Forum Discussion

John_131301's avatar
John_131301
Icon for Nimbostratus rankNimbostratus
Aug 07, 2013

Virtual 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.

 

basic
getting started
new to f5

4 Replies

Sort By
  • Matt_Dierick's avatar
    Matt_Dierick
    Icon for Employee rankEmployee
    Aug 07, 2013
    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_131301's avatar
    John_131301
    Icon for Nimbostratus rankNimbostratus
    Aug 09, 2013

    If 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 0

     

     

    If 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.

     

     

  • nitass's avatar
    nitass
    Icon for Employee rankEmployee
    Aug 09, 2013
    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

    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_131301's avatar
    John_131301
    Icon for Nimbostratus rankNimbostratus
    Aug 09, 2013
    OK, 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.