Subject: [Hipsec] HOST_ID_FQDN vs HOST_ID & FQDN

From: [email-masked] (Petri Jokela)
Date: Thu Mar 4 00:10:01 2004

On Sun, 29 Feb 2004, Miika Komu wrote:

> Ok. There may some other strings (e.g. NAI) which may be longer than FQDNs
> but I guess 4096 bytes is still enough.

Actually it is too much. The HIP header has 8-bit payload length, setting
the limit to the HIP parameters field. The maximum size of the HIP
parameters section is thus 2008 bytes (in section 6.1 Payload format). In
HOST_ID, 11 bits for the length would be enough to fill a HIP packet.

Due to the 2008 bytes limit, Will we run into problems with other TLVs in
the packet (e.g. D-H).

/petri

-- 
Petri Jokela                        Tel:    +358 9 299 2413
Research scientist                  Fax:    +358 9 299 3535
NomadicLab, Ericsson Research       Mobile: +358 44 299 2413
Oy L M Ericsson Ab                  email: [email-masked]

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From: [email-masked] (Petri Jokela)
Date: Thu Mar 4 04:32:04 2004

> Due to the 2008 bytes limit, Will we run into problems with other TLVs in

Still few words about this...

The current I2 packet size with the Oakley group 1 is around 760 bytes.
This means that with 8192-bit group the size is around 1700 bytes. And
this is without the FQDN, for which we leave some 300 bytes with this
packet content (usually it should be enough). This, however, does not
leave any space for future DH-group modifications (or even for large
NAI/FQDNs).

/petri

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From: [email-masked] (Pekka Nikander)
Date: Thu Mar 4 05:43:00 2004

> leave any space for future DH-group modifications (or even for large

I think that it would be good enough just to document this,
and leave it (mostly) as it is.

--Pekka

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From: [email-masked] (Petri Jokela)
Date: Fri Mar 12 04:35:00 2004

> and leave it (mostly) as it is.

I added a sentence in 6.1 Payload format, beginning from "Note:"

   The Header Length field contains the length of the HIP Header and the
   length of HIP parameters in 8 bytes units, excluding the first 8
   bytes.  Since all HIP headers MUST contain the sender's and
   receiver's HIT fields, the minimum value for this field is 4, and
   conversely, the maximum length of the HIP Parameters field is
   (255*8)-32 = 2008 bytes.  Note: this sets an additional limit for
   sizes of TLVs included in the Parameters field, independent of the
   individual TLV parameter maximum lengths.

/petri

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From: [email-masked] (Pekka Nikander)
Date: Fri Mar 12 04:43:01 2004

>    individual TLV parameter maximum lengths.

Ok to me.

--Pekka