We tested Cisco's FabricPath architecture, the company's answer to TRILL - the IETF Transparent Interconnection of Lots of Links RFC - for enabling shortest path multihop routing in large-scale Ethernet and FibreChannel-over-Ethernet data center networks. Actually, David Newman, a member of the Network World Lab Alliance and president of Network Test, an independent test lab and engineering services consultancy, conducted the testing.
In a nutshell, Newman found that FabricPath showed marked improvement over Ethernet's venerable Spanning Tree Protocol in the ability to increase bandwidth, reroute around failures and simplify network management. But Newman's test only looked at FabricPath functionality - it did not test scalability or latency. Network Test plans to revisit these other areas in the future.
Functionality was tested in five ways: validating that FabricPath would support 16 redundant paths between switches, as Cisco claims; the ability to load-share across those connections; the ability to group together EtherChannels at the edge switches, each comprising 16 10G links; uniform distribution of MAC addresses; and load-sharing of multicast and unicast traffic, as well as a mixture of multicast/unicast flows.
Newman's tests also found FabricPath to reroute traffic sent to a disabled switch in milliseconds vs. seconds with Spanning Tree; and to take no time nor drop any packets when reconverging the network after a switch was added.
For management, Cisco's Data Center Network Manager passed four tests, including discovering six Nexus switches, sending alerts when FabricPath utilization exceeded 80%, displaying an alarm on FabricPath link failure, and applying and removing weighted random early detection queuing.
The only downside to FabricPath Newman found was its limited availability. Currently, it is only supported on the latest 1/10G Ethernet cards for the Cisco Nexus 7000.
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