Processing EVPN MAC interface change on peer triggered on non EVPN peers

[ardenisov]

Discussed in #17890

^{Originally posted by ardenisov January 21, 2025}
Hello!
When enable debug bgp updates I see a lot of messages like below for every bgp peer:

2025/01/17 12:11:02 BGP: [TPJB2-AQ2TG] Processing EVPN MAC interface change on peer 10.37.96.8 
2025/01/17 12:11:02 BGP: [TPJB2-AQ2TG] Processing EVPN MAC interface change on peer 10.37.96.104 
2025/01/17 12:11:02 BGP: [TPJB2-AQ2TG] Processing EVPN MAC interface change on peer 10.37.128.62 
2025/01/17 12:11:02 BGP: [TPJB2-AQ2TG] Processing EVPN MAC interface change on peer 10.37.128.126 
2025/01/17 12:11:02 BGP: [TPJB2-AQ2TG] Processing EVPN MAC interface change on peer 10.37.160.62 
2025/01/17 12:11:02 BGP: [TPJB2-AQ2TG] Processing EVPN MAC interface change on peer 10.37.160.126 

The strangest thing is that EVPN AF is not enabled on host, all peers direct and IPV4 only.
Also the state of host interfaces and each peer is stable for weeks.
Sometimes on host flaps tap interfaces, when VMs redeployed.
But taps don't participate in bgp and not mentioned in FRR config.
Could some one help me to investigate root cause of this messages?

frr version 9.1.2

UPD:
I found, that message of "Processing EVPN MAC interface change on peer" triggers every time tap interface created/deleted and for all BGP peers.
As I understand in the code, the message of "Processing EVPN MAC interface change on peer" should be triggered only if peer has soft reconfiguration inbound configured for EVPN address family, but in my case all peers IPv4 only:

Example of bgp peer config:

router bgp 4237321009
 bgp router-id 10.32.180.25
 bgp bestpath as-path multipath-relax
 neighbor bgp_int peer-group
 neighbor bgp_int bfd
 neighbor bgp_int password int
 neighbor 10.32.148.62 remote-as 4236323007
 neighbor 10.32.148.62 peer-group bgp_int
 neighbor 10.32.148.62 timers connect 3
 !
 address-family ipv4 unicast
  redistribute connected route-map connected
  neighbor bgp_int route-map net_10_0_0_0 in
  neighbor bgp_int route-map int_out out
  neighbor 10.32.148.62 soft-reconfiguration inbound
  maximum-paths 2
 exit-address-family
exit
!

Example of bgp peer state:

pd32-srv-009.kvm.mng.cloud.ru# show bgp neighbors 10.32.148.62 json
{
  "10.32.148.62":{
    "remoteAs":4236323007,
    "localAs":4237321009,
    "nbrExternalLink":true,
    "localRole":"undefined",
    "remoteRole":"undefined",
    "hostname":"Unknown",
    "peerGroup":"bgp_int",
    "bgpVersion":4,
    "remoteRouterId":"10.32.24.17",
    "localRouterId":"10.32.180.25",
    "bgpState":"Established",
    "bgpTimerUpMsec":432240000,
    "bgpTimerUpString":"5d00h04m",
    "bgpTimerUpEstablishedEpoch":1737110845,
    "bgpTimerLastRead":32000,
    "bgpTimerLastWrite":0,
    "bgpInUpdateElapsedTimeMsecs":221000,
    "bgpTimerConfiguredHoldTimeMsecs":180000,
    "bgpTimerConfiguredKeepAliveIntervalMsecs":60000,
    "bgpTimerHoldTimeMsecs":180000,
    "bgpTimerKeepAliveIntervalMsecs":60000,
    "bgpTcpMssConfigured":0,
    "bgpTcpMssSynced":1460,
    "extendedOptionalParametersLength":false,
    "bgpTimerConfiguredConditionalAdvertisementsSec":60,
    "neighborCapabilities":{
      "4byteAs":"advertisedAndReceived",
      "extendedMessage":"advertised",
      "addPath":{
        "ipv4Unicast":{
          "rxAdvertised":true
        }
      },
      "longLivedGracefulRestart":"advertised",
      "routeRefresh":"advertisedAndReceived",
      "enhancedRouteRefresh":"advertised",
      "multiprotocolExtensions":{
        "ipv4Unicast":{
          "advertisedAndReceived":true
        }
      },
      "hostName":{
        "advHostName":"pd32-srv-009.kvm.mng.cloud.ru",
        "advDomainName":"n\/a"
      },
      "softwareVersion":{
      },
      "gracefulRestartCapability":"advertised"
    },
    "gracefulRestartInfo":{
      "endOfRibSend":{
      },
      "endOfRibRecv":{
      },
      "localGrMode":"Helper*",
      "remoteGrMode":"Disable",
      "rBit":false,
      "nBit":false,
      "timers":{
        "configuredRestartTimer":120,
        "configuredLlgrStaleTime":0,
        "receivedRestartTimer":0
      }
    },
    "messageStats":{
      "depthInq":0,
      "depthOutq":0,
      "opensSent":3,
      "opensRecv":1,
      "notificationsSent":0,
      "notificationsRecv":0,
      "updatesSent":1,
      "updatesRecv":43,
      "keepalivesSent":7205,
      "keepalivesRecv":8401,
      "routeRefreshSent":0,
      "routeRefreshRecv":0,
      "capabilitySent":0,
      "capabilityRecv":0,
      "totalSent":7209,
      "totalRecv":8445
    },
    "minBtwnAdvertisementRunsTimerMsecs":0,
    "addressFamilyInfo":{
      "ipv4Unicast":{
        "peerGroupMember":"bgp_int",
        "updateGroupId":2,
        "subGroupId":2,
        "packetQueueLength":0,
        "inboundSoftConfigPermit":true,
        "commAttriSentToNbr":"extendedAndStandard",
        "inboundPathPolicyConfig":true,
        "outboundPathPolicyConfig":true,
        "routeMapForIncomingAdvertisements":"net_10_0_0_0",
        "routeMapForOutgoingAdvertisements":"int_out",
        "acceptedPrefixCounter":90,
        "sentPrefixCounter":1
      }
    },
    "connectionsEstablished":1,
    "connectionsDropped":0,
    "lastResetTimerMsecs":250000,
    "lastResetDueTo":"Waiting for peer OPEN",
    "lastResetCode":32,
    "softwareVersion":"n\/a",
    "externalBgpNbrMaxHopsAway":1,
    "hostLocal":"10.32.148.25",
    "portLocal":45736,
    "hostForeign":"10.32.148.62",
    "portForeign":179,
    "nexthop":"10.32.148.25",
    "nexthopGlobal":"fe80::7a58:60ff:fe60:e850",
    "nexthopLocal":"fe80::7a58:60ff:fe60:e850",
    "bgpConnection":"sharedNetwork",
    "connectRetryTimer":3,
    "estimatedRttInMsecs":165,
    "authenticationEnabled":1,
    "readThread":"on",
    "writeThread":"on",
    "peerBfdInfo":{
      "type":"single hop",
      "detectMultiplier":3,
      "rxMinInterval":300,
      "txMinInterval":300,
      "status":"Up",
      "lastUpdate":"5:00:03:58"
    }
  }
}

Seems that CHECK_FLAG should return false but obviously it return true for non EVPN peers which have soft-reconfiguration-inbound configured.

BTW In my opinion the structure of message "Processing EVPN MAC interface change on peer" incorrect, because bgp peer has nothing to do with interface which MAC changed.