FRAMINGHAM 8 FEBRUARY 2011 - Networking rivals HP and Cisco have abandoned their common ground in data center switching, with HP accusing Cisco of diverting an IEEE standard and Cisco insisting that customers drove the change.
At issue are two as-yet unratified standards in the IEEE for data center switching that were being defined in concert but are now diverging. IEEE 802.1Qbg and 802.1Qbh were intended to work closely together to enable physical switches to offload much of the network-intensive processing from virtual switches on blade servers and NICs. A year ago, Cisco and HP were driving the effort in a rare show of unity.
Among the capabilities of bg and bh are Virtual Ethernet Port Aggregation (VEPA) and port extension. VEPA allows physical end stations to collaborate with an external switch to provide bridging support between external networks and multiple virtual end stations and VMs. Port extension allows users to deploy remote switches as the policy-controlling switches for the virtual environment.
Both initially used a tagging scheme, based on Cisco’s VN-Tag technology, for frame-to-VM identification and to run multiple virtual switches and multiple VEPAs simultaneously on the endpoint.
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. They can still do that - but bh’s role is being broadened beyond the data center to the service provider network, and a new tagging mechanism is being defined for that purpose.
According to HP, this breaks the spirit of the original bg and bh work and forces switch and NIC vendors to implement two tagging schemes instead of one to support both bg and bh.
“Cisco decided to change the scope and it broke a lot of the cooperation,” says Paul Congdon, CTO of HP Networking. “Where we might have had a vision, we now really see two (specifications) without commonality, which is really unfortunate.”
Hogwash, says Cisco.
“Cisco did not drive this,” says Joe Pelissier, technical lead at Cisco. “This additional capability was driven by feedback from the (bh) committee during the normal ballot process. Of course, Cisco enthusiastically supports providing this capability in bh as it greatly enhances the versatility of the technology, extends its longevity, and enhances its usefulness to our customers.
”Provider networking has broadened its scope into the data center, Pelissier notes, by helping to address VLAN scalability in large multi-tenant or cloud-based data centers. It is important then that new data center technologies - like bh - accommodate this trend, he says.
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