[c-nsp] What MTU for Bellsouth BBG / BRAS <-> LNS l2TP tunnel?

[Brian Feeny]

True,

But in the Bellsouth BBG model, the L2TP tunnel is privately numbered 
as well, so even if it could send an
ICMP for PMTU discovery purposes, it wouldn't make it far.

Brian

On Oct 28, 2004, at 5:47 AM, Ueli Heuer wrote:

> as long as the IP MTU of the 10/100 ethernetsegment ist fixed to max
> 1500 byte you'll use some bytes for the PPPoE encapsulation and these
> bytes are missing in the paylod.
> the problem are firewalls- administrators (and vendors) who think
> _all_ icmp-packets are bad and they block  any icmp-messages.  so the
> source will not be notified to send smaller packets.
>
>
> On Thu, 28 Oct 2004 10:59:48 +0200, Gert Doering <gert at greenie.muc.de> 
> wrote:
>> Hi,
>>
>> On Thu, Oct 28, 2004 at 11:42:14AM +1000, Ash Garg wrote:
>>> This gives me 10-12 bytes "extra" in the IP packet and 8 bytes 
>>> "extra" in
>>> the AAL5 frame which covers any weird stuff that may occur and does 
>>> not "I
>>> think" put extra load on the LNS.
>>
>> Just leaving the ATM MTU at 4470 won't cause any extra load either.
>>
>> gert
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---------------------------------------------
Brian Feeny, CCIE #8036, CISSP
Network Engineer
ShreveNet Inc.

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