[c-nsp] Question about manually configuring 1000/Full on Cisco switches

[Christopher.Marget at usc-bt.com]

> On Sun, Oct 31, 2010 at 6:18 PM,  <Christopher.Marget at usc-bt.com> wrote:
> > "speed 1000" on a copper port capable of 10/100/1000 disables 10 and 100
> Mb/s operation by removing those modes from the list of those advertised
> to the link partner.
> >
> > This may be useful if you would prefer a cable failure on pins 4, 5, 7 or 8 to
> drop the link and keep it down, rather than renegotiating it at 100 Mb/s.

> That's what I thought. So, if a link is already successfully negotiating at
> 1000/Full with no errors, there really is no point in hard setting it to 1000/Full,
> in my opinion.

Depends on the link.

In a shared buffer architecture with lots of broadcast traffic in the segment, renegotiating the link can mean that a cable failure on one port takes out 7 neighboring ports too.

Or maybe this link is one of a redundant set of OSPF links with manual cost applied.  A failure won't change traffic paths, in spite of the reduced bandwidth availability.

/chris