The MPLS WG Archive

["James R. Leu" <jleu@laurelnetworks.com>]

On Thu, Apr 13, 2000 at 04:19:17PM +0200, NENDERLE@bouyguestelecom.fr wrote:
> Hello, 
> 
> I have a few questions about IP routing capability of  LSRs : 
> 1 - Does a core LSR is able to achieve classic IP routing and is there a
> special label to mean that the MPLS packet is to be considered as an IP
> packet ?

Yes and no :-)

If your planning on running RSVP-TE the LSR will need to have some form of
IP forwarding (and Router Alert Bit procesing) while with (CR)LDP the LSR
only needs to be able to create and terminate TCP sessions.  The LDP protocol
terminates and possible re-originates every LDP message.

A good place to start understanding this differnce it to look at the source
and destination addresses in the PDUs of the differnt MPLS signaling protocol.
In RSVP the destination address is the address of the LER that will terminate
the LSP.  In LDP the destination address is one of the interfaces on the
directly connected peer.

I hope this helps.
-- 
James R. Leu            |    Laurel Networks
Software Engineer       | Switching Systems for the
jleu@laurelnetworks.com |    Optical Internet 


> 
> 2 - If not, how LDP (relying on TCP) messages (LABEL_REQUEST and
> LABEL_MAPPING) can be adressed to a core LSR without a label ?
> 
> Thanks,
> 
> Nicolas.
> > **************************************************************************
> > ****
> > Nicolas ENDERLE
> > Bouygues Telecom - R & D
> > Engineer at the Research and Developpement Center
> > Tél :	+33 1 39 45 38 67
> > 	+33 6 61 31 38 67    email : nenderle@bouyguestelecom.fr
> > Fax :	+33 1 39 26 86 13
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