Subject: MPLS and ATM

From: "Constantine Protopapas" <[email-masked]>
Date: Sun, 9 Jan 2000 20:50:47 +0200

How does exactly MPLS fits in a network with ATM core?
On network that has an ATM core, ATM takes care of switching and
prioritising, so instead of using MPLS-enabled routers (that need quite a
lot of processing power), MPOA-enabled ATM switches can be used.

Constantine Protopapas
Systems/Network Engineer
Applied Science
62 Karpenisioti Str.
GR 115 24 N. Filothei
Athens
GREECE
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From: Jeremy Lawrence <[email-masked]>
Date: Mon, 10 Jan 2000 13:41:28 +1100

Constantine,

>lot of processing power), MPOA-enabled ATM switches can be used.

There are, broadly, two modes of relationship between MPLS and ATM:

In ATM MPLS, IP routing (OSPF, IS-IS, etc.) and MPLS act as a
connection control system for a (typically) AALx-compliant ATM
fabric. ATM is still taking care of switching and prioritizing,
but IP routing and MPLS are routing and signalling the ATM
connections. (IP routing and MPLS may do this either instead
of, or in parallel with, an (S)PVC/SVC routing system like
PNNI.) An ATM switch with an IP routing/MPLS control system is
referred to as an ATM Label Switch Router (ATM-LSR).

MPLS can also be tunneled through non-MPLS capable ATM switches,
either using (S)PVCs (which act much like any other
point-to-point link between MPLS-capable routers), or (S)PVPs.
If (S)PVPs are used, then they form ATM virtual trunks which can
be used to link ATM edge LSRs (ATM MPLS-capable routers) and/or
ATM-LSRs.

MPOA and MPLS are different solutions which are not closely
related to each other. MPOA is intended largely for LAN/MAN
applications, i.e. linking hosts to each other, and linking
hosts to routers. MPLS, on the other hand, is designed for
applications involving the use of many routers, typically
in WANs.

Hope this helps,

Jeremy Lawrence