The MPLS WG Archive

["Peter Ashwood-Smith" <petera@nortelnetworks.com>]

Title: RE: [mpls] what routing protocols have what to do with QoS?

I like Kireeti's better ;) ... I'm reminded of that wonderful chapter in Hitch Hiker's guide ... Hopefully MPLS won't disappear in a 'puff of logic' ;)

I used to present MPLS as an L3 protocol controlling an L2.5 data path.
I.e. between Ethernet and IP.

GMPLS was described as an L3 protocol controlling an L0(lambda) or L1(TDM) data path.

Many people get confused by this separation of control/data plane when learning about (G)MPLS.

Peter

-----Original Message-----
From: mpls-bounces@lists.ietf.org [mailto:mpls-bounces@lists.ietf.org]
Sent: Saturday, November 13, 2004 5:49 PM
To: Kireeti Kompella
Cc: mpls@ietf.org
Subject: Re: [mpls] what routing protocols have what to do with QoS?

Kireeti,

> On Thu, 11 Nov 2004, SP wrote:
>
> > since MPLS over ip over ethernet...
> > and since ip over ethernet (layer 3 over layer 2)...
>
> Let MPLS be Layer N.
>
> By the above, N > 3.
>
> You can also carry Ethernet over MPLS,
>
> Hence, 2 > N.
>
> Therefore, 2 > 3.  QED.
>
> Hope that helps :-)

Just to help more, here are few points from one of my presentations on (G)MPLS:

(G)MPLS is not a Network Layer on its own, as it does not have routing and addressing on its own - it uses IP addressing + IP routing (with

extensions)

(G)MPLS is not a Link Layer because MPLS works over various Link Layer technologies (e.g., SONET, Ethernet, ATM, etc.)

(G)MPLS is not a Layer in the OSIRM (OSI Reference Model) sense as it does not have a single format for transport of the data from the layer above (e.g., (G)MPLS uses "shim" on SONET, VCI/VPI on ATM, time slot on TDM, lambda on OXC, etc...).

Yakov.

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