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Summary:

VMware this morning announced VXLAN, the company’s attempt to allow virtual machines to span geographical data centers as part of the same LAN. Herrod said it will create “software-based networks that can be created on-demand, enabling enterprises to leverage capacity wherever it’s available.”

vxlan

During his keynote this morning at VMworld, VMware CTO Steve Herrod announced VXLAN, the company’s attempt to allow virtual machines to span geographical data centers as part of the same Local Area Network. Short for Virtual eXtensible LAN, Herrod wrote on his blog that it “enables multi-tenant networks at scale, and it is the first step towards logical, software-based networks that can be created on-demand, enabling enterprises to leverage capacity wherever it’s available.”

In other words, VXLAN could help companies build true global clouds that are the sum of their parts rather than distinct sets of parts. Currently, virtual resources such as storage and compute are limited to the constraints of a single physical network within a single physical data center. Even when tools such as VMware’s vMotion or DRS move workloads or VMs from machine to machine, they can’t escape the data center’s four walls. Herrod describes the problem using a telephony analogy:

One of the fundamental challenges with today’s networking is that we use an IP address for two unrelated purposes, as an identity AND as a location. Tying these together restricts a (virtual) machine from moving around as easily as we would like. We had the same challenge with telephony before wireless came of age. . . our phone number rang for us at a specific destination rather than following us wherever we went!

VXLAN separates a VM’s network ID from its physical location using a Layer 2 abstraction. The result, writes Herrod, is that “VMs are completely unaware of the physical networks constraints and only see the virtual layer 2-adjacency [and] the fundamental properties of virtualization such as mobility and portability are extended across traditional network boundaries.”

Cisco already supports a similar capability with its Overlay Transport Virtualization technology, but the main difference appears to be that OTV is limited to Layer 2 networks (i.e., LANs) and Cisco Nexus gear. VXLAN can cross even Layer 3 boundaries to let users incorporate even cloud-based resources. Cisco’s Omar Sultan wrote on his blog that “VXLAN is the basis of a scalable cloud network where lots of logical networks (over 16M …) can be created instantly to meet the needs of the even the most complex and dynamic cloud.”

Also, VMware is pushing to make VXLAN a standard, and had broad network industry support, including from Cisco, Arista, Broadcom, Brocade, Emulex and Intel.

More information about the technology is available on Herrod’s blog, as well as on the group’s IETF submittal.

  1. Juergen Brendel Tuesday, August 30, 2011

    This is nothing new, though. Companies like vCider ( http://vcider.com ) are offering this as a service already. And contrary to a vendor specific solution, you can actually set up networks that span different cloud, from different providers (EC2, Rackspace and machines in your data center all on the same LAN).

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    1. Yes, but it is non-standard. This is isn’t new indeed, but the relevant thing is that it comes from the biggest virtualization player and networking player together, and it comes as IETF standard proposal backed by other vendors (incl. Citrix, not mentioned on the article).

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  2. Derrick,

    Your comment about OTV being limited to a Layer 2 environment is incorrect. OTV is meant to extend Layer 2 over Layer 3 (IP) networks.

    Cisco VXLAN white paper has a section on VXLAN vs. OTV and LISP.
    http://www.cisco.com/en/US/prod/collateral/switches/ps9441/ps9902/white_paper_c11-685115.html

    “Working with OTV and LISP
    VXLAN is intended for creating more logical networks in a cloud environment. Overlay Transport Virtualization (OTV) while using similar frame format as VXLAN, is a data center interconnect technology extending Layer 2 domains to different data centers over Layer-3. Unlike VXLAN, OTV has simpler deployment requirements since it does not mandate multicast-enabled transport network. Locator ID Separation Protocol (LISP) goes a step further by providing IP address mobility between data centers with dynamic routing updates. While VXLAN, OTV, and LISP may share similar frame format, they serve very different networking purposes and are hence complimentary to each other.”

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  3. Derrick,

    Your comment about OTV being limited Layer 2 is incorrect. OTV is meant to extend L2 over L3 (IP) networks.

    Cisco white paper on VXLAN has a comparison on VXLAN vs. OTV and LISP:
    http://www.cisco.com/en/US/prod/collateral/switches/ps9441/ps9902/white_paper_c11-685115.html

    Quote:
    “Working with OTV and LISP
    VXLAN is intended for creating more logical networks in a cloud environment. Overlay Transport Virtualization (OTV) while using similar frame format as VXLAN, is a data center interconnect technology extending Layer 2 domains to different data centers over Layer-3. Unlike VXLAN, OTV has simpler deployment requirements since it does not mandate multicast-enabled transport network. Locator ID Separation Protocol (LISP) goes a step further by providing IP address mobility between data centers with dynamic routing updates. While VXLAN, OTV, and LISP may share similar frame format, they serve very different networking purposes and are hence complimentary to each other.”

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  4. VMware has yet again won the hearts of its clients because of regularly updating and upgrading their features and services.
    http://v12ntoday.com/blogposts/vmware-plans-on-strengthening-the-storage-department-after-altering-their-computing-model.html

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