VM-Net

VMotion is one of those features of  VSphere, and of VMware infrastructure 3, that is quite simply amazing the first time you watch it move a live vm from one ESX server to another with any disruption. However to achieve this magical feat VMotion requires a network link of at least LAN speed to complete the task.

As cool as this is, one question often asked is, “How do we take that one step further, and perform VMotion between datacentres?” This, of course, is a non-trivial thing to do.  There is the challenge of moving a VM over distance (which involves some degree of additional latency) without dropping sessions. To maintain sessions with existing technologies means stretching the L2 domain between the sites, not pretty from a network architecture standpoint. And then there is the storage piece. If you move the VM, it has to remotely access its disk in the other site until a Storage VMotion occurs.  

Last year, Cisco and VMware began the task of trying to solve these long distance VMotion issues with the target of seamlessly migrating a VM between two  separated by a reasonable distance. The joint Cisco/VMware lab in San Jose has run number of tests over varying distances (simulated with reels of optic fiber) as a proof of concept.

This was demonstrated at Cisco Live in San Francisco. The demo as it stood incorporates a distance of 80km (50 miles). See above the above diagram.

This proof of concept is aimed at the following requirements:

1. Load balance compute power over multiple sites: Migrate VMs between datacentres to “follow the sun”  or to simply load balance over multiple sites. Enterprises with multiple sites can also conserve power and cooling by dynamically consolidating VMs to fewer datacenters (automated by VMware Dynamic Power Management (DPM))—another enabler for the Green datacenter of the future.
2. Avoid downtime during DC maintenance:applications on a server or datacenter infrastructure requiring maintenance can be migrated offsite without downtime.
3. Disaster Avoidance: Data centers in the path of natural calamities (e.g. hurricanes) can proactively migrate the mission critical application environment over to another data center.

Use cases #2 and #3 above also require a Storage VMotion to move the disk image to the alternative datacentre.

Now that Cisco have released its Nexus 1000V virtual switch for VMware vSphere Cisco is has started to release detailed demos of the product in action.

The company just uploaded two new HD videos on Facebook that amongst other topics cover what are port-profiles, how to create them with a SSH console and how to apply them with the vSphere client, how vEthernet interfaces relate to VMware vNICs andhow to monitor the network statistics of a virtual machine despite its migration from a host to another with vMotion. Head over to Facebook and check them out.

Cisco Nexus 1000v  Video Part 1 (11 mins)

Cisco Nexus 1000v  Video Part2 (10 mins)

One of the new features in VMware’s vSphere 4 product (VI 4’s official new title and currently at the release candidate stage of development) is its extensible architecture. This new architecture  allows VMware administrators to  not only enhance but even replace parts of vSphere’s functionality.

In the first wave of third parties to develop plugin’s to enhance vSpheres functionality is Cisco Systems. This is too not supprising considering Cisco, along with Intel, has recently purchased a stake in VMware.

The Cisco Nexus 1000v is Cisco’s first totally software based switch designed to replace the standard VMNet virtual switches provided by VMware. Currently still in beta the Cisco Nexus 1000v switch takes advantage of VMware’s vNetwork Distributed switch framework to offer tightly integrated network services as part of a server virtualisation strategy.

The Nexus 1000v consists of two distinct components, see below. The first component the VEM (virtual ethernet module)  is installed on each physical vSphere server and acts like a traditional line card in a physical modular switch. In fact if you telnet on the Nexus 1000v switch and type ’show modules’ each of the VEM’s will be identified as switch modules and will have their characteristics shown just like a physical Cisco chassis based switch. It is the VEM  component that replaces the traditional VMNet switch.

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