The MPLS WG Archive

[Maarten Vissers <mvissers@lucent.com>]

Neil, Nuno,

I get the impression that a LSP is being used for both the trail and a
tandem connection (subnetwork connection). But also as a tributary slot
identifier. 

	Note - Tributary slot identifiers in other technologies are: 
	VPI, VCI, time slot, frequency slot (wavelength).

A tributary slot identifier is bound to a "link connection". 
A signal passing through from an incoming link connection (via a "matrix
connection" in a fabric) to an outgoing link connection may see a
tributary slot identifier change. E.g. VPI_in=124 => VPI_out=765,
timeslot_in=1, timeslot_out = 18, lambda_in = 15 => lambda_out = 63, and
label_in=5354 => label_out=678521.

TTP and CTP are terms defined in association with the information
modelling. 
*	A TTP in the information model is equivalent with a Trail Termination
function (_TT) and the common part of the Adaptation function (_A) in
the functional model. 
*	A CTP in the information model is equivalent with the Connection Point
at the Connection function (_C) and the client specific part of the
Adaptation function (_A) in the functional model.

A link connection (LC) starts at a CTP and ends at the next CTP:
	Link Connection: CTP - server layer trail - CTP

A matrix connection (MC) starts at a TTP/CTP and ends at the TTP/CTP at
the other end of the fabric (connection function):
	Matrix Connection: TTP/CTP - TTP/CTP

A matrix connection is the smallest subnetwork connection (SNC).
A subnetwork connection is in general defined as:
	SNC: SNC - LC - SNC, with the smallest SNC being a MC.



>  TTPs - are the IP interfaces/ports?

TTPs are the LSP termination points, where bits 20-31 of the MPLS label
are added/removed and the information in the payload of this MPLS packet
extracted.

>  CTPs- are the labels?

CTPs are the boundaries of the link connection. The 20-bit label value
is added/removed here. A link connection starts/ends at each LSR and
LER.

Associated with a CTP may be a tandem connection TTP. Such tandem
connection TTP adds another 32-bit MPLS label and associated MPLS OAM
packet flow.

>  LCs - are the connections/associations between 2 labels in two
>  different LSRs?

A LC is the connection between the egress of one LSR [or LER] and the
ingress of the next LSR [or LER].

>  SNCs- are the forwarding tables in the LSRs and LERs? (a connection
>  between the TTP and CTP in the LER, or a connection between CTPs in
>  the LSRs)?

The set of MCs (matrix connections) are the forwarding tables in the
LSRs and LERs.


Up to so far.

Regards,

Maarten


Nuno Silva wrote:
> 
> Neil et all,
> 
>  Under the scope of G.805 (March 2000), do you think it makes sense to model
> an LSP as a Network Connection, composed by a concatenation of SNCs and LCs
> (if so, what would be the subnetwork connections, the link connections, the
> TTPs and CTPs), or as an IP trail?
> 
>  TTPs - are the IP interfaces/ports?
>  CTPs- are the labels?
>  LCs - are the connections/associations between 2 labels in two different
> LSRs?
>  SNCs- are the forwarding tables in the LSRs and LERs? (a connection between
> the TTP and CTP in the LER, or a connection between CTPs in the LSRs)?
> 
>  So the question is indeed, is the functional architecture defined in G.805
> applicable to the MPLS/MPlambaS worlds?
>  How does this cope with G.cls (connectionless) work?
> 
>  Thanx ahead. Nuno.
> 
> 
> Nuno Carvalho Silva
> PT Inovação, SGR
> 
> Phone: + 351 234 403 394
> Fax: + 351 234 424 160
> E-mail: nunos@ptinovacao.pt
> 
> > -----Original Message-----
> > From: neil.2.harrison@bt.com [SMTP:neil.2.harrison@bt.com]
> > Sent: Wednesday, December 06, 2000 10:07 PM
> > To:   Juergen.Heiles@icn.siemens.de; jdrake@calient.net; mpls@UU.NET
> > Cc:   ip-optical@lists.bell-labs.com
> > Subject:      RE: [IP-Optical] GMPLS - Hierarchies
> >
> > <snipped>
> >
> > > Furthermore a LSP -at least for circuit switching - doesn't have to
> > start
> > > and end at the trail termination where you extract your payload.
> >       NH=> I fudamentally disagree *if* we are adhering to functional
> > arch.
> > >  A LSP could be used only for a sub part of the overall connection, e.g.
> > a
> > > DS1 signal starts in a user domain with tradional TMN path setup or even
> > > manual connections, the DS1 comes to a operator which uses GMPLS for
> > path
> > > -setup (in this case a permanent connection set-up by himself as the
> > user
> > > doesn't support the UNI). The LSP starts in the middleof the overall DS1
> > > connection and no access to the paylaod of the DS1 is requried at that
> > > point.
> >       NH=> The DSI signal is 'an LSP' in its own right......it is, after
> > all, a clear layer network trail entity.  The fact that it may be served
> > (on
> > link connections, which are a partition of the end-end DS1 trail) by lower
> > layer "LSPs" (which could be a DS3, VC4, ODU, etc.......and which
> > themselves
> > are trails *but* only between their points of source/sink) is
> > academic.....the DS1 trail is completely unaware of this, and the layering
> > recursion of client_links=>server_trails can recurse many times.......its
> > stops at the duct network.
> >       Your example *must*, and indeed does, fit this.
> >       neil
> >
> > >
> >
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> > IP-Optical@lists.bell-labs.com
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> 
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