Hi Zach, I second your concern
There was recently a discussion specifically about the number of contexts needed. There seemed to be a consensus that multiple contexts was useful for renumbering only, which is rare, and that 2 contexts was enough. Was there new input since then which justifies the use of 4-bit contexts? Cheers, Julien -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Zach Shelby Sent: vendredi 10 octobre 2008 14:58 To: Jonathan Hui Cc: 6lowpan Subject: Re: [6lowpan] Fwd: New Version Notification fordraft-ietf-6lowpan-hc-01 Hi, Here are my comments on hc-01. Overall I think we are quite close with the comments from Pascal and Julien. I found the DDF name confusing. Now it has been renamed CTX in the latest formats on the list, great. As Pascal pointed out, nodes need to be able to decode all these options. One thing that worries me in having 16 contexts, is that nodes are forced to store them all. That is worst case 272 bytes of memory consumption. Worth it? Is it possible that an ultra-simple node would only have to understand the default context? The default context identifier '0000' could be clarified more in the draft. When CTX is '10' then the default context identifier '0000' is used. It should be made clear that this is the prefix advertised in RAs as useable for SAA. Regarding the ND for 6lowpan draft, HC-01 means we need to add a 4-bit context identifier flag to the 6LoWPAN Prefix Information Option. To make things clear that should always be '0000' if the A flag is '1'? - Zach Jonathan Hui wrote: > > http://tools.ietf.org/html/draft-ietf-6lowpan-hc > > This new version reflects the recent discussions on the list. The > changes are: > - HC back to 1 byte by default by stealing a few bits from the > dispatch field. > - Added better support for multicast address compression. > - Fixed alignment for UDP port compression. > - Better support for Traffic Class and Flow Label compression. > - Pascal joined as an author. > > Happy reading! > > -- > Jonathan Hui > > > > Begin forwarded message: > >> From: IETF I-D Submission Tool <[EMAIL PROTECTED]> >> Date: October 8, 2008 7:15:35 PM PDT >> To: [EMAIL PROTECTED] >> Cc: [EMAIL PROTECTED] >> Subject: New Version Notification for draft-ietf-6lowpan-hc-01 >> >> >> A new version of I-D, draft-ietf-6lowpan-hc-01.txt has been >> successfuly submitted by Jonathan Hui and posted to the IETF repository. >> >> Filename: draft-ietf-6lowpan-hc >> Revision: 01 >> Title: Compression Format for IPv6 Datagrams in 6LoWPAN Networks >> Creation_date: 2008-10-09 >> WG ID: 6lowpan >> Number_of_pages: 15 >> >> Abstract: >> This document specifies an IPv6 header compression format for IPv6 >> packet delivery in 6LoWPAN networks. The compression format relies >> on shared context to allow compression of arbitrary prefixes. This >> document specifies compression of multicast addresses and a framework >> for compressing next headers. This framework specifies UDP >> compression and is prepared for additional transports. >> >> >> >> The IETF Secretariat. >> >> > > _______________________________________________ > 6lowpan mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/6lowpan -- Zach Shelby Head of Research Sensinode Ltd. Kidekuja 2 88610 Vuokatti FINLAND mobile: +358 40 7796297 This e-mail and all attached material are confidential and may contain legally privileged information. If you are not the intended recipient, please contact the sender and delete the e-mail from your system without producing, distributing or retaining copies thereof. _______________________________________________ 6lowpan mailing list [email protected] https://www.ietf.org/mailman/listinfo/6lowpan _______________________________________________ 6lowpan mailing list [email protected] https://www.ietf.org/mailman/listinfo/6lowpan
