To: Kenneth E. Phillipps who wrote (11312 ) 3/26/1999 2:08:00 AM From: jach Respond to of 12559
IP-Over-ATM Benchmark Put To An Early Test By Joe McGarvey March 16, 1999 12:57 PM ET Service providers finally have access to a benchmark that measures the ability of Asynchronous Transfer Mode switches to process Internet Protocol traffic. Now, the question is whether equipment makers will develop a meaningful framework for the tests. Netcom Systems, a maker of testing equipment for routers and switches, recently delivered a test module that company officials claim will yield an accurate indication of Asynchronous Transfer Mode (ATM) switch performance in handling Internet Protocol (IP) traffic. The IP Over ATM Mesh Test is designed to measure the ability of ATM switches to process IP packets for transport across the network core. "A few years ago, the testing issue was confined to figuring out how well an ATM switch could forward ATM cells," says Bahaa Moukadam, senior director of product marking at Netcom. "The issue now is how do those switches perform when you actually use them to send real IP traffic." The ability of ATM switches to forward IP traffic is difficult to measure because of the computational overhead associated with converting IP packets to ATM cells and then back to IP packets, a process known as segmentation and reassembly. Netcom officials say the IP Over ATM Mesh Test can compare the performance of ATM switches being evaluated for deployment in IP environments. ATM switch maker Fore Systems (www.fore.com) has used the Netcom tool to showcase the IP handling abilities of its ForeRunner ASX-4000 backbone switch. Fore commissioned The Tolly Group, an independent testing lab, to test the ASX-4000 using the Netcom benchmark. The Tolly Group reported that the Fore switch, which was fitted with a 40-gigabit-per-second backplane, could process more than 90 million packets per second, without dropping a single packet. But one analyst questions the way the test was conducted. Dave Passmore, an analyst at NetReference, cautions that the Fore test may not be a true measurement of real-world performance, because it was based on the exclusive use of 40-byte IP packets, which fit neatly into ATM's 53-byte cells. Including larger packets is essential in a test that measures IP-over- ATM performance, Passmore says, because chopping large IP packets into 53-byte ATM cells is responsible for much of the conversion overhead. "If the test only includes 40-byte frames," Passmore says, "you might as well be pumping ATM cells through the switch." Both Fore and Kevin Tolly, chief executive of the Tolly Group, defend the relevancy of the test. Even though the Fore test did not include packets larger than 40 bytes, Tolly says it is still relevant because almost half of the traffic on the Internet is transported in packets of 40 bytes or smaller. That traffic, Tolly says, is generated primarily due to the manner in which Transport Control Protocol moves data. Netcom would not comment on the methodology used in the Fore test. The IP Over ATM Mesh Test can be downloaded free from Netcom's Web site at www.netcomsystems.com. The software requires Netcom's SmartBits test hardware.