The MPLS WG Archive

["David Allan" <dallan@nortelnetworks.com>]

Title: RE: question on e-lsp and l-lsp

That and the fact that VCCs by design do not support multiple queuing disciplines. Shuffling the cell order tends to cause problems ;-)

Dave

> -----Original Message-----
> From: Proch, Daniel [mailto:Daniel.Proch@marconi.com]
> Sent: Thursday, November 01, 2001 4:40 PM
> To: 'Vishal M'; mpls@UU.NET
> Subject: RE: question on e-lsp and l-lsp
>
>
> Vishal,
>
> Somewhere I read that E-LSP shouldn't be used for
> ATM-LSR. Could someone please explain why ?
>
> MPLS over ATM (cell) interfaces uses the existing ATM cell
> structure and
> what were the contents of the VPI field or the combined
> VPI/VCI fields to
> infer a label.  There are no EXP bits in the header and therefore only
> L-LSPs can be supported on LC-ATM interfaces. 
>
> dan
>
> -----Original Message-----
> From: Vishal M [mailto:vishal_study@yahoo.com]
> Sent: Thursday, November 01, 2001 3:59 PM
> To: mpls@UU.NET
> Subject: Re: question on e-lsp and l-lsp
>
>
>
> Hi,
>
> I have some followup questions on L-LSP and E-LSPs:
>
> 1. Can we map multiple CTs onto a single L-LSP ? The
> draft seem to suggest that creation of a separate LSP
> can be done for every CT.
>
> Is creation of separate L-LSP mandatory for every CT
> or  is it left to the implementation?
>
> 2. Somewhere I read that E-LSP shouldn't be used for
> ATM-LSR. Could someone please explain why ?
>
> Thanks for your time,
> Vishal.
>
> "Fan, Zhong" wrote:
> >
> > Can anybody shed some light on the differences
> between e-lsp and
> > l-lsp please? I'm reading
> draft-ietf-mpls-diff-ext-09.txt at the
> > moment. Although the draft gives denifition of these
> two kinds of
> > LSPs, I am still confused. Is this all about the
> mapping of diffserv
> > classes to MPLS FEC or EXP?
>
> The draft explains the differences.
>
> In superbrief summary;
>
> - An L-LSP has one QoS for all packets.  It is
> determined at LSP
>   setup.  This is similar to setting up an LSP without
> any DiffServ
>   extensions, except that the objects used in the
> signaling are
>   different.
>
> - An E-LSP has up to 8 QoS levels for the single LSP.
> The EXP bits
>   determine the appropriate QoS on a per-packet basis.
>  The QoS that
>   is assigned to each EXP value is signaled at LSP
> setup (or is a
>   configured default if the values are not signaled.)
>
> -- David
>
>
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