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Linux - Networking This forum is for any issue related to networks or networking.
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Old 10-03-2001, 02:38 PM   #1
Griffon26
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Unhappy Pings go way up after a day


I've been running a firewall with kernel 2.4.9 & iptables for a couple of weeks now (used to be 2.2.14 & ipchains) and I have a problem.

After it's been up for a day or maybe two, the ping to a server quite close to me rises to 3000+ (usually is about 40). I'm not at home during the day to check if it suddenly rises or steadily increases. (Will make a script to log this if it's useful)

I've checked cpu load and memory usage, but I can't find anything wrong with that.

Does anyone have an idea what to check next?
 
Old 10-05-2001, 07:07 AM   #2
raz
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Is the server on the same internal LAN as you or an external server on your ISP's network, or outside this ?
Do you experience performance issues to other servers ?

/Raz
 
Old 10-05-2001, 08:20 AM   #3
Griffon26
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Quote:
Originally posted by raz
Is the server on the same internal LAN as you or an external server on your ISP's network, or outside this ?

Do you experience performance issues to other servers ?



/Raz
The server I pinged is not on my LAN.
Here is some more info:
- Pings to other computers on the LAN are fine.
- The server is 3 hops away (1st hop is my firewall with iptables). Part of the university network that provides the internet to us.
- Pings to all other internet servers I tried were also very high.

But:
- The firewall's been up now for 1 day and 18 hours, and no sign of problems yet.
- I was not able to do much debugging the previous time because at that time it was important to get the inet connection back to normal again. I could only do the few tests that I did before I had to restart the computer.
 
Old 10-08-2001, 09:44 AM   #4
raz
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It could be that a Hub or switch on the network is over loaded and as time goes on too many system are communicating and packets are colliding, causing a random resend on each lost packet causing a cascade hub failure.

Is there are pattern to the times you see this, like at peak hours in the evening.

Try and sniff the network for packets to see if your getting an abnormal about of requests from ICMP packets.

What does ifconfig -a say.
Look at the line
RX packets:351694 errors:0 dropped:0 overruns:0 frame:0

Do you have any dropped or overruns. ?

When the network is normal type "ping -s 1024 -c 100 -f the_ip_address_of_server_your_pinging"
recorde it.

Then do it again when the network is slower and post both results here.

/raz
 
Old 10-08-2001, 01:44 PM   #5
Griffon26
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It got slow again and I checked the packets floating around the LAN. It looked like the problem was caused by people using eDonkey, so I've used CBQ to limit that kind of traffic.

I'll have to see if it happens again.

Thanx for your help btw =)
 
  


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