We have a topology like the given below , we have tested on 3 different server. Firewalld , Iptables and selinux all closed .

I am suspecting the issue should be about the sysctl rpf/arp etc settings but i am not sure .

Also interfaces can not ping theirselves

Operating system is centos 7 with LTS (4.12.x kernel and also tested with 3.10 default centos kernel)

loopback interface is up

Any body faced with an issue like this

Router side | 37.123.98.137/30 <-------------> p1p2 37.123.98.138/30 | Server side

Router side |37.123.98.141/30 <--------------> p1p1 37.123.98.142/30 | Server side

Results ; interfaces can not ping each other , but kernel ping all interfaces.

From p1p2 results :

[root@fw network-scripts]# ip route show dev p1p2
default via 37.123.98.137  proto static  metric 101 
37.123.98.136/30  proto kernel  scope link  src 37.123.98.138  metric 100 
37.123.98.137  proto static  scope link  metric 100 
37.123.98.138  scope link 
37.123.98.142  proto static  scope link  metric 100 
[root@fw network-scripts]# ping -I p1p2 37.123.98.137
PING 37.123.98.137 (37.123.98.137) from 37.123.98.138 p1p2: 56(84) bytes of data.

    64 bytes from 37.123.98.137: icmp_seq=1 ttl=64 time=0.401 ms
    64 bytes from 37.123.98.137: icmp_seq=2 ttl=64 time=0.407 ms
    64 bytes from 37.123.98.137: icmp_seq=3 ttl=64 time=0.354 ms
    64 bytes from 37.123.98.137: icmp_seq=4 ttl=64 time=0.343 ms

^C
--- 37.123.98.137 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3086ms
rtt min/avg/max/mdev = 0.343/0.376/0.407/0.031 ms
[root@fw network-scripts]# ping -I p1p2 37.123.98.138
PING 37.123.98.138 (37.123.98.138) from 37.123.98.138 p1p2: 56(84) bytes of data.
^C
--- 37.123.98.138 ping statistics ---
20 packets transmitted, 0 received, 100% packet loss, time 19455ms

[root@fw network-scripts]# ping -I p1p2 37.123.98.142
PING 37.123.98.142 (37.123.98.142) from 37.123.98.138 p1p2: 56(84) bytes of data.
^C
--- 37.123.98.142 ping statistics ---
5 packets transmitted, 0 received, 100% packet loss, time 4098ms

[root@fw network-scripts]# ping -I p1p2 37.123.98.141
PING 37.123.98.141 (37.123.98.141) from 37.123.98.138 p1p2: 56(84) bytes of data.
^C
--- 37.123.98.141 ping statistics ---
6 packets transmitted, 0 received, 100% packet loss, time 5156ms

from p1p1

 [root@fw network-scripts]# ip route show dev p1p1
default via 37.123.98.141 
37.123.98.140/30  proto kernel  scope link  src 37.123.98.142  metric 100 
37.123.98.141  scope link 
[root@fw network-scripts]# ping -I p1p1 37.123.98.137
PING 37.123.98.137 (37.123.98.137) from 37.123.98.142 p1p1: 56(84) bytes of data.
^C
--- 37.123.98.137 ping statistics ---
4 packets transmitted, 0 received, 100% packet loss, time 3080ms

[root@fw network-scripts]# ping -I p1p1 37.123.98.138
PING 37.123.98.138 (37.123.98.138) from 37.123.98.142 p1p1: 56(84) bytes of data.
^C
--- 37.123.98.138 ping statistics ---
10 packets transmitted, 0 received, 100% packet loss, time 9225ms

[root@fw network-scripts]# ping -I p1p1 37.123.98.141
PING 37.123.98.141 (37.123.98.141) from 37.123.98.142 p1p1: 56(84) bytes of data.

    64 bytes from 37.123.98.141: icmp_seq=1 ttl=64 time=0.384 ms
    64 bytes from 37.123.98.141: icmp_seq=2 ttl=64 time=0.293 ms
    64 bytes from 37.123.98.141: icmp_seq=3 ttl=64 time=0.391 ms
    64 bytes from 37.123.98.141: icmp_seq=4 ttl=64 time=0.376 ms


^C
--- 37.123.98.141 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3053ms
rtt min/avg/max/mdev = 0.293/0.361/0.391/0.039 ms
[root@fw network-scripts]# ping -I p1p1 37.123.98.142
PING 37.123.98.142 (37.123.98.142) from 37.123.98.142 p1p1: 56(84) bytes of data.
^C
--- 37.123.98.142 ping statistics ---
7 packets transmitted, 0 received, 100% packet loss, time 6144ms

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