odc010007 mpls te overview issue1_0

8/13/2019 Odc010007 Mpls Te Overview Issue1_0

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HUAWEI TECHNOLOGIES CO., LTD. All rights reserved

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ODC010007 MPLS TE

overview

ISSUE 1.0

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HUAWEI TECHNOLOGIES CO., LTD. Page 1All rights reserved

MPLS (Multiprotocol Label Switching)

has been successfully configured and

applied in a number of large network.MPLS TE is a perfect combination

technology of MPLS and TE, with best

resources architecture and most

resources usage percentage.

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References

l VRP5 operation manual MPLS

chapter

l MPLS TE user guide!



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Upon completion of this course, you will be

able to:

[ Be known detailed TE concepts and

models

[ Be known MPLS technology specifics

and priorities

[ Master MPLS TE background and

function module



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Chapter 1 What is TEChapter 1 What is TE

Chapter 2 MPLS introductionChapter 2 MPLS introduction

Chapter 3 MPLS TEChapter 3 MPLS TE



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1.1 What is TE1.1 What is TE

1.2 TE before MPLS1.2 TE before MPLS



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Concept of TE

l Two engineering concepts appear accompany with the growth of

network size:

[ NE (Network Engineering)

NE is the process of how to plan, design and implement a

network to satisfy the real traffic requirements. First real traffic

requirements, then network design and implementation.

[ TE (Traffic Engineering)

TE is the process of how to configure and implement the

already exists network equipments to make the traffic beennormally transmitted. First exists network equipments, then

reconfigure them.

NE (Network Engineering) and TE (Traffic Engineering)



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What is TE

l !Traffic Engineering is the process of controlling

how traffic flows through one"s network so as to

optimize resource utilization and networkperformance#"

(Global Crossing, IEEE)



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Why we need TE

A major goal of Internet Traff ic Engineeri ng is to facil itate eff icient and

reliable network operations whiles simultaneously optimizing network

resource uti l ization and performance.

#RFC 2702 Requirements for Traffic Engineering over MPLS$



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Why we need TEcont.!

l Reduce OPEX costs through more efficient bandwidth

usage

l

Avoid possible part link busy or empty throughappropriate rearranging traffic

l Make the best network resources usage and improve

network performance through good redesigning traffic

TE target



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TE performance

l TE performance consists of two parts%

[ Performance oriented services: enhanced services QoS

performance. i.e. effect to packet loss, latency, throughput and

SLA#Service Level Agreement$

[ Performance oriented resources: optimize resources usage.

Bandwidth is precious resource, to arrange them efficiently is the

core target of TE

performance



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1.1 What is TE1.1 What is TE

1.2 TE before MPLS1.2 TE before MPLS



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Earlier TE introduction

l TE is not the result of MPLS, it is general technology project

l Before MPLS TE, technology mainly used to generate TE are:

[ ATM TE

[ IP TE

ATM TE and IP TE



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IP TE

l IP TE can be easily used without much detailed technology

l IP TE cannot control transmission path based on traffic sources,

but on destination forwarding

l IP TE mainly change special link cost value of IGP metric to

control traffic

IP TE



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IP TE"fish problem

R2

R8

R1

IP routing: destination-based shortest path route

under-utilized alternate path

Path for R2-R3-R4-R5-R8 traffic


l All traffic from R1 or R2 will select R3-R4-R5 path arriving R8

R3

R4

R5

R6 R7

1010

10

10

10



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IP TE"fish problem

l Change R3-R6-R7-R5 cost value, all traffic from R1 or R2 will shift on it

R2

R8

R1

under-utilized alternate path



R3

R4

R5

R6 R7

1010

5

5

5

IP routing: destination-based shortest path route



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IP TE weakness

l It is far less enough that calculate path only based on IGP metric value,

instead of considering bandwidth, link properties and others factor

l IP TE is essentially destination-based forwarding technology, it is hop-by-

hop forwarding, can not control traffic by sources

l IP TE is connectionless-oriented, can not support Explicit Routing

IP TE weakness



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ATM TE

l ATM TE mainly generated by PVC through traffic source to traffic

destination

l ATM TE is connection-oriented, can be well and easily done to arrange

traffic flow and put QoS

l ATM TE is necessarily applied in full-mesh network, which exists of O#N$$

problem, results in bad extensibility

l ATM TE is end-to-end TE, not so as to IP TE hop-by-hop

ATM TE



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ATM TE"Overlay Solution

l Physical architecture: Layer 2#ATM/FR$ built base on ATM TE

l Logically: the full-mesh network consists of all Layer 3#Routers$

equipments, in this network, each router has unique VC connected with anyother router

L3L3

L3L3

L3L3

L3L3

L3L3

L3L3

L3L3

L2L2

L2L2

L2L2

L2L2

L2L2

L2L2

L3L3

L3L3

L3L3

L3L3 L3L3

Physical Logical



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ATM TE weakness

l In case of carry out ATM TE in traditional IP network, telecom operator

need to buy new ATM/FR equipments, it will increases OPEX costs in a

large scale

l ATM TE will bring extra and more complex network management costs

[ Two layer network: ATM and IP equipments are difficult to manage

together

[ Different equipment will bring extra training works, technique support

works, and project implement works

l

Full-mesh network architecture exists of O#N$$ problem, bad extensibility

l IP over ATM will results in extra Cell Tax

ATM TE weakness



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Question

l IP TE and ATM TE have their superiority and inferiority

respectively, how can we do to keep superiority and to

discard inferiority



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2.1 MPLS basis2.1 MPLS basis

2.2 MPLS superiority2.2 MPLS superiority



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MPLS basis

l In MPLS network, the IP packet is added with one or more MPLS header at

the length of 32 bits

l

MPLS is a concept between OSI layer 2 and layer 3 which can supportvariety of network protocol (IPV4/IPV6/ATM/FR)

l Earlier MPLS technology intent is improving router forwarding speed

MPLS packetMPLS packet

IP Packet

32-bit

MPLS Header



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MPLS basiscont.!

l 20 bits label, mapping traffic into LSP, in the range of 16-1,000,000

l EXP consists of 3 bits, indicate MPLS QoS

l S has only 1 bit, indicate the last label in the label queue

l TTL has the same function as IP has, the purpose is inspecting and avoiding

generating routing loop in Frame mode

MPLS headerMPLS header

TTLLabel EXP S



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2.1 MPLS basis2.1 MPLS basis

2.2 MPLS superiority2.2 MPLS superiority



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MPLS superiority

l MPLS technology use fixed length label searching instead of traditional

IP routing longest match search method, rapidly improve forwarding

speed, this is the beginning MPLS intension

l MPLS can combine IP and ATM well, save extra cell tax of IPOA

l MPLS true superiority is to provide variety of value-added service:

[ MPLS VPN

[ MPLS QoS

[ MPLS Traffic Engineering

MPLS superiorityMPLS superiority

Network goingdirection



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3.1 MPLS TE development3.1 MPLS TE development

3.2 MPLSTE necessary condition3.2 MPLSTE necessary condition

3.3 MPLSTE elements3.3 MPLSTE elements



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MPLS TE development

l In Sept, 1999, RFC 2702#Requirements for Traffic Engineering Over

MPLS$give detailed necessary conditions of building network based

on MPLS TE, make a good fundamental for MPLS TE development

and application

l Since TE is a global complex system project, generating and

implementation is fairly difficult, nowadays, only small number of

network provider can provide scaleable application

l MPLS TE is a perfect combination of MPLS and TE, which is definite

trend of large scale network provider building core network andbackbone

MPLS TE developmentMPLS TE development



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MPLS TE realization method

l Nowadays main MPLS TE realization method:

[ RSVP-TE

RSVP-TE technology is mature, has been scaleable applied, but

too complex and bad extensibility

[ CR LDP-TE

CR LDP-TE technology is not very mature, rarely applied, but

simple, good extensibility

[ RSVP-TE is widely and mainly used

MPLS TE realization methodMPLS TE realization method



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MPLS TE necessary condition1!

l Support creating end-to-end LSP-based tunnel

l Support tunnel preempt function by different priority

l Support failure inspection switch function, when one link or node

fail, the other can quickly take over

l Support pre-creating backup LSP

MPLS TE necessary conditionMPLS TE necessary condition



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l Support LSP tunnel auto re-optimize by the change of network

resource

l Support LSP tunnel bandwidth auto adjustment by the change

of network bandwidth

l Support explicit path, can be set include or exclude node by

field requirement

l Support priority LSP tunnel, different priority traffic will input into

different tunnel respectively with DiffServ

MPLS TE necessary condition2!

MPLS TE necessary conditionMPLS TE necessary condition



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MPLS TE four elements

l MPLS TE four elements:

[ Information distribution

[ Path calculation

[ Signaling#or path setup$

[ Packet forwardingl Four elements can guarantee basic traffic forwarding, but not very

accurate

l MPLS TE also support some high level specification

[ FRR#Fast Reroute$

[ Tunnel backup

[ Auto Bandwidth Allocation

[ Path Re-optimum

MPLS TE four elementsMPLS TE four elements



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l TE is separate from MPLS essentially, the

original intent is well utilize whole network

resources

l MPLS is a combination of IP and ATM both

superiority, can provide variety ofapplications, i.e. MPLS VPN, MPLS TE

l MPLS TE is perfect combination of MPLS

and TE technology, can make network

resources well optimized, improve network

performance

SummarySummary



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