Figuring out the data center fabric maze

Despite vendor pledges to support existing or developing industry standards, users are expected to deploy single-vendor data center and cloud switching fabrics from their primary suppliers.

Standards such as Transparent Interconnect of Lots of Links (TRILL), Shortest Path Bridging, andMulti-Chassis Link Aggregation will be embraced by those vendors looking to dent Cisco's dominance in data center switching. The standards support will soothe customers looking to avoid vendor lock-in, but it's unlikely IT shops will mix and match multivendor switches within and between data centers.

"In the data center, customers do look for that path with the least bumps in the road just because of the critical need of the data center," says Zeus Kerravala, principal at ZK Research.

IT'S WAR! Fabric wars: Cisco vs. Brocade vs. Juniper

Cisco, meanwhile, will continue to expand and enhance its FabricPath approach to data center fabric switching -- which the company says supports TRILL but is not founded on it. Juniper will continue advocating a tagging mechanism in the Broadcom silicon inside its QFabric line to support multiple active paths and one-hop reachability in data centers and cloud environments.

Brocade says the current implementation of its VCS fabric technology does not include all of the features that are found in the TRILL standard. The company says its VDX data center switches can operate in VCS mode or in "classic" mode, which is more adherent to IEEE 802.x standards. The data plane in a VCS implementation uses TRILL; but the control plane does not, it uses Fabric Shortest Path First (FSPF), an ANSI standard used by all Fibre Channel SAN fabrics as the link-state routing protocol.

Alternative link-state routing protocols can be supported in VCS when they are standardized and available, Brocade says. But the link state protocol in TRILL, Intermediate System-to-Intermediate System (IS-IS), has been documented since July 2011 and even tested for interoperability at the University of New Hampshire almost a year before that, says Donald Eastlake, chairman of the TRILL working group in the IETF.