LAN interconnect problem

  • Thread starter Thread starter BGY
  • Start date Start date
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BGY

Hi all !
I have 2 LANs. They are connected via a cat5 cable linking
an Inmac 10baseT 8-ports hub to a Netwin 10/100baseT 5-ports switch.
So far so good.
To get more ports, I changed the Inmac hub for a Procurve 10/100baseT 12-ports
hub:
the Netwin LAN gets isolated. PCs dont get DHCP from a PC on the Procurve LAN
I changed the Procurve for a Netgear 16-ports 10/100baseT auto-uplink switch:
idem
The cable between both hub/switch is 25m long and can sustend 100Mbits for
if I directly connect my laptop instead of the Netwin switch, I get connected at
100Mbits fdx.
I swapt the Netwin for a 3Com 4-ports fast ethernet hub.
When connecting the cable, I get a warning led: "partitioned"
What does that mean ?
Thanks for your help
 
Just a thought, you are not using a "straight" cat5 cable when you need
a crossover, or vice-versa, are you?
 
Mon, 20 Feb 2006 08:52:40 GMT, aut: Stephen Whitlock
Just a thought, you are not using a "straight" cat5 cable when you need
a crossover, or vice-versa, are you?
Click to expand...

Hi, Stephen ! The cable is a straight one but on the various hub/switch, I tried
both options (normal/uplink)
 
Are any of the switches managed? If so for some reason best known to
themselves they might be blocking each other. If they are managed you
should be able to reset them. Some cisco routers and switches behave in
this way nesessitating an cisco engineer to reset them.
 
votre msg du Sun, 26 Feb 2006 15:05:35 -0500 (EST)
I caught the message thread about your network problem on Usenet.
In the various configurations you've tried, you seem to be avoiding using the
same equipment at both ends of the link. Is there a reason for this? You can
often get into trouble when you mix types of hardware (hub vs. switch) or
sometimes even different manufacturers. A hub will always run at half-duplex,
but a switch will try to auto-negotiate duplex (as well as speed, and sometimes
polarity). It's not uncommon for this auto-negotiation to fail. For example,
we used to have an old Epson printer with a network interface that was attached
to a 10/100 (unmanaged) switch. The switch was unable to negotiate the right
speed. When we attached the printer to a different switch on which we could
hardcode the port to 10Mbps and half-duplex (a managed switch), the printer
worked fine. In general, if you have an auto-sensing switch at one end,
that's what you should have at the other end. If you can mirror the
manufacturer and model at both ends, that would be even better.

Note, also, that many hubs and switches have dedicated uplink ports.
I've seen a few models that have no physical marking on the box to indicate
which port is the uplink port, so you should check the device's documentation
to be sure. You should also check to see if by utilizing the dedicated uplink
port, if that doesn't disable the adjacent port--a common limitation. If so,
then you should make sure not to plug anything into the port adjacent to the
uplink port. If a device supports auto-negotiation of polarity (a.k.a. "auto
MDI/MDX"), then you can use either kind of cable (stright-thru or cross-over),
but if you are using a dedicated uplink port, then you need to use a straight-
thru cable. (You should not connect the dedicated uplink port from one device
to the dedicated uplink port of another.)

HTH,
Mike
Click to expand...

Thanks Mike !
I think you are right, but I dont have the same equipment at both ends and no
one is "manageable".

In summary,

1- 2 PCs at both ends of the 25m cat5, I can get a 100Mbps fdx connection
2- 1 hub/switch in-between, I have to set the PC on the 25m cable at 10Mbps hdx
or fdx
3- 2 hubs/switchs in-between, no connection if both are 100Mbps capable and
auto-sensing
4- 2 hubs/switch in-between, but one of them is only 10Mbs capable, ok

Regards
 
From what you are saying we can assume that there is nothing wrong with
the network cards or the cables because when the machine are connected
directly to each other everything seems to work fine. When you insert a
switch/hub do you then use different straight-thru cables that are known
good ones? Have any of the switches/hubs been seen to work correctly in
a known good network? Are there any known compatability issues between
switches/hubs and network cards?
 
Sat, 04 Mar 2006 14:08:37 GMT, aut: Stephen Whitlock
From what you are saying we can assume that there is nothing wrong with
the network cards or the cables because when the machine are connected
directly to each other everything seems to work fine.
Click to expand...

You are right
When you insert a switch/hub do you then use different straight-thru cables that are known
good ones?
Click to expand...

No, always the same straigth-thru cable. It is cast in the wall (inside a tube
of course)
Have any of the switches/hubs been seen to work correctly in a known good network?
Click to expand...

When working alone, everything is ok
Only when 2 hubs/switchs 10/100 capable are at each end of that cable, there is
no data flowing. But, surprisingly, DHCP works ! (IP address is got), not DNS,
not HTTP, not ping

Are there any known compatability issues between switches/hubs and network cards?
Click to expand...

As a home user, I have a no idea about such issues.
By experience, I have found that between 2 hubs/switches, only 10Mbps works
and to get that, one of the 2 hubs/switchs must not be 10/100 autosensing, only
10BT; I have no managed hub/switch so, I can't force a given speed.
 
The only other thing I can think of is when the two hub/switches are
connected is one end of the cable in an "uplink" port? if so you might
find this "replaces" one of the normal ports, usually the one it is
directly next to. If one end of the cable is not in and uplink port then
this could be the problem as this configuration usually requires a
crossover cable unless the hubs/swithcjhes are clever enough to sense this.
 
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