Scott Roberts wrote:
>
> if I understand what you're saying, I think its always been
> like that, cisco
> hasn't changed it.
What he's saying is that if you manually configure the duplex mode, the IEEE
standards don't say if the port should participate in autonegotiation or
not. Since there's no standard, Cisco and other devices have unpredictable
behavior that changes with models, software versions, the whim of the
programmer, etc. If a device doesn't participate in autonegotiation, the
other end may assume it's too old to do so, and must be an old 10/half device.
>
> you're refering to the fact that the IOS switch don't let you
> change the
> speed?
He didn't mention that, but it's an interesting comment. Is it true? What
happened to the speed {auto|10|100) command. That used to be available on
IOS switches??
> I think thats strange also, the set based switch can
> allow you to
> change speed, but after the IOS "upgrading" of switches they
> don't allow you
> to change a 10/100 at the switch, but rather require you to
> configure the
> desktop to 10 or 100 speed manually.
>
> I suppose the idea is that everyone should be using
> autonegotiation
> according to cisco.
Many experts are starting to say use autonegotiation. It will avoid lots of
problems these days.
But it is a lot like the "plug and PRAY" days of old. :-)
_______________________________
Priscilla Oppenheimer
www.troubleshootingnetworks.com
www.priscilla.com
>
> scott
>
> ""John Neiberger"" wrote in
> message
> news:[EMAIL PROTECTED]
> > I wanted to mention that we've been in the process of
> upgrading our
> > switches, as well, and I discovered that since we've started
> using the new
> > Cisco switches we've been having all sorts of problems
> getting the speed
> and
> > duplex settings set correctly.
> >
> > We've discovered that if you have relatively new NICs with
> updated
> drivers,
> > set both sides to AUTO. Never, ever, set only one side to
> AUTO. I'd also
> > avoid manually configuring the speed and duplex unless you
> have to do so
> to
> > fix a specific problem. Here's why:
> >
> > There is no standardized behavior for 100BaseTX when you
> manually
> configure
> > settings! The only setting mentioned in the specification is
> AUTO; the
> > behavior of the NIC with any other setting is up to the
> vendor and not
> > everyone handles it the same way. Cisco appears to have
> changed the way
> > they handle it, which is the cause of a lot of our problems.
> >
> > If you hard-set the speed and duplex there are two ways to
> handle this:
> >
> > 1. Use the configured settings and still participate in
> autonegotiation
> > only offering the configured settings.
> >
> > 2. Use the configured settings and do not participate in
> autonegotiation
> >
> > Cisco's new switches seem to use option #2, while a great
> number of our
> end
> > devices use option #1. Why is this a problem? Here's what
> happens when
> you
> > connection an option #1 device to an option #2 device:
> >
> > #1 participates in autonegotiation, only offer the configured
> settings.
> > #2 does not participate in autonegotiation at all and will
> forcefully use
> > the configured settings.
> > #1, seeing that there's nothing on the other side using auto
> assumes it is
> > connected to a HUB, and just might set itself to 10/Half
> regardless of the
> > manually configured settings!
> >
> > As you can guess, this is bad mojo. The moral of the story
> is that you
> > should try to start using AUTO on BOTH sides if you're using
> newer Cisco
> > switches, in particular the 2950 series. In some cases this
> won't work
> and
> > you'll have to resort to manual settings.
> >
> > HTH,
> > John
> >
> >
> > >>> Priscilla Oppenheimer 3/10/03 10:58:56 AM >>>
> > Mike Momb wrote:
> > >
> > > To all,
> > >
> > > We recently replaced our Nortel switches and routers with
> Cisco
> > > 2980 switches and 6509 routers. We have two buildings, 10
> > > floors each and a router in each building. We have a
> > > combination of NT and Novell servers. After replacing all
> > > this equipment, we have noticed that when we access files on
> > > the NT servers, the speed is acceptable. When we access
> files
> > > on the Novell servers, it is very very slow. Could the
> > > switches or routers be configured incorrectly for IPX. Is
> > > there something that we can change. On Cisco's web page it
> > > mentioned something about enabling ipx
> > > broadcast-fastswitching. Any input or comments would be
> > > appreciated.
> >
> > I doubt that ipx broadcast-fastswitching will help you unless
> you are
> using
> > an ipx helper-address. With ipx helper-address (just like ip
> helper-address)
> > you can tell a router to forward a broadcast, which it
> normally doesn't
> do.
> > This would be useful for some rare IPX application that sent
> broadcasts
> that
> > needed to reach the other side of the router. In typical IPX
> networks,
> > there's no such need. When there is a need, you can speed it
> up with the
> ipx
> > broadcast-fastswitching command.
> >
> > You titled your message "10 half or 100 full." I think this
> was a Freudian
> > slip. I bet your problem is related to a full-duplex
> mismatch. Perhaps the
> > NICs in the NT servers negotiated correctly but the NICs in
> the Novell
> > servers did not and you have a mismatch.
> >
> > With a mismatch, the full duplex side will send whenever it
> wants. The
> half
> > duplex will get upset if it sees the other side sending while
> it is also
> > sending and will backoff and retransmist, leaving behind a
> CRC-errored
> runt.
> > That side will reports a collision. The other side will
> report runts and
> CRC
> > errors.
> >
> > So, look for lots of Ethernet errors when you do a show int
> or show port.
> >
> > Also feel free to send us the output of various show commands
> and your
> > router config. There are some IPX gurus on this list.
> >
> > _______________________________
> >
> > Priscilla Oppenheimer
> > www.troubleshootingnetworks.com
> > www.priscilla.com
> >
> >
> >
> > >
> > > thanks
> > > Mike
>
>
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