ospfd: OSPF SR is not turned on - "segment-routing node-msd" always enabled by default

[c-po]

Describe the bug

frr-reload.py fails as OSPF process always installs a segment-routing config line segment-routing node-msd 5

• Did you check if this is a duplicate issue?
• Did you test it on the latest FRRouting/frr master branch?

To Reproduce

** With vtysh **

cpo@LR1.wue3:~$ vtysh -c "show run" -d ospfd
Building configuration...

Current configuration:
!
frr version 9.1
frr defaults traditional
hostname LR1.wue3
log syslog
log facility local7
service integrated-vtysh-config
!
end

Now start OSPF

cpo@LR1.wue3:~$ vtysh -c "conf" -c "router ospf" -d ospfd
cpo@LR1.wue3:~$ vtysh -c "show run" -d ospfd
...
!
router ospf
 segment-routing node-msd 5
exit
!
end

This behavior manifests in un-reloadable configurations using frr-reload:

cpo@LR1.wue3:~$ cat no-ospf.txt
!
end

Unloading config works: /usr/lib/frr/frr-reload.py --reload --daemon ospfd --debug --stdout no-ospf.txt

Now start OSPF process using frr-reload:

cpo@LR1.wue3:~$ cat ospf.txt
!
router ospf
 log-adjacency-changes detail
exit
!
end

sudo /usr/lib/frr/frr-reload.py --reload --daemon ospfd --stdout ospf.txt

The first run is successful and you get:

cpo@LR1.wue3:~$ vtysh -c "show run" -d ospfd
...
!
router ospf
 log-adjacency-changes detail
 segment-routing node-msd 5
exit
!

Any subsequent run will result in:

cpo@LR1.wue3:~$ sudo /usr/lib/frr/frr-reload.py --reload --daemon ospfd --debug  --stdout ospf.txt
2023-11-29 20:34:01,853  INFO: Called via "Namespace(input=None, reload=True, test=False, debug=True, log_level='info', stdout=True, pathspace=None, filename='ospf.txt', overwrite=False, bindir='/usr/bin', confdir='/etc/frr', rundir='/var/run/frr', vty_socket=None, daemon='ospfd', test_reset=False)"
2023-11-29 20:34:01,853  INFO: Loading Config object from file ospf.txt
2023-11-29 20:34:01,889 DEBUG: LINE router ospf                                       : enter context ['router ospf']
2023-11-29 20:34:01,889 DEBUG: LINE log-adjacency-changes detail                      : add to current context ['router ospf']
2023-11-29 20:34:01,890 DEBUG: LINE exit                                              : exit context ['router ospf']
2023-11-29 20:34:01,929 DEBUG: New Frr Config
!
router ospf
log-adjacency-changes detail
exit
!

end

2023-11-29 20:34:01,929  INFO: Loading Config object from vtysh show running
2023-11-29 20:34:01,968 DEBUG: LINE frr version 9.1                                   : single-line context
2023-11-29 20:34:01,968 DEBUG: LINE frr defaults traditional                          : single-line context
2023-11-29 20:34:01,968 DEBUG: LINE hostname LR1.wue3                                 : single-line context
2023-11-29 20:34:01,969 DEBUG: LINE service integrated-vtysh-config                   : single-line context
2023-11-29 20:34:01,969 DEBUG: LINE router ospf                                       : enter context ['router ospf']
2023-11-29 20:34:01,969 DEBUG: LINE log-adjacency-changes detail                      : add to current context ['router ospf']
2023-11-29 20:34:01,969 DEBUG: LINE segment-routing node-msd 5                        : add to current context ['router ospf']
2023-11-29 20:34:01,969 DEBUG: LINE exit                                              : exit context ['router ospf']
2023-11-29 20:34:01,969 DEBUG: Running Frr Config (Pass #0)
frr version 9.1
frr defaults traditional
hostname LR1.wue3
service integrated-vtysh-config
!
router ospf
log-adjacency-changes detail
segment-routing node-msd 5
exit
!
end
2023-11-29 20:34:01,969  INFO: "frr version 9.1" cannot be removed
2023-11-29 20:34:01,969  INFO: "frr defaults traditional" cannot be removed
2023-11-29 20:34:01,969  INFO: "service integrated-vtysh-config" cannot be removed
2023-11-29 20:34:02,007  INFO: Executed "no hostname LR1.wue3"
2023-11-29 20:34:02,046  INFO: Failed to execute router ospf  no segment-routing node-msd 5 exit
2023-11-29 20:34:02,046   ERROR: "router ospf --  no segment-routing node-msd 5 -- exit" we failed to remove this command
2023-11-29 20:34:02,046   ERROR: % OSPF SR is not turned on

2023-11-29 20:34:02,046  INFO: Loading Config object from vtysh show running
2023-11-29 20:34:02,085 DEBUG: LINE frr version 9.1                                   : single-line context
2023-11-29 20:34:02,085 DEBUG: LINE frr defaults traditional                          : single-line context
2023-11-29 20:34:02,086 DEBUG: LINE hostname LR1.wue3                                 : single-line context
2023-11-29 20:34:02,086 DEBUG: LINE service integrated-vtysh-config                   : single-line context
2023-11-29 20:34:02,086 DEBUG: LINE router ospf                                       : enter context ['router ospf']
2023-11-29 20:34:02,086 DEBUG: LINE log-adjacency-changes detail                      : add to current context ['router ospf']
2023-11-29 20:34:02,086 DEBUG: LINE segment-routing node-msd 5                        : add to current context ['router ospf']
2023-11-29 20:34:02,086 DEBUG: LINE exit                                              : exit context ['router ospf']
2023-11-29 20:34:02,086 DEBUG: Running Frr Config (Pass #1)
frr version 9.1
frr defaults traditional
hostname LR1.wue3
service integrated-vtysh-config
!
router ospf
log-adjacency-changes detail
segment-routing node-msd 5
exit
!
end
2023-11-29 20:34:02,086  INFO: "frr version 9.1" cannot be removed
2023-11-29 20:34:02,086  INFO: "frr defaults traditional" cannot be removed
2023-11-29 20:34:02,086  INFO: "service integrated-vtysh-config" cannot be removed

Expected behavior

Reload completes

Screenshots

Versions

• OS Version: Debian 12

• Kernel: 6.1.64

• FRR Version: 9.1 5cd2981

Additional context

[odd22]

Hi,

I'm seeing what's wrong. Default value should not be written if Segment Routing is disabled. I'll have a look to correct the problem.

Olivier

[c-po]

@odd22 anything we can help you with?

[c-po]

Can also be reproduced within vtysh:

Enable SR and MSD

LR1.wue3(config-router)# router ospf
 segment-routing on
 segment-routing node-msd 5

Disable SR

LR1.wue3(config-router)# router ospf
 no segment-routing on

MSD can no longer be removed

LR1.wue3(config-router)# no segment-routing node-msd 5
% OSPF SR is not turned on

Even removing the entire OSPF process does not help

LR1.wue3(config)# no router ospf
LR1.wue3(config)# router ospf
LR1.wue3(config-router)# end

router ospf
 segment-routing node-msd 5
exit

Assumption

In ospf_sr_stop the value of OspfSR.msd should be set back to 0 as in ospf_sr_init