collisions on hub

collisions on hub

Post by marc onrus » Sat, 08 Jun 2002 23:12:24



Hi all,

I have a laptop running Suse 7.3 which I use both at home and at work.

At home I connect through a Sitecom hub to a router (also Suse 7.3,
connected to a cablemodem).

At work I connect through a 3com hub to an adsl router (brand Eicon).

Now, when surfing or downloading, I see a lot of collisions on my hub at
home, but at work there is hardly any collision to see (assume the led
still works :-).

Any idea whether it could be some setting on my Suse 7.3 router or is it the
rather cheap Sitecom hub which doesn't work too well?

Thanks for any help,
Marc

 
 
 

collisions on hub

Post by choprbo » Sun, 09 Jun 2002 00:50:07


[snip]
Quote:> Any idea whether it could be some setting on my Suse 7.3 router or is it the
> rather cheap Sitecom hub which doesn't work too well?

Most likely the hub. Collisions happen on the physical layer, so it
can't be Suse (the ASIC of the network cards control actual
transmit/wait cycles). My guess would be your running 100Base
full-duplex on the network cards and the cheap hub can't handle it.
Trying knocking back to half-duplex and see if that helps (not that it's
a real matter of concern in the first place, unless you have serious
node-to-node bandwidth problems).

Adrian

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collisions on hub

Post by Steve Wolf » Sun, 09 Jun 2002 01:29:23


  If you're on a hub, you are going to see collisions when it's under
load - that's just how it works.  The good part is that unless the numbers
get ridiculously high, there's also nothing to worry about!

   Now if you really, really can't stand collisions, pick yourself up a
switch instead of a hub.  Be careful to avoid "switching hubs".  However,
unless you put the network under a pretty good load fairly regularly, you
probably don't need one.

steve

 
 
 

collisions on hub

Post by marc onrus » Sun, 09 Jun 2002 19:20:39




> [snip]
>> Any idea whether it could be some setting on my Suse 7.3 router or is it
>> the rather cheap Sitecom hub which doesn't work too well?

> Most likely the hub. Collisions happen on the physical layer, so it
> can't be Suse (the ASIC of the network cards control actual
> transmit/wait cycles). My guess would be your running 100Base
> full-duplex on the network cards and the cheap hub can't handle it.
> Trying knocking back to half-duplex and see if that helps (not that it's
> a real matter of concern in the first place, unless you have serious
> node-to-node bandwidth problems).

> Adrian

> -----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
> http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
> -----==  Over 80,000 Newsgroups - 16 Different Servers! =-----

Someone else adviced me to go back to half duplex too. Now my next question,
how will I do that? As far as I can see there's no option like that on the
hub.

Marc

 
 
 

collisions on hub

Post by choprbo » Sun, 09 Jun 2002 22:29:31





> > [snip]
> >> Any idea whether it could be some setting on my Suse 7.3 router or is it
> >> the rather cheap Sitecom hub which doesn't work too well?

> > Most likely the hub. Collisions happen on the physical layer, so it
> > can't be Suse (the ASIC of the network cards control actual
> > transmit/wait cycles). My guess would be your running 100Base
> > full-duplex on the network cards and the cheap hub can't handle it.
> > Trying knocking back to half-duplex and see if that helps (not that it's
> > a real matter of concern in the first place, unless you have serious
> > node-to-node bandwidth problems).

> > Adrian

> > -----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
> > http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
> > -----==  Over 80,000 Newsgroups - 16 Different Servers! =-----

> Someone else adviced me to go back to half duplex too. Now my next question,
> how will I do that? As far as I can see there's no option like that on the
> hub.

> Marc

Virtually all hubs (atleast, not a single one I've encountered) are
unmanaged and you can't control things like duplex control from the hub.
It acts as a passive repeater, completely oblivious to the network
traffic, and in the cheap ones, each hub port can only transmit OR
receive at a specific time, not both (hence the full duplex problem).

You should be able to pass an argument to the network card drivers at
boot/module insertion to force them into 10/100 full/half mode.
Otherwise they will auto-negotiate for the highest available speed.
Forcing one card shoud be enough to cause the other to fall back as
well. But those arguments vary from driver to driver, so you'll have to
tell us what cards your using or dig thru the driver notes.

Adrian

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collisions on hub

Post by marc onrus » Mon, 10 Jun 2002 19:35:56






>> > [snip]
>> >> Any idea whether it could be some setting on my Suse 7.3 router or is
>> >> it the rather cheap Sitecom hub which doesn't work too well?

>> > Most likely the hub. Collisions happen on the physical layer, so it
>> > can't be Suse (the ASIC of the network cards control actual
>> > transmit/wait cycles). My guess would be your running 100Base
>> > full-duplex on the network cards and the cheap hub can't handle it.
>> > Trying knocking back to half-duplex and see if that helps (not that
>> > it's a real matter of concern in the first place, unless you have
>> > serious node-to-node bandwidth problems).

>> > Adrian

>> > -----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
>> > http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
>> > -----==  Over 80,000 Newsgroups - 16 Different Servers! =-----

>> Someone else adviced me to go back to half duplex too. Now my next
>> question, how will I do that? As far as I can see there's no option like
>> that on the hub.

>> Marc

> Virtually all hubs (atleast, not a single one I've encountered) are
> unmanaged and you can't control things like duplex control from the hub.
> It acts as a passive repeater, completely oblivious to the network
> traffic, and in the cheap ones, each hub port can only transmit OR
> receive at a specific time, not both (hence the full duplex problem).

> You should be able to pass an argument to the network card drivers at
> boot/module insertion to force them into 10/100 full/half mode.
> Otherwise they will auto-negotiate for the highest available speed.
> Forcing one card shoud be enough to cause the other to fall back as
> well. But those arguments vary from driver to driver, so you'll have to
> tell us what cards your using or dig thru the driver notes.

> Adrian

> -----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
> http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
> -----==  Over 80,000 Newsgroups - 16 Different Servers! =-----

My LAN-connected ethernetcard is a Farallon fitted with a DECchip (Tulip
dc21040), the one connected to the internet cablemodem is a 3com 3c59x.

Hope you still can help me further,
Marc

 
 
 

collisions on hub

Post by choprbo » Mon, 10 Jun 2002 20:43:09


[snip]

Quote:> My LAN-connected ethernetcard is a Farallon fitted with a DECchip (Tulip
> dc21040), the one connected to the internet cablemodem is a 3com 3c59x.

Well, it's strange but it looks like the 3com driver doesn't have a
force half-duplex mode, though it does have a force full-duplex mode. I
believe the correct argument would be "options=0x004" to set 100Base. Or
add the following line to your conf.modules file:
  module "3c59x" opts "options=0x004"

You should also be able to manipulate it as root while running witht the
"mii-diag" program (works with most cards,
http://www.scyld.com/diag/index.html).

To force the Tulip card use the argument "options=0x013" or 0x003, an
argument of 0x005, 0x014, or 0x203 would force full-duplex. See
http://www.scyld.com/network/tulip.html. You can use the tulip-diag as
well.

Adrian

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collisions on hub

Post by marc onrus » Tue, 11 Jun 2002 06:02:37




> [snip]
>> My LAN-connected ethernetcard is a Farallon fitted with a DECchip (Tulip
>> dc21040), the one connected to the internet cablemodem is a 3com 3c59x.

> Well, it's strange but it looks like the 3com driver doesn't have a
> force half-duplex mode, though it does have a force full-duplex mode. I
> believe the correct argument would be "options=0x004" to set 100Base. Or
> add the following line to your conf.modules file:
>   module "3c59x" opts "options=0x004"

> You should also be able to manipulate it as root while running witht the
> "mii-diag" program (works with most cards,
> http://www.scyld.com/diag/index.html).

> To force the Tulip card use the argument "options=0x013" or 0x003, an
> argument of 0x005, 0x014, or 0x203 would force full-duplex. See
> http://www.scyld.com/network/tulip.html. You can use the tulip-diag as
> well.

> Adrian

> -----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
> http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
> -----==  Over 80,000 Newsgroups - 16 Different Servers! =-----

Thanks for the help, I'll see if it helps me further!

Cheers,
Marc