Avaya 8800 Planning And Engineering, Network Design page 155

SPBM reference architectures
Figure 69: Traditional routing before moving VMs
A VM is a virtual server. When a VM is moved, the virtual server is moved as is. This means that the
IP addresses of that server remain the same when the server is moved from one data center to the
other. This in turn dictates that the same IP subnet (and hence VLAN) be present in both data
centers.
In the following figure, the VM (red device) 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 below, one VM move results in a convoluted 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.
June 2016 Planning and Engineering — Network Design 155
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