Hi,
On 10/16/2012 10:00 PM, Miika Komu wrote:
5.2.5. SOLUTION
Here, I suggest removing 1 byte of reserved space and the 2 byte,
echoed opaque value for the same reason presented above. The type
number could be moved to 323 (SOLUTION + 2). If we need to modify the
puzzle parameter for some reason in the future, I suggest to design a
new parameter instead of using the reserved field. That is how new
semantics are handled for any other parameter as well (see MAC_X).
I am not really objecting to your change but it would helpful to
understand the real need and see some numbers (with ECC HIP) behind your
suggestions. IEEE 802.15.4 payload size is between 72–116. Here's some
numbers:
http://www.cs.helsinki.fi/u/gurtov/papers/hip-medical.pdf
While DEX MTU is considerably smaller, HIP BEX payload size with
ECDH+ECDSA is reported (in bytes) as follows:
* 40 (I1)
* 916 (R1)
* 644 (I2)
* 108 (R2)
So, the main problem is the R1 and I2 that are fragmented and their
"tail" (modulo) size is as follows (first number with 72 and the second
with 116 payload size):
* R1: 52 / 104
* I2: 68 / 639
(with R2 the modulo is 107 when MTU is 72)
DEX figures were reported as follows:
* 40 (I1)
* 92 (R1)
* 148 (I2)
* 102 (R2)
So I think we should be should be able to shrink packet size at least 20
or preferably 30 bytes to reduce the number of fragments and make all
this worthwhile just for DEX:
* R1: 20 / fits
* I2: 146 / 32
* R2: 30 / fits
But I am getting tired and perhaps I got something wrong.
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