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Re: sdh Doubt
Manoj, Sasha,
Once you have connected two STM-N (e.g. STM-256) ports together you have
created a MSn (e.g. MS256) trail. Such MSn trail supports a HOVC
topological link (G.85x terminology). This HOVC link contains a number
of HOVC link connections.
An STM-256 trail may support the following link connection types: VC-3,
VC-4, VC-4-4c, VC-4-16c, VC-4-64c and VC-4-256c.
The specific set of HOVC link connections supported by a particular HOVC
link is STM-N port pair dependent. This depends on the capabilities
supported by the AU pointer processor circuits in these ports and the
capabilities supported by the fabrics to which these ports are
connected.
E.g. STM-256 port A may support AU-4, AU-4-4c and AU-4-16 pointer
processing, whereas the STM-256 port B to which it is A is connected may
support AU-3, AU-4 and AU-4-4c pointer processing. The STM-256 port pair
then supports VC-4 and VC-4-4c link connections within this HOVC
topological link.
If at time Ta a particular AUG-4 entity within the STM-256 is
provisioned to operate as AU-4-4c and transport a VC-4-4c signal, and
the associated connection is removed at time Tb, then this AUG-4
bandwidth may be used at Tc > Tb for wither 4 VC-4 connections or 1
VC-4-4c connection. For the former case (4x VC-4) the VC-4-4c link
connection supported by AU-4-4c pointer processing must be converted
into 4 VC-4 link connections supported by 4x AU-4 pointer processing.
The same is applicable if a STM-256 trail supporting a HOVC link with
VC-4-256c link connection capability has to transport e.g. a VC-4-64c.
The transport of a VC-4-64c is only possible if the VC-4-256c connection
is not longer present. If not longer present, the whole HOVC link
bandwidth is available for other services, and to support a VC-4-46c the
VC-4-256c link connection is replaced by a VC-4-64c link connection
(supported by AU-4-64c pointer processing) and the remainder of the
bandwidth is set to support e.g. VC-3 link connections. These latter
ones will then carry VC-3 UNEQ signals. But any other VC-n level may
also be choosen... but both ends of the HOVC link must decide one the
same VC-n type; otherwise you get a series of AU-LOP alarms from these
endpoints.
Note that according G.707 the AUG-X isn't a signal; it is only a means
to describe the ordering and multiplex structure of AUs. In reality, you
have a mix of AU-3, AU-4, AU-4-4c, AU-4-16c, AU-4-64c or one AU-4-256c
processing active. In most equipment you can change this mix when
required.
Regards,
Maarten
Sasha Vainshtein wrote:
>
> Manoj,
> AFAIK, the answer is YES. In SDH, once you have performed concatenation,
> on a certain stream, you cannot allocate access separate substreams.
>
> With best regards,
> Sasha Vainshtein
> email: sasha@axerra.com <mailto:sasha@axerra.com>
> tel: +972-3-7659993 (office)
> +972-8-9254948 (res.)
> +972-58-674833 (cell.)
>
>
> > -----Original Message-----
> > From: manoj juneja [mailto:manojkumarjuneja@hotmail.com]
> > Sent: Wednesday, June 27, 2001 9:12 PM
> > To: ccamp@ops.ietf.org
> > Subject: sdh Doubt
> >
> >
> > Hi All,
> > AUG-256 may consist of :
> > 1. 4 AUG-64
> > 2. 1 AU-4-256c
> >
> > If AUG-256 consists of 1 AU-4-256c, does this mean it can't
> > allocate
> > signals of less granularity than this (viz. one VC-4 or
> > VC-4-64c or VC-4-16c
> > etc) ?
> >
> > Regards,
> > manoj.
> >
> > _________________________________________________________________
> > Get your FREE download of MSN Explorer at http://explorer.msn.com
> >
> >
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