segment-routing config loss after frr restart/node reboot

[zsoltkrenak]

Description

When configuring ISIS with segment-routing (in my case srv6) and configuring srv6 locators under segment-routing config mode, after a restart of frr, or a reboot of node causes to lose segment-routing config to be lost under segment-routing config mode.

Version

frr# show version 
FRRouting 10.1 (frr) on Linux(6.6.45-0-lts).
Copyright 1996-2005 Kunihiro Ishiguro, et al.
configured with:
    '--prefix=/usr' '--localstatedir=/run/frr' '--sbindir=/usr/lib/frr' '--sysconfdir=/etc/frr' '--libdir=/usr/lib/frr' '--with-moduledir=/usr/lib/frr/modules' '--disable-dependency-tracking' '--enable-rpki' '--with-libpam' '--enable-doc' '--enable-doc-html' '--enable-snmp' '--enable-fpm' '--disable-protobuf' '--disable-zeromq' '--enable-ospfapi' '--enable-bgp-vnc' '--enable-multipath=256' '--enable-user=frr' '--enable-group=frr' '--enable-vty-group=frrvty' '--enable-configfile-mask=0640' '--enable-logfile-mask=0640' 'CC=gcc' 'CXX=g++' 'PYTHON=python3'

How to reproduce

Take the following (simplified config):

frr# show running-config 
Building configuration...

Current configuration:
!
frr version 10.1
frr defaults traditional
hostname frr
log syslog informational
service integrated-vtysh-config
!
router isis ISIS_CORE
 is-type level-2-only
 net 49.0001.0000.0000.0004.00
 lsp-mtu 1300
 topology ipv6-unicast
 log-adjacency-changes
 segment-routing srv6
  locator ISIS_LOC
exit
!
segment-routing
 srv6
  locators
   locator ISIS_LOC
    prefix X:Y:0:Z::/64 block-len 48 node-len 16 func-bits 16
   exit
   !
   locator BGP_LOC
    prefix X:Y:0:Z:8000::/65 block-len 48 node-len 17 func-bits 15
   exit
   !
  exit
  !
 exit
 !
 traffic-eng
  pcep
  exit
 exit
exit
!
end

Then in case of alpine linux which I have tested on:

frr:~# /etc/init.d/frr restart

Expected behavior

After FRR restart:

frr# show running-config 
Building configuration...

Current configuration:
!
frr version 10.1
frr defaults traditional
hostname frr
log syslog informational
service integrated-vtysh-config
!
router isis ISIS_CORE
 is-type level-2-only
 net 49.0001.0000.0000.0004.00
 lsp-mtu 1300
 topology ipv6-unicast
 log-adjacency-changes
 segment-routing srv6
  locator ISIS_LOC
exit
!
segment-routing
 srv6
  locators
   locator ISIS_LOC
    prefix X:Y:0:Z::/64 block-len 48 node-len 16 func-bits 16
   exit
   !
   locator BGP_LOC
    prefix X:Y:0:Z:8000::/65 block-len 48 node-len 17 func-bits 15
   exit
   !
  exit
  !
 exit
 !
 traffic-eng
  pcep
  exit
 exit
exit
!
end

Actual behavior

frr# show running-config 
Building configuration...

Current configuration:
!
frr version 10.1
frr defaults traditional
hostname frr
log syslog informational
service integrated-vtysh-config
!
router isis ISIS_CORE
 is-type level-2-only
 net 49.0001.0000.0000.0004.00
 lsp-mtu 1300
 topology ipv6-unicast
 log-adjacency-changes
 segment-routing srv6
  locator ISIS_LOC
exit
!
segment-routing
 traffic-eng
  pcep
  exit
 exit
exit
!

Additional context

The issue is clearly caused by missing exit statement in isis routing configuration. Manually editing frr.conf and adding the right exit statement solves the problem:

frr:~# cat /etc/frr/frr.conf
frr version 10.1
frr defaults traditional
hostname frr
log syslog informational
service integrated-vtysh-config
!
router isis ISIS_CORE
 is-type level-2-only
 net 49.0001.0000.0000.0004.00
 lsp-mtu 1300
 topology ipv6-unicast
 log-adjacency-changes
 segment-routing srv6
  locator ISIS_LOC
 exit
exit
!
segment-routing
 srv6
  locators
   locator ISIS_LOC
    prefix X:Y:0:Z::/64 block-len 48 node-len 16 func-bits 16
   exit
   !
   locator BGP_LOC
    prefix X:Y:0:Z:8000::/65 block-len 48 node-len 17 func-bits 15
   exit
   !
  exit
  !
 exit
 !
 traffic-eng
  pcep
  exit
 exit
exit
!

This is also reproducible on 9.1, 10.0 and 10.1.

Checklist

• I have searched the open issues for this bug.
• I have not included sensitive information in this report.

[SPYFF]

Happened to me too, but I was unable to find the cause, nice investigation.

This bug is really annoying, I used to dump sh run and copy back, but this bug essentially breaks this workflow for every SRv6 ISIS configs.