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The router does not send correct LSA in OSPFv3 when DR is down
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Description

The router does not send a correct LSA in OSPFv3 when the DR is down, and only one router is left to participate in DR/BDR election.
Example:
There are four OSPFv3-enabled routers in the broadcast domain.

image.png (467×388 px, 26 KB)

R1,R2,R3 are VyOS
R4 - Cisco Router

R1- is a DR
R2 - is a BDR
R3, R4 - have priority eq 0, They do not participate in DR/BDR election.
When R1 goes down. R2 becomes DR, and no BDR is elected.
After that, R3 does not install routes in RIB. R2 and R4 do not install routes from R3 in the RIB.
R2 installs routes from R4, and the same vice versa.
Configurations:
R1:

set interfaces dummy dum0 address '2001:db9::1/128'
set interfaces ethernet eth0 address '2001:0DB8::2/64'
set protocols ospfv3 interface dum0 area '0'
set protocols ospfv3 interface eth0 area '0'
set protocols ospfv3 interface eth0 priority '100'
set protocols ospfv3 parameters router-id '1.1.1.1'

R2:

set interfaces dummy dum0 address '2001:db9::2/128'
set interfaces ethernet eth0 address '2001:0DB8::3/64'
set protocols ospfv3 interface dum0 area '0'
set protocols ospfv3 interface eth0 area '0'
set protocols ospfv3 interface eth0 priority '90'
set protocols ospfv3 parameters router-id '1.1.1.2'

R3:

set interfaces dummy dum0 address '2001:db9::3/128'
set interfaces ethernet eth0 address '2001:0DB8::4/64'
set protocols ospfv3 interface dum0 area '0'
set protocols ospfv3 interface eth0 area '0'
set protocols ospfv3 interface eth0 priority '0'
set protocols ospfv3 parameters router-id '1.1.1.3'

R4:

interface Loopback0
 no ip address
 ipv6 address 2001:DB9::6/128
 ipv6 ospf 1 area 0
!
interface GigabitEthernet0/0
 no ip address
 duplex auto
 speed auto
 media-type rj45
 ipv6 address 2001:DB8::6/64
 ipv6 address autoconfig
 ipv6 ospf 1 area 0
 ipv6 ospf priority 0
!
router ospfv3 1
 router-id 1.1.1.6
 !

LSA from R3 on R2 before failure of R1

vyos@vyos:~$ show ipv6 ospfv3 database adv-router 1.1.1.3 linkstate-id 0.0.0.0 detail

        Area Scoped Link State Database (Area 0)

Age:  108 Type: Router
Link State ID: 0.0.0.0
Advertising Router: 1.1.1.3
LS Sequence Number: 0x8000001d
CheckSum: 0x965e Length: 40
Duration: 00:01:46
    Bits: -------- Options: --|-|--|-|-|--|R|-|--|E|V6
    Type: Transit-Network Metric: 1
    Interface ID: 0.0.0.2
    Neighbor Interface ID: 0.0.0.2
    Neighbor Router ID: 1.1.1.1

Age:  108 Type: Intra-Prefix
Link State ID: 0.0.0.0
Advertising Router: 1.1.1.3
LS Sequence Number: 0x80000023
CheckSum: 0x8cd7 Length: 52
Duration: 00:01:46
     Number of Prefix: 1
     Reference: Router Id: 0.0.0.0 Adv: 1.1.1.3
     Prefix Options: --|--|--|--|--
     Prefix: 2001:db9::3/128
     Metric: 1

        I/F Scoped Link State Database (I/F dum0 in Area 0)

        I/F Scoped Link State Database (I/F eth0 in Area 0)

        AS Scoped Link State Database

LSA from R3 on R2 after failure of R1

vyos@vyos:~$ show ipv6 ospfv3 database adv-router 1.1.1.3 linkstate-id 0.0.0.0 detail

        Area Scoped Link State Database (Area 0)

Age:    8 Type: Router
Link State ID: 0.0.0.0
Advertising Router: 1.1.1.3
LS Sequence Number: 0x8000001e
CheckSum: 0xc945 Length: 24
Duration: 00:00:07
    Bits: -------- Options: --|-|--|-|-|--|R|-|--|E|V6

Age:  255 Type: Intra-Prefix
Link State ID: 0.0.0.0
Advertising Router: 1.1.1.3
LS Sequence Number: 0x80000023
CheckSum: 0x8cd7 Length: 52
Duration: 00:04:13
     Number of Prefix: 1
     Reference: Router Id: 0.0.0.0 Adv: 1.1.1.3
     Prefix Options: --|--|--|--|--
     Prefix: 2001:db9::3/128
     Metric: 1

        I/F Scoped Link State Database (I/F dum0 in Area 0)

        I/F Scoped Link State Database (I/F eth0 in Area 0)

        AS Scoped Link State Database

On the other hand, Cisco works without this issue.

LSA from R4 on R2 after failure of R1

vyos@vyos:~$ show ipv6 ospfv3 database adv-router 1.1.1.6 linkstate-id 0.0.0.0 detail

        Area Scoped Link State Database (Area 0)

Age:  142 Type: Router
Link State ID: 0.0.0.0
Advertising Router: 1.1.1.6
LS Sequence Number: 0x8000001c
CheckSum: 0x5d74 Length: 40
Duration: 00:02:21
    Bits: -------- Options: --|-|--|-|-|DC|R|-|--|E|V6
    Type: Transit-Network Metric: 1
    Interface ID: 0.0.0.2
    Neighbor Interface ID: 0.0.0.2
    Neighbor Router ID: 1.1.1.2

Age:  226 Type: Intra-Prefix
Link State ID: 0.0.0.0
Advertising Router: 1.1.1.6
LS Sequence Number: 0x80000008
CheckSum: 0x4f26 Length: 52
Duration: 00:03:45
     Number of Prefix: 1
     Reference: Router Id: 0.0.0.0 Adv: 1.1.1.6
     Prefix Options: --|--|--|LA|--
     Prefix: 2001:db9::6/128
     Metric: 0

        I/F Scoped Link State Database (I/F dum0 in Area 0)

        I/F Scoped Link State Database (I/F eth0 in Area 0)

        AS Scoped Link State Database

Details

Version
VyOS 2026.02.13-0029-rolling, VyOS 1.4.4
Is it a breaking change?
Perfectly compatible
Issue type
Bug (incorrect behavior)

Event Timeline

a.apostoliuk created this task.Feb 16 2026, 4:48 PM
a.apostoliuk triaged this task as Normal priority.
pasik subscribed.Feb 16 2026, 6:20 PM
hedrok subscribed.Feb 26 2026, 5:38 PM

FRR PR: https://github.com/FRRouting/frr/pull/20947

Viacheslav changed the task status from Open to In progress.Mar 24 2026, 12:05 PM
Viacheslav assigned this task to hedrok.
dmbaturin renamed this task from The router does not send correct LSA in OSPFv3 when DR is down. to The router does not send correct LSA in OSPFv3 when DR is down.Mar 24 2026, 5:28 PM
dmbaturin changed the task status from In progress to Open.
dmbaturin edited projects, added VyOS 1.5 Circinus (1.5.0), VyOS 1.4 Sagitta (1.4.5); removed VyOS 1.5 Circinus, VyOS 1.4 Sagitta.
Viacheslav closed this task as Resolved.Apr 16 2026, 1:37 PM
Viacheslav moved this task from Need Triage to Completed on the VyOS Rolling board.