2950 Switch Gb ports not coming up

[Vachaun22]

We have a Catalyst 2950 switch with 2 gigabit ports in it.

If I plug the 2 Gb ports in to each other, the links come up, however anything else plugged in (even with the same cable) they do not. We've not done much for configuring the switch. The config is listed as:

!
! Last configuration change at 13:34:16 UTC Mon Sep 26 2011
! NVRAM config last updated at 13:34:19 UTC Mon Sep 26 2011
!
version 12.1
no service single-slot-reload-enable
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname [obscured]
!
enable password [obscured]
!
clock timezone EST 0
clock summer-time UTC recurring 1 Sun Apr 0:00 last Sun Oct 0:00
ip subnet-zero
!
spanning-tree extend system-id
!
!
interface FastEthernet0/1
 no ip address
!
interface FastEthernet0/2
 no ip address
!
interface FastEthernet0/3
 no ip address
!
interface FastEthernet0/4
 no ip address
....
(rest of interfaces the same)

All interfaces are configured the same, basically no configuration.

Any suggestions?

 

[vipergg]

Sure you are using the right cable , ports on a 2950 are not mdix compatible so you can't use just any cable . Switch to switch will be crossover, pc will be straight thru .

 

[Vachaun22]

vipergg, yep I checked the cable. I forgot to mention that in the first post. That was actually my first thought. In fact, I even tried multiple cables. Each one is straight through, not a crossover.

I might just for hoots and hollers make up a crossover and see what happens.

Until then, any other possible suggestions?

 

[Vachaun22]

Ok, so I thought there was an edit button to update a previous post, but I can't seem to find it now.

Anyway, so I tried a crossover from a machine directly to the switch and got nothing, and when I plugged both ports in I got nothing. So crossover cables definitely do not work.

So I plugged a small 5 port SOHO 10/100/1000 switch in to one of the gigabit ports, and that caused the port to come up.

So what I'm not getting now is why you can't plug a machine directly into one of the ports. Is there some way to put those ports in some kind of uplink only mode where they only work when connected to a switch?

Any suggestions based on this information?

 

[vipergg]

Still think its a cable issue , most small home routers are mdix compatible and you can use either a straight or crossover and it will compensate for the cable . The 2950 does not have that capability, a line to a user pc will be straight , a line to another switch has to be xover .I believe those ports might be gig only also so your machines would have to be gig compatible not say 100 meg and it must be a patch with 4 good pairs in it . Gig speed uses all 8 wires to transmit at those speeds. If you went to another switch then you would have to make a gigabit xover which is different than say a 100 meg xover . You could search on how to make those.

 

[Vachaun22]

vipergg, you hit the nail on the head with the ports are gig only.

That it seems was my problem. I also had to force the server NIC to gig speeds rather than auto negotiate.

Thanks.

 

[ADB100]

I am not sure what model 2950 it is but if it has built-in copper GigE ports then they are 10/100/1000 and will auto-sense, but no Auto-MDIX. If they are GBICs then its 1Gbps only and you will need a fully-wired cable.
Although a GigE crossover cable is different from a 10/100 crossover cable you shouldn't actually need one as the 1000BaseT copper interface is intelligent enough to do the crossing for you - i.e. if its GigE to GigE and you use a straight cable or a GigE crossover cable it will (should?) come up.

Andy