Tuesday, June 21, 2011

Cisco Nexus 1000v Virtual Switch for VMWare ESX

Recently the server group came to me and let me know that they had purchased Nexus 1000v licensing for the new ESX cluster.  As a Cisco geek, I was pretty stoked to get to work with the Nexus 1000v as it was virtual and the first Nexus platform I would get to work on.

In this article, I am going to try to lay out some of the basic nomenclature surrounding the Nexus 1000v.  If you are like me and have been living in your network world with little exposure to the guts of VMWare, this article will hopefully help bring you up to speed.

The first concept that can get a bit confusing in the VMWare world is the way they refer to their NICs.  The physical NICs on the server are referred to as vmnic<x> starting with vmnic0.  When I was first getting started, I kept wanting to think that these were virtual NICs since it started with VM, but that is not the case.  Usually the onboard NICs are the first vmnics and then any expansion cards are after that.

Next there is the matter of the different types of virtual switches that can be configured.  The most basic type is the standard vSwitch.  To the average networking guy this is basically configuring the ESX host's interfaces to be used as tagged (trunked) VLAN interfaces.  Each VLAN that you want to support is added as a standard vSwitch.  Once added the vSwitch can be associated with any VM.  The drawback to vSwitch from a VMWare perspective is that they need to be identically configured on every ESX host in the cluster to allow for vMotion of VMs since their network has to be present for them to move.  From a network guy's point of view the drawbacks are numerous including:

  • No ACL capabilities.
  • No SNMP monitoring of traffic counters.
  • No Netflow monitoring.
Realizing the problems with vSwitch design for vMotion, VMWare came up with the distributed vSwitch or DVS.  This switch is configured for the entire cluster and ensures that all members of the cluster have the same network configuration available for VMs.  From a VMWare perspective this is the cat's meow, but it still lacks SNMP, ACL and Netflow capabilities that us networking nerds crave.  

That's where the Nexus 1000v comes in.  It is a cisco developed distributed vSwitch that uses the VMWare APIs to give a full NX-OS controlled DVS.  If you can do it in NX-OS you can do it with the Nexus 1000v.  In my next post I will discuss how the Nexus 1000v architecture interacts with VMWare.

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