Re: [DNA] leaving out options on Landmark RA=Yes(draft-pentland-dna-protocol-00.txt)?

[Sathya Narayanan <sathya@research.panasonic.com>]

Greg -

Under the assumption that the 'Yes' case is more likely, i.e. the ratio AP/AR is big, it makes sense to emphasize the importance of this optimization by making it a MUST/SHOULD, IMHO. With the size of PIOs, possibly many of them and wireless channels etc., there is possibly significant savings in link-utilization.

- Sathya

----- Original Message -----
From: Greg Daley <greg.daley@eng.monash.edu.au>
Date: Wednesday, June 1, 2005 0:52 am
Subject: [DNA] leaving out options on Landmark RA = Yes(draft-pentland-dna-protocol-00.txt)?

> Dear WG,
> 
> The contents of Landmark RAs with the Yes flag set
> are described in two locations:
> 
> Section 3.2:
> 
> "In the case when the host is still attached to the same link, which
>  might occur when the host has changed from using one layer 2 access
>  point to another, but the access points are on the same link, the
>  Router Advertisement(s) it receives will contain a "yes, that prefix
>  is on this link" answer, and no other information.  Thus, such RA
>  messages are quite small."
> 
> Section 5.1.5:
> 
> "If the RS contains a Landmark Option whose prefix matches one
>  of those in the interface's stored prefix list, then the
>  Landmark option with the Landmark prefix is included in the RA
>  but with the Yes flag set.  At this point the RA is ready for
>  transmission, and is scheduled as specified in Section 5.1.7."
> 
> I have a comment and question.
> 
> Comment:
> 
> The descriptions here ignore SEND options, which need to be included
> if SEND is used.  This will increase the size of the RA.
> 
> Question:
> 
> Can we have standards language for this?
> 
> There's no flexibility in the description of what options are
> able to be included in the "Yes" Landmark. That sounds like a
> MUST NOT include other PIO, DNAO. etc.
> 
> Personally, I'd prefer something saying something like
> 
> "RAs with the 'Yes' Flag set in a Landmark option MAY leave out all
> configuration related options such as PIOs, DNAOs, Advertisement
> Intervals etc, since this information is assumed to have
> already been received to be able to construct a matching
> Landmark Router Solicitation".
> 
> I'd prefer MAY to SHOULD or MUST, since it's an optimization,
> and the presence of additional options doesn't harm hosts.
> 
> In RADVD, it's easier for me to not remove the other options
> in the RA just because the Landmark option Yes flag is set.
> 
> Greg
> 
>