There is one data center - dc1. There is a business need to setup another data center - dc2 in another geography and there might be more in the future say dc3.

Within the data center dc1:

• There are two web servers say WS1 and WS2. These two webservers do not share anything currently. There isnt any necessity foreseen to have more webservers within each dc.
• dc1 also has a local load balancer which has been setup with session stickiness. So if a user say u1 lands on dc1 and if the load balancer decides to route his first request to WS1 then from there on all u1's requests will get routed to WS1.
• Local load balancer and webservers are invisible to the user. Local load balancer listens to the traffic on a virtual ip which is assigned to the virtual cluster of webservers ws1 and ws2. Virtual ip is the ip to which the host name is resolved to in the DNS.
• There are no client specific subdomains as of now instead there is a client specific url(context). ex: www.example.com/client1 and www.example.com/client2.

Given above when dc2 is onboarded I want to route the traffic between dc1 and dc2 based on the client. The options that I have found so far are.

• Have client specific subdomains e.g. client1.example.com and client2.example.com and assign each of them with the virtual ip of the data center to which I want to route them.

or

• Assign www.example.com and www1.example.com to first dc i.e. dc1 and assign www2.example.com to dc2. All requests will first get routed to dc1 where WS1 and WS2 will redirect the user to www1.example.com or www2.example.com based on whether the url ends with /client1 or /client2.

I need help in the following

• If I setup a global load balancer between dc1 and dc2 do I have any alternative solutions. That is, can a global load balancer route the traffic based on the url ?
• Are there drawbacks to subdomain based solutions compared to www1 solution? With www1 solution I am worried that it creates a dependency on dc1 atleast for the first request and the user will see that he is getting redirected to a different url.