Arch Linux

Sadface

Member

From: Germany

Registered: 2009-12-09

Posts: 47

Unstable networking

I have this server here, which I use for storage and other purposes, but it's got problems..
The network is really unstable, sometimes I am able to connect to it, and sometimes it won't
work at all.

For example SSH, at times it works and then again sometimes it does NOT work, when it
will fail with "No route to host". The same with Ping and any other networking.

It's running on Wifi because there's no more available cables right now, but as all of my computers
around here, which all run arch also all use Wifi, it should not be the problem. Is there any
way I can chase that problem down to find it's cause?

I'll just paste some command outputs, shall I?

$ uname -a
Linux minizero 2.6.32-ARCH #1 SMP PREEMPT Mon Jan 25 20:33:50 CET 2010 x86_64 Intel(R) Atom(TM) CPU D410 @ 1.66GHz GenuineIntel GNU/Linux

~$ ifconfig wlan0
wlan0     Link encap:Ethernet  HWaddr 00:27:19:BC:E1:2F 
          inet addr:192.168.2.120  Bcast:192.168.2.255  Mask:255.255.255.0
          inet6 addr: fe80::227:19ff:febc:e12f/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:120700 errors:0 dropped:0 overruns:0 frame:0
          TX packets:10097 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:84209584 (80.3 Mb)  TX bytes:990539 (967.3 Kb)

Any helpful logfiles?

Any pointers (not the xkcd style) are appreciated!

Last edited by Sadface (2010-03-10 15:51:50)

toffyrn

Member

Registered: 2008-10-07

Posts: 221

Re: Unstable networking

how do you connect to network? (wicd, networkmanager etc...)

Sadface

Member

From: Germany

Registered: 2009-12-09

Posts: 47

Re: Unstable networking

Simple Netcfg profile:

$ cat /etc/network.d/main
CONNECTION="wireless"
DESCRIPTION="..."
INTERFACE="wlan0"
SECURITY="wpa"
ESSID="..."
KEY="..."
IP="dhcp"
TIMEOUT="20"

Shouldn't cause trouble.
I do the same on all of the computers here.. my desk PC and my laptop

toffyrn

Member

Registered: 2008-10-07

Posts: 221

Re: Unstable networking

I have noticed my network disconnects sometimes under heavy load, after upgrade to networkmanager 0.8...

But that would not be related I think.

wriggary

Member

Registered: 2009-06-30

Posts: 65

Re: Unstable networking

Out of curiosity, what kind of wireless adapter are you using? 

Also, is the wireless access point also a router?  sometimes if i pile too many connections (bittorrent mostly) on my wrt54gv8, it starts dropping packets on the wireless due to a lack of memory.

Sadface

Member

From: Germany

Registered: 2009-12-09

Posts: 47

Re: Unstable networking

The wireless adapter in this case is a TP-Link WN321G USB Dongle.
Before buying it, I extensivly researched it's linux compatibility, and it's well supported on Linux (rt2x00usb).

And yes, the AP is a router that currently handles 2 IPTVs and a notebook on cable, and at _maximum_ 3 wireless devices.
There have been no problems with it yet.

wriggary

Member

Registered: 2009-06-30

Posts: 65

Re: Unstable networking

another stupid question... does it work better if you don't use dhcp and specify the ip/gateway/netmask/dns manually?  I only trust DHCP for my laptop, the rest of the machines in my house (especially the file server) run static IPs.

Oh, and do you have iptables (or any other firewall) rules in effect on this box?

Sadface

Member

From: Germany

Registered: 2009-12-09

Posts: 47

Re: Unstable networking

I never tried static ip setups (they never worked for me somehow ), but I'll try.
No firewalls on there!

wriggary

Member

Registered: 2009-06-30

Posts: 65

Re: Unstable networking

Unfortunately, I'm in the middle of moving, so I can't test much from my side, but give it a try.  (router/ap and all the fun stuff is in the new apartment, waiting for the DSL to be transferred.)

Sadface

Member

From: Germany

Registered: 2009-12-09

Posts: 47

Re: Unstable networking

I've made it connect using a static IP, let's see how things work out
Lots of thanks so far!

Sadface

Member

From: Germany

Registered: 2009-12-09

Posts: 47

Re: Unstable networking

Problem still haunting me. But I found out something interesting...
It seems the server shuts off the network when it's "going to sleep"

After a long inactivity (without me trying to access it remotely) it can't be reached from outside, but when I hit the keyboard up on it, and basically wake it up, it can be reached again.

So long story short, if I physically do something on it to wake it, network comes back.
Now that's a pointer, how can I use that knowledge?

CountDuckula

Member

Registered: 2010-02-28

Posts: 151

Re: Unstable networking

So long story short, if I physically do something on it to wake it, network comes back.
Now that's a pointer, how can I use that knowledge?

I would check any power saving setting (if any) you have configured on server and check the BIOS power settings as they may be configured to send your server into a low power state if idle.