January 18, 2010, 8:59 AM — Cisco, HP and others are waging an epic battle to gain control of the data center, but at the same time they are joining forces to push through new Ethernet standards that could greatly ease management of those increasingly virtualized IT nerve centers.
The IEEE 802.1Qbg and 802.1Qbh specifications are designed to address serious management issues raised by the explosion of virtual machines in data centers that traditionally have been the purview of physical servers and switches. In a nutshell, the emerging standards would offload significant amounts of policy, security and management processing from virtual switches on network interface cards (NIC) and blade servers and put it back onto physical Ethernet switches connecting storage and compute resources.
The IEEE draft standards boast a feature called Virtual Ethernet Port Aggregation (VEPA), an extension to physical and virtual switching designed to eliminate the large number of switching elements that need to be managed in a data center. Adoption of the specs would make management easier for server and network administrators by requiring fewer elements to manage, and fewer instances of element characteristics -- such as switch address tables, security and service attribute policies, and configurations -- to manage.
"There needed to be a way to communicate between the hypervisor and the network," says Jon Oltsik, an analyst at Enterprise Systems Group. "When you start thinking about the complexities associated with running dozens of VMs on a physical server the sophistication of data center switching has to be there."
But adding this intelligence to the hypervisor or host would add a significant amount of network processing overhead to the server, Oltsik says. It would also duplicate the task of managing media access control address tables, aligning policies and filters to ports and/or VMs and so forth.
"If switches already have all this intelligence in them, why would we want to do this in a different place?" Oltsik notes.
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VEPA does its part by allowing a physical end station to collaborate with an external switch to provide bridging support between multiple virtual end stations and VMs, and external networks. This would alleviate the need for virtual switches on blade servers to store and process every feature -- such as security, policy and access control lists (ACLs) -- resident on the external data center switch.
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Together, the 802.1Qbg and bh specifications are designed to extend the capabilities of switches and end station NICs in a virtual data center, especially with the proliferation and movement of VMs. Citing data from Gartner, officials involved in the IEEE's work on bg and bh say 50% of all data center workloads will be virtualized by 2012.
Some of the other vendors involved in the bg and bh work include 3Com, Blade Network Technologies, Brocade, Dell, Extreme Networks, IBM, Intel, Juniper Networks and QLogic. While not the first IEEE specifications to address virtual data centers, bg and bh are amendments to the IEEE 802.1Q specification for virtual LANs and are under the purview of the organization's 802.1 Data Center Bridging and Interworking task groups.
The bg and bh standards are expected to be ratified around mid-2011, according to those involved in the IEEE effort, but pre-standard products could emerge late this year. Specifically, bg addresses edge virtual bridging: an environment where a physical end station contains multiple virtual end stations participating in a bridged LAN. VEPA allows an external bridge -- or switch -- to perform inter-VM hairpin forwarding of frames, something standard 802.1Q bridges or switches are not designed to do.
"On a bridge, if the port it needs to send a frame on is the same it came in on, normally a switch will drop that packet," says Paul Congdon, CTO at HP ProCurve, vice chair of the IEEE 802.1 group and a VEPA author. "But VEPA enables a hairpin mode to allow the frame to be forwarded out the port it came in on. It allows it to turn around and go back."
