ping
6 TopicsUnstable communication L2 and ARP
Hi, I have a very wired problem with one of our F5. This is a single armed partition, so the LB VS and pool members and everything is all on the same L2 network segment. The thing is, the pool memebers (four) are going down every other minute, and then come back after a while, maybe a few minutes. Digging into the issue, I found that I am not able to ping those nodes from the F5 tmsh when they are down, while I can ping them from my workstation just fine. Just the F5 looses communication for a reason. I checked the ARP table, and the entries for those hosts are in there with the right MAC address. However, when the problem occurs, as soon as I clear the ARP table entry for any of these hosts, I am immideately able to ping them again - for some minutes, then the ping dies again. Clearing the ARP again brings them back to life right away - and so on. As I said, I can see the correct ARP table entry when the ping is not working, so I dont get why clearing the ARP entry brings them back to life. All other communication to those hosts is just running fine, e.g. I run a RDP session from my workstation to them which just runs fine while they are not ping-able from the tmsh. Question is, whats up with the F5 it looses communication. I tried to add static ARP entries for those pool members as I am running out of ideas, but that didnt change anything. Also, we have the same set up in our dev environment, same F5, same versions, all the same, which just runs fine. Any help or ideas are appreciated, Tx&Greetings, JoSolved47Views0likes3Commentsping output shows truncated entry from not pinged address
I noticed following strange output when pinging a node: [prompt] # ping x.x.x.x PING x.x.x.x (x.x.x.x) 56 (84) bytes of data. 64 bytes from x.x.x.x: icmp_seq=1 ttl=61 time=xx ms 64 bytes from x.x.x.x: icmp_seq=2 ttl=61 time=xx ms 64 bytes from x.x.x.x: icmp_seq=3 ttl=61 time=xx ms 64 bytes from x.x.x.x: icmp_seq=4 ttl=61 time=xx ms 64 bytes from x.x.x.x: icmp_seq=5 ttl=61 time=xx ms ... 32 bytes from y.y.y.y: icmp_seq=26978 ttl=61 (truncated) 64 bytes from x.x.x.x: icmp_seq=54 ttl=61 time=xx ms 64 bytes from x.x.x.x: icmp_seq=55 ttl=61 time=xx ms When stopping the ping I see in the statistics one more packet received than transmitted. Where does this comes from? Has this any special meaning? Is this indicating any strange behavior or misconfiuration in the network? Thanks for any helpful ideas or information to further investigate this! Regards, Stefan 🙂2.1KViews0likes2CommentsPing received route from BGP and Kernel fails
Have difficulties in pinning an address which I receive as part of BGP adverrtisement. The same also for the address which comes through an address which I have advertised to the Kernel. The ping gives : connect: Network is unreachable Altho I have the route in my routing table. Any thoughts please237Views0likes1CommentHealth monitor to mark pool member up when a ping FAILS (inverse ping health check)
Hello, I am attempting to figure out the best way to create a health monitor that is an inverse of the ICMP monitor-when ping to an IP fails, I want the pool member to be marked UP. When ping to an IP succeeds, I want the pool member to be marked DOWN. My first attempt at this was using an external monitor with the below script; that does not seem to be working. #!/bin/sh ping -c 5 [IP here] > /dev/null && exit || echo "down" exit $? I am running 11.5.3 HF2. Does anyone know if the best way to achieve this beahvior, or why my script isn't working? It looks like it outputs nothing to stdout (should cause the monitor to fail) unless the ping fails, at which point it outputs something (should cause the monitor to pass)730Views0likes4CommentsUnable to load VIP in Browser
Hi, I am setting up a Lab Environment in VMWare at the moment. I have 3 servers on the internal vlan which I can ping and telnet to port 80 from the BIG IP CLI and from my physical machine. These are in a pool and associated with a virtual server. I can also PING the VIP I have setup from the BIG IP CLI and from my physical machine. The issue that I am having is that I cannot load the VIP in a browser. If I try telnet VIP PORT, I connect however when I try to get the page with GET / HTTP/1.1 the connection is closed with the message "Connection Closed by Foreign Host". Any help would be greatly appreciated. Thank you.Solved355Views0likes1CommentUsing Selective ACK on Virtual Address
We have a 2 tier system whereby Tier 1 needs to know quickly if Tier 2 services have stopped, be that VS or the pools or the box itself. To that end we've setup an ICMP monitor at tier 1 to ping the VS at Tier 2 and we've configured the ICMP option within Virtual Address to be Selective (ie don't respond if VS is red). This works well most of the time. However every now and again we'll see that a service has been marked down at Tier 1 and the ICMP monitor is the one saying it had marked the service down. You go to Tier 2 and the VS is green (it has been down but come back up) and a TCPDUMP shows that the ICMP request is getting to Tier 2 but Tier 2 is NOT sending an ICMP response. Typically the only fix is to reboot the Tier 2 box - which is not ideal in a production environment. I have opened a case with F5 for this but wondered if anybody else had come across something similar etc.275Views0likes0Comments