Hi,

Jiří:
>> Can anyone tell me what it means when I get the error message "Bogus
>> PPPoE length field (1502)" a few hundred times a day, usually in
>> bunches? Always the same number, 1502, never any other.

Jeremy:
> Have you tried negotiating a differently sized MTU to see if it changes
> the length field displayed in the error message?

No, I haven't... Part of the problem is that I don't know what triggers
it, which makes it hard to debug. It appears from time to time in the
log, usually in a bunch, but not associated with any activity that I've
been able to notice.

Also, I'm on the wrong end of the link; if I mess something up, I'm
fixing it over the phone...

> Also, it is possible that TPG support RFC 4638, [0] and your PPPoE
> implementation doesn't understand that.

But then it should fall back to 1492, especially since that's what I
have in my config? Also, if it negotiated a bigger MTU, it would show in
ifconfig output?

> On a side note, while we're on the topic of MTUs -- changing the MTU
> rarely has any effect.  I recommend that you fix the MSS value on your
> router, so your LAN clients don't hit the MTU limit.
> 
> Something like this out to do the trick:
> 
>   # iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN \
>       -j TCPMSS --clamp-mss-to-pmtu

OK... Although I've set the MTU on the LAN side to 1412, so that should
already cover it? Anyway, I'll give that a try tomorrow.

> I'd be interested to see a full packet capture of the PPPoE negotiation
> while it generates that error.

Hmm, not sure how to capture that, given that I don't know how to
trigger the error.


Jiri
-- 
Jiří Baum <[email protected]>
Sabik Software Solutions Pty Ltd
0413 183 117
http://www.baum.com.au/sabik
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