Hello Pascal, I agree with you that a well defined and standardized way of doing fragment recovery and controlling the flow of these fragments are quite needed.
I also agree with you, that it belongs functionally (if not academically) in the 6loWPAN NWK layer. THks "The nice thing about standards is that there are so many to choose from." - Andrew S. Tanenbaum Robert Assimiti Executive Staff Engineer Office: [678]-202-6859 Mobile: [404]-578-0205 [EMAIL PROTECTED] -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Pascal Thubert (pthubert) Sent: Tuesday, May 20, 2008 3:12 AM To: Mark Townsley (townsley) Cc: [email protected] Subject: Re: [6lowpan] New charter for 6lowpan Hi again Mark >> - The issue of fragmentation. Applying RFC 4944 over a multihop radio >> mesh exposes the network to congestion collapse, as described in >> http://www.tools.ietf.org/html/draft-thubert-6lowpan-simple-fragment-rec >> overy . I think that the WG should dedicate some bandwitdth to provide >> additional functions that would improve the LoWPAN operation WRT flow >> control and recovery of fragments. >> >Fragmentation, OK, but why is flow control a network layer issue rather >than a transport layer issue? [Pascal] I'm talking about flow control on the fragments themselves; this is either a LLC (the likes of 802.2 or LAPB) or a shim layer above LLC problem (that would be us). The 802.15.4 MAC/PHY was not design to cope with IPv6 MTU and when the IPv6 stack sends a NLPDU of 1280 bytes minimum, it causes a burst of fragments that should be paced and windowed. I suggest we do it in 6LoWPAN and handle the consequences of our own fragmentation rather than rely on a LLC mechanism that might not be there or adapted. Pascal _______________________________________________ 6lowpan mailing list [email protected] https://www.ietf.org/mailman/listinfo/6lowpan This e-mail (including any attachments to it) is confidential, proprietary, legally privileged, subject to copyright and is sent for the personal attention of the intended recipient only. If you have received this e-mail in error, please reply to advise us immediately, delete it and destroy any printed copies of it. You are notified that reading, disclosing, copying, distributing or taking any action in reliance on the contents of this information is strictly prohibited. No employee is authorized to conclude any binding agreement on behalf of NIVIS LLC with another party by e-mail without express written confirmation by an officer of the company. Although we have taken reasonable precautions to ensure no viruses are present in this e-mail, we cannot accept responsibility for any loss or damage arising from the viruses in this e-mail or attachments. _______________________________________________ 6lowpan mailing list [email protected] https://www.ietf.org/mailman/listinfo/6lowpan
