Design Reference

Table Of Contents
Figure 43: Traditional routing before moving VMs
A VM is a virtual server. When you move a VM, the virtual server is moved as is. This action
means that the IP addresses of that server remain the same after the server is moved from
one data center to the other. This in turn dictates that the same IP subnet (and hence VLAN)
exist in both data centers.
In the following figure, the VM moved from the data center on the left to the data center on the
right. To ensure a seamless transition that is transparent to the user, the VM retains its network
connections through the default gateway. This method works, but it adds more hops to all
traffic. As you can see in the figure, one VM move results in a complicated traffic path. Multiply
this with many moves and soon the network look like a tangled mess that is very inefficient,
difficult to maintain, and almost impossible to troubleshoot.
Data Center Routing — Traditional (post VM move):
Reference architectures
Network Design Reference for Avaya VSP 4000 February 2014 93