Your BGP neighbors, one in the USA and one in France, are not establishing a connection with each other. Referring to the exhibit, which statement is correct?
A.
The BFD liveness is set too low.
B.
The BFD liveness must be configured on the BGP neighbor.
C.
The BFD liveness must be configured on the BGP group.
In the configuration shown, BFD (Bidirectional Forwarding Detection) is configured globally under bfd-liveness-detection, but it is not applied to the specific BGP groups or neighbors. For BFD to function with BGP, it must be explicitly enabled at the BGP group or neighbor level. Without this configuration, BGP will not use BFD to detect liveness, and this can prevent neighbors from establishing a connection.
A is the safest and most logical answer. If the BFD liveness interval is set too low, especially for long-distance links like those between the USA and France, it can cause frequent BFD session flaps due to the inherent latency in long-distance communication.
Some will confuse it with configuration schematics, since B and C are both viable configuration method.
BFD, is typically configured on a per-neighbor basis to monitor the health of the BGP session.
However, with groups present, BFD parameters are applied to the entire group of BGP peers.
BFD is an intensive protocol that consumes system resources. Specifying a minimum interval for BFD less than 100 milliseconds for Routing Engine-based sessions and less than 10 milliseconds for distributed BFD sessions can cause undesired BFD flapping.
Answer is A
BFD can be set at the neighbour or group level. The average ms from the UK to a US gaming server is around 75 to 130ms, which would be around the same for France.
BFD is configured under the group hierarchy
https://www.juniper.net/documentation/mx/es/software/junos/bgp/topics/topic-map/bfd-for-bgp-session.html#d58e97__d103382e192
Bfd can config under protocols bgp too.
And also bfd session established.
# show protocols bgp
group ibgp {
type internal;
local-address 10.2.2.2;
neighbor 10.6.6.6;
}
bfd-liveness-detection {
minimum-interval 500;
}
# run show bfd session
Detect Transmit
Address State Interface Time Interval Multiplier
10.6.6.6 Up 1.500 0.500 3
r5ben, BFD can be configured at the PROTOCOL, GROUP, and NEIGHBOR level.
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