Header extension format differences between RFC4326 and draft-ietf-ipdvb-ule-ext-04.txt

[Fausto Vieira <fausto.vieira@uab.cat>]

Hello all,

I missed the discussion on the draft-ietf-ipdvb-ule-ext-04.txt so my question has probably been raised before:

Why is it that for the timestamp extension header, the format is:

   0               7               15              23              31
   +---------------+---------------+---------------+---------------+
   |     0x03      |      0x01     |       time stamp HI           |
   +---------------+---------------+---------------+---------------+
   |         time stamp LO         |            Type               |
   +---------------+---------------+---------------+---------------+

        Figure 7 The format of the 32-bit Timestamp Extension Header

where the HLEN (0x03) is at the start of the extension header, when in the RFC4326 the extension headers are defined as:

          0                   1
          0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         |0 0 0 0 0|H-LEN|    H-Type     |
         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  Figure 7: Structure of ULE Next-Header Field


Where it is stated that the H-Type is 8-bit and not 16-bit. To my knowledge, Ethertype should always be 16-bit.

However, my question is:
What is the meaning of the 0x01 byte in the Timestamp Header?
Is this the 1 microsecond resolution value or is this some type of byte alignment?


Many thanks

Fausto Vieira