Re: 6LSA Slides and QoS

Brian E Carpenter <brc@zurich.ibm.com> Wed, 25 May 2005 12:28 UTC

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Date: Wed, 25 May 2005 14:28:03 +0200
From: Brian E Carpenter <brc@zurich.ibm.com>
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Subject: Re: 6LSA Slides and QoS
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Jim, you've stated that 6LSA respects the RFC 3697 requirement
to deliver the original, unmodified flow label.

draft-chakravorty-6lsa-01.txt makes that statement but does not
define any mechanism to explain how it's done. As far as I can see,
the ingress 6LSA router would have to signal downstream, and the
egress 6LSA router would have to keep state.

The mystery is solved in draft-chakravorty-bcc-fec-00.txt, where I find:

>    Because of the requirement to maintain the integrity of the Flow
>    Label field, the 6LSA switching technique can only be applied to
>    packets arriving at an edge port with their Flow Label field set to
>    zero.  In future work on 6LSA, more generalized treatment of packets
>    that arrive with non-zero Flow Label will be presented. 

In other words, 6LSA as defined today is incapable of delivering the
original flow label except for default traffic. That seems like
a substantial limitation.

     Brian

Bound, Jim wrote:
> You can see good example of 6LSA in Charts at:
> 
> http://www.nav6tf.org/documents/arin-nav6tf-apr05/5.QoS_and_IPv6_SC.pdf
> 
> The rest of the slides for IPv6 may be interesting to some from this
> joint ARIN+NAv6TF meeting too.
> 
> http://www.nav6tf.org/html/nav6tf_events.html
> 
> /jim
> 
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