So we now need to fix this link between 20 and on 51 and 20 9:52 both switches are showing messages
that there's a duplex problem.
So CGP does a nice job here.
Of showing us that there's a problem rather show run interface if zero slash four we can see the speed
and duplex are hard coded show run interface if Zeerust last for on the side it's 100 half duplex on
the side it's 100 full duplex.
So that's a simple fix of setting the duplex to full the interface has gone down and comes up again.
And hopefully that's resolved the problem.
We could play the counters as an example when if Syria slash for and do the same here play a count as
if 0 4 and then we could.
After a while we look at those counters and see if we find any problems.
But that should have solved the problem of a duplex mismatch to confirm it show interface F-0 slash
for right at the top here we can see.
So here's the command.
Here's the speed and duplex of the interface interfaces up up and it's connected show interface.
If there's Slash for on switch to he has the command once again Duplaix and speed are shown here as
well.
Interfaces up up and it's connected.
We've not seeing any errors on the interface and on this one we are also not seeing any errors.
So that hopefully has resolved the problem on this link and this link.
So be careful hard coding speed and duplex what a negotiation may negotiate correctly but it may not
generally today with gigabit and foster lengths.
Your problems are not as bad as they used to be on 10 100 links.
Let's see what happens if we can figure speed and duplex on one site and leave the other side for negotiation.
So on 29 51 we will configure this interface
with a speed of 100 Duplaix of full interfaces gone down interface will hopefully come up.
And there you go.
Here is the 30 750 and we can see that it's complaining about a duplex mismatch.
So show run interface if 0 EF 1 0 3 No Duplaix will speed as being configured on the interface show
interface.
EF 1 0 3 the side is using 100 make half duplex whereas the side
is using 100 make full duplex.
So if you have one side configured for negotiation and the other side is hardcoded you may have a problem
because the site is not negotiating with the other side and the side may take a fallback position.
Sometimes it's able especially on gigabit and Lady interfaces to still work out what the other side
is using and set its duplex and speed accordingly.
But it wasn't able to do that because the 29 50s or older switches so to resolve this let's configure
the twenty nine fifty four or two negotiation so if zero is 1 the interface speed or the Duplaix water
interface has gone down hopefully it will come up.
And hopefully they'll be able to negotiate successfully.
So thirty seven fifty is showing up 29 50 showing up show interface.
EF 1 0 3 full duplex 100 make.
So that side is 100 make full duplex to show interface f 0 1 on the site full duplex 100 make.
So they've negotiated successfully.
So moral of the story is either configure both sides for negotiation or hard code both sides generally
today you're going to allow both sides to want to negotiate.
Show run interface if 1 0 1 show run into face.
EF 1 0 1.
Now this is the link between the two thirty seven fifties if one is 0 or 1 the interfaces and currently
connected.
So we've got one interface.
If 1 0 1 between the 2:37 fifties one site is not set for speed and duplex It's set for Orta the other
side is using one hundred Hauffe.
But in this case
the site set for negotiation has reverted to 100 make half duplex.
So that's worked out OK.
In this example However if I change this to have a duplex or full the negotiation will probably fail
and we'll have a duplex mismatch interfaces of come up.
Let's see what it's done.
In this example it's negotiated correctly.
Full duplex 100 make the site do show interface 1 0 1
full duplex 100 meg.
So we manually configured the site with speed and duplex.
The site
has been able to work out what the speed and duplex should be.
So let's set the speed to 10 and the duplex to have
and let's see if the switches can successfully negotiate that.
So interfaces come up show interface if one does 0 1 and I'll simply include the duplex so we don't
see all the output.
Notice how it's negotiated properly so on this switch
it's been manually configured for half duplex 10 meg and the switch has successfully negotiated that.
If I change the duplex here to full Let's see what happens.
Now when the interface comes up so here it's 10 meg full duplex on the side it's also 10 make full duplex
so the thirty seven fifty's are negotiating correctly without any problems.
But that wasn't happening between a 37 50 and a 29 50.
So let's set the speed to 100
so show interface and look at the duplex that's been set.
Try that again 100 full duplex the side 100 full duplex.
So in this case when I set the one side it successfully negotiating with the other side.
But we had problems with negotiation between the 37 50 and 29 50.
So generally the moral of the story is what to negotiation on both sides or hard code on both sides.
Mixing and matching can cause problems.
Today the general recommendation is use auto everywhere except perhaps between called links where you
want to hard code both sides to increase the speed of that interface.
Coming up.