Internet

1

datagram

H1AH2H2

virtual circuit

2 InternetThe Internet is an interconnected collection of many networks.

internetworkinginternetworkinternet

internet layerTCP/IPTCPIPTCP/IPIPInternet ProtocolICMP

2.1 IPbest-efforts IPIPv4IPv6

1 IPv4

IPIPIP

2IPIPIPIPv432IP11000001 00100000 11011000 00001001 193.32.216.9IP

IPIPABC

IPIPICANNABC

IP01 013213200127.xx.yy.xx

ABCA224-2 = 16777214B216-2 = 65534C28-2 = 254ABCA27-2 = 126B214-2 = 16382C221-2 = 2097152ABCA1.0.0.0~126.255.255.255B128.1.0.0~C

3subnet

IP

+

subnet mask +320255.255.255.0+IP 128.10.1.1 AND 255.255.255.0 = 128.10.1.0

4 IPdirect deliveryindirect delivery

IP

Cloud

Mac II

202.38.64.0

Q

A

20.0.0.0

R

30.0.0.0

S

40.0.0.0

202.38.64.1

20.0.0.5

20.0.0.6

30.0.0.6

30.0.0.7

40.0.0.7

20.0.0.0

30.0.0.0

202.38.64.0

255.0.0.0

255.0.0.0

255.255.255.0

40.0.0.0

255.0.0.0

R

A

0

20.0.0.5

30.0.0.7

0

1

0

1

0

1

202.38.64.0

default

255.255.255.0

0.0.0.0

202.38.64.1

0

0

IPIP D N if DIP then protocol else if N then D else if D then else if N then else if then else

5CIDRCIDRaggregate

200020482121CIDRL232-log2L194.24.0.0 255.255.248.0/194.24.0.0/21

CIDRISP194.24.0.0 20481140961210241010

194.24.0.0/2111111111 11111111 11111000 00000000194.24.8.0/22 11111111 11111111 11111100 00000000 194.24.16.0/20 11111111 11111111 11110000 00000000 194.24.17.4194.24.17.4 AND 255.255.248.0 = 194.24.16.0194.24.17.4 AND 255.255.252.0 = 194.24.16.0194.24.17.4 AND 255.255.240.0 = 194.24.16.0

ISP16192.4.16.0~192.4.31.016C16192.4.16.0/2016

RFC 1519IPv443200194.0.0.0195.255.255.255198.0.0.0199.255.255.255200.0.0.0201.255.255.255202.0.0.0203.255.255.255

IPIPCIDR

CIDRIP192.4.23.0 192.4.16.0/20192.4.23.0/24

6MTUMTU1500MTU576MTUMTUIPIPMTUfragmentation

138HNN H + N MTU N 8

HMTUNNN H + NMF01 /8

4000IPMTU1500IP20 N 1480148014801020

MTU

IPMF=0

IP

2.2 IP

ARPIPABIP IBIBBIP

ARP/RARP1IP0800166IP4ARP1ARP2RARP3RARP4ARP080616

ABIPMACAARPMACIPBIPAARPARPIPIPBARPMAC2BARPAMAC

ARPARPARPARPARPARPARPARP15

ARPARPARPARPAARPIPARPAARPAARP

ARPIPARPARP1ARPIPIPARP

Three interconnected /24 networks: two Ethernets and an FDDI ring.Three interconnected /24 networks: two Ethernets and an FDDI ring.

2.3 ICMPICMPICMPICMPIPIPICMPICMPICMPIP

ICMPICMPTTL0ICMP//

ICMPtype15codeChecksumICMP

ICMPpingPingICMP Type=8Code=0 Echo Request Type=0Code=0 Echo ResponseEcho Response

Process

type(0 or 8)

code(0)

checksum

optional data

0

7

8

15

16

31

5-27 ICMP

sequence number

identifier

8 bytes

ICMPTracerouteTracerouteTracerouteType=8Code=0Echo RequestIPTTL1TTL1TTL0ICMPTracerouteIPType=8Code=0Echo RequestIPTTL2 IPTTL3ICMPType=0Code=0Echo Response

3

3.1 Distance Vector

Connect

Process

Text

B

B

B

B

B

B

2

1

3

1

2

5

6

1

5-4

DVBellman-FordBellman-Fordxy N(x)xc(x,p)xpN(x)xydx(y)dx(y) = minp{c(x,p) + dp(y)}pN(x)p xyBellman-FordDVBellman-Ford

DVBellman-Ford

DV(a) A subnet. (b) Input from A, I, H, K, and the new routing table for J.

Route Information ProtocolRIPRIP303016RIP16RIPRIPRIPUDP

3.2 Link State

HELLOECHO2

32

LS

Dijkstra

Open Shortest Path FirstOSPFOSPFOSPFOSPFRIPOSPFIP89

3.3 ASarea

3.4 N-Way-Unicast

1

(a) A subnet. (b) a Sink tree. (c) The tree built by reverse path forwarding.

3.5

(a) A network. (b) A spanning tree for the leftmost router. (c) A multicast tree for group 1. (d) A multicast tree for group 2.

DVMRPpruneGGSG

4

-CPU

CPU

1admission controltraffic shapingtraffic policing

2warning bit

3choke packetshop-by-hop choke packets

4Ramdom Early Detection, RED p AvgLen = (1- Weight)AvgLen + WeightSampleLen p TCP

5

(a) Two Ethernets connected by a switch. (b) Two Ethernets connected by routers.

5.1

IPDst IP addr = H2Src IP addr = H1Dst MAC addr = M1Src MAC addr= H1IPDst IP addr= H2Src IP addr = H1Dst addr = M2Src addr = M1IPDst IP addr = H2Src IP addr = H1Dst MAC addr = H2Src MAC addr= M2

MBoneoverlay networkMBone

MBone

Direct access storage

Process

Dst addr =

Dst addr =

IP

IP

Dst IP addr = M2

Src IP addr = M1

Dst addr =

M2

M1

C

D

IP

5.2

Autonomous SystemASASASICANNASASAS

routing metricInternet

InternetIGPASOSPFRIPEGPASBGP

ASASASAS

BGPASASASBGP speakerBGPBGPASASBGPtransitASstubAS

ASAS2BGP speaker128.96, 192.4.153, 192.4.32, 192.4.3AS2AS1BGP speaker128.96, 192.4.153, 192.4.32, 192.4.3

QAS5

A AS2

B (AS3)

P(AS4)

AS1

RAS6

SAS7

128.96192.4.153

192.4.32192.4.3

192.12.69

192.4.54192.4.23

5-10

routing arbiterBGPAS

6 IPIPmigratoryroamingIPIPIP

home networkhome addressforeign networkcare-of addresshome agentforeign agent

IPARPARPMACARPARPARP

:MAC

7 IPv6IPv6...IPv6IPv4

IPv6128168000:0:0:0:123:4567:89AB:CDEF08000::123:4567:89AB:CDEFIPv6IPv6anycast

IPv6IPv640IPv4IPv6IHLIPv640Next headerIPv6

IPv6IPv4

IPv4IPv6IPv4IPv6

8 CPUCPU

IP

IPCPUI/OCPUCPUCPUCPU

I/O

IPCPUCPUCPUCPUCPU

IP

DMA

MAC

CPU

DMA

MAC

CPU

DMA

MAC

CPU

CPU

5-30

IPMGRMulti-gigabit routerCPUcrossbarCPUCrossbar

CPU

5-31

MGR

IPIPIPIP/CIDRARP

914333438394043

134142

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