hciers和参考-hcie电子版2-2mpls协议原理

前

言本课程分析了传统IP在转发速率、Qos和流量工程方面的缺陷，介绍了MPLS转发的基本特点。Page1培训目标学完本课程后，您应该能：描述IP转发流程描述IP转发的缺点解释MPLS转发基本原理描述MPLS应用Page2MPLS概述MPLS基本原理

MPLS环路检测Page3MPLS

概述传统IP转发MPLS

转发特点MPLS应用Page4传统IP转发SWASWBSWCSWD10.1.0.0/2410.2.0.0/24v1v110.1.1.0/30

v2

v210.1.1.4/30v3v310.1.1.8/3010.1.0.0/3010.2.0.0/30Data10.2.0.1Page5传统IP转发(SWA)10.1.0.0/24SWAv110.1.1.0/30NetworkNexthop10.1

0.0/2410.1.0.210.1.0.1/3210.1.0.110.1.1.0/3010.1.1.110.1.1.2/3210.1.1.210.1.1.4/3010.1.1.210.1.1.8/3010.1.1.210.2.0.0/2410.1.1.210.1.0.0/3010.2.0.1

DataPage6传统IP转发(SWB)SWB

v1

10.1.1.0/30v210.1.1.4/30NetworkNexthop10.1

0.0/2410.1.1.110.1.1.0/3010.1.1.210.1.1.1/3210.1.1.110.1.1.4/3010.1.1.510.1.1.6/3210.1.1.610.1.1.8/3010.1.1.610.2.0.0/2410.1.1.6Page7传统IP转发(SWC)SWC

v210.1.1.4/30v310.1.1.8/30NetworkNexthop10.1

0.0/2410.1.1.510.1.1.0/3010.1.1.510.1.1.4/3010.1.1.610.1.1.5/3210.1.1.510.1.1.8/3010.1.1.910.1.1.10/3210.1.1.1010.2.0.0/2410.1.1.10Page8传统IP转发(SWD)10.2.0.0/24SWD

v310.1.1.8/30NetworkNexthop10.1

0.0/2410.1.1.910.1.1.0/3010.1.1.910.1.1.4/3010.1.1.910.1.1.8/3010.1.1.1010.1.1.9/3210.1.1.910.2.0.0/2410.2.0.210.2.0.1/3210.2.0.110.2.0.0/30Page9传统IP转发在流量工程方面的缺陷SWASWBSWDSWESWCNetwork

ASWFSWGSWHGEGEFEFEFE100%

Traffic100%

TrafficNetwork

CNetwork

BPage10MPLS

TE应用SWASWBSWDSWENetworkBNetwork

CSWCNetwork

ASWFSWGSWHGEGEFEFE70%

TrafficFE70%

Traffic30%

Traffic30%

TrafficPage11MPLS转发SWBSWCSWD10.1.0.0/24

v2

v2

10.1.1.4/30v3v310.1.1.8/301.1.1.1/32SWAv1v110.1.1.0/30DataIPHeaderMPLS1024DataIPHeaderMPLS

HeaderDataIP

Headeread1029

H

IP

er

Data1039DataIPHeaderDataIPHeader10.2.0.0/24Page12MPLS应用ABABMPLSPEPEPEPEPPPPCECECECECECECECEABABPage13MPLS

Qos应用Network

ANetworkBPEPEPPCECEMPLSClassify

TrafficMap

to

DSCPMap

into

labelMap

DSCP

to

EXPPQ/CQ/CBQ

accordingto

EXPPage14MPLS概述MPLS基本原理MPLS环路检测Page15MPLS基本原理MPLS基本结构MPLS

格式MPLS转发流程传统IP转发Page16Data1039

IPHeaderData1029

IPHeader1024DataIPHeaderMPLS网络模型SWASWBSWCSWDIP

NetworkLERIP

NetworkLERSWFSWGLSRSWEMPLSLSPDataIPHeaderDataIPHeaderLER

Label

Edge

RouterLSR

Label

Switch

RouterLSP

Label

Switch

PathPage17MPLS结构Routing

ProtocolLabel

DistributionProtocolLabel

Forwarding

Table控制平面交换路由信息IP

Forwarding

TableIP

Routing

Table数据平面交换发送带

报文发送IP报文接收带

报文接收IP报文Page18MPLS基本原理MPLS基本结构MPLS

格式MPLS转发流程传统IP转发Page19帧模式MPLSFrameHeaderIP

HeaderPayloadFrameHeaderMPLSHeaderIP

HeaderPayload二层帧格式MPLS帧模式封装Page20MPLS

HeaderMPLS头部总长度为4bytes(32bits)Label长度20bitsEXP（Experimental

Use）长度3bitsS（Bottom

of

Stack）长度1bitTTL长度8bitsLABELEXP

STTL03119

2022

23

24Page21MPLS嵌套FrameHeaderLabel

1Label

2Label

3IP

HeaderPayloadS=0

S=0S=1PID=MPLS-IPPID

标识二层头部后面的报文类型Ethernet 0x0800

IPv4 0x8847

MPLS

单播报文0x8848

MPLS多播报文PPP

0x8021

IPv4

0x8281

MPLS

单播报文0x8283

MPLS多播报文S

标识是否是栈底嵌套应用MPLSMPLS

TEPage22MPLS基本原理MPLS基本结构MPLS

格式MPLS转发流程传统IP转发Page23MPLS转发－Ingress

LERSWBSWCSWD10.1.0.0/2410.2.0.0/24

v2

v2

10.1.1.4/30v3v310.1.1.8/301.1.1.1/32SWAv1v110.1.1.0/3010.2.0.1

DataMPLS1030DataIPHeader10.1.0.0/3010.2.0.0/30Page24MPLS转发－Ingress

LERFEC：Forwarding

Equivalence

Classes（转发等价类）NHLFE：Next

Hop

Label

Forwarding

Entry

（下一跳转

项）<SWA>display mpls

lsp

include

10.2.0.0

24

verboseLSP

Information:

LDP

LSPNo

:VrfIndex

:1Fec

:10.2.0.0/24Nexthop

:10.1.1.2In-Label

:NULLOut-Label

:1030In-Interface

:----------Out-Interface

:Vlanif1LspIndex

:10249Token

:0x22005LsrType

:IngressOutgoing

token

:0x0Label

Operation

:PUSHMpls-Mtu

:1500TimeStamp

:822secPage25MPLS转发－Ingress

LER（SWA）FTN：FECto

NHLFE（

到

HLFE）SWBSWCSWD10.1.0.0/2410.2.0.0/24v1v110.1.1.0/30

v2

v210.1

1.4/30v3v310.1.1.8/301.1.1.1/32SWAMPLS10.1.0.0/3010.2.0.0/30FECNHLFENextHopOut

InterfaceLabel

OperationOthers10.2.0.010.1.1.2Vlanif1Push……10.2.0.1

Data1030IP

DataHeaderPage26MPLS转发－LSR

（SWB）SWBSWCSWD10.1.0.0/2410.2.0.0/24

v2

v2

10.1.1.4/30v3v310.1.1.8/301.1.1.1/32SWAv1v110.1.1.0/30MPLSData1030

IPHeader10.2.0.1

Data1030DataIPHeader10.1.0.0/3010.2.0.0/30Page27MPLS转发－LSR

(SWB)ILM ing

Label

Map<SWB>display

mpls

lsp

include

10.2.0.0

24

in-label

1030

verboseLSP

Information:

LDP

LSPNo

:1VrfIndex

:Fec

:10.2.0.0/24Nexthop

:10.1.1.6In-Label

:1030Out-Label

:1030In-Interface

:----------Out-Interface

:Vlanif2LspIndex

:10256Token

:0x2200cLsrType

:TransitOutgoing

token

:0x0Label

Operation

:SWAPMpls-Mtu

:1500TimeStamp

:11100secPage28MPLS转发－LSR

(SWC)InLabelNHLFENextHopOut

InterfaceLabel

OperationOthers103010.1.1.10Vlanif3SWAP……SWBSWCSWD10.1.0.0/2410.2.0.0/2410.1.1.0/3010.1.1.4/30v1v2v2v3v310.1.1.8/301.1.1.1/32SWAv1MPLS1030DataIPHeaderData10.2.0.11030DataIPHeaderDataIPHeader103210.1.0.0/3010.2.0.0/30Page29MPLS数据转发－LSR

（SWC）<SWC>display

mpls

lsp

include

10.2.0.0

24

in-label

1030

verboseLSP

Information:

LDP

LSPNoVrfIndexFecNexthopIn-LabelOut-LabelIn-InterfaceOut-InterfaceLspIndexTokenLsrTypeOutgoing

tokenLabel

OperationMpls-MtuTimeStamp:

1::

10.2.0.0/24: 10.1.1

10:

1030:

1032:

----:

Vlanif3:

10268:

0x22015:

Transit:

0x0:

SWAP:

1500:

40secPage30MPLS转发－Egress

LER

（SWD）InLabelNHLFENextHopOut

InterfaceLabel

OperationOthers103210.2.0.2--POP……SWBSWCSWD10.1.0.0/2410.2.0.0/24

v2

v2

10.1.1.4/30v3v310.1.1.8/301.1.1.1/32SWAv1v110.1.1.0/30MPLS103010.2.0.1

Data10.2.0.1

Data103010.2.0.1Data1030

10.2.0.1

Data103210.2.0.1Data10.1.0.0/3010.2.0.1

Data10.2.0.0/30Page31MPLS转发－Egress

LER

（SWD）<SWD>display

mpls

lsp

include

10.2.0.0

24

in-label

1032

verboseLSP

Information:

LDP

LSPNo

:1VrfIndex

:Fec

:10.2.0.0/24Nexthop

:10.2.0.2In-Label

:1032Out-Label

:NULLIn-Interface

:----Out-Interface

:-------LspIndex

:10258Token

:0x0LsrType

:EgressOutgoing

token

:0x0Label

Operation

:POPMpls-Mtu

:------TimeStamp

:924secTimeStamp

:40secPage32MPLS概述MPLS基本原理MPLS环路检测Page33MPLS环路检测MPLS

TTL环路检测LDP环路检测Page34MPLS环路检测IGP环路检测机制TTL环路检测帧模式的MPLS中使用TTL信元模式的MPLS中无TTLLDP环路检测机制距离向量法最大跳数法Page35MPLS对TTL的处理10.1.0.0/2410.2.0.0/24v1v110.1.1.0/30

v2

v210.1.1.4/30v310.1.1.8/30MPLS1.1.1.1/3SWA22.2.2.2/32SWB3.3.3.3/32SWCv34.4.4.4/32SWD10109

108Label

TTLIP

TTLIP

TTL减1，并拷贝到Label

TTL7810IP

TTL不变，LabelTTL减1Label

TTL减1，拷贝回IP

TTL.Page36MPLS

TTL配置与实例分析MPLSv11.1.1.1/32SWAv110.1.1.0/302.2.2.2/32SWBv2v210.1.1.4/303.3.3.3/32SWCv3v310.1.1.8/304.4.4.4/32SWDSWJSWK10.1.0.0/30v3v310.2.0.0/30v1v1<SWJ>-h

11

10.2.0.1Page37MPLS

TTL配置与实例分析<SWA>debug

mpls

packet<SWA>debug

ip

packet

acl

3000<SWA>terminal

monitor<SWA>terminal

debugging*0.86297391

SWA

IP/8/debug_case:Receiving,

interface

=

Serial3,

version

=

4,

headlen

=

20,

tos

=

0,pktlen

=

84,

pktid

=

2273,

offset

=

0,

ttl

=

11,

protocol

=

1,checksum

=

37572,

s

=

10.1.0.1,

d

=

10.2.0.1prompt:

Receiving

IP

packet

from

Serial3*0.86297391

SWA

IP/8/debug_case:Sending,

interface

=

Serial3,

version

=

4,

headlen

=

20,

tos

=

0,pktlen

=

84,

pktid

=

2273,

offset

=

0,

ttl

=

10,

protocol

=

1,checksum

=

37572,

s

=

10.1.0.1,

d

=

10.2.0.1prompt:

Sending

the

packet

by

lsp*0.86297391

SWA

MFW/8/MPLSF

CKET:PUSH

Label=1030,

EXP=0,

TTL=10Sending

to

V1,

PktLen=88,

Label(s)=1030,

EXP=0,

TTL=10Page38MPLS

TTL配置与实例分析<SWB>debug

mpls

packet<SWB>debug

ip

packet

acl

3000<SWB>terminal

monitor<SWB>terminal

debugging*0.189653734

SWB

MFW/8/MPLSF

CKET:Receiving

from

V1,

PktLen=88,

Label(s)=1030,

EXP=0,

TTL=10SWAP

Label=1029,

EXP=0,

TTL=9Sending

to

V2,

PktLen=88,

Label(s)=1029,

EXP=0,

TTL=9<SWC>debug

mpls

packet<SWC>debug

ip

packet

acl

3000<SWC>terminal

monitor<SWC>terminal

debugging*0.189533719

SWC

MFW/8/MPLSF

CKET:Receiving

from

V2,

PktLen=88,

Label(s)=1029,

EXP=0,

TTL=9SWAP

Label=3,

TTL=8Sending

to

V3,

Dest=10.2.0.1,

Nexthop=10.1.1.10Page39MPLS

TTL配置与实例分析<SWD>debug

mpls

packet<SWD>debug

ip

packet

acl

3000<SWD>terminal

monitor<SWD>terminal

debugging*0.64991297

SWD

IP/8/debug_case:Receiving,

interface

=

Serial3,

version

=

4,

headlen

=

20,

tos

=

0,pktlen

=

84,

pktid

=

2273,

offset

=

0,

ttl

=

8,

protocol

=

1,checksum

=

38340,

s

=

10.1.0.1,

d

=

10.2.0.1prompt:

Receiving

IP

packet

from

Serial3*0.64991297

SWD

IP/8/debug_case:Sending,

interface

=

Serial1,

version

=

4,

headlen

=

20,

tos

=

0,pktlen

=

84,

pktid

=

2273,

offset

=

0,

ttl

=

7,

protocol

=

1,checksum

=

38596,

s

=

10.1.0.1,

d

=

10.2.0.1prompt:

Sending

the

packet

from

Serial3

at

Serial1<SWJ>tracert

10.2.0.1traceroute

to

10.2.0.1(10.2.0.1)

30

hops

max,40

bytes

packet1

10.1.0.22

10.1.1.23

10.1.1.631

ms62

ms94

ms32

ms 1

ms94

ms 62

ms94

ms 94

ms4

10.1.1.10

125

ms 125

ms 125

ms5

10.2.0.1

156

ms 156

ms 156

msPage40MPLS对TTL的处理10.1.0.0/2410.2.0.0/24v1v110.1.1.0/30

v2

v210.1.1.4/30v310.1.1.8/30MPLS1.1.1.1/3SWA22.2.2.2/32SWB3.3.3.3/32SWCv34.4.4.4/32SWD25510254

1010Label

TTLIP

TTLIP

TTL

减1，但不拷贝Label

TTL。LabelTTL

强制设为255925310IP

TTL

不变，Label

TTL

减1。Label

TTL

减1，去掉标签。Page41MPLS

TTL配置与实例分析MPLS1.1.1.1/32SWAv1v110.1.1.0/302.2.2.2/32SWB

v2

v210.1.1.4/303.3.3.3/32SWCv3v310.1.1.8/304.4.4.4/32SWDSWJSWK10.1.0.0/30v3v310.2.0.0/30v1v1[SW]mpls[SW-mpls]undo

ttl

propagate

public<SWJ>-h

11

10.2.0.1Page42MPLS

TTL配置与实例分析<SWA>debug

mpls

packet<SWA>debug

ip

packet

acl

3000<SWA>terminal

monitor<SWA>terminal

debugging*0.81886516

SWA

IP/8/debug_case:Receiving,

interface

=

Serial3,

version

=

4,

headlen

=

20,

tos

=

0,pktlen

=

84,

pktid

=

1318,

offset

=

0,

ttl

=

11,

protocol

=

1,checksum

=

38527,

s

=

10.1.0

1,

d

=

10.2.0.1prompt:

Receiving

IP

packet

from

Serial3*0.81886516

SWA

IP/8/debug_case:Sending,

interface

=

Serial3,

version

=

4,

headlen

=

20,

tos

=

0,pktlen

=

84,

pktid

=

1318,

offset

=

0,

ttl

=

10,

protocol

=

1,checksum

=

38527,

s

=

10.1.0.1,

d

=

10.2.0.1prompt:

Sending

the

packet

by

lsp*0.81886516

SWA

MFW/8/MPLSF

CKET:PUSH

Label=1030,

EXP=0,

TTL=255Sending

to

V1,

PktLen=88,

Label(s)=1030,

EXP=0,

TTL=255Page43MPLS

TTL配置与实例分析<SWD>debug

mpls

packet<SWD>debug

ip

packet

acl

3000<SWD>terminal

monitor<SWD>terminal

debugging*0.99910344

SWD

IP/8/debug_case:Receiving,

interface

=

Serial3,

version

=

4,

headlen

=

20,

tos

=

0,pktlen

=

84,

pktid

=

9625,

offset

=

0,

ttl

=

10,

protocol

=

1,checksum

=

30476,

s

=

10.1.0.1,

d

=

10.2.0.1prompt:

Receiving

IP

packet

from

Serial3*0.99910344

SWD

IP/8/debug_case:Sending,

interface

=

Serial1,

version

=

4,

headlen

=

20,

tos

=

0,pktlen

=

84,

pktid

=

9625,

offset

=

0,

ttl

=

9,

protocol

=

1,checksum

=

30732,

s

=

10.1.0.1,

d

=

10.2.0.1prompt:

Sending

the

packet

from

Serial3

at

Serial1Page44MPLS1.1.1.1/32SWAv1v110.1.1.0/302.2.2.2/32SWB

v2

v210.1.1.4/303.3.3.3/32SWCv3v310.1.1.8/304.4.4.4/32SWDSWK10.1.0.0/30v3v310.2.0.0/30v1v1MPLS

TTL配置与实例分析SWJ<SWJ>tracert

10.2.0.1traceroute

to

10.2.0.1(10.2.0.1)

30

hops

max,40

bytes

packet1

10.1.0.2

31

ms 31

ms2

10.1.1.10

156

ms 94

ms3

10.2.0.1

125

ms 125

ms32

ms125

ms125

msPage45MPLSv11.1.1.1/32SWAv110.1.1.0/302.2.2.2/32SWBv2v210.1.1.4/303.3.3.3/32SWCv3v310.1.1.8/304.4.4.4/32SWDSWJSWK10.1.0.0/30v3v310.2.0.0/30v1v1MPLS

TTL配置与实例分析1The traceroute

packetwith

TTL=1

is

dropped

bySwitchADiscardPage46v1v110.1.1.0/30

v2

v2

10.1.1.4/30v310.1.1.8/30MPLS1.1.1.1/3SWA22.2.2.2/32SWB3.3.3.3/32SWCv34.4.4.4/32SWDSWJSWK10.1.0.0/30v3v310.2.0.0/30v1v1MPLS

TTL配置与实例分析2The traceroute

packet

withTTL=1

is

dropped

by

SwitchADiscard2551254

11Page47TTL和环路检测10.1.0.0/2410.2.0.0/24v1v110.1.1.0/30v21.1.1.1/3SWA22.2.2.2/32SWBv23.3.3.3/32SWCv3v310.1.1.8/304.4.4.4/32SWD10109

10Label

TTLIP

TTL710.1.1.4/308

10MPLS7

10…….1

10Page48MPLS环路检测MPLS

TTL环路检测LDP环路检测Page49LDP路径向量法10.1.0.0/2410.2.0.0/24MPLS1.1.1.1/32SWAv1v110.1.1.0/302.2.2.2/32SWB

v2

v210.1.1.4/303.3.3.3/32SWCv3v310.1.1.8/304.4.4.4/32SWDLabel

Request(length

1

)(4.4.4.4)Label

Request(length

2)

)(4.4.4.4,3.3.3.3)Label

Request(length

3)

)(4.4.4.4,3.3.3.3,2.2.2.2)Label

Request(length