[CentOS] how to enable Flow Control on CentOS?

Giles Coochey giles at coochey.net
Fri Jul 8 22:50:57 UTC 2011

On 07/07/2011 17:30, Les Mikesell wrote:
> Old Cisco switches - and Cisco's advice about how to work around their 
> problems - are just the main reason that anyone would ever have turned 
> off auto-negotiate. And it is a big problem if you only turn if off at 
> one end which is what you end up with as you start to change 
> equipment, because the other end will always get it wrong. These days, 
> if a device doesn't negotiate properly you should probably just 
> replace it. 

The problem is not the auto-negotiation iteself, but the fact that if 
one side hard codes its speed to 100-Full Duplex then the other side 
cannot auto-negotiate to 100-Full Duplex. It also needs to be hard-coded 
to 100-Full duplex - The auto-negotiation is not a "I'll do what you're 
set to" type protocol, but a "let's see what's best for us" protocol.

There was actually never any problem with auto-negotiation itself - it 
did exactly what it said on the box, just that it didn't work if either 
end turned it off and hard coded it's speed.

Having seen my fair share of performance problems, if you don't have 
console access to both interfaces then agree on the speed and duplex and 
hard code it - saves a lot of faffing about and almost always works a treat.

Best Regards,

Giles Coochey
NetSecSpec Ltd
NL T-Systems Mobile: +31 681 265 086
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Business Email: giles.coochey at netsecspec.co.uk
Email/MSN/Live Messenger: giles at coochey.net
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