ProActive Routing in Scalable Data Centers with PARIS

Abstract:

Modern data centers must meet many challenges and expectations: (a) They must scale to a large
number of servers, while offering high bisection bandwidth and
flexible placement of virtual machines.
(b) They must allow tenants to specify network policies and realize them by forwarding traffic
through the desired sequences of middleboxes. (c) They must allow tenants to bring their own IP
address space to the cloud to ease transition of enterprise applications and middlebox configuration.
The traditional approach of connecting layer-two pods through a layer-three core constrains VM
placement. More recent "flat"
designs are more
flexible but have scalability limitations due to

flooding/broadcasting or querying directories of VM locations. Rather than reactively learn VM
locations, our PARIS architecture has a controller that pre-positions IP forwarding entries in the
switches. Switches within a pod have complete information about the VMs beneath them, while each
core switch maintains complete forwarding state for part of the address space. PARIS offers network
designers the
flexibility to choose a topology that meets their latency and bandwidth requirements.
PARIS also allows tenants to bring their own IP address space and utilizes lightweight virtualization
using Linux namespaces to oer middlebox service in a manner that truly reflects
the pay-as-you go
model of cloud computing. It utilizes MPLS label forwarding and aggregation in the network core and
uses source routing at the network edge to realize middlebox policies specified by tenants. Finally,
we evaluate our PARIS prototype built using Open
ow-compliant switches and NOX controller.
Using PARIS we can build a data center network that can support up to 500K VMs.