When a user accesses an application running in a distant resource, the client must be able to use the optimal path and be dynamically redirected to the data center supporting the active application or VM. However, as explained previously, the routed Layer 3 network cannot determine the physical location of an IP device within the same subnet when it is stretched between different locations.
Without any ingress optimization, for long distances between remote sites, more bandwidth is consumed and some delays may be noticeable for the service offered by the cloud.
For example, assuming a default application “A” available on the primary data center “X”, migrates to a data center “Y”, the requests from the remote user will be directed to the primary data center “X” and then the extended Layer 2 path to reach the active application that has moved to data center “Y”, and vice versa for the return traffic.
It is therefore important to optimize the path for a remote user as soon as the application has migrated to the next location.
Cisco provides a number of IP localization services that, combined with other IP functions, support path optimization:
- Intelligent Domain Name Server
- Host Route Injection
- Locator/ID Separator Protocol, LISP