Re: Question on CRC-32 (MPE)

[Gorry Fairhurst <gorry@erg.abdn.ac.uk>]

Please do note the CURRENT ULE draft is:

http://www.ietf.org/internet-drafts/draft-ietf-ipdvb-ule-01.txt

And not the version quoted - the version that you mentioned is now obsolete.

The CRC algorithm in ULE is intended to follow that for MPE (see the ISO
Spec) - please do tell us of any differences or ambiguities. The new text is
intended to be clearer - in particular there is a hex dump of a packet
encoded using ULE that may be used to verify your algorithm implementation.

Best wishes,

Gorry

On 23/8/04 9:53 am, "Moritz Vieth" <moritz.vieth@fokus.fraunhofer.de> wrote:

> Simon Teh wrote:
>> Dear all members,
>> 
>>  
>> 
>>           Currently I¹m doing a study on MPE encapsulation. I got a
>> question on crc-32 field. From my understanding, I know that the crc-32
>> is compute from the whole datagram section including the crc-32 bit
>> tailer, but what I¹m confusing is if we would like to compute the
>> crc-32, what is the original value for that field (crc-32). Hope some
>> expert could give me some guidance. Thanks in advance!
>> 
>>  
> 
> Dear Simon,
> 
> Taking a look in the current ULE draft (draft-fair-ipdvb-ule-02) helps
> on this issue as well. The same paragraph that says for which part of
> the packet the CRC is to be calculated states:
> "The Encapsulator initialises the CRC-32 accumulator register to the
> value 0xFFFF FFFF."
> 
> Regards,
> 
> Moritz
>