Forum Discussion
Virtual Server/Server IP Address Conflict
We encountered an unusual situation yesterday where a server in an internal LTM VLAN suddenly became inaccessible. The server became inaccessible because it had been rebooted and saw an IP address conflict, which prevented networking from starting. It turns out that a Standard-type TCP port 80 virtual server was assigned the same IP address as the server in the internal VLAN. To resolve, we removed the VS and restarted networking on the server.
The server was not a member of any LTM pools, but should have been accessible via a wildcard VS.
I have never heard of this configuration before, where a VS address in the external VLAN was assigned the same address as a server in an internal VLAN. I read through the doc on VS types, and my configuration did not seem to match any of those types. It seems that everything was working fine from an application and accessiblity standpoint, up until the server was rebooted and saw the address conflict. We suspect the VS was assigned the conflicting address some time after the last time the server was rebooted. It's difficult to say as both those events were a long time ago.
I have a couple of general questions about this situation, though I am finding it a little difficult to verbalize. So feel free to interject any additional thoughts.
1) Is this a "valid" configuration? By valid, I mean should this configuration be expected to work? It seems to me that any IP address conflict is bad.
2) As I mentioned, the services that were running on this system seemed to be functioning fine up until it was rebooted, and I'm trying to understand why. My theory is that everything other than the VS traffic (i.e. TCP port 80) was being processed by the lower-priority wildcard VS. Is that plausible?
3) We did not receive an IP address conflict notification from the LTM when the server rebooted, nor was there a log message. I have received these notifications in the past, so I'm wondering why not this time? Could it be that the LTM doesn't consider it a conflict if the two addresses are in different VLANs?
I'd appreciate any thoughts or comments on this weird situation. Thanks.
- hooleylistCirrostratusHi SMP,
- smp_86112CirrostratusHi hoolio, thanks for your response.
- hooleylistCirrostratusYep, I got that :). I just wanted to explain that a config "like" the one you described can be valid. But it's a bit convoluted as you need to have static ARP entries on each client.
- Abhzi_114202NimbostratusHello Experts,
- Kevin_StewartEmployeeI just answered your other similar post without reading this one first. Can you elaborate on your issue? Did you intentionally assign the same IP address to the Linux server and F5 virtual server?
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