Re: [Hipsec] Segmentation within HIP

For starters i would look at the UDP NAT tunneling mechinism to provide it.

On 03/25/2016 09:16 PM, Tom Henderson wrote:
>
> On 03/25/2016 03:49 PM, Derek Fawcus wrote:
>> Recently I've been working on middlebox s/w:  Firewalls and NAT.
>>
>> One thing this has brought home to me is just how unreliable
>> fragmentation is on the current Internet.  NAT will often
>> simply break it (such that they can not be reassembled) or
>> just discard them,  and firewalls are often set up to block them.
>>
>> As such,  almost every protocol now would seem to need protocol
>> level segmentation/fragmentation,  rather than depend up IP
>> level fragmentation.
>>
>> It struck me that it should be quite simple to extend HIP to
>> support such.
>>
>> 1) Add a Controls bit which advertises that the sender supports
>>      segmentation.
>> 2) Define a new parameter,  numbered 1 such that it is first in
>>      the parameters,  and is critical.
>>      Within the parameter have a seqno/identifier, offset and
>>      more segments / final segment bit, possibly also a total
>>      size field.  Define some simple reassembly rules,  similar
>>      to those for IP fragments, such that one could reassemble
>>      a HIP packet larger than 2008 bytes if desired (how big?).
>> 3) Possibly also define a none critical parameter within the
>>      non signed,  non MACed range which advertises the max size
>>      packet the sender is willing to reassemble.  In fact I guess
>>      this might remove the need to use a Controls bit,  since it
>>      would imply the sender can reassemble.
>>
>> Then have a rule that once one party has seen the other party
>> advertise the segmentation capability within the current BEX
>> session, it is free to make use of segmentation towards that peer.
>>
>> Thoughts?
>>
>> DF
> Hi Derek, I don't remember the details, but in the early days of HIP, it was decided to avoid the burden of supporting fragmentation.  I guess I'd prefer to see some evidence that HIP messages are being fragmented in the wild before starting a work effort to add support.
>
> - Tom
>
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