Subject: Re: [ipfix] new element: fragmentOffsetIPv6 ?

From: Juergen Quittek <[email-masked]>
Date: Mon, 08 May 2006 03:07:08 +0200

Dear all,

It's OK, if you want to have this new IE.
Please help me to specify it correctly.

RFC 2460 defines for the IPv6 fragment extension header:
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Next Header  |   Reserved    |      Fragment Offset    |Res|M|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         Identification                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Fragment Offset      13-bit unsigned integer.  The offset, in 8-octet
                        units, of the data following this header,
                        relative to the start of the Fragmentable Part
                        of the original packet.

   Res                  2-bit reserved field.  Initialized to zero for
                        transmission; ignored on reception.

   M flag               1 = more fragments; 0 = last fragment.

If we define a fragment offset IE for IPv6,
we probably should also define the a fragment flag IE for IPv6.
Below is a suggestion for their definitions.  Comments are welcome.

5.3.29.  fragmentOffsetIPv6

   Description:
      The value of the IPv6 fragment offset field in the IPv6 fragment
      extension header.
   Abstract Data Type: unsigned16
   Data Type Semantics: identifier
   ElementId: 211
   Status: current
   Reference:
      See RFC 2460 [RFC2460] for the specification of the fragment
      offset in the IPv6 fragment extension header.

5.3.30.  fragmentFlagIPv6

   Description:
      The value of the M flag in the IPv6 fragment extension header.

         Bit  0:    M flag.
         Bits 1-7: (DC) Don't Care, value is irrelevant.

             0   1   2   3   4   5   6   7
           +---+---+---+---+---+---+---+---+
           |   | D | D | D | D | D | D | D |
           | M | C | C | C | C | C | C | C |
           +---+---+---+---+---+---+---+---+

   Abstract Data Type: octet
   Data Type Semantics: flags
   ElementId: 212
   Status: current
   Reference:
      See RFC 2460 [RFC2460] for the specification of the M flag in the
      IPv6 fragment extension header.

Thanks,

    Juergen

--On 21.04.2006 15:08 Uhr +0200 Benoit Claise wrote:
>
> Lutz, Paul,
>>
>>> We have #88 = fragmentOffsetIPv4 - but no equivalent for IPv6
>>> fragment offset?
>>>
>>> See section 4.5 of RFC 2460.
>>>
>>> I suggest we allocate #211 for this.
> Since this is a gap in the I.E. list, this makes sense!
>>>
>>>
>>> BTW, there are also no elements to report Hop-by-Hop Options (section
>>> 4.3) or Destination Options (section 4.6).
>>>
>>
>> for IPv4 this elem is part of the IPv4 header while
>> in IPv6 there is a special extension header for
>> the fragment data. So maybe this should be made
>> clear by the IE name.
>>
>> eg. IPv6ExtHdrFragmentOffset
> Agreed.
>
> Regards, Benoit.
>>
>>
>> --
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>
>
>

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