Hi all,

I was trying to configure bgp using BIRD on a server running rhel 7.6. The issue I am facing is that the neighbor AS seems to be rejecting the routes sent by my local AS. However, my server seems to be learning routes sent by the neighbor AS router. Have provided some details from the logs below. I wanted to ask what could be the probable reason that the remote is rejecting the packets?

2021-04-22 17:48:56 <TRACE> bgp1 > added [best] 172.19.1.192/28 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 < rejected by protocol 172.19.1.192/28 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 > added [best] 172.19.1.200/30 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 < rejected by protocol 172.19.1.200/30 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 > added [best] 172.19.1.200/29 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 < rejected by protocol 172.19.1.200/29 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 > added [best] 172.19.1.201/32 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 < rejected by protocol 172.19.1.201/32 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 > added [best] 172.19.42.0/24 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 < rejected by protocol 172.19.42.0/24 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 > added [best] 172.19.43.0/24 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 < rejected by protocol 172.19.43.0/24 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 > added [best] 172.19.44.0/24 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 < rejected by protocol 172.19.44.0/24 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 > added [best] 172.19.48.0/24 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 < rejected by protocol 172.19.48.0/24 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 > added [best] 172.19.42.101/32 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 < rejected by protocol 172.19.42.101/32 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 > added [best] 172.19.42.102/32 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 < rejected by protocol 172.19.42.102/32 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 > added [best] 172.19.42.103/32 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 < rejected by protocol 172.19.42.103/32 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 > added [best] 172.19.42.104/32 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 < rejected by protocol 172.19.42.104/32 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 > added [best] 172.19.42.105/32 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 < rejected by protocol 172.19.42.105/32 via 10.33.5.33 on enp26s0d1
2021-04-22 17:48:56 <TRACE> bgp1 > added [best] 172.19.43.101/32 via 10.33.5.33 on enp26s0d1

In consequence to this, BIRD throws an error after sometime saying `bgp1: Error: Hold timer expired ` and `bgp1: Received: Hold timer expired` However from the logs I figured out that the difference between most latest KEEPALIVE message and the error being thrown is 2 secs. Since I have set HOLD time to 180 sec in config shouldn't this error be never thrown since the KEEPALIVE message will reset it? Sharing that logs too below

2021-04-22 20:12:44 <TRACE> bgp1: Got KEEPALIVE
2021-04-22 20:12:45 <TRACE> bgp1: Got KEEPALIVE
2021-04-22 20:12:46 <TRACE> bgp1: Got KEEPALIVE
2021-04-22 20:12:47 <TRACE> bgp1: Got KEEPALIVE
2021-04-22 20:12:48 <TRACE> bgp1: Got KEEPALIVE
2021-04-22 20:12:49 <TRACE> bgp1: Got KEEPALIVE
2021-04-22 20:12:50 <TRACE> bgp1: Got KEEPALIVE
2021-04-22 20:12:51 <TRACE> bgp1: Got KEEPALIVE
2021-04-22 20:12:53 <TRACE> bgp1: Got KEEPALIVE
2021-04-22 20:12:53 <TRACE> bgp1: Got KEEPALIVE
2021-04-22 20:12:55 <TRACE> bgp1: Got KEEPALIVE
2021-04-22 20:12:56 <TRACE> bgp1: Got KEEPALIVE
2021-04-22 20:12:57 <TRACE> bgp1: Got KEEPALIVE
2021-04-22 20:12:59 <RMT> bgp1: Error: Hold timer expired

I am new to configuring routing and hence my understanding can be wrong somewhere. Please feel free to correct me and ask for more details if required. Thanks in advance.

Thanking you,
Dhruv Bhagadia.