We recently faced a situation where ICMP Ping window is showing responses as timeout while the firewall logging rules are showing the echo reply being received.
The setup is pretty simple:
Phisically, A CCR1072 and a CCR1036 connected via a 10G Huawei switch, both using a VLAN tagged on the CCRs.
The IP configuration:
CCR1072: 10.1.1.132/32 network=10.1.1.133 on the Vlan
CCR1036: 10.1.1.133/32 network=10.1.1.132 on the Vlan
The other odd fact is that pinging its own IP (10.1.1.132) from the CCR1072 is also not responding.
The attached image shows the log and Ping window being contradictory:
The real problem is that traffic is in fact not flowing at all through this interfaces when the situations appears.
A reboot on the 1072 solves the issue. No complains on any of those devices about ‘loops’, etc… Also, no firewall rules other than the logging ones.
Any ideas about the cause?