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BGP IPv6 only peer-group not supported
Closed, DuplicatePublicBUG

Description

It looks like that IPv6 only BGP peering sessions over a peer group are not supported.

The following configuration applies with an error:

must set remote-as or peer-group with remote-as defined

but the configuration is then present in the CLI.

Looking down into FRR vtysh -c "show run" reveals that the neighbors are completely missing.

config

vyos@vyos# show protocols
show protocols
 bgp 65000 {
     address-family {
         ipv6-unicast {
             network 2001:dba::/32 {
             }
         }
     }
     neighbor 2001:db8:1::2 {
         address-family {
             ipv6-unicast {
                 peer-group AS65001
             }
         }
     }
     parameters {
         log-neighbor-changes
         router-id 172.18.254.202
     }
     peer-group AS65001 {
         address-family {
             ipv6-unicast {
             }
         }
         remote-as 65001
     }
 }
 static {
     route6 2001:dba::/32 {
         blackhole {
         }
     }
 }

commit

vyos@vyos# commit
[ protocols bgp 65000 ]
[ protocols bgp 65000 neighbor 2001:db8:1::2 ]
  must set remote-as or peer-group with remote-as defined

FRR

vyos@vyos# vtysh -c "show run"
Building configuration...

Current configuration:
!
frr version 7.0.1-20190514-01-gcd305c0
frr defaults traditional
hostname vyos
log syslog informational
agentx
service integrated-vtysh-config
!
ipv6 route 2001:dba::/32 Null0
!
router bgp 65000
 bgp router-id 172.18.254.202
 bgp log-neighbor-changes
 neighbor 2001:db8:1::2 remote-as 65001
 !
 address-family ipv4 unicast
  network 10.0.0.0/9
  network 10.128.0.0/9
 exit-address-family
!
line vty
!
end

ugly workaround

as soon as I change my configuration like the following everything works - but now I have multiprotocol configuration which I tend to avoid

vyos@vyos# show protocols bgp 65010 neighbor 2001:db8::101:2
 address-family {
     ipv6-unicast {
         peer-group AS65020
     }
 }
 peer-group AS65020

Details

Difficulty level
Unknown (require assessment)
Version
1.2.2
Why the issue appeared?
Will be filled on close
Is it a breaking change?
Unspecified (possibly destroys the router)

Event Timeline

c-po updated the task description. (Show Details)
syncer triaged this task as Normal priority.
syncer edited projects, added VyOS 1.3 Equuleus; removed VyOS 1.2 Crux.
c-po set Is it a breaking change? to Unspecified (possibly destroys the router).
c-po updated the task description. (Show Details)

The set protocols bgp XXX neighbor XXX address-family ipv6-unicast peer-group XXX command generate the router bgp XXX; address-family ipv6; neighbor XXX peer-group XXX', for vtysh, which does not supported (anymore? I cannot find any commits in FRR about syntax change, maybe this was migrated from old quagga).

peer-group supported only at the router bgp XXX neighbor XXX level. Thus, we should simplify our CLI by deletion obsoleted address-family ipv6-unicast peer-group command with value migration to the general peer-group for a peer.
This will make BGP configuration more clear.