ISIS graceful-restart timers and planned restart toggle

[rszarecki]

Change Scope

• add ISIS graceful-restart timer parameters - T2 (restart-time), T1 (interface-time), and number of T1 expirations after which adjacency is considered GR not capable.
• adding graceful-restart container under level, as per RFC5306/8706 timers and capabilities as well as GR procedures are on per-level basis.
• toggle to enable/disable support for RFC8706 planned restart.

Changes to ISIS global configuration:

module: openconfig-network-instance
module: openconfig-network-instance
  +--rw network-instances
     +--rw network-instance* [name]
        +--rw protocols
           +--rw protocol* [identifier name]
              +--rw isis
                 +--rw global
                    +--rw graceful-restart
                       +--rw config
                       |  +--rw enabled?                      boolean
                       |  +--rw helper-only?                  boolean
                       |  +--rw non-planed-only?              boolean                        <<< NEW
                       |  +--rw restart-time?                 int64                          <<< NEW
                       |  +--rw interface-timer?              int64                          <<< NEW
                       |  +--rw interface-time-expirations?   int64                          <<< NEW
                       +--ro state
                          +--ro enabled?                      boolean
                          +--ro helper-only?                  boolean
                          +--ro non-planed-only?              boolean                        <<< NEW
                          +--ro restart-time?                 int64                          <<< NEW
                          +--ro interface-timer?              int64                          <<< NEW
                          +--ro interface-time-expirations?   int64                          <<< NEW

Changes to ISIS level configuration. Allows distinct timer per LSDB.

module: openconfig-network-instance
  +--rw network-instances
     +--rw network-instance* [name]
        +--rw protocols
           +--rw protocol* [identifier name]
              +--rw isis
                 +--rw levels
                    +--rw level* [level-number]
                       +--rw graceful-restart                          <<< NEW
                          +--rw config
                          |  +--rw enabled?        boolean
                          |  +--rw restart-time?   int64
                          +--ro state
                             +--ro enabled?        boolean
                             +--ro restart-time?   int64

Changes to ISIS interface configuration. Allows distinct timer per interface.

module: openconfig-network-instance
  +--rw network-instances
     +--rw network-instance* [name]
        +--rw protocols
           +--rw protocol* [identifier name]
              +--rw isis
                 +--rw interfaces
                    +--rw interface* [interface-id]
                       +--rw graceful-restart                          <<< NEW
                          +--rw config
                          |  +--rw interface-timer?              int64
                          |  +--rw interface-time-expirations?   int64
                          +--ro state
                             +--ro interface-timer?              int64
                             +--ro interface-time-expirations?   int64

change is non-breaking

Platform Implementations

• CISCO IOS-XR: ISIS NSF

RP/0/RP0/CPU0:router# configure
RP/0/RP0/CPU0:router(config)# router isis isp
RP/0/RP0/CPU0:router(config-isis)# nsf ietf
RP/0/RP0/CPU0:router(config-isis)# nsf interface-expires 1
RP/0/RP0/CPU0:router(config-isis) nsf interface-timer 3
RP/0/RP0/CPU0:router(config-isis)# nsf lifetime 30

• Juniper JUNOS: Configuring Graceful Restart Options for IS-IS
  

protocols {
    isis {
        graceful-restart {
            disable;
            helper-disable;
            restart-duration seconds;
        }
    }
}

[dplore]

/gcbrun

[OpenConfigBot]

No major YANG version changes in commit 0be94bb

[dplore]

/gcbrun

[dplore]

Will review on next OC operators call 2024-03-05

[dplore]

/gcbrun

[dplore]

@rszarecki does it make sense to add the same leafs within each level of hierarchy?

ie: shouldn't these be at global, isis level and interface level?

                          +--ro enabled?                      boolean
                          +--ro helper-only?                  boolean
                          +--ro non-planed-only?              boolean                        <<< NEW
                          +--ro restart-time?                 int64                          <<< NEW
                          +--ro interface-timer?              int64                          <<< NEW
                          +--ro interface-time-expirations?   int64                          <<< NEW

[rszarecki]

@dplore
No.

• restart-time is LSDB (level) attribute. Can't be interface attribute.
• On P2P links restart can distinguish among level. So, enabled may not be implemented on levels level.
• helper-only could be interface attributes, but it has little sense. It implys that it is can be active restarter, but not inform peer about it. The way RFC5306 is working, restarter can signal restart to peer. If peer do not support GR-helper. it will ignore.
• non-planed-only is just toggle between RFC5306 and newer one, which is backward compatible. I do not see value in doing it per peer. Of peer do not support planned restart, is ignores restart time hint. I add it mainly to allow operator to set all systems in network to behave the same - unification. to lowest common denominator
• interface-timer/expiration can be per level, because on P2P links levels are not disseminated (one IIH for both).

[dplore]

/gcbrun

[dplore]

/gcbrun

[dplore]

LGTM