100baseT slowness summary

2007-12-25 9:20:00

The problem I was experiencing with slow 100baseT performance has largely

been cleared up, although not the way I was expecting.

As preported before, I was getting pitiful performance through our 100baseT

network on in-bound network operations to two Sun 250 boxes running Solaris 2.6

connected to a Cisco Catalyst 5000 switch. I could barely get 35 kb/s,

sometimes only 0.5 kb/s, throughput, although outbound operations could

reach into several hundred kb/s.

The advice of almost everyone was to kill autonegotiation of speed and duplex

settings on both the switch and /dev/hme on the Sun boxes, forcing them

manually to do either full or half duplex 100baseT. About half insisted

half duplex was the way to go; the other half quoted Sun documentation

supporting full duplex.

Turning off negotiation and forcing traffic to full duplex improved

inbound throughput to about 250kb/s, a vast improvement but still not

as fast as they should be able to support. Forcing half-duplex on both

ends offered the same level of improvement.

For a lark, I forced the machine to 10baseT, half-duplex. Suddenly,

performance jumps to 800kb/s. I have entirely given up trying to make

any sense of this brain-damaged thing.

Thanks to:

Oleg Olovyannikov

Matt Reynolds

Cyril Liu

Meenakshisundaram Paramasivam

Bismark Espinoza

Benjamin Kearns

"ebs .

Sebastian Benoit

Todd M. Wilkinson

Paul V. Alukal

Ian Parkin

Chris Griffin

Cheers,

Brian

---
Brian A. Jarvis, Independent Unix Contractor
jarvis@office-assist.com 9506 Boyer Place, Silver Spring, MD 20910
http://www.office-assist.com/~jarvis tel: (202) 246-0660 fax: (301) 565-4503

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