SDN and Overlay Networks – It’s all about fit and features

This post has been sitting in my queue since October, I felt it was time to let it go.

It’s all about fit and features in Software Defined Overlay Networks

Midokura MidoNet:

What is it?

Midokura’s MidoNet creates a fully-meshed overlay network built on top of your current IP network.  MidoNet’s defining feature is the claimed ability to fully process a packet at the edge of the network, applying any needed features before forwarding the traffic directly to the end host.  Midokura officially launched October 16th, 2012 at the OpenStack conference in San Diego.

What is the SDN angle?

The MidoNet Agent is a client that runs on commodity PCs and virtualizes the infrastructure, one feature is the ability to combine multiple physical machines into a single virtualized router. When a packet hits a MidoNet edge node, the MidoNet agent queries a database that holds the mapping information for the end nodes along with any features that need to be applied. Once the packet has been processed, a flow is created and the packet is put onto a tunnel directly to the end host.

Nicira NVP:

What is it?

Recently purchased by VMWare, Nicira provides network overlay solutions for data centers.  The NVP product creates and controls a virtual network using OVS (Open vSwitch) and allows for the separation of traffic via tunnels that extend between OVS instances.  Nicira uses a technology they call Distributed Virtual Network Infrastructure (DVNI) to handle the packet flow.

What is the SDN angle?

Since the data for forwarding the packets is stored in NVP, many limitations such as VLAN and MAC scale are removed.  NVP also allows for multi-tenant separation, QoS and Virtual Port Isolation.  The forwarding data and feature information is kept within NVP rather than being on the underlying IP network.

LISP (Location/ID Separation Protocol)

What is it?

LISP is one of the original SDN based forwarding projects having been conceptualized in 2006.  LISP provides full separation of an IP (EID) from any specific location (RLOC).  LISP provides solutions to issues that were either previously too expensive or complex including: Ingress Load Balancing without BGP, IP Mobility (The ability to move a single IP address to another location such as moving a VM from one datacenter to another) and IPv6 transition.  Another value of LISP is that it can allow you to aggregate prefixes, potentially removing excess routes from the local and global routing tables.

What is the SDN Angle?

LISP stores routing, traffic engineering and other forwarding policies in a mapping system that is designed to be distributed and redundant.  LISP queries the mapping system only when the first packet hits a ingress LISP router and uses the reply to process the packets including applying the forwarding policies.

Open vSwitch

What is it?

Open vSwitch or OVS is a Open Source virtual switch available under the Apache 2.0 license that allows interconnection between multiple virtual hosts using bridging.  It is used by XenServer as the default switch and is a part of Pica8’s PicaOS operating system.  Open vSwitch competes with dVswitch from VMware and the Nexus 1000v virtual switch from Cisco.

What is the SDN Angle?

Open vSwitch is being used as a vSwitch in many Open Source projects such as OpenStack, Xen, KVM and others.  The vSwitch embodies the SDN concept.

Wrapping Up:

We’ve discussed four different technologies (many of which can work together) that are either based on or used in SDN Overlay Networks.  Midokura and Nicira are commercial companies offering solutions based partly on Open Source software addressing MAC and VLAN scaling issues.  LISP does overlay via IPinIP allowing for separation of the host and it’s location.  While Open vSwitch is a popular hypervisor switching solution.

All of these products can stand on their own or be combined together in different ways to produce solutions that are only recently possible.  They utilize Open Standards and can help in lowering CapEx and OpEX.

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