[c-nsp] full duplex mismatch speed - dynamips

[Adam Armstrong]

On 19/08/2010 18:26, Justin M. Streiner wrote:
> On Thu, 19 Aug 2010, Adam Armstrong wrote:
>
>> On 17/08/2010 23:50, Justin M. Streiner wrote:
>>> On Tue, 17 Aug 2010, Alessandro Braga wrote:
>>>
>>> > Verify duplex and speed configurations on interface, the rule is:
>>> > autoXauto, forcedXforced. If problem not solve, disable cdp.
>>>
>>> Also, while auto speed/duplex negotiation is fine for user
>>> workstation/PC ports in most cases, I recommend against using it on your
>>> network infrastructure if you can help it.
>>
>> This is horribly terrible advice.
>>
>> Autonegotiation should always be used as default, nailing should be
>> the fix for when things don't work, and where very old devices don't
>> do autoneg properly.
>>
>> Note that for gigabit, autonegotiation is MANDATORY.
>
> For 1000baseT, yes, autoneg support is mandatory.
>
> I'll qualify my original statement. My FE experience is somewhat dated,
> but at that time, enabling autoneg would also often set the evil bit. It
> created more problems than it solved.
>
> It's been 5+ years since I had to worry about speed and duplex autoneg to
> any significant extent in my network infrastructure since the place I
> moved to was already GE over fiber when I came in and much of it has
> been upgraded to 10G since. The only time I worry about speed and duplex
> autoneg anymore is on end-user ports that don't always link up the way
> one would think they should, and this more often than not ends up being
> caused by older NICs and/or sketchy drivers.

Well now you know better, so please don't go repeating that anywhere else.

adam.