Cisco introduces data center Layer 2 multipath NX-OS feature for the Nexus 7000 that has the goal of increasing network performance by eliminating barriers imposed by STP (Spanning Tree Protocol).
Cisco is turning on yet another new feature in the Nexus 7000
platform that basically eliminates the ancient and universally deployed
spanning tree protocol from network designs, thus enabling much larger
Layer 2 networking domains within the data center. The FabricPath
Switching System (FSS) is the foundation of a push by Cisco to combine
NX-OS software features with the hard capabilities of the Nexus 7000 F1
series module to build the next generation of high-performance network
Make no mistake, unlike incremental feature changes Cisco previously
released for the Nexus 7000 platform including OTV (Overlay Transport
Virtualization), FabricPath is a much bigger jump up in terms of
bandwidth, network performance and virtualization feature support. At
the same time Cisco went out of its way to ensure that
FabricPath-enabled Nexus devices and software features wouldn't
existing network implementations. Thus, while FabricPath is a radical
departure from network designs built around the spanning tree protocol,
it should be on the "evaluate now" track for large data center managers.
When used together, FabricPath-enabled modules will benefit
organizations that want to implement workload mobility such as
VMware vMotion in a much larger resource pool, while also gaining
significant bandwidth and N+1 redundancy and fast network convergence
after a link failure.
During prerelease conversations with Cisco engineers that included a
demonstration of the first-generation release, the performance numbers
were pretty astounding. FabricPath-enabled modules use
active-active links between devices--losing the line blocking that
spanning tree required--and instead use ECMP (equal-cost multipath) to
direct traffic. First-generation modules can support up to 16-way
ECMP, which can be combined with 16-port 10G bps PortChannels, for
a total of 2.56T bps between switches.
When I looked at Cisco's OTV feature of the Nexus 7000 in
February of this year, I concentrated on Cisco's extension of Layer 2
functionality to enhance data center interconnect. OTV was still
dealing with the limitations imposed by spanning tree protocol.
FabricPath builds on technologies that were involved in creating OTV
and rachets up the performance and simplification case for enterprises
moving to the Nexus 7000 and NX-OS.
At the time, I wrote, "the measure that data center managers will need
to use when evaluating OTV is how much labor and network implementation
effort...will be eliminated relative to the cost of putting in Cisco's
hardware." The same holds true for FabricPath, except that the cost
savings will likely be much bigger and easier to measure. This is
especially true for organizations that move large amounts of network
traffic between data centers. When you add to that the resiliency that
is enabled by the active use of all links between devices, the case
becomes even more interesting.
Those pesky, long-lived Catalyst 6500 chassis will start to look a lot
more aged with the release of the FSS (FabricPath Switching Service).
This is going to be especially true for organizations that are
embracing server virtualization platforms of any variety. As the number
of virtual systems increases--and the use of business continuity
features including vMotion become more prevalent--the more keenly Layer 2 network limitations will be felt.
And it's clear that Cisco plans on increasing the capacity and
capability of the Nexus 7000 and FabricPath to accommodate the tempo of
virtualization adoption. For one thing, Cisco has "skin in the game" in
the form of its UCS offering. For another, the obvious benefits of
server virtualization are an escaped genie that cannot be rebottled.
When combined with the ever-increasing deployment of x86 multicore
systems, the two-year outlook for existing, spanning-tree-bounded
networks is pretty bleak.