F5 LTM deployment across 2 DC's.

Usually you would add a DNS/GTM at each DC and both DNS/GTMs would be in sync. DNS/GTM can be configured as Active/Active, if you wish. However, your applications must be able to support active/active configuration. You should discuss your design requirement with your local account manager.

I will admit, this is often met by GTM/DNS. GTM/DNS is not just for site redundancy in an active/standby state but also to serve active/active sites that serve the same content. is one of those. F5 hosts its site and content across many data centers all over the world.

BIG-IP DNS provides tiered global server load balancing (GSLB). BIG-IP DNS distributes DNS name resolution requests, first to the best available pool in a wide IP, and then to the best available virtual server within that pool. BIG-IP DNS selects the best available resource using either a static or a dynamic load balancing method. Using a static load balancing method, BIG-IP DNS selects a resource based on a pre-defined pattern. Using a dynamic load balancing method, BIG-IP DNS selects a resource based on current performance metrics collected by the big3d agents running in each data center.

If you are looking to use only LTM it may become difficult. As sent in my DM, I will try and provide additional details though you should really see if your organization or customer would be interested in utilizing DNS/GTM as well. If you already have LTM's, it would be a fairily easy license change to include DNS or DNS and AFM using F5's better licensing model found here https://www.f5.com/pdf/licensing/good-better-best-licensing-overview.pdf.

https://support.f5.com/kb/en-us/products/big-ip-dns/manuals/product/bigip-dns-load-balancing-13-1-0/1.html https://devcentral.f5.com/articles/what-is-big-ip-dns-26999

I will admit, this is often met by GTM/DNS. GTM/DNS is not just for site redundancy in an active/standby state but also to serve active/active sites that serve the same content. is one of those. F5 hosts its site and content across many data centers all over the world.

BIG-IP DNS provides tiered global server load balancing (GSLB). BIG-IP DNS distributes DNS name resolution requests, first to the best available pool in a wide IP, and then to the best available virtual server within that pool. BIG-IP DNS selects the best available resource using either a static or a dynamic load balancing method. Using a static load balancing method, BIG-IP DNS selects a resource based on a pre-defined pattern. Using a dynamic load balancing method, BIG-IP DNS selects a resource based on current performance metrics collected by the big3d agents running in each data center.

If you are looking to use only LTM it may become difficult. As sent in my DM, I will try and provide additional details though you should really see if your organization or customer would be interested in utilizing DNS/GTM as well. If you already have LTM's, it would be a fairily easy license change to include DNS or DNS and AFM using F5's better licensing model found here https://www.f5.com/pdf/licensing/good-better-best-licensing-overview.pdf.

https://support.f5.com/kb/en-us/products/big-ip-dns/manuals/product/bigip-dns-load-balancing-13-1-0/1.html https://devcentral.f5.com/articles/what-is-big-ip-dns-26999

Using only LTM leads to the following design questions:

What will happen if one data center internet link goes down, how are you going to redirect the traffic to the other data center? Do you have intelligent DNS services or are you simply going to add multiple A records to your external DNS server and do round robin without intelligent monitoring? The business has to address this risk by accepting it or dealing with it using GTM.

Are both datacenters connected at layer 2, in other words are vlans replicated between sites if so you could realize one cluster?

We've done away with GTM and instead, we use Amazon Route53 to load balance across multiple geographic sites. Using health check pages served by an iRule on the F5 LTM, we allow Route53 to make the decisions to either load balance across all sites, and then failover all traffic if a site fails.