Re: [Manet-dt] SMF: Usage of IPv4 Identification field
Brian Adamson <adamson@itd.nrl.navy.mil> Fri, 20 April 2007 13:11 UTC
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Date: Fri, 20 Apr 2007 09:10:59 -0400
To: Teco Boot <teco@inf-net.nl>, manet-dt@ietf.org
From: Brian Adamson <adamson@itd.nrl.navy.mil>
Subject: Re: [Manet-dt] SMF: Usage of IPv4 Identification field
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I don't think the rules have been well-followed by some, most or maybe any operating systems. I think most (Win32, BSD, while Linux seems to exhibit bit different behaviors) simply increment the ID field for each packet sent regardless of the destination ... This probably results in compliance with RFC 791, but is increasingly problematic for multi-homed cases or when there is great disparity of transmission rate for different flows that end up taking different paths through the network. I think it is quite likely if one has a high bandwidth interface and another lower bandwidth (and perhaps long delay such as cellular, SATCOM) interface that a flow on the high speed interface could wrap the 16-bit sequence space in parallel with some low duty cycle flow on the slow interface. In the age of higher speeds and multi-homing, etc ... I think it is worthwhile to clarify that sequence space SHOULD be managed at least on a per <source:destination> tuple basis I suppose the <protocol> could be added, but that doesn't typically have bearing on the path the data takes ... although I guess it could for forms of policy-based routing, etc .... The main thing is that it would be nice for operating systems to have some consistent behavior here ... in lieu of this, we made a specific recommendation to support SMF needs. I am curious as to what others think here ... At 11:36 AM +0200 4/13/07, Teco Boot wrote: >The SMF ID deviates from RFC791 for the Identification field. > >791: "The originating protocol module of an internet datagram sets the >identification field to a value that must be unique for that >source-destination pair and protocol" > >SMF: "In the case that resequencing is deemed necessary, it is RECOMMENDED >that sequence numbering be applied such that a different sequence number >space per <sourceAddress::destinationAddress> duple be used" > >The difference is the protocol field. I see two options, modify SMF or add >text clarifying the deviation and analyze for consequences. Or are the rules >for Identification changed since 791? > >Teco > > >_______________________________________________ >Manet-dt mailing list >Manet-dt@ietf.org >https://www1.ietf.org/mailman/listinfo/manet-dt -- Brian __________________________________ Brian Adamson <mailto:adamson@itd.nrl.navy.mil> _______________________________________________ Manet-dt mailing list Manet-dt@ietf.org https://www1.ietf.org/mailman/listinfo/manet-dt
- [Manet-dt] SMF: Usage of IPv4 Identification field Teco Boot
- [Manet-dt] RE: SMF: Usage of IPv4 Identification … Teco Boot
- [Manet-dt] RE: SMF: Usage of IPv4 Identification … Brian Adamson
- Re: [Manet-dt] SMF: Usage of IPv4 Identification … Brian Adamson
- RE: [Manet-dt] RE: SMF: Usage of IPv4 Identificat… Teco Boot
- RE: [Manet-dt] RE: SMF: Usage of IPv4 Identificat… Templin, Fred L