GBIC TO GBIC CONNECTION

[hclna001]

The following is the actual scenario of my company ..The four switches are cascaded

(3508=1 nos and 3524=3 nos)this switches r connected by gbic stack modules which comes in two port .and 3508 is having 7 single gbic port and 1 two port gbic stack module .when i try to connect the single gbic port of 3508 to single gbic port of 3524 the link shows down (gigabit interface is down,line protocol is down)will u pls tell me wat will be the cable sequence and the configuration for making connetivity between this two switches

[joel.moore]

Have you tried the basic's, ie: issuing the no shutdown cmd, for that int.?

I would start there.

[rjackson]

When you say single Gbic do you mean fiber? In any case, dont forget you need a crossover connection if you are not using the Giga stack gbic and cable.

[hclna001]

dear joel

i am using cat5 e UTP cable and the module which i am using r single port means single Rj 45 Interface ..not like the two RJ 45 interface which comes in gbic stack modules.......will u pls send me the cable sequence used for this type of connection.......

thanx

[hclna001]

ya i have tried with no shut and all but it didn't work........i am using cat 5 e cable and the Gbic module which i am using is single port that is it is having only one RJ 45 interface and not like the gbic stack modules.......

thank u..

[konigl]

Stupid question: what's the revision(s) of software running on your 3508G and 3524 switches?

Minimum Cisco IOS Release required for model WS-G5482= 1000BASE-T GBIC is 12.0(5)XW or later.

Minimum Cisco IOS Release required for model WS-G5483= 1000BASE-T GBIC is 12.0(5)WC3 or later.

If a 3500 XL series switch is running an IOS release earlier than the minimums stated above, it does not detect and enable the GBIC.

Also, I have seen some confusion in the documentation. One data sheet says the -5483 GBIC will autodetect whether it needs to be MDI or MDI-X (straight-through pinout or crossed). While an installation note for the same says "When connecting the GBIC to a workstation, server, or router, use four twisted-pair, straight-through cabling. When connecting the GBIC to a hub or other switch, use four twisted-pair, crossover cabling."

Have you tried a cross-over cable? If you do, then make sure that it does the traditional Ethernet and Fast Ethernet cross-over (local pins 1 and 2 go to remote pins 3 and 6; and local pins 3 and 6 go to remote pins 1 and 2) *_AND_* you also cross the other two pairs (local pins 5 and 4 go to remote pins 7 and 8; and local pins 7 and 8 go to remote pins 5 and 4).

There is no trick to bringing the interfaces up, with respect to which patch cable end you plug in first, etc. If both ends of the link have GBICs recognized in IOS, the interfaces are NOT shutdown, and the configurations match (that is, trunk-to-trunk with common encapsulation and native VLAN; or access-to-access, with same VLAN on both sides), just patch in and it should go.

Spanning-tree may influence how quickly the link comes up (if you don't have portfast enabled, it takes a little longer), but it should come up within a minute in either forwarding or blocking state.

What do the LEDs look like when you make the connection?

[hclna001]

For ur information I think I have written that I have connected the switches by gbic stack Modules ,and those r working.so there is no question of what version I am using……

For ur information I am using 12.0(5.2) XU..

But I think that there may be the reason that I am using spanning tree so the other port may be blocked ..so is there any solution for making two port simultaneously in to forwarding state.

thanx

[konigl]

OK, now I understand a little better. Connections between your 3508G and your first 3524 is through a pair of GigaStack GBICs. For best performance, it should be a point-to-point configuration, that is, the 3524 connects to the 3508G through one GS GBIC cable, and there are no redundant connections, or other switches connected to the second port on either GBIC. This gives you full-duplex performance on the link. (Do NOT use two cables. Even though each GS GBIC comes with a cable, connecting two GS GBICs together requires one and only one cable.)

If you have two cables plugged into one of the GS GBICs, for example if you use the one GS GBIC on the 3508G to connect to two 3524 switches, where each 3524 has its own GS GBIC, then the GS GBICs will run in half-duplex mode. I think you might be doing something like this, or chaining the other 3524 switches off the first one (called "cascading").

The GigaStack GBICs are NOT hot-swappable; the 1000BASE-T and fiber optic GBICs are. I have had some customers forget this, and they end up having to replace the GS GBICs. I have also had situations where one port of the GS GBIC works, but the other doesn't. (Try moving the cable to another port on the GS GBIC, and see if it works.) For these reasons, I do not recommend them.

If you have spanning tree enabled on the switch, and you want to send a particular port directly to forwarding state, go into config, and on the interface enter the command "spanning-tree portfast". Don't forget to save after you exit config. Enabling portfast on an interface with a GS GBIC affects the whole GBIC; you can't limit it to one port or the other on a GS GBIC, it affects both ports. Do NOT enable portfast if you are cascading; I mean, if you only have one GS GBIC in each switch and you connect 3508G to 3524-1, and 3524-1 to 3524-2, and 3524-2 to 3524-3, and 3524-3 back to 3508G.

[konigl]

Tried to get back to edit my previous message, but not quick enough.

I tried to find some documentation on Cisco's website to back up what I was telling you about the hot-swap capability of the GS GBIC, but couldn't find any in time. I remember reading that or hearing that somewhere, though, so feel free to take what I said about the lack of GS GBIC hot-swap with a grain of salt.

I have had only half a GS GBIC work, however. And as a general rule, I do not recommend to customers that they implement cascaded GigaStack links. If they can afford to buy switches, and they need Gigabit connections between them, then those links should be full-duplex. It doesn't cost that much more to go from a pair of GS GBICs to a pair of TX GBICs, and you get to extend your distance between switches to more than 1 meter.

[hclna001]

sir i do have cascaded the switches,as u have written,but the way i did in that particular situation if one of my path fails i get a redundant,although i am getting half duplex .and as u know that there is no redundancy in point to point connection......

and sir u told that if i have cascaded the switches ,i shouldn,t enable the portfast on n interface,can i know the reason for this,is it network loop?.and in wat way is it going to affect my network?..

Mr konigl if u don't mind can i get ur personal email-id ,so that i can send u the actual scenario by which i hope u can easily help me....

thanx