Date: Tue, 18 Jun 2002 21:47:00 -0400 From: Mike Tancsa <mike@sentex.net> To: Tom Samplonius <tom@sdf.com> Cc: freebsd-net@FreeBSD.ORG Subject: Re: tracking down strange MTU issues with PPPoE) Message-ID: <5.1.0.14.0.20020618213845.01c42aa0@192.168.0.12> In-Reply-To: <Pine.BSF.4.05.10206181654290.23627-100000@misery.sdf.com> References: <5.1.0.14.0.20020618191155.01c08f18@192.168.0.12>
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At 05:16 PM 6/18/2002 -0700, Tom Samplonius wrote:
> Possibly. There is a PPPoE session to the Redback (or ERX), then
>usually a L2TP session to the ISP. A PPPoE client connecting to the
>Redback (or ERX) should be told a valid MTU. PPP tunel to L2TP tunnel
>raises some interesting possiblities. I wonder how much mucking about the
>SMS does to the protocol. Obviously it is doing something, since the
>Redback works, but the ERX does not. Or the Bell network is broken :)
b) is always a possibility. Actually, there is some bug in the ERX where
the setting "IP TUNNEL REASSEMBLY" gets turned off when doing unrelated
configs. The first time we encountered this, we had no end of trouble for
2 days and tracking down the right people to talk to was insane. There are
groups in Bell who look after the DSL concentrators, groups who look after
the DSLAMS, groups who look after the ATM network, but it seems not one
individual knows how all the components work together, or at least they are
not reachable. At one point one of the ATM guys said something to the
effect that this was a known bug and I had to set the MTU on my terminating
router's ethernet to 1450. I asked why and where the document was to which
he responded that he was not allowed to share such information.....
whatever.... Its ironic that the old kids game of "broken telephone" comes
into play with the telco :-( ...
But, Brian@freebsd.org's suggestion of set max mtu did the trick. I am
curious to know why this is necessary on the ERX and not on the SMSes.
---Mike
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Mike Tancsa, tel +1 519 651 3400
Sentex Communications, mike@sentex.net
Providing Internet since 1994 www.sentex.net
Cambridge, Ontario Canada www.sentex.net/mike
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