Mirroring of the Hash to server association table

A more common problem is the mobile switching between mobile network and wifi to get Internet, going/leaving home/office.

There is no built-in configuration for that. However, you can do that with iRules and cookie, and I have seen this implemented.

Add a cookie that has the datacenter reference. When processing the traffic in any of the LTMs pair, read the cookie. If no cookie or cookie referencing current datacenter, just load balance as normal. If cookie refers to the other datacenter, you have 2 options:

1 - Second virtual server Using iRule direct the traffic to a second virtual server, this virtual server will have a pool with one member, and the member will be the virtual server of the other datacenter. This access will probably use the internal connection between the datacenters, or maybe the Internet, depends which ip you use as destination (and your routing of course). Anyway, there will a very small number of connection when comparing with users that stay within the same network, so not a big problem if uses internal connection.

2 - Redirect Send a HTTP redirect to a new URL, and remove cookie. Something like, datacenterA.url.com. The user will then go to the other datacenter, where he will get a new cookie referencing that datacenter. Don't forget that this may cause SSL alerts, if you don't have a wildcard certificate.