Connecting two switches together

lynchie

I am trying to connect two switches together. One is a 3Com 3300 SuperStack III and the other is a Cisco Catalyst 2900XL. I have two identical cables (Roline Quality Patch Cord Cat.5 UTP E164469 Type CM (UL) 24AWGx4P). Both cables are working fine normally when connected from switch -> PC but only one of them works fine from Switch -> Switch. I have tried other brands of cables and it seems that only one of the cables works from Switch->Switch. I thought that maybe it was a crossover cable and the others were not. But they have identical labels on the cable (as Above) so if both ARE the same, how come only one cable out of 10 works from Switch->Switch?

Btw, I know switches can be connected at the back via matrix port but this is a quick fix for the moment.

Rew

U can only conect switch <-> switch using a cross over OR the uplink port on one of the switches and a regular cable... (excluding gbics, AUI ports etc...) not sure whats up with ure cables are u using the same 2 ports in each test?

lynchie

Yeah im using the same two ports. Its strange because the cable MUST be a crossover cable yet it bears the same markings as the other patch cables. Ive given up hope on this problem. Just spent 4 hours re-patching 6 24-port switches to make room for the extra connections. It'll do for the moment and ill let someone else sort it out when we run out of connections again!!!

Rew

Markings on the cable have nothing to do with it. The cable will be Cat 5 or 6 cable, its how its wired that matters. Look at the ends of the cable stick em side by side and see if the colours are in the same position on both ends. If its cross over 2 of the colours will be swaped

spongebob

1 x 3300 24 3com
1 x 2924 xl cisco

as the backplanes do not unersatand each other

3com 4Gb
Cisco 10 or 12GB

when connected thru proprietary cables to anothe rmodel from the same manufacturer the only choice is crossover which will give you 100Mbit

it is not possble to soft cross over a port on a cisco or a 3com switch or to press a button to do so.

therefore the cable is the only solution

pinouts

1-3
2-6
3-1
6-2
4-7
5-8
8-5
7-4

M

spongebob

a 'matrix cable ' (€100) makes 2 x 3com swithces talk to each otehr at 4GB, ciscos conenct thru Gbic fibre modules again to each other

Gavin

Originally posted by Muck
1 x 3300 24 3com
1 x 2924 xl cisco

as the backplanes do not unersatand each other

3com 4Gb
Cisco 10 or 12GB

when connected thru proprietary cables to anothe rmodel from the same manufacturer the only choice is crossover which will give you 100Mbit

it is not possble to soft cross over a port on a cisco or a 3com switch or to press a button to do so.

That's not quite true. You can connect differing hubs/switches via their uplink port. A rj45 socket designated as an uplink, or selected by pressing a switch. An ordinary straight cat5 cable from the uplink port to a standard port on the other device will work.

All the uplink port does is cross over the cable.

Gav

spongebob

...if one of them has an uplink port a straight thru cable will work becasue the crossover is carried out in the switch.

The 3com 3300 does not have an uplink port (the 1100 does)

Neither does the Catalyst 29nn series

In this specific case he must make up the cable.


M

Gavin

Fair enough, but you didn't specifiy that above

when connected thru proprietary cables to anothe rmodel from the same manufacturer the only choice is crossover which will give you 100Mbit

it is not possble to soft cross over a port on a cisco or a 3com switch or to press a button to do so.

Gav

spongebob

which bit of

"cable is the only solution"

along with the pinouts for the cable itself, did you find confusing?

???

Gavin

You said

it is not possble to soft cross over a port on a cisco or a 3com switch or to press a button to do so.

therefore the cable is the only solution

That is if I must point it out. On A cisco or a 3com. You did not say a 3com 3300 or a Catalyst 29nn series.

You implied that no 3Com could be connected to a Cisco via an uplink port, as a pose to saying that just these particular models could not be.

Gav

spongebob

I mentioned a 3300 and a 2924

explicitly

then told him what to do with them!

down to the pinouts

the 3com 1100 series being a 10 MBIT switch not a 100Mbit switch does have an Uplink but this was removed in the 100Mbit switches in favour of the matrix connector which allows 4Gb from one 3com to another but is a proprietary connector which only works with 3coms.

Catalysts use a different and equally proprietary set of connectors which allow a 10 or 12 GB backplane between cisco switches.

They are NOT interconnectable except thru a 100Mb crossover cable unless one can do it thru fibre in which case someone will no doubt post the config in here......but not me.

M

Gavin

you are not reading the sentence i am quoting. But how in ever. I think people have gotten the point

Gav

spongebob

like!

use a crossover cable only!

bofh him

M

lynchie

Have you two finished arguing yet?

I have it working now using a crossover cable. The only thing that puzzled me was the fact that both cables had the same markings yet one was wired as a crossover cable which confused me as I thought it would be clearly marked as crossover.

Thanx for all the help