Ok, what rp_filter params do you have?

this is ok

what?

net.ipv4.ip_forward = 1
net.ipv4.tcp_timestamps = 0
net.ipv4.tcp_sack = 0
net.ipv4.tcp_rmem = 10000000 10000000 10000000
net.ipv4.tcp_wmem = 10000000 10000000 10000000
net.ipv4.tcp_mem = 10000000 10000000 10000000
net.core.rmem_max = 52428
net.core.wmem_max = 524287
net.core.rmem_default = 524287
net.core.wmem_default = 524287
net.core.optmem_max = 524287
net.core.netdev_max_backlog = 300000
net.ipv4.tcp_fin_timeout = 20
net.ipv4.tcp_timestamps = 0
\

configurations

#net.ipv4.conf.default.rp_filter=1
#net.ipv4.conf.all.rp_filter=1

config is it ok

try

ok

i try now

cat /proc/sys/net/ipv4/conf/all/rp_filter
0

2020/07/23 15:27:01 BGP: %NOTIFICATION: sent to neighbor 77.78.156.124 4/0 (Hold Timer Expired) 0 bytes
2020/07/23 15:27:01 BGP: Notification sent to neighbor 77.78.156.124:0: type 4/0
2020/07/23 15:27:01 BGP: %ADJCHANGE: neighbor 77.78.156.124 Down BGP Notification send
2020/07/23 15:27:12 BGP: 77.78.156.124 unrecognized capability code: 5 - ignored
2020/07/23 15:27:12 BGP: %ADJCHANGE: neighbor 77.78.156.124 Up

not need 9000 mtu in eth1 ?

for bgp it’s not important

ok

ping 77.78.156.121
PING 77.78.156.121 (77.78.156.121) 56(84) bytes of data.
^C
--- 77.78.156.121 ping statistics ---
3 packets transmitted, 0 received, 100% packet loss, time 21ms

not have ping to neighbour

ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
^C
--- 8.8.8.8 ping statistics ---
3 packets transmitted, 0 received, 100% packet loss, time 17ms