[c-nsp] Negotiation problem with Catalyst 2950 and Cisco 2821

[Dave Temkin]

Fully agree.  One thing people also fail to recall is that autoneg is
basically *required* (though you can generally disable advertising of
slower link speeds) with 1000BaseTX.  It's part of the standard, and the
closer people get to setting all of their links to auto the easier the
transition will be for them later.

-Dave




On Sat, 3 Dec 2005, John Neiberger wrote:

> > I find it quite odd that as a service provider you would ever trust your
> > network to autonegotiation.
> >
> > Hard code the port - leave nothing to chance. Is just one
> > extra command, and you should be doing that after you label the port,
> > with a description and putting it in a vlan, correct ?
>
> We have the opposite philosophy. We set everything to auto. We have
> *far* more problems with hard-set switch settings. It's been my
> experience--and I have documentation at work to back this up--that
> hard setting your devices to 100/Full is the worst possible choice.
>
> The short story is that there is no standard method of behavior when a
> NIC or switch port is hard set. Some devices still participate in Nway
> autonegotiation even when hard set, while others completely disable
> Nway. You run into problem when you connect devices that behave
> differently. Some NICs that still participate in Nway will see that
> there is no autonegiating link partner, so they'll try to be "helpful"
> and fall back to half duplex under the assumption that they are not
> connected to a device capable of full duplex.
>
> I have successfully got Cisco to change their documentation to reflect
> this behavior, but I don't have the link to that documentation here at
> home. I'd have to go look for it.
>
> John
>
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