[lug] OT Netwerking Layers 101

[Warren Sanders]

Zan Lynx wrote:
> On Tue, 2003-02-18 at 15:21, Warren Sanders wrote:
> 
>>I'm testing out NTOP; a network traffic probe that shows the network usage 
>>(ntop.org) on our lan.
>>
>>Our main panel is an HP ProCurve switch 4000M and is configured to allow my 
>>connection to monitor the network.
>>
>>Was connected with a 5 port Linksys switch and found I was getting info from 
>>only what was going through this switch.  I then replaced it with an old 4 
>>port 10 base Netgear hub and I could then see all the network traffic.
>>
>>Now I replaced the 5 port Linksys switch with a 5 port Linksys 100 base hub 
>>(EFAH05W) and I'm back to only seeing my branch of the network.  Just for 
>>kicks I linked off this with another Linksys 10 base hub and moved only my 
>>connection to this and can see all the network again!
>>
>>So I'm wondering if the Linksys 100 hub is doing something to the network 
>>layers that you normally see in a switch (private lines)?  I'm confused!  I 
>>don't want to have to us a 10 base hub whenever I need to monitor; why can't 
>>the 100's do it?
> 
> 
> If the Linksys 100 hub is dual speed, then it might have a switch.  Dual
> speed hubs that can accept 10 and 100 mbit connections at the same time
> have a hidden switch that handles moving packets from the 10mbit to the
> 100mbit, and vice versa.
> 
> If you need high efficiency, don't put a hub on your monitoring port at
> all.  Use a direct connection to your monitoring equipment.  A hub will
> introduce collisions and you lose full duplex support.
> 

Thanks guys!  It is a dual and makes all the sense in the world.  Now I just 
need to look into the wiring in this old joint because I'm currently coming 
out of the wall (not a jack) and it may be a patch; it's going to the uplink 
port.

-- 
Warren Sanders
http://MontanaLinux.Org