tolerant (FT) type-length-value (TLV) that signals a runtime change in graceful restart capability and a status TLV carrying a status code, distinct from existing LDP status codes, to indicate that capability change, wherein the runtime change occurs during the LDP session after session establishment without tearing down the LDP session, and wherein the FTV TLV includes an FT flags field comprising a graceful restart enable/disable bit that indicates whether graceful restart is enabled or disabled for the LDP session; and
responsive to failing to receive the second notification message, leaving the graceful restart capability as it was prior to the change.
18 . The non-transitory computer-readable medium of claim 17 , wherein the LDP session is one of
initially created with an initialization message not having graceful restart, and wherein the change is to enable graceful restart at runtime without disrupting the LDP session; and
initially created with an initialization message having graceful restart, and wherein the change is to disable graceful restart dynamically at runtime without disrupting the LDP session.
19 . The non-transitory computer-readable medium of claim 17 , wherein the LDP session is initially created with an initialization message not having graceful restart; and wherein the change is to enable graceful restart dynamically at runtime without requiring a session teardown disrupting the LDP session.
20 . The non-transitory computer-readable medium of claim 17 , wherein the LDP session is initially created with an initialization message having graceful restart; and wherein the change is to disable graceful restart dynamically at runtime without disrupting the LDP session.