Forum Discussion
Derek_21893
Aug 10, 2009Nimbostratus
So I've done some more work on this today, and discovered that our enterprise actually has a pair of LTMs without any floating self-ip addresses. They have self-ip addresses assigned to their respective vlans, yet they do not have any floating self-ip addresses assigned. Are there any conceivable designs where this could be a proper configuration? I don't think this particular pair was configured correctly, but it has proven that this case can exist, and that this configuration does appear to work in this scenario. Since the servers do not use the F5 as their default gateway (we have a pair of core routers for that), the only benefit I came up with to having a floating self-ip would be that the connections in progress could be failed over to the standby LTM in case of failure, if connection mirroring was enabled.
I'm trying to determine if there are fringe cases in which no floating self-ip addresses would exist, thus I would be unable to correctly identify a redundant pair. I can imagine that in some more complex networks (or networks operated by people that like pain and agony) you could run across OSPF or other routing protocol which would be relied on instead of a floating IP address for failover. Has anyone seen such a design?
Also, I am curious if there is any distinct drawback to not having a floating self-ip assigned to the internal VLAN. If there is no requirement for the F5 to be the default gateway, the floating self-ip seems to not be as critical.
I considered making an assumption that any self-ip addresses within the same netmask (say 10.0.0.100/24 and 10.0.0.101/24) would give me a good enough "guess" that these two LTMs are a redundant pair. I can already think of reasons this assumption would be wrong, in that possibly an enterprise would have a large subnet for application servers (such as 10.10.0.0/20). There could conceivably be multiple LTM pairs with self-ip addresses on this large network.
So, do you folks think that I can safely assume that coming across a pair of redundant LTMs without any floating IP between them would be a fringe case of mis-configuration?
Thanks,
-Derek