RE: draft-arberg-pppoe-mtu-gt1492-00
Frank Cusack <[email protected]>
| Newsgroups | gmane.ietf.pppext |
|---|---|
| Message-ID | <[email protected]> |
Just chiming in ... On May 18, 2005 10:39:35 PM -0400 Peter Arberg <[email protected]> wrote: >> - In the scenario identified as "Fig. 3" (PPPoA to PPPoE >> conversion), why wouldn't the device labeled "DSLAM" in that >> picture just alter the LCP negotiation messages in flight, so that >> if the PPPoA side attempts anything over 1492, the MRU is just >> negotiated downwards as necessary? > > > The intention discussed in DSL Forum at the moment is that the DSLAM > only initiate the PPPoE session, and not alter the actual PPP or LCP > packets. > > I guess that it would be doable for the DSLAM to alter the LCP packets > in flight, but if the main concern here is that some existing PPPoA > client will not accept a smaller MRU than 1500 bytes, then the fact > that the DSLAM will downsize the MRU, will leave a PPP session with > 2 end-points having a wrong view of the other end-points MRU, and as such > this will either result in no connection, or the DSLAM having to perform > PPP packet fragmentation, as I see it ? And how would the DSLAM be able to fragment? (It couldn't, AFAIK, in a pass- through scenario.) If the two peers had an incorrect idea of the other's actual MRU, this doesn't matter because the incorrect MRU would be *smaller* than the actual MRU and so all transmitted packets would be acceptable. Is it broken for PPPoA clients to not accept small MRUs? /fc _______________________________________________ Pppext mailing list [email protected] https://www1.ietf.org/mailman/listinfo/pppext