Abstract

Extreme Networks, Inc. commissioned The Tolly Group to benchmark the performance of its BlackDiamond 6808 Switch, with 48 fiber Gigabit Ethernet ports. Extreme Networks requested that The Tolly Group measure the throughput of two BlackDiamond 6808 switches when configured for two link aggregation trunk groups consisting of eight ports each, and compare the results with those of a Cisco Systems, Inc. Catalyst 6509 switch with distributed forwarding, in the same testing scenario. 

This Tolly Group competitive evaluation examines Gigabit Ethernet link aggregation performance on the Extreme Networks BlackDiamond 6808 and compares it with the Cisco Catalyst 6509 equipped with a Distributed Forwarding Card. Commissioned by Extreme Networks and tested in July 2001, the report focuses on a common backbone-switching requirement: delivering wire-speed or near-wire-speed throughput when multiple physical Gigabit Ethernet links are combined into higher-bandwidth logical trunks. Tolly evaluated two BlackDiamond 6808 switches, each configured with two eight-port link aggregation trunks and Open Shortest Path First Equal Cost Multipath (OSPF ECMP), against an equivalent Cisco Catalyst 6509 test scenario.    

The benchmark used a partial-mesh Layer 3 traffic pattern across two eight-port fiber aggregation trunks, with 16 Gigabit Ethernet input streams and a total of 32 Gigabit Ethernet ports per switch. Tests were run with 64-byte and 1,518-byte packets. According to the report, the BlackDiamond 6808 delivered 100% of theoretical maximum throughput at both packet sizes, while the Catalyst 6509 achieved 64% wire speed with 64-byte packets and 91% with 1,518-byte packets. In packet-per-second terms, the BlackDiamond reached 47.6 million packets per second with 64-byte packets and 2.6 million packets per second with 1,518-byte packets, compared with 30.5 million and 2.4 million packets per second respectively for the Cisco platform.    

The report argues that link aggregation is valuable only if it scales bandwidth without introducing performance penalties. In this test, Tolly concluded that the BlackDiamond 6808 could scale bandwidth as intended across aggregated trunks under OSPF ECMP, while maintaining zero-loss forwarding for both minimum and maximum standard Gigabit Ethernet packet sizes.  

The methodology used two BlackDiamond 6808 switches running software version 6.1.8 Build 7 and two Catalyst 6509 switches running IOS 12.1(5c)EX with DFC, each connected to a Spirent SmartBits SMB-6000 with 32 Gigabit Ethernet fiber interfaces. Tolly configured each port as a separate IP subnet, disabled ancillary features such as Spanning Tree and Flow Control, and ran three one-minute zero-loss iterations for each configuration. Overall, the report presents the BlackDiamond 6808 as a high-performance Layer 3 backbone switch capable of sustained wire-speed throughput across aggregated Gigabit Ethernet trunks.