Hi Guys,
As the one in charge of the technical ADSL issues in Netvision, I can answer
all the questions below...
We have encountered a problem with our RedBack machine, which was not
fragmenting packets with the DF bit set (as normal routers should do). It
WAS sending the ICMP unreachable message, but walla are filtering ICMP, so
the web servers never got the ICMP message, and could not make the MTU
smaller.
The 1424 MTU size was an attempt in circumventing the problem (which of
course did not work - and was quite a stupid thing to do on my behalf) - We
have changed that back to the normal 1452 size, and there is no need to
change it to 1424 on Linux hosts... (BTW: we are sending this parameter over
the PPP's LCP session, so the parameter can be changed automatically...)
Anyway, the problem was fixed by an upgrade to a newer software from RedBack
- which has an option of ignoring the DF bit, and fragment packets even if
is set (like is common with dialup RAS devices).
Hope the solution came quick enough, and did not make you too angry with
us...
Arie Vayner
Netvision - Network Engineering
-----Original Message-----
From: Dani Arbel [mailto:[EMAIL PROTECTED]]
Sent: Thursday, July 05, 2001 14:14
To: Hetz Ben Hamo
Cc: ILUG
Subject: Re: My ADSL saga - Updates
Hetz,
any idea WHY they did it? Is it just to break the masquerading setup, or
is there some technical reason (say, if they do a tunnel inside a tunnel
.).
Cause if they did it just because, next they will reduce another 20 bytes
of the MTU ...
Dani
On Thu, 5 Jul 2001, Hetz Ben Hamo wrote:
> Hi All,
>
> Well, my good friend Andrei and I sat on my machines and decided that will
> solve this issue - no matter what the costs ;)
>
> So we found out...
>
> 1. Netivision changed the MTU to 1424 - anyone got an email notification
> about this? cause I didn't..
>
> 2. My firewall is based still on kernel 2.2.x - meaning - it won't fix the
> mtu bug which was fixed on kernel 2.4.x - thats why my Linux workstation
had
> those problems..
>
> So - if you are connected to Netvision - set your ADSL firewall to MTU
1424.
> Is it based on kernel 2.2.x? then either upgrade it to 2.4.6 (which came
out
> today) or do the more pain way - update all machines behind it to mtu 1424
on
> their ethernet...
>
> Fun Fun Fun....
>
> Hetz
>
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