Issue with GTM loadbalancing for Active-Active sites

Hi,

 

Below is the detail regarding the end users, application requirement, GTM/LTM setup and configuration.

 

Details about end users:

 

• 80% users are from 3 private LANs located at different sites
• 20% users are from internet

Number of Sites: 2

 

Application requires persistence

 

Each site is having two 1600 F5 units running as Active-Standby(LTM).

 

And all the 4 units are having GTM module enabled and configured in Active-Active mode.

 

Current Configuration and Issues

 

• GTM Loadbalancing Method: Topology
• Persistence: Enabled

Topology Details:

 

• Private End user LAN Segments are grouped as PRIVATE_LAN - 80% of users
• IPs not matched PRIVATE_LAN are grouped as PUBLIC - 20% of users

GTM pool is selected based on the end user type

 

• Both private and public GTM pools are having pool members(LTM VIPs) of both the sites.
• pool members are having loadbalancing method as round robin.

GTM Loadbalancing Issue

 

In this setup, DNS requests from internet users (PUBLIC) are loadbalanced properly and resolved to both the site LTM VIPs properly, since DNS queries are coming from different ISPs at geographically different location.

 

However, PRIVATE_LAN user DNS queries are originated via very few DNS servers and hence loadbalancing is not happening properly.

 

Note: Consider we have enabled GTM persistence. (as per application requirement)

 

If 1000 requests originated from a private LAN, all those DNS requests resolved to single site LTM VIP since DNS persisted.

 

We require both PUBLIC and PRIVATE_LAN user requests should be loadbalanced to both the GTM sites and persistence should work for the application.

 

It will be great if someone suggest a best solution.