Re: [Roll] 'S' field in MPL Options
Robert Cragie <robert.cragie@gridmerge.com> Tue, 04 December 2012 14:39 UTC
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Date: Tue, 04 Dec 2012 14:41:31 +0000
From: Robert Cragie <robert.cragie@gridmerge.com>
Organization: Gridmerge Ltd.
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To: Michael Richardson <mcr+ietf@sandelman.ca>
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Cc: Roll WG <roll@ietf.org>, "Jonathan Hui (johui)" <johui@cisco.com>
Subject: Re: [Roll] 'S' field in MPL Options
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I agree we should keep the 'S' field as it gives more flexibility for future versions. I'm not sure we reached a conclusion regarding the reserved bits and version numbering. Here are the choices as I see them: 1) 5-bit version number: * Allocate all reserved bits to be a unsigned 5-bit version field: o V = Version. Set to 0. Must be received as 0. If received as 1 or higher, packet is discarded In future revisions, this allows: * Extension of the frame using TLV suboptions * Complete change to the option formatting if V is set to 1 or higher 2) n-bit (1 <= n <= 4) version number: * Allocate n reserved bits to be a unsigned n-bit version number: o V = Version. Set to 0. Must be received as 0. If received as 1 or higher, packet is discarded * Change behavior for remainder of reserved bits: o rsv = reserved. Set to 0. Ignored on receipt In future revisions, this allows: * Extension of the frame using TLV suboptions * Use of remainder of reserved bits * Complete change to the option formatting if V is set to 1 or higher 3) No version number: * Change behavior for reserved bits: o rsv = reserved. Set to 0. Ignored on receipt In future revisions, this allows: * Extension of the frame using TLV suboptions * Use of reserved bits In draft 02, it is most like (1), except the reserved bits are not called a version number. My preference would be for (2), with n=1. Anyone else? Robert On 30/11/2012 7:49 PM, Michael Richardson wrote: >>>>>> "Robert" == Robert Cragie <robert.cragie@gridmerge.com> writes: > Robert> 2. Allow future revisions to change the format > > I suggest that we keep the S bit. We might introduce additional fixed > format items using additional reserved bits to flag that they are there. > > If we run out of reserved bits, then that would be a reason to bump the > version and go for a full subTLV format. Given that bytes are scarce, > this results in the most efficient packing for now. > > This is my suggestion. If you agree, then we should add this to issue #108. >
- [Roll] 'S' field in MPL Options Robert Cragie
- Re: [Roll] 'S' field in MPL Options Dario Tedeschi
- Re: [Roll] 'S' field in MPL Options Jonathan Hui (johui)
- Re: [Roll] 'S' field in MPL Options Robert Cragie
- Re: [Roll] 'S' field in MPL Options Dario Tedeschi
- Re: [Roll] 'S' field in MPL Options Robert Cragie