Forum Discussion
NimbostratusVirtual Server not Responding to clients on different subnet
We are in a One -Arm Network Configuration. Created a standard virtual server to load balance a web site. Virtual server will respond to all request then periodically stop responding to client request that are not on the same subnet as the virtual server. If I telnet to virtualhost port 80 from a client not on same subnet I get no response, if I do the same from a client on same subnet I am able to connect. If I force a failover than web site is accessible to clients not on same vlan. Any suggestions on what to check. We are also running ASM.
4 Replies
- Matt_Dierick
Employee
Hi John,
It's weird. Can you do a tcpdump and check if you see the connection on the VS ? If not, should be ARP issue or upstream route issue.
We need to check if the connection is reset or if nothing arrive into the VS.
tcpdump -nni 0.0 host IPADDRESS
Use IP address of the VS or the client.
Matt 
John_131301If I run the tcpdump from my desktop going to the IP of the virtual server this is what I get (changed IP's to protect the inncoent)
listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
10:49:50.305248 IP 10.1.1.180.42486 > 10.1.2.220.80: Flags [S], seq 2453712361, win 14600, options [mss 1460,sackOK,TS val 1956707925 ecr 0,nop,wscale 7], length 0
10:49:50.306024 IP 10.1.2.220.80 > 128.244.47.180.42486: Flags [R.], seq 1607238968, ack 2453712362, win 0, length 0
10:49:50.308312 IP 10.1.1.180.42487 > 10.1.2.220.80: Flags [S], seq 3272362573, win 14600, options [mss 1460,sackOK,TS val 1956707928 ecr 0,nop,wscale 7], length 0
10:49:50.309435 IP10.1.2.80 >10.1.1.180.42487: Flags [R.], seq 1096721166, ack 3272362574, win 0, length 0If I run tcpdump on the F5 using IP of the virtual server I get nothing returned when trying to connect form my desktop. If I try to connect from a system on same subnet everything works as expected.
- nitass10:49:50.306024 IP 10.1.2.220.80 > 128.244.47.180.42486: Flags [R.], seq 1607238968, ack 2453712362, win 0, length 0
can you check what mac address of 10.1.2.220 is (i understand tcpdump -e option will show mac address)? reset may be sent by device in the middle between client and bigip.
- John_131301OK, there are two mac addresses in the middle of the conversation. Have to track down these addresses and see what they are. I know they are not associated with the two IP's in the tcpdump.
