BGP peer failure detection is by default based on the keep-alive and hold time. For cases where fast failure detection is needed, a BFD session can be used to control the operational state of the BGP peer. Fast failure detection for ESM dynamic BGP peers using BFD is supported for IPoE and PPPoE subscribers. It is not supported for L2TP LNS subscribers.
BFD for ESM dynamic BGP peers is enabled in the bgp-peering-policy in classic CLI.
config>subscr-mgmt
bgp-peering-policy "bgpv4-policy-1" create
bfd-enable
local-address 10.3.2.254
local-as 65536
peer-as 65501
type external
exit
BFD for ESM dynamic BGP peers is enabled in the BGP peering policy in MD-CLI.
[pr:/configure subscriber-mgmt]
bgp-peering-policy "bgpv4-policy-1" {
bfd-liveness true
local-address 10.3.2.254
peer-as 65501
type external
local-as {
as-number 65536
}
}
The parameters for the BFD sessions must be configured on the group interface or retail subscriber interface in classic CLI.
config>service>vprn>sub-if>grp-ifconfig>service>vprn>sub-if
bfd 100 receive 100 multiplier 3
ipv6
bfd 100 receive 100 multiplier 3
exit
The parameters for the BFD sessions must be configured on the group interface or retail subscriber interface in MD-CLI.
[pr:/configure service vprn "submgmt-vprn-2000" subscriber-interface "sub-int-1" group-interface "group-int-1-1"]
ipv4 {
bfd {
admin-state enable
transmit-interval 100
receive 100
multiplier 3
}
}
ipv6 {
bfd {
admin-state enable
transmit-interval 100
receive 100
multiplier 3
}
}
The BFD session is always established as a single hop BFD session and therefore fast-failure detection using BFD works for single hop ESM dynamic BGP peers only. The local address for the BGP peer must be a local IPv4 or IPv6 address configured on the subscriber interface.
To verify the state of the BFD session, use the show commands in the following output examples:
A:pe2# show router 2000 bfd session
===============================================================================
Legend:
Session Id = Interface Name | LSP Name | Prefix | RSVP Sess Name | Service Id
wp = Working path pp = Protecting path
===============================================================================
BFD Session
===============================================================================
Session Id State Tx Pkts Rx Pkts
Rem Addr/Info/SdpId:VcId Multipl Tx Intvl Rx Intvl
Protocols Type LAG Port LAG ID
Loc Addr LAG name
-------------------------------------------------------------------------------
group-int-1-1 Up 3077793 3077716
10.3.2.201 3 100 100
bgp iom N/A N/A
10.3.2.254
group-int-1-1 Up 2988250 2988469
2001:db8:b002:201::aaa:1 3 100 100
bgp iom N/A N/A
2001:db8:b002:201::1
-------------------------------------------------------------------------------
No. of BFD sessions: 2
===============================================================================
A:pe2# show router 2000 bfd session dest 2001:db8:b002:201::aaa:1 src 2001:db8:b002:201::1
===============================================================================
BFD Session
===============================================================================
Remote Address : 2001:db8:b002:201::aaa:1
Local Address : 2001:db8:b002:201::1
Admin State : Up Oper State : Up
Protocols : bgp
Rx Interval : 100 Tx Interval : 100
Multiplier : 3 Echo Interval : 0
Recd Msgs : 2988898 Sent Msgs : 2988679
Up Time : 2d 16:46:10 Up Transitions : 1
Down Time : None Down Transitions : 0
Version Mismatch : 0
Forwarding Information
Local Discr : 23 Local State : Up
Local Diag : 0 (None) Local Mode : Async
Local Min Tx : 100 Local Mult : 3
Last Sent : 08/23/2021 08:18:43 Local Min Rx : 100
Type : iom
Remote Discr : 19 Remote State : Up
Remote Diag : 0 (None) Remote Mode : Async
Remote Min Tx : 100 Remote Mult : 3
Remote C-flag : 1
Last Recv : 08/23/2021 08:18:43 Remote Min Rx : 100
===============================================================================
===============================================================================
The following events are generated for a BFD protected ESM dynamic BGP peer.
ESM dynamic BGP peer established:
2602 2021/08/20 15:32:32.609 UTC MINOR: BGP #2019 vprn2000 Peer 2:
2001:db8:b002:201::aaa:1 "(ASN 65501) VR 2: Group esm-dyn-peer-group-1: Peer
2001:db8:b002:201::aaa:1: moved into established state"
BGP added as protocol to track by the BFD session:
2603 2021/08/20 15:32:32.610 UTC MINOR: VRTR #2064 vprn2000
2001:db8:b002:201::aaa:1 "The protocol(BGP) using BFD session on node
2001:db8:b002:201::aaa:1 has been added."
BFD session to track the ESM dynamic BGP peer with peer address 2001:db8:b002:201::aaa:1 is up. This indicates that the ESM dynamic BGP peer is tracked by the BFD session and fast failure detection is enabled:
2604 2021/08/20 15:32:33.507 UTC MINOR: VRTR #2062 vprn2000
2001:db8:b002:201::aaa:1 "BFD: Local Discriminator 23 BFD session on node
2001:db8:b002:201::aaa:1 is up"