GBit Ethernet over Cu evaluation

[Eugen Leitl]

http://www.cs.uni.edu/~gray/gig-over-copper/

Gigabit Over Copper Evaluation

DRAFT

Prepared by Anthony Betz and Paul Gray

April 2, 2002

University of Northern Iowa

Department of Computer Science

Cedar Falls, IA 50614



Given the relatively low cost, backwards-compatibility, and 
widely-availability solutions for gigabit over copper network interfaces, 
the migration to commodity gigabit networks has begun. Copper-based 
gigabit solutions are now providing an alternative to the often more 
expensive fiber-based network solutions that are typically integrated in 
high performance environments such as today's tightly-coupled cluster 
systems.

But how do these cards compare with their fiber based counterparts? Are 
the Linux-based drivers ready for prime-time? The intent of this paper is 
to provide an extensive comparison of the various Gigabit over copper 
network interface cards available. Since performance is based on numerous 
factors such as bus architecture and the network protocol being used, 
these are the two main subjects of our investigation.

Our bandwidth benchmarks look at sustained throughput using TCP. While 
other communication protocols are available, indeed preferred, for high- 
performance computing, TCP-based benchmarks provide an immediate insight 
into the expected performance of the cards. With PCI-X coming into the 
marketplace in more and more motherboards as well as the multitude of 
systems with more traditional 32-bit PCI subsystems, numerous cards are 
available for today's 64bit and 32bit computer systems. The 64bit cards 
tested were as follows: Syskonnect SK9821, Syskonnect SK9D21, Asante 
Giganix, Ark Soho-GA2000T, 3Com 3c996BT and Intel's E1000 XT. The 32bit 
cards were Ark Soho-GA2500T, D-Link DGE500T. Comparisons for the various 
cards were made with respect to operation in alternate bus configurations 
and varied maximum transmission unit (MTU) sizes of TCP frames (jumbo 
frames). Results were gathered using Netpipe 2.4. By using Netpipe the 
peak sustained throughput would be provided as well as the transfer rate 
for varying packet sizes.

Note: All cards were tested at 1500, 3000, 4000, and 6000 values for the 
TCP MTU size. The drivers for the cards were not modified. Cards based 
upon the dp83820 chipset were limited to 6000MTU due to driver defaults. 
All other cards were tested through 9000MTU.

[results too voluminous to post]