  A virtual network (VN) contains a collection of virtual nodes and links
assigned to underlying physical resources in a network substrate. VN migration
is the process of remapping a VN's logical topology to a new set of physical
resources to provide failure recovery, energy savings, or defense against
attack. Providing VN migration that is transparent to running applications is a
significant challenge. Efficient migration mechanisms are highly dependent on
the technology deployed in the physical substrate. Prior work has considered
migration in data centers and in the PlanetLab infrastructure. However, there
has been little effort targeting an SDN-enabled wide-area networking
environment - an important building block of future networking infrastructure.
In this work, we are interested in the design, implementation and evaluation of
VN migration in GENI as a working example of such a future network. We identify
and propose techniques to address key challenges: the dynamic allocation of
resources during migration, managing hosts connected to the VN, and flow table
migration sequences to minimize packet loss. We find that GENI's virtualization
architecture makes transparent and efficient migration challenging. We suggest
alternatives that might be adopted in GENI and are worthy of adoption by
virtual network providers to facilitate migration.
