Re: [Roll] [6lo] call for consensus for the RPL RPI / RH3 compression
Robert Cragie <robert.cragie@gridmerge.com> Mon, 12 January 2015 20:38 UTC
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Subject: Re: [Roll] [6lo] call for consensus for the RPL RPI / RH3 compression
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My views on what I think are the salient points in the discussion so far: 1) Use of interop to validate a way forward I don't agree that a specification has to be set in stone for an interop. The whole point of an interop sometimes is to test the specification and expect it to change afterwards. If there are a number of proposals, then it doesn't seem unreasonable to clearly specify each proposal and implement all proposals. This in itself will give an idea of complexity; the interop will give an idea of issues arising and therefore it should help in deciding which one is the best as clearly there doesn't seem to be consensus based solely on the drafts. 2) Choice of proposals Assuming elimination isn't going to occur via the mailing list, the three options are: a. draft-thubert-roll-flow-label-02 (RPI only) b. draft-thubert-6lo-rpl-nhc-02 but pick one of the three (greedy, conservative, efficient) first (RPI only) c. draft-thubert-6lo-routing-dispatch-01 (RPI and RH3) This implies the current method would be used for RH3 in cases (a) and (b). 3) Compression of RH3 using NHC This could be developed as an alternative. I don't recall the NHC approach being abandoned. 4) Time schedule Carsten gave a good summary earlier. I can't see why draft-thubert-6lo-routing-dispatch-01 would take any longer to finalise than draft-thubert-6lo-rpl-nhc-02, especially if the latter would include RH3 as well. 5) Sub-IP protocol The mesh header as it stands is not significantly different to what is being proposed for 6LoRH as it too could be used to carry IPv6 addresses in a compressed format on the basis that link layer addresses are already used with autoconfigured IPv6 addresses. I would therefore see 6LoRH as a general more flexible replacement for the mesh header and therefore 6LoRH used in conjunction with RPI/RH3 would not be a sub-ip protocol. In essence, the difference is really this: RFC4944: mesh[0..a] | FRAG1 | IPHC | {IPHC[0..b] | NHC[0..c]}[0..d] | Payload mesh[0..a] | FRAGN | Payload draft-thubert-6lo-routing-dispatch-01: 6LoRH[0..a] | FRAG1 | 6LoRH[0..b] | IPHC | {IPHC[0..c] | NHC[0..d]}[0..e} | Payload 6LoRH[0..a] | FRAGN | Payload All the above really shows is that 6LoRH can be used in place of a mesh header for sub-ip purposes simply as a "less greedy" way or it can be used to replace an IPHC header as used currently in conjunction with a more efficient header extension. If I have one issue, it is calling them all "6LoRH" - the RPI can sit a "6LoRH-style" header extension alongside an IPHC header if there is no encapsulation, I believe? This is where I have some sympathy with James Woodyatt's e-mail - the options start to look a little hairy and it becomes significantly more complex to figure out what goes where. 6) Bump-in-the-stack I have seen both bump-in-the-stack and full decompression/recompression. In addition to what Pascal points out, there are some other subtle considerations which need to be applied for BITS, especially with regard to eliding what look like padding fields - I have seen one issue where a value of 0 was considered to be padding and not included correctly. On 07/01/2015 16:43, Carsten Bormann wrote: > On 2015-01-06 18:03, Michael Richardson wrote: >> An experiment which I have yet to do is to see what happens if one >> applies >> GHC (https://tools.ietf.org/html/rfc7400) to 6553 and 6554. > > Little point -- there is very little inherent redundancy on the byte > sequence level. > > Gruesse, Carsten > > _______________________________________________ > Roll mailing list > Roll@ietf.org > https://www.ietf.org/mailman/listinfo/roll >
- [Roll] call for consensus for the RPL RPI / RH3 c… Pascal Thubert (pthubert)
- Re: [Roll] call for consensus for the RPL RPI / R… Michael Richardson
- Re: [Roll] [6tisch] call for consensus for the RP… Xavier Vilajosana
- Re: [Roll] call for consensus for the RPL RPI / R… Carsten Bormann
- Re: [Roll] call for consensus for the RPL RPI / R… Pascal Thubert (pthubert)
- Re: [Roll] call for consensus for the RPL RPI / R… Brian Haberman
- Re: [Roll] call for consensus for the RPL RPI / R… Pascal Thubert (pthubert)
- Re: [Roll] call for consensus for the RPL RPI / R… Brian Haberman
- Re: [Roll] call for consensus for the RPL RPI / R… Robert Cragie
- Re: [Roll] [6tisch] call for consensus for the RP… Xavier Vilajosana
- Re: [Roll] call for consensus for the RPL RPI / R… Carsten Bormann
- Re: [Roll] call for consensus for the RPL RPI / R… Pascal Thubert (pthubert)
- Re: [Roll] call for consensus for the RPL RPI / R… Michael Richardson
- Re: [Roll] call for consensus for the RPL RPI / R… Adrian Farrel
- Re: [Roll] call for consensus for the RPL RPI / R… Ralph Droms
- Re: [Roll] call for consensus for the RPL RPI / R… Pascal Thubert (pthubert)
- Re: [Roll] [6lo] call for consensus for the RPL R… Ralph Droms
- Re: [Roll] call for consensus for the RPL RPI / R… Ralph Droms
- Re: [Roll] [6tisch] [6lo] call for consensus for … Pascal Thubert (pthubert)
- Re: [Roll] [6tisch] [6lo] call for consensus for … Michael Richardson
- Re: [Roll] [6lo] call for consensus for the RPL R… Michael Richardson
- Re: [Roll] [6tisch] [6lo] call for consensus for … Ralph Droms
- Re: [Roll] [6tisch] [6lo] call for consensus for … Michael Richardson
- Re: [Roll] [6tisch] [6lo] call for consensus for … Tom Taylor
- Re: [Roll] [6tisch] [6lo] call for consensus for … Pascal Thubert (pthubert)
- Re: [Roll] [6tisch] [6lo] call for consensus for … Michael Richardson
- Re: [Roll] [6tisch] [6lo] call for consensus for … Pascal Thubert (pthubert)
- Re: [Roll] [6lo] call for consensus for the RPL R… Carsten Bormann
- Re: [Roll] [6lo] call for consensus for the RPL R… Robert Cragie