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Re: 96% packet loss on my network



Paul Nathan Puri wrote:
> I just set up my network (laptop to desktop).  I'm running linux on
> both.
> 
> I pinged my desktop and it seems there is 96% packet loss there.  Why
> would this be?
>
> On both machines there is a fast ethernet NIC, and I have a fast
> ethernet 3Com hub.
> 
> When I telnet my desktop from my laptop, a prompt comes up, but very
> slowly.  It won't let me type in my login, and then it times out.

Is your hub one of those listed at 
http://www.3com.com/products/dsheets/400317a.html and do you 
have access to it so you can check the port LEDs? Since the 
cards work at least a little, they are probably running 
correctly at 100Mbs. However, if your hub is autosensing 10/100 
Mbits it might have problems doing the speed conversion if one 
of your cards is in 10Mbits and the other is 100Mbits mode. I'm 
only guessing here since I have no experience about how well 
hubs do the speed conversion.

One thing I know that has caused problems is NIC having different 
view on duplexness than the hub or switch. If the NIC runs in 
full-duplex mode and the hub is only half-duplex, the hub may 
partition (shut down) the port. The reason for this is the NIC
causing too many collisions if it does not listen the receive 
pair before it starts to transmit. The port LEDs on the hub
should indicate if the port has been partitioned, so you might
want to check the hub before and after the connection dies.

> Any help in this matter would be greatly appreciated.

I hope this helps

// Heikki
-- 
Heikki Vatiainen                  * hessu@cs.tut.fi
Tampere University of Technology  * Tampere, Finland



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