Connecting two Gigabit Switches Together

Hi,

I was wandering if someone could help me..

I have a home network setup that includes two US robotics Gigabit switches a 16 Port Swithch (USR 997932A) and an 8 port (USR 997933).. I am trying to connect these two switches together using a standard (working) cat 5e cable without any success.

If i connect a server to the 16 port switch and then connect a pc to the 8 port switch and try to ping the server it fails... however if I connect the pc to the same 16 port switch it all works fine... is there a problem with connecting two gigabit switches together?

Constants:-

  • I have tested both switches independently and they work fine
  • i have tested and replaced all cat 5e cables and again they are fine.
  • The PC's have DLINK Gigabit NIC cards installed and these work fine.

Can anyone suggest why I might be having a problem?

regards Ajay

Reply to
ajay.sood
Loading thread data ...

(snip)

How sure are you that the cable is good? Specifically that it isn't mispaired? Is it a commercial four pair cable, or homemade?

-- glen

Reply to
glen herrmannsfeldt

Do they have Auto-X, or do you need to use a crossover cable ?

Reply to
Justa Lurker

(snip)

Gigabit transmits and receives on all four pairs at the same time. It is most obvious to connect two ports with a straight cable, but they are supposed to also work with a crossover.

-- glen

Reply to
glen herrmannsfeldt

Bonjour Glen,

And now, reading your reply, I'm wondering how full-duplex is possible. The Ethernet 100Base-T4 (never used) was also on four pairs, and full-duplex was not possible.

For the Ajay question, what is the impact of Master and Slave configuration for 1G?

Best regards, Michelot

Reply to
Michelot

Reply to
Orchid

Thanks for your response... The cable is home made, it runs beetween two floors.. It was tested with a cat5e cable tester and all pairs are connected in the right sequence.. It' also works fine (1GB) if i was just to connect a pc to the end rather than the 8-port hub.

ajay

Reply to
Orchid

Justa, I am not sure what Auto-X is... do i need to use a crossover cable to connect 2 switches?

ajay

Reply to
Orchid

Bonjour Glen,

And now, reading your reply, I'm wondering how operates 1G in full- duplex if the all four pairs are used at the same time. The Ethernet

100Base-T4 (never applied) was like this, abd full-duplex was not possible.

For the Ajay question, I'm also wondering what is the impact of Master and Slave configuration with 1G?

Best regards, Michelot

Reply to
Michelot

Reply to
LAWAL

Orchid wrote: (snip)

Just to be sure, the twisted pairs are on pins (1,2), pins (3,6), pins (4,5) and pins (7,8)?

I have had cables where some didn't make contact some of the time, such that it would work plugged into one device and not another device.

Also, the PC you say it works is also running at gigabit speed?

Have you tested with the two switches close together with various cables?

-- glen

Reply to
glen herrmannsfeldt

It is not easy, but it is possible.

Each end has to subtract the signal that it is sending from the signal on the pin to detect the signal it is receiving.

It is the same problem that speakerphones have.

Even more, gigabit has to subtract any echoes from impedance discontinuities along the cable. It takes a lot more processing than previous ethernet standards.

-- glen

Reply to
glen herrmannsfeldt

Bonjour Glen,

Thanks for that particularity I missed.

I remember that. And this practise is also used in microwaves to transmit the bidirectional signal along the feeder (large coaxial).

OK, and now I see that in the section 40.1.3 of 802.3:2005 (sorry, I am much standard): "The use of hybrids and cancellers enables full duplex transmission by allowing symbols to be transmitted and received on the same wire pairs at the same time" (in baseband, not like in

10Pass-TS e.g.).

Thanks for that, Michelot

Reply to
Michelot

I will try this out later today and report back... thanks again for all your ideas and help.

Reply to
Orchid

Hi Folks...

Ok, I did a whole bunch of additional tests today, not sure if this is going to help.

Firstly I bought 3 good Quality Cat 5e patch cables and 1 Crossover cable, these were tested to see if they work and they are fine.

1) I connected the 8 port swithch to the 16 port switch using a standard patch cable, and then plugged a laptop into the 8 port switch to see if i could "ping" the server... initially the answer was no, but then if i turned the power off/on on the 16 port switch I got a ping from my server 20 consecutive times before it gave up and responded with "timed out".

2) I tried connecting the crossover cable to connect the 2 switches, and got no response whatsoever.

3) I noticed the lights on the 8 port switch are flashing... does this provide any clues??

I really appreciate all the help folk have provided so far... thank you for your time.

Reply to
Orchid

(snip)

Does it have all four pairs? Many crossover cables don't.

I suppose it is possible that it isn't supported, but as I understand it, it is common for gigabit to work with crossovers as long as all four pairs get to the other end.

-- glen

Reply to
glen herrmannsfeldt

yes, the cross over cable has all 4 pairs connected.. i tried it with a cable tester and all seems ok..

Reply to
Orchid

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