An additional benefit, Pelissier says, is that enabling bh to operate using provider networking technologies in the data center “by default” enables its operation in traditional provider networks.
Moreover, an additional tag was needed to support multicast traffic – the initial tag in bg specifies unicast forwarding, Pelissier says. Also, it was always the intention of the bg and bh working groups to support two tags – one for VEPA and multichannel, the other for port extension.
“Whether or not we create a new tag… just wasn’t that big a deal,” Pelissier says. “We needed a new tag anyway.”
And broadening bh for service provider data center/cloud networking doesn’t negate the standard’s role in the data center, Pelissier stresses.
“The main intent is still for data center use,” he says. “But the original approach didn’t meet the intended scope.”
HP’s Congdon says the data center focus of bh has been stripped from it.
“It’s not a data center solution,” he says. “It was originally a data center solution, but now it’s an anywhere-type solution.”
Congdon admits that bh could still be used for port extension in a data center environment. But a new and different tagging scheme will make things a little more troublesome for switch and NIC vendors, and users, in that it will require additional silicon or software, operational oversight, and cost.
“We don’t really need an alternative,” he says. “The change in direction makes it more painful for people to support both. It’s much more significant. And it’s quite possible there won’t be as much port extension for the data center.”
HP and Cisco are still together on discovery protocols for both standards, however. Pelissier says that work, which a year ago was still on the to-do list, is “99% complete.” Some of it is based on the existing Link Layer Discovery Protocol (LLDP), others on new or enhancements to existing discovery protocols.
Both bg and bh are expected to be ratified towards the end of 2011.
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