NIC Collisions

Jase · 02-18-2002, 10:32 PM

I had a netgear FA310TX I was using as my WAN adapter in my router,...it was getting a ton of collisions on it. So I took my friends advice and got an Intel Pro 100 S. Well I am still getting collisions on the WAN side. The new Intel card is giving me collisions. Not nearly as many as the netgear but the collisions are still there. Since the new Intel card has been installed, 3 hours I think, I have "collisions:141"

Is this normal? Should I be concerned?

TIA -- Jase

Mik · 02-19-2002, 04:42 AM

Depending on the amount and traffic on the network and the number of machines on that network segment that could be a normal number.
This is what my server says after 12 days of uptime, there is never much network traffic on it though:

eth0: 104 collisions (100 Mbit network)
eth1: 773 collisions (10 Mbit network)
eth2: 39765 collisions (10 Mbit coax network)

The 100 Mbit network has a lot less collisions. The only one really having troubles is the coax network but I wouldn't expect much better from it anyways.
The more computers you have on the network the greater the chance of collisions. I'd say you probably wouldn't have to worry about a number like that.

Jase · 02-19-2002, 09:16 AM

well,...after 1 full day of up time with 2 computers on my network I am getting

collisions:3583

odd?

:edit: This is a switched network I might add

finegan · 02-19-2002, 04:54 PM

If this thing is NAT'ing, collisions are going to be more common. I don't understand the networking behind it, but the quality of the card isn't going to alleviate the problem as well as learning the snot out of IPtables.

This is what I've got:

World: eth0(3com 905)-collisions:614
LAN: eth1(SMC card using epic100 module)-collisions:7983

Uptime is just under 4 days. This is with 4 machines on the LAN, pretty minimal traffic, and under old-school 2.2.x ipchains. The collisions soar when I'm downloading say... ISOs on one of the boxen behind the NAT.

Cheers,

Finegan

Malicious · 02-19-2002, 06:25 PM

Collisions are expected. IEEE 802.3 CSMA/CD (ETHERNET) is the protocol. CSMA = Carrier Sensed Multiple (NIC) Access. CD = Collision Detection. If one NIC is sending, all others sense carrier and are listening. If there is no carrier sensed and two NICs try to send at one time, each NIC detects the collision, and both back off and wait a random number of tics to try again. Highly simplified, but close.