RE: question about MPE and AAL5 over satellites

[William StanisLaus <williams77@mailandnews.com>]

Hi Raf,
      Good Day, I don't see any limitations on 1500 bytes for AAL5 or MPE, 
Since for MPE we have length Field as 12 bits which means can carry upto 2^12 
4096 bytes including MPE header. and for AAL5 we have length Field as 16 bits 
which means 2^16 65536 bytes including AAL5 header. So it should not be a 
problem for you to apply security overhead, which can be max of 100 bytes 
overhead if you are using IPSec.

Have a nice day

Regards,
William.




>===== Original Message From ip-dvb@erg.abdn.ac.uk =====
>Hi Raf,
>
>I'm not familiar with AAL5, and do not have the specification available.
>However, about MPE I can tell following:
>
>Length of an MPE section is indicated with 12 bits, and shall not exceed 4093 
(Bytes).
>Overhead caused by the MPE section header is 13 Bytes, leaving 4080 Bytes for 
the payload.
>
>As one datagram may be divided on max 256 sections, the absolute maximum size 
for Layer 3 datagram carried on MPE is (256 * 4080) = 1 044 480 Bytes.
>
>However, in case of IP datagrams, one datagram shall be delivered in a single 
MPE section.
>This results the maximum size of an IP datagram being 4080 Bytes.
>
>
>Matti Puputti, Senior System Specialist
>Nokia Ventures Organization/IPDC
>P.O.Box 4, FIN-20521 TURKU
>Phone: +358 7180 33473, Fax: +358 7180 33 232
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