Re: [LARTC] Random ping jumps

From: "R. Steve McKown" <rsmckown@yahoo.com>
To: lartc@vger.kernel.org
Subject: Re: [LARTC] Random ping jumps
Date: Thu, 08 Jan 2004 18:15:37 +0000	[thread overview]
Message-ID: <200401081115.39334.rsmckown@yahoo.com> (raw)
In-Reply-To: <3FFC7969.1040103@h2o.pieva.net>

Can you provide some more detail on your network configuration?  I'm unclear 
if the linux server is your internet router or just another client computer 
on your local LAN, where the test pings to "the internet" are going (i.e. 
nexthop router, etc.), and if/where CIPE tunnels are involved in the 
equation.  Perhaps a small network map would be helpful.

I'm also unclear about the pings that you've tried.  After you've shown the 
network map, perhaps you can identify the two machines (and interfaces) 
involved in each of the different ping tests you've performed.

I had a similar problem recently.  A linux-based router with four interfaces 
serving three local LANs and a T-1 (via the provider's router) to the 
internet.  The router was forwarding traffic between all combinations of 
networks (that were allowed by rule) correctly, except between LANs 1 and 2.  
In this case, pings would vary much as in your case.  Interestingly, it 
turned out to be bad hardware.  Moved the boot media to an identically 
configured machine and the problem went away.  Returned the boot media to the 
original machine and the problem returned.

On Wednesday 07 January 2004 02:26 pm, Artūras Šlajus wrote:
> Hello,
>
>    I've got this problem. There is an linux server with 2.4.24 kernel
> and pinging from him to internet (or from lan) ping randomly jumps up:
>
> 64 bytes from fortas.ktu.lt (193.219.160.131): icmp_seq87 ttlY
> time0.0 ms 64 bytes from fortas.ktu.lt (193.219.160.131): icmp_seq88
> ttlY time2.6 ms 64 bytes from fortas.ktu.lt (193.219.160.131):
> icmp_seq89 ttlY time4.9 ms 64 bytes from fortas.ktu.lt
> (193.219.160.131): icmp_seq90 ttlY time\x198 ms 64 bytes from
> fortas.ktu.lt (193.219.160.131): icmp_seq91 ttlY time@7 ms 64 bytes
> from fortas.ktu.lt (193.219.160.131): icmp_seq92 ttlY time@7 ms 64
> bytes from fortas.ktu.lt (193.219.160.131): icmp_seq93 ttlY timeC0 ms
> 64 bytes from fortas.ktu.lt (193.219.160.131): icmp_seq94 ttlY
> time0.9 ms 64 bytes from fortas.ktu.lt (193.219.160.131): icmp_seq95
> ttlY time1.6 ms
>
>    Internet line isn't loaded up, server load fine. QOS isn't used, qdiscs
> default. I don't realize what the problem is and even how to debug it.
> Sysctl config: net/ipv4/ip_forward = 1
> net/ipv4/icmp_ignore_bogus_error_responses = 1
> net/ipv4/icmp_echo_ignore_broadcasts = 1
> net/ipv4/tcp_syncookies = 1
> net/ipv4/tcp_timestamps = 0
> net/ipv4/tcp_window_scaling = 0
> net/ipv4/tcp_sack = 0
> net/ipv4/tcp_fin_timeout = 30
> net/ipv4/tcp_keepalive_time = 1800
> net/ipv4/tcp_low_latency = 1
>
> Thanks for any thoughts.
>
>
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