Windows Server 2012 Supports Data Center Bridging (DCB)


Data Center Bridging (DCB) is a collection of standards-based end-to-end networking technologies that allow Ethernet to act as the unified fabric for multiple types of traffic in the data center. You cannot put a bunch of traffic types / protocols on the same physical pipes if you have no way of guaranteeing that they will each get what they need when they need it based on priority and impact. Even with ludicrous over provisioning you could still run into issues and even if that’s not the case that’s a very expensive option. When you think about iSCSI, Remote Direct Memory Access (RDMA) and Fibre Channel over Ethernet (FCoE) you can see where the benefits are to be found. We just can keep adding network after network infrastructure for all these applications on a large scale.

  • Integrates with the standard Ethernet networks
  • Prevents congestion in NIC & network by reserving bandwidth for particular traffic types giving better performance for all
  • Windows 2012 provides support & control for DCB and allows to tags packets by traffic type
  • Provides lossless transport for mission critical workloads

You can see why this can be handy in a virtualized world evolving in to * cloud infrastructure. By enabling multiple traffic types to use an Ethernet fabric you can simplify & reduce the  network infrastructure (hardware & cabling).  In some environments this is a big deal. Imagine that a cloud provider does storage traffic over Ethernet on the same hardware infrastructure as the rest of the Ethernet traffic. You can get rid of the isolated storage-specific switches and HBAs reducing complexity, and operational costs. Potentially even equipment costs, I say potentially because I’ve seen the cost of some unified fabric switches and think your mileage may vary depending on the scale and nature of your operations.

Requirements for Data Center Bridging

DCB is based on 4 specifications by the DCB Task Group

  1. Enhanced Transmission Selection (IEEE 802.1Qaz)
  2. Priority Flow Control (IEEE 802.1Qbb)
  3. Datacenter Bridging Exchange protocol
  4. Congestion Notification (IEEE 802.1Qau)

3. & 4. are not strictly required but optional (and beneficial) if I understand things correctly. If you want to dive a little deeper have a look here at the DCB Capability Exchange Protocol Specification and have a chat with your network people on what you want to achieve.

You also need support for DCB in the switches and in the network adaptors. 

Finally don’t forget to run Windows Server 2012 as the operating systems Winking smile. You can find some more information on TechNet  Data Center Bridging (DCB) Overview but it is incomplete. More information is coming!

Understanding what it is and does

So, in the same metaphor of a traffic situation like we used with Data Center TCP  we can illustrate the situation & solution with traffic lanes for emergency services and the like. Instead of having your mission critical traffic stuck in grid lock like the fire department trucks below

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You could assign an reserved lane, QOS, guaranteed minimal bandwidth, for that mission critical service.  Whilst you at it you might do the same for some less critical services that none the less provide a big benefit to the entire situation as well.

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