We have a requirement to present a service unavailable page when all GTM pool members are down, but can't really afford to dedicate new IP addresses at each site just for this.
There are two ind...
Yes you can - using Fallback IP - you don't specify a virtual name, you specify an IP address. Even if that happens to be the same as a virtual that GTM thinks is down, it will return the Fallback IP as DNS response if your LTM virtuals are down.
Yes, you're right. I had Last Resort Pool on my mind, so that's what I "read".
So, what I thought was ideal, was to have a last resort pool, same members as the "main" pool, but then last resort members go 'red', and won't be used in the LB decision.
We came up with a solution, but it is stretching the KISS principle a bit: gtm has a pool and last resort pool. Main pool monitors a url on the VS which is supplied by an irule depending on pool member availability. Last resort pool a simple http monitor. Virtuals have no default pool, they have a rule which responds to the gtm monitor request, and for other requests either responds with the offline page or sets the pool depending on member availability.
I would love to hear a better way, and I will be impressed by anyone who tries to understand what I just wrote.
Altostratus
