can any tell me about positive and negative justification in detail
Mr.Kool
what is positve and negative justification and why is it needed in STM
frame.
is there any web link or some tutorial in which this is explained in
detail?
if the data is coming from a node to another node and if both the
nodes are having same clock with some ppm difference. will the
receiver nodel be able to know it is having PPM difference with
transmitter node,
Pieter Hulshoff
> frame.
VCs mapped into an STM-n frame may not be based on the same clock as the STM-n
frame nor off each other. As such, the VC payload must be able to float within
the STM-n frame, and a pointer is used to locate the start of the VC within the
STM-n frame. Positive and negative pointer adjustments are needed to compensate
for the difference in frequency between the VC payload and the enveloping STM-n
frame.
> is there any web link or some tutorial in which this is explained in
> detail?
You can probably find some on Google (like the ITU standards), but I'd advice
getting a good book on SDH in stead. I'm sure someone will be along shortly to
give you advice on which book to get. :)
> if the data is coming from a node to another node and if both the
> nodes are having same clock with some ppm difference. will the
> receiver nodel be able to know it is having PPM difference with
> transmitter node,
When the node performs pointer processing, the elastic store will quickly
indicate frequency differences, and a proper pointer processing algorithm will
be able to handle that within certain boundaries.
Kind regards,
Pieter Hulshoff
Huub van Helvoort
In additioon to what Peter replied:
>> what is positve and negative justification and why is it needed in STM
>> frame.
>
> VCs mapped into an STM-n frame may not be based on the same clock as the STM-n
> frame nor off each other. As such, the VC payload must be able to float within
> the STM-n frame, and a pointer is used to locate the start of the VC within the
> STM-n frame. Positive and negative pointer adjustments are needed to compensate
> for the difference in frequency between the VC payload and the enveloping STM-n
> frame.
Indeed.
>> is there any web link or some tutorial in which this is explained in
>> detail?
>
> You can probably find some on Google (like the ITU standards), but I'd advice
> getting a good book on SDH in stead. I'm sure someone will be along shortly to
> give you advice on which book to get. :)
If you go to this site:
http://www.lagrit.etsmtl.ca/seminaires/SonetFlash/
ans click on 7.3 you get a life demo of pointer adjustments
that you can control yourself... ;-)
If you look for books, check my website below.
If you can wait a few month then you can buy an SDH/SONET
pocketguide from the IEEE that provides the information
you want.
>> if the data is coming from a node to another node and if both the
>> nodes are having same clock with some ppm difference. will the
>> receiver nodel be able to know it is having PPM difference with
>> transmitter node,
Because SDH and SONET are synchronous networks using a single clock
for the whole network, this should not normally happen, only temporary
differences of clock caused by jitter and wander may be seen.
> When the node performs pointer processing, the elastic store will quickly
> indicate frequency differences, and a proper pointer processing algorithm will
> be able to handle that within certain boundaries.
Because each node supports pointer justification, the received
(extracted) clock is used for the incoming STM frame recovery.
The incoming clock is not locked to the outgoing clock.
Cheers, Huub.
--
reply to hhelvooort with 2 'o's
================================================================
http://www.van-helvoort.eu/
================================================================
Always remember that you are unique...just like everyone else...
Pieter Hulshoff
> In additioon to what Peter replied:
...and we used to work about 40 meters away from each other...
Pieter Hulshoff
Huub van Helvoort
You wrote:
>> In additioon to what Peter replied:
> -----
>
> ...and we used to work about 40 meters away from each other...
At least in English it is pronounced the same.
Actually more the same as *someone* vs *Huub*...
Regards, Huub.