multi-protocol label switchingmulti-protocol label switching · multi-protocol label...

© M. Baldi: see page 2MPLS - 1

MPLSMulti-protocol label switching

MPLSMulti-protocol label switching

Mario BaldiPolitecnico di Torino

(Technical University of Torino)

http://staff.polito.it/mario.baldi

Mario BaldiPolitecnico di Torino

(Technical University of Torino)

http://staff.polito.it/mario.baldi


Copyright noticeThis set of transparencies, hereinafter referred to as slides, is protected by copyright laws and provisions of International Treaties. The title and copyright regarding the slides (including, but not limited to, each and every image, photography, animation, video, audio, music and text) are property of the authors specified on page 1.

The slides may be reproduced and used freely by research institutes, schools and Universities for non-profit institutional purposes. In such cases, no authorization is requested.

Any total or partial use or reproduction (including, but not limited to, reproduction on magnetic media, computer networks, and printed reproduction) is forbidden, unless explicitly authorized by the authors by means of written license.

Information included in these slides is deemed as accurate at the date of publication. Such information is supplied for merely educational purposes and may not be used in designing systems, products, networks, etc. In any case, these slides are subject to changes without any previous notice. The authors do not assume any responsibility for the contents of these slides (including, but not limited to, accuracy, completeness, enforceability, updated-ness of information hereinafter provided).

In any case, accordance with information hereinafter included must not be declared.

In any case, this copyright notice must never be removed and must be reported even in partial uses.


The ideaThe idea

Instead of the IPdestination addressInstead of the IP

destination address

Forwarding packets according to a labelForwarding packets according to a label

LabelLabel IP packetIP packet


Why?Why?

The label may be used as an indexThe label may be used as an index

Faster lookupFaster lookup

Traffic engineeringTraffic engineering

Instead of longest prefix matchingInstead of longest prefix matching


Network architectureNetwork architecture

Label edge routerIngress/egress LSRLabel edge routerIngress/egress LSR

Label switch router (LSR)Label switch router (LSR)

MPLS networkMPLS cloud

MPLS networkMPLS cloud


Egress LSREgress LSR

Ingress LSRIngress LSR

Label Switched Path (LSP)Label Switched Path (LSP)


Label switchingLabel switching

DD

DD

11223344

0033

00

1122

33

0011

00

22

AA

DD

XX

00

00

11

11

InIn OutOut

22

22

11

InIn OutOut

00

11

InIn OutOut

00

11InIn OutOut

00

11112222

00

DD


MPLS “header”MPLS “header”

Contains the labelContains the label

MPLS key elementsMPLS key elements

Upgraded routing protocolsUpgraded routing protocols

Constraints in choosing pathsConstraints in choosing paths

Protocols for label distribution Protocols for label distribution

SignalingSignaling


MPLS introduces a connection-oriented

paradigm in IP networks

MPLS introduces a connection-oriented

paradigm in IP networks


Shim headerShim headerMPLS headerMPLS header

Level 2Level 2 IP packetIP packet

LabelLabel ExpExp SS TTLTTL20 bit20 bit 3 bit3 bit 8 bit8 bit11

TTL: Time to liveTTL: Time to live

Exp: Experimental bits (CoS)Exp: Experimental bits (CoS)S: Bottom of stackS: Bottom of stack


VCI/VPI (ATM)VCI/VPI (ATM)

MPLS labels in layer 2 headerMPLS labels in layer 2 header

Connection oriented layer 2protocols

Connection oriented layer 2protocols

ATM and frame relayATM and frame relay

DLCI (Frame relay)DLCI (Frame relay)


Forwarding equivalence class (FEC)Forwarding equivalence class (FEC)

Packets thatPackets that

Follow the same pathin MPLS network

Follow the same pathin MPLS network

Are treated the same wayby each LSR

Are treated the same wayby each LSR

Receive the same label Receive the same label


Input labelInput label

Output portOutput port

LSP CreationLSP Creation

Label MappingLabel Mapping

The label used by the downstream switch of a link for packets

belonging to a FEC is associated to

The label used by the downstream switch of a link for packets

belonging to a FEC is associated to


Static label binding (and mapping)Static label binding (and mapping)

Through managementThrough management

Non-scalableNon-scalable

Equivalent to PVC ATMEquivalent to PVC ATM

No interoperability among managing systemsNo interoperability among managing systems

Impossible to have LSPs through different networksImpossible to have LSPs through different networks


Dynamic label bindingDynamic label binding

Protocol (IP) drivenProtocol (IP) driven

Explicit creation of LSPExplicit creation of LSP

The creation of LSPs is linked to the discovery of routes towards destinations

The creation of LSPs is linked to the discovery of routes towards destinations

Explicit signalingExplicit signaling

Initiated by label edge routersInitiated by label edge routers


Routing protocol: BGPRouting protocol: BGP

Only protocol drivenOnly protocol driven

Designed for allocation in integrated service networksDesigned for allocation in integrated service networks

Resource reservation protocol (RSVP)Resource reservation protocol (RSVP)

Label distribution protocolsLabel distribution protocols

Three alternatives (incompatible)Three alternatives (incompatible)

Label distribution protocol (LDP)Label distribution protocol (LDP)

Designed for the purposeDesigned for the purpose


Routing protocolsRouting protocols

Used to determine LSP routingUsed to determine LSP routing

Guide label binding proceduresGuide label binding procedures

They indirectly determine packet routingThey indirectly determine packet routing


carry topology informationcarry topology information

Routing protocolsRouting protocols

Existing protocolsExisting protocols

IS-ISIS-IS

OSPFOSPF

BGP-4BGP-4

In MPLS context

they are enhanced d to...

In MPLS context

they are enhanced d to...


New possibilitiesNew possibilities

Traffic engineeringTraffic engineering

Per-class traffic engineeringPer-class traffic engineering

Guaranteed quality of serviceGuaranteed quality of service

Fast fault recoveryFast fault recovery

Not yet supportedNot yet supported

In less than 50 msIn less than 50 ms

Synergy with DiffServSynergy with DiffServ


StandardizationStandardization

IETF –Internet Engineering Task ForceIETF –Internet Engineering Task Force

FR/MPLS AllianceFR/MPLS Alliance

MPLS working groupMPLS working group

Consortium of producersConsortium of producersSpeed up spreadingSpeed up spreadingAspects omitted by IETFAspects omitted by IETF

VoMPLS, ADSLVoMPLS, ADSL


BibliographyT. Tofoni, “MPLS – Fondamenti e applicazioni alle reti IP”, Hoepli, 2003

IETF MPLS Working Group, http://www.ietf.org/html.charters/mpls-charter.html

E. Rosen, A. Viswanathan, R. Callon, “Multiprotocol Label Switching Architecture,” RFC 3031, Standards Track, Jan. 2001

E. Rosen, D. Tappan, G. Fedorkow, Y. Rekhter, D. Farinacci, T. Li, A. Conta, “MPLS Label Stack Encoding,” RFC 3032, Standards Track, Jan. 2001


Bibliography

F. Le Faucheur, et al., “Multi-Protocol Label Switching (MPLS) Support of Differentiated Services,” RFC 3170, Standards Track, May 2002

Davie, B., Lawrence, J., McCloghrie, K., Rekhter, Y., Rosen, E., Swallow, G. and P. Doolan, "MPLS using LDP and ATM VC Switching", RFC 3035, January 2001.

Andersson, L., Doolan, P., Feldman, N., Fredette, A. and B. Thomas, "LDP Specification", RFC 3036, January 2001.

multi-protocol label switchingmulti-protocol label switching · multi-protocol label...

Documents