LocalDirector Server Farm Communication

Question

We are utilizing a Localdirector for load balancing several server farms. Some of which need to communicate amongst themselves using the virtual address. For instance, if real servers A and B have a virtual address AB and real servers C and D have a virtual address CD. We have a need for either real server A or B to talk to the virtual CD. Can the localdirector accomplish this with a single interface, or do we need to segment these servers on a switch and use multiple interfaces on the localdirector?
Thanks

Answer 1

Topology is the key here. Depending on who needs to access the virtual is the most important aspect of this type of configuration. If a client from the Internet needs to hit virtual AB, then real server A or B needs to communicate with virtual CD, this can be accomplished by simply placing the real servers C and D on the Internet side of the LD. For instance, client comes through ethernet 0 hits virtual AB and gets load balanced to server B off of ethernet 1. Server B initiates a separate connection to virtual CD and comes through ethernet 1and gets load balanced to server C. Server C responds back through the LD to server B. Server B then responds back to the client.
The above description is typical of web servers being servers A and B and database servers being C and D. If Internet clients need to hit both virtuals AB and CD then this configuration will not work.
If Internet clients need to hit both virtuals AND the each pair of real servers need to hit the other's virtual then you will need to use 3 interfaces of the LD. One for the Internet or client side, one for real servers A and B, and one for real servers C and D.
I hope this helps.
Best regards,
Chip Schneider
Cisco TAC