Hello. We have 2 RDGW servers (2012R2) configured in a NLB cluster.
Both servers have 2 NICs, 1 LAN, 1 WAN - NLB is configured on the WAN interface. NLB configured in anycast mode.
We have found out that if the cluster IP or the individual WAN IPs are pinged from a Linux machines, there are ping duplicates being returned. Windows doesn't return duplicates (or hides them).
Can someone confirm if this is a normal behavior or this shouldn't be happening?
Thanks in advance
Example:
64 bytes from <NLB_cluster_IP> (<NLB_cluster_IP>): icmp_seq=1 ttl=117 time=32.2 ms
64 bytes from <NLB_cluster_IP> (<NLB_cluster_IP>): icmp_seq=1 ttl=117 time=32.2 ms (DUP!)
64 bytes from <NLB_cluster_IP> (<NLB_cluster_IP>): icmp_seq=1 ttl=117 time=32.3 ms (DUP!)
64 bytes from <NLB_cluster_IP> (<NLB_cluster_IP>): icmp_seq=1 ttl=117 time=32.3 ms (DUP!)
64 bytes from <NLB_cluster_IP> (<NLB_cluster_IP>): icmp_seq=2 ttl=117 time=32.2 ms
64 bytes from <NLB_cluster_IP> (<NLB_cluster_IP>): icmp_seq=2 ttl=117 time=32.2 ms (DUP!)
64 bytes from <NLB_cluster_IP> (<NLB_cluster_IP>): icmp_seq=2 ttl=117 time=32.3 ms (DUP!)
64 bytes from <NLB_cluster_IP> (<NLB_cluster_IP>): icmp_seq=2 ttl=117 time=32.3 ms (DUP!)
64 bytes from <NLB_cluster_IP> (<NLB_cluster_IP>): icmp_seq=3 ttl=117 time=32.2 ms
64 bytes from <NLB_cluster_IP> (<NLB_cluster_IP>): icmp_seq=3 ttl=117 time=32.2 ms (DUP!)
64 bytes from <NLB_cluster_IP> (<NLB_cluster_IP>): icmp_seq=3 ttl=117 time=32.3 ms (DUP!) a
64 bytes from <NLB_cluster_IP> (<NLB_cluster_IP>): icmp_seq=3 ttl=117 time=32.3 ms (DUP!)
64 bytes from <NLB_cluster_IP> (<NLB_cluster_IP>): icmp_seq=4 ttl=117 time=32.0 ms
--- <NLB_cluster_DNS> ping statistics ---
4 packets transmitted, 4 received, +9 duplicates, 0% packet loss, time 1502ms
rtt min/avg/max/mdev = 32.084/32.274/32.352/0.232 ms
Thread source link: https://social.technet.microsoft.com/Forums/zh-CN/fb8ca609-89b5-4cfe-af4d-48929dcb5b5d/rdgw-nlb-cluster-responding-with-dup-icmp-echo?forum=winserverPN