Subject: per neighbor packet buffering "issue"

From: "Julien Abeille (jabeille)" <[email-masked]>
Date: Tue, 21 Oct 2008 16:08:09 +0200

Dear all,
 
last week was released uIPv6, an IPv6 host implementation for very
constrained device (http://www.sics.se/contiki).
uIPv6 holds on 11K of flash, and a minimum of 1.8K of RAM (3K with IP
fragmentation support)
 
We learnt from the implementation that a few IPv6 mandated features are
rather heavy for such device.
- The most costly feature is "per neighbor packet buffering", mandated
by RFC4861. On constrained platforms, there is no dynamic memory
allocation, hence if the neighbor cache can hold  four entries (a
minimum in a sensor network), we must define four 1280 bytes buffer,
which is huge in comparison to the initial 1.8K.
 
Note that  other people also see security issues with per neighbor
packet buffering. Benoit, can you elaborate on this?
 
My question is: do you think it makes sense to change the MUST into a
SHOULD?
 
Regards,
Julien

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From: Rob Austein <[email-masked]>
Date: Tue, 21 Oct 2008 12:13:02 -0400

> My question is: do you think it makes sense to change the MUST into a

I would support SHOULD.  Packet buffers are a precious resource when
you get far enough into the embedded world.  Protocol specifications
have to allow for the possiblity that both packet buffers might
already be in use. :)
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