How do I change media types on the Gigabyte ports. The command that I used for the 4948 doesn't exist on the 3550.

That does not work on a 3550 switch.

interface GigabitEthernet0/1
MSPSW5(config-if)#media-type sfp
                                   ^
% Invalid input detected at '^' marker.

Media-type is not a valid command on the 3550 at least not on this one.

sorry, incorrectly read your question first,

but 3550 is rather old and is equipped with Gbics, not sfps.

if it's type is unknown, then gbic is not recognized by the system

WS-G5484-AA

That is the module plugged into the 3550.  We have had the copper gbics in use but we recently upgraded the runs with Fiber and this is the module that we are trying to use in the 3550.  So we are terminating Fiber into the Gigabyte slots.

Okay we now have it so that it recognizes the device.

However the port won't come up.  It is connected to an SFP on the 4948.  Both sides say down down - however they are connected.

have you tried to change polarisation? (on one side change tx with rx, cross patchcord in other words)
try to set both sides with:
speed 1000
duplex full
for 3550 and
speed nonegotiate
media-type sfp
for 4948

we both boxes at our site with the same connection.

The 3550 only accepts Speed nonnegotiate for the Speed command.
MSPSW11(config-if)#speed ?
  nonegotiate  Do not negotiate speed

That is all it accepts.

I am having them switch the lines in the fiber box so it acts like a crossover.

Now we get one side to come UP/UP but the other still says down down.

ok, what type of spf do you use?
WS-G5484-AA  is SX.

and which side is up and which is down?

The 3550 side is now UP and it uses the WS-G5584 GBIC.

The 4948 is down down using a standard Cisco sfp module.

So what we did so far was to swap the fiber cables on the 3550 side and that brough the 3550 port UP/UP but the 4948 side that is utilizing the SFP is DOWN DOWN.  We will try switching the cables there too but we're confused as to why one side would come up while the other side is DOWN?

cables can be a problem, but please check, that sfp module is SX also.
the pairs only LX-LX, SX-SX. Sometimes LX is refered as LH.

Frustrating!

Here is what eventually brough them UP UP on both sides.

We had to force the 3550 SHUTDOWN - then SHUTDOWN the 4948 ports.

We then brought UP the 3550 ports.  After we verified they were UP we brought UP the 4948 ports and they worked.

So we then shut them all back down again.  Brought up the 4948 ports then the 3550 ports and the 3550 ports were UP UP but again the 4948 ports were DOWN DOWN.

So we tried just shutting down the 3550 ports and bringing them back up but that didn't work.

So we went through the whole process again of shutting them all down, bringing UP the 4948 ports and then bringing up the 3550 ports and it works again!

Then we unplugged the 3550 and plugged it back in and after it bboted they came UP UP on both switched and we did the same with the 4948 so we verified that it will work through a power failure.

We then for the hell of it tried the opposite way again and the same result.  If the 4948 ports are turned ON before the 3550 ports it won't bring both side UP UP but IF the 4948 ports are set for UP and THEN you turn UP the 3550 ports they work.

I am sorry I have been working with switches a long time and I haven't ever seen anything like this before!

So it's working now but I'd sure like to know why the 4948 ports have to be turned on prior to a 3550 fiber port being turned on.

have you tried to play around with auto negotiation turning it on and off?

Yes right now they are set for 1000 Full and that's what we have had them at since they came UP.

We tried auto-negotiation at first but we switched to 1000 full on each interface.

We haven't played with auto-negotiation since they began working however.

I take that back, they are not set on the fiber ports - the 4948 accepts negotiate 1000 or non-negotiate and it is set at negotiate 1000.

i understand. the only think, to my mind, that can lead to the behavior llike yours - speed negotiation problems.
even if interface support 1000 full only, it still try to negotiate speed with the second side...

I think I understand your point and I always try to set speeds on devices manually.  There are times when I have cheaper devices that simply don't 'set well' but negotiate for whatever reason but being that these are both Cisco switches I know I can get their port speeds and I generally do unless I have problems like I did with these two.

We just received a 3560 switch and even though I won't be using it the same way I place some sfp's into the 3560 to test and that baby was UP/UP with the 4948 right away. I know it's a lot newer than the 3550 too but the settings were the same.  It might just be something with the 3550 too or I should say this specific 3550.

btw, have you tried to check for release notes for newer software for 3560? it is possible, that they have discovered some kind of flow within your soft and it was patched then

I spoke with our Cisco technical representative.  He said the software on the 3560 is newer in the way that it is written.  It is still level 3 IOS but that it is a "fresher" release of the code and written after the 3550s were released.

He says even if the 3550 and 3560 have the same IOS the 3560 handles it slightly different and more efficienly that the older 3550.

Even though he explained it I still don't really get it.  Faster running of the code maybe but running it different I don't understand.  They both have to eventually function the same way depending on what I am doing with it and after all it's just software running over hardware.  I can see it running faster but not different.  I will give them the benefit of the doubt after all I don't build them.