Re: [tcpm] TCP-AO Option Layout - Alignment and Padding
Stefanos Harhalakis <v13@v13.gr> Tue, 29 July 2008 13:10 UTC
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From: Stefanos Harhalakis <v13@v13.gr>
To: tcpm@ietf.org
Date: Tue, 29 Jul 2008 16:09:51 +0300
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References: <20080729.060448.112613043.yoshfuji@linux-ipv6.org> <488EF15F.4070302@isi.edu> <20080729.065149.22600370.yoshfuji@linux-ipv6.org>
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Subject: Re: [tcpm] TCP-AO Option Layout - Alignment and Padding
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On Tuesday 29 July 2008, YOSHIFUJI Hideaki / 吉藤英明 wrote: > > If we want to reduce padding and keep the MAC aligned, the best option > > is: > > > > ~ +---------+---------+---------+---------+ > > ~ | Kind=?? | Length | KeyID | 0 | > > ~ +---------+---------+---------+---------+ > > ~ ... > > ~ ... > > ~ +---------------------------------------+ > > ~ | MAC... | > > ~ +---------------------------------------+ > > I support this. > > > I.e., pad ourselves. We suggest that the option start word-aligned. This > > wastes space, IMO. > > I don't think this is a waste of space and good thing to have - > to save CPU cycle(s). Please don't do this. Leave the padding as an issue for the OS implementation just like all other TCP options do. Any OS implementation may add a NOP at the begging and solve this problem (if it actually exists). Also, noone can say whether there will be a 5 bytes option in the future that will be able to be effectively combined with this one. Btw, how sure can you be that *all* TCP implementations out there (PCs, Non-PCs, small-embedded, mobiles etc) benefit from exactly 32bit writes? IMHO, when talking about thinks like this one, the underlying hardware should not be considered at all. _______________________________________________ tcpm mailing list tcpm@ietf.org https://www.ietf.org/mailman/listinfo/tcpm
- Re: [tcpm] TCP-AO Option Layout - Alignment and P… Joe Touch
- Re: [tcpm] TCP-AO Option Layout - Alignment and P… YOSHIFUJI Hideaki / 吉藤英明
- Re: [tcpm] TCP-AO Option Layout - Alignment and P… Stefanos Harhalakis
- Re: [tcpm] TCP-AO Option Layout - Alignment and P… Joe Touch
- Re: [tcpm] TCP-AO Option Layout - Alignment and P… Lars Eggert
- Re: [tcpm] TCP-AO Option Layout - Alignment and P… Ron Bonica