Re: Duplex/Speed Hardcoding

In article <1147868346.769558.235150@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
"yvanog" <robmonty@xxxxxxxxxxx> wrote:

Need opinions:

Have a colleague who insists every port on every switch be hardcoded to
most logical duplex/speed for that port (depending on what is behind
it). He will not leave auto/auto on because he believes the default
settings result in too many errors. What is your opinion on this? Has
anyone ever experienced so many problems with the defaults - on a
general app - that they now only hardcode the duplex settings?

Autonegotiation used to be unreliable, especially, ISTR, on some early
Cisco Cats, but it hasn't been that way for years[1]. There are still
occurrences of problems[2] but not commonly. If you're talking about
fixing the speed and duplex of every port in a large campus or
enterprise then I wouldn't bother - unless you set them to HD there
would be no point anyway. Even if you're talking about, say, just some
central servers then if you've got reasonably up to date switches and
NICs[3] you'd just be making more work for yourself.

Sam Wilson
Network Development Team, Infrastructure Services Division
Computing Services, The University of Edinburgh
Edinburgh, Scotland, UK

[1] A long while ago we had a pair of non-Cisco switches and if you
connected them together with autonegotiation they were guaranteed not to
bring the link up. They would work fine when speed and duplex were set.

[2] Just today we came across a dual-homed Sun with connections to a
pair of identical switches (non-Cisco). One connection has come up
100FD, the other 100HD; all ports set to auto.

[3] Novell servers with early 100Mbps NICs would drop packets when
running FD, either set or negotiated; HD was fine.
.

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