[sdnog] Common problem in sudan | Duplex mismatch

Jan Zorz - ISOC zorz at isoc.org
Wed Jan 28 13:04:11 SAST 2015

On 28/01/15 09:21, Tarig Yassin wrote:
>  > In cisco's routers:
>  > conf t
>  > int f1/0/1
>  > speed 100
>  > duplex full
> Yeah this would solve most of them, but for links between Cisco & Huawei
> sometime it needs very weird settings, e.g. Cisco part sets to "duplex
> full" and huawei part sets to "auto"   :)


This is a known problem for last 20 (at least) years and I'm surprised 
it still pops up everywhere. Problem is that autonegotiation process and 
protocol is so poorly specified that everybody reads it differently.

This was also the case 20 uears ago between Sun servers and Cisco 
routers/switches and it still is today between Cisco boxes and some 
other equipment (in my network for example I have ASR1001 box connected 
over fiber to Mikrotik CCR box and I need to set the speed/duplex on one 
end to make it work).

So, as suggested, fix the speed/duplex settings on one end and it should 

I would also suggest that you maybe consider writing this down to a 
document that oter people could use when thy are using some good 
operational practices how to make their networks better and maybe ask 
other people to write parts of it where other equipment does the same 
thing and how to fix it.

Cheers, Jan Zorz

Jan Zorz
Internet Society
mailto:<zorz at isoc.org>
"Engineering is always positive in results..." N. Tesla

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