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Maniphest T7731

Static ARP entries are missing after an interface status change
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Description

Summary

Static ARP entries are not synchronized after any changes are made to an interface status

How to reproduce

Configure basic settings:

set interfaces ethernet eth9 address '192.168.122.5/24'

Check neighbors:

[edit]
vyos@vyos# sudo ip neighbor

Add static ARP entries:

set protocols static arp interface eth9 address 192.168.122.2 mac '00:11:22:33:44:55'
set protocols static arp interface eth9 address 192.168.122.3 mac '00:11:22:33:44:66'

Check neighbors again:

[edit]
vyos@vyos# sudo ip neighbor
192.168.122.2 dev eth9 lladdr 00:11:22:33:44:55 PERMANENT 
192.168.122.3 dev eth9 lladdr 00:11:22:33:44:66 PERMANENT 
[edit]     sudo vppctl show ip neighbors
     Age                       IP                    Flags      Ethernet              Interface       
     28.1721              192.168.122.3                S    00:11:22:33:44:66 eth9
     28.1734              192.168.122.2                S    00:11:22:33:44:55 eth9

Flap the link (externally or with commands provided below):

sudo ip l set eth9 down
sudo ip l set eth9 up

Check neighbors again:

[edit]
vyos@vyos# sudo ip neighbor

What is expected / Suggested solution

It is expected that static ARP entries will not disappear after an interface status change.

It seems we are missing calling a dependency for protocols static arp after the interfaces reinitialization. We need to ensure that after an interface status is flapped or it is recreated, we will reapply static ARP settings.

Details

Version
2025.10.17-0019-rolling
Is it a breaking change?
Perfectly compatible
Issue type
Bug (incorrect behavior)

Related Objects
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StatusSubtypeAssignedTask
 OpenFEATURE REQUESTNoneT7221 VPP related features the root task
 ResolvedFEATURE REQUESTnatali-rs1985T7731 Static ARP entries are missing after an interface status change

Event Timeline

Viacheslav created this task.Aug 18 2025, 4:01 PM
Viacheslav triaged this task as Normal priority.Aug 18 2025, 4:15 PM
Viacheslav renamed this task from VPP add static ARP neighbor enries configurable to VPP add static ARP neighbor entries configurable.Aug 18 2025, 4:30 PM
pasik subscribed.Aug 18 2025, 6:35 PM
zsdc renamed this task from VPP add static ARP neighbor entries configurable to VPP: Synchronize static ARP entries from kernel.Oct 21 2025, 1:35 PM
zsdc updated the task description. (Show Details)
zsdc changed Version from - to 2025.10.17-0019-rolling.
zsdc changed Is it a breaking change? from Unspecified (possibly destroys the router) to Perfectly compatible.
zsdc changed Issue type from Feature (new functionality) to Bug (incorrect behavior).
zsdc renamed this task from VPP: Synchronize static ARP entries from kernel to Static ARP entries are missing after an interface status change.Oct 21 2025, 3:00 PM
zsdc updated the task description. (Show Details)
natali-rs1985 changed the task status from Open to In progress.Nov 4 2025, 9:04 AM
natali-rs1985 claimed this task.
natali-rs1985 added a comment.Nov 6 2025, 8:49 AM

https://github.com/vyos/vyos-1x/pull/4835

natali-rs1985 mentioned this in rVYOSONEXccf4972f8dd9: T7731: Static ARP entries are missing after an interface status change.Thu, Nov 13, 2:47 PM
Restricted Repository Identity mentioned this in rVYOSONEX23e61833f4ac: Merge pull request #4835 from natali-rs1985/T7731.Thu, Nov 13, 2:47 PM
natali-rs1985 closed this task as Resolved.Fri, Nov 21, 12:49 PM
natali-rs1985 moved this task from Need Triage to Completed on the VyOS Rolling board.