AW: [802.21] IS Higher Layer Transport Requirements: update on conf call on December 8

["Kalyan Koora" <kalyan.koora@benq.com>]

Hi Yoshihiro,

the option defined in .16 gives some flexibilty at the cost of complexity. If you ask me,
I too favour the option of fixing the length field to 2 bytes. :-)

Regards,
Kalyan

PS: "Flexibilty is inversly proportional to the Complexity".

-----Urspr¨¹ngliche Nachricht-----
Von: Yoshihiro Ohba [mailto:yohba@TARI.TOSHIBA.COM] 
Gesendet: Donnerstag, 8. Dezember 2005 14:59
An: STDS-802-21@listserv.ieee.org
Betreff: Re: [802.21] IS Higher Layer Transport Requirements: update on conf call on December 8


Kalyan,

On Thu, Dec 08, 2005 at 02:46:53PM +0100, Kalyan Koora wrote:
> Hi Yoshihiro,
> 
> thank you for your reply. Yes, I mean that what you said. As far as I 
> understood the .16, they defined default size of lenght filed to be 1 
> Byte where the MSB is 0 if the length of the payload is less than 127. 
> If it is greater than that then the MSB is 1 and the 1st byte of the 
> length field indicates, how many bytes are following the present 
> length field.
> 
> => Result: The size of length field is by default 1 Byte and only on 
> need, it is extended further. Well if we think of using TLV format for 
> all services (IS, CS, ES) then it is in most cases valid that the 
> "Value" filed, i.e. payload of the IE is (statistically
> seen) less than 127 Byte.

This actually that the length of the Length field is variable as ASN.1 encoding does.  I this this will make TLV implementation complicated.  It is simpler to make it a constant length, say 2-octet.

Yoshihiro Ohba


> 
> Hope I put it in correct words.
> 
> Regards,
> Kalyan
> 
> -----Urspr£¿ngliche Nachricht-----
> Von: Yoshihiro Ohba [mailto:yohba@TARI.TOSHIBA.COM]
> Gesendet: Donnerstag, 8. Dezember 2005 14:34
> An: STDS-802-21@listserv.ieee.org
> Betreff: Re: [802.21] IS Higher Layer Transport Requirements: update on conf call on December 8
> 
> 
> On Thu, Dec 08, 2005 at 04:07:33AM -0800, Gupta, Vivek G wrote:
> > 
> > > - Do you mean with Length = variable, that the size of this field
> > > can
> > be
> > >   extended depending on the information sent (like in .16)?
> > [Vivek G Gupta]
> > Yes
> 
> I think that Kalyan's question is as to whether the length of the 
> Length field is variable.  The length of the Length field should be 
> constant.  So the answer should be *No*.
> 
> > 
> > >   I find, having a Length field of 2 Bytes is, in most cases, more
> > than
> > > enough.
> > >   i.e., 1 Byte can server the purpose in most of the cases.
> > > 
> > [Vivek G Gupta]
> > 1 byte is definitely inadequate. We can go with 2.
> 
> Yes, we can go with 2.
> 
> Yoshihiro Ohba
> 
> > 
> > > 
> > > With best regards,
> > > Kalyan
> > > 
> > 
> 
> 


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