2005/03/11(C) Herbert Haas

The Internet Protocol (IP)

The Blood of the Internet

"Information Superhighway is really an acronym for 'Interactive Network For Organizing, Retrieving, Manipulating,

Accessing And Transferring Information On National Systems, Unleashing Practically

Every Rebellious Human Intelligence, Gratifying Hackers, Wiseacres,

And Yahoos'."

Keven Kwaku

3(C) Herbert Haas 2005/03/11

The Internet Protocol (IP)

Introduction IP Addressing

IP Header IP Address Format

Address Classes Class A - E

Subnetting, VLSM IP Fragmentation

4(C) Herbert Haas 2005/03/11

Need of an Inter-Net Protocol (1)

Different Data-Link Layer Different frames Different protocol handling

Different Physical Layer Different hardware Different signals

No interconnection possible !!!

Host 1

Host 2 Host 3

Host 1

Host 2

Host 3

Host 1

Host 3 Host 2

5(C) Herbert Haas 2005/03/11

Need of an Inter-Net Protocol (2)

Network 1

Network 3

Network 2

Common internetworking layer One packet type

Gateways terminate layer 1 and 2 Layer 3 addresses identify

Not only Host But also Network

Gateway

Gateway

1.1

1.2 1.3

2.1

2.2

3.4

3.1

3.3 3.2

2.3

2.4

6(C) Herbert Haas 2005/03/11

IP Introduction (1)

Packet switching technology Packet switch = router = "gateway" (IETF terminology) End system is called IP host Layer 3 address (Structured)

Datagram Service Connectionless Best effort delivery

7(C) Herbert Haas 2005/03/11

Packet Switching Principle

T1

T2

T3

TA T2

T3

T1

T4 T4

T4 T4T1 TB

User A2

User B5

Address Information

• Each switch must analyze address information

• "Store and Forward"

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A

D C

B

PS2 PS3 PS4

IP packet forwarding is based on routing tables only (Connectionless PS, Best-Effort Service, Datagram Service)

A B

... Packet payload

A B A B

A B time t0

time t2 time t4

time t6

time t1 forwarding decision

of PS2 time t3

forwarding decision of PS3

time t5 forwarding decision

of PS4

A B ... Source Address / Destination Address

B PS3 C PS3 D PS3

to next hop

B PS4 C PS5 D PS6

to next hop

B local C PS5 D PS3

to next hop

Routing Table of PS 4

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14 CR A B

A

E C

B

PS2 PS3 PS4

CR ... Call Request

X.25/FR/ATM packet forwarding is based on X25/FR/ATM switching tables; but call-setup uses routing tables (Connection Oriented PS, Virtual Call Service)

A :14

from to

from to

from to B PS3 C PS3 E PS3

to next hop

Switching Table of PS 4

unique addresses

local connection identifier

packet type

Routing Table of PS 2

Virtual Call Setup 1

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23 CR A B

A

E C

B1

2 3 4

5 6

CR ... Call Request

14

Virtual Call Setup 2

A :14 3:23

from to

2 :23

from to from to

B PS4 C PS5 E PS6

to next hop

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A

E C

B1

2 3 4

5 6

CR ... Call Request

14

07 CR A B

23

Virtual Call Setup 3

3:07

from to

A :14 3:23

from to

2 :23 4:07

from to

B local C PS5 E PS3

to next hop

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44 CR A B

A

E C

B1

2 3 4

5 6

CR ... Call Request

14

23

07

Virtual connection A - B: 14-23-07-44

Virtual Call Setup 4

A :14 3:23

from to

3:07 B:44

from to

2 :23 4:07

from to

2005/03/11 13 CA ... Call Accepted

A B CA 44

A

E C

B1

2 3 4

5 6

14

23

07

Virtual connection A - B: 14-23-07-44

44

Virtual Call Setup 5

A :14 3:23

to from

3:07 B:44

to from

2 :23 4:07

to from

2005/03/11 14 CA ... Call Accepted

A

E C

B1

2 3 4

5 6

14

23

07

Virtual connection A - B: 14-23-07-44

44 A B CA 14

Virtual Call Setup 6

A :14 3:23

to from

3:07 B:44

to from

2 :23 4:07

to from

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A

E C

B1

2 3 4

5 6

14

23

07

Virtual connection A - B: 14-23-07-44

44 D 14

D ... Data Packet … payload

Data Transfer 1

A :14 3:23

from to

3:07 B:44

from to

2 :23 4:07

from to

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A

E C

B1

2 3 4

5 6

14

23

07

Virtual connection A - B: 14-23-07-44

44

D 23

D ... Data Packet … payload

Data Transfer 2

A :14 3:23

from to

3:07 B:44

from to

2 :23 4:07

from to

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A

E C

B1

2 3 4

5 6

14

23

07

Virtual connection A - B: 14-23-07-44

44

D 07

D ... Data Packet … payload

Data Transfer 3

A :14 3:23

from to

3:07 B:44

from to

2 :23 4:07

from to

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A

E C

B1

2 3 4

5 6

14

23

07

Virtual connection A - B: 14-23-07-44

44 D 44

D ... Data Packet … payload

Data Transfer 4

A :14 3:23

from to

3:07 B:44

from to

2 :23 4:07

from to

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IP Datagram Service

User A.2

User B.5

R1 R2

R4

R3

R5

Destination Next Hop A local B R2 C R2

..... .....

A2 B5

A2 B5

A2 B5

Destination Next Hop A R1 B R4 C R3

..... .....

A 2

B 5

Destination Next Hop A R2 B R5 C R2

..... .....

A2 B5

Destination Next Hop A R4 B local C R4

..... .....IP address (structured address Net-ID:Host-ID)

IP Host IP Router

IP Routing Table of R1

Destination Based Routing

20(C) Herbert Haas 2005/03/11

IP Introduction (2)

Shared responsibility Both network and hosts must take care for delivery (!) Routers deliver datagrams to remote hosts based on IP address Hosts responsible for end-to-end control

End-to-end control relies on TCP Layer 4

21(C) Herbert Haas 2005/03/11

IP Introduction (3)

Physical

Application

Presentation

Session

Transport

Network

Link IP over

Internet Protocol (IP)

TCP (Transmission Control Protocol)

ATM RFC 1483

IEEE 802.2 RFC 1042

X.25 RFC 1356

Frame Relay RFC 1490

PPP RFC 1661

UDP (User Datagram

Protocol)

HTTP FTP DNSTelnetSMTP TFTPDHCP etc.

Routing Protocols

RIP, OSPF, BGP, EGP

OSI 7 Layer Model

TCP/IP Protocol Suite

ARPRARP

ICMP

(US-ASCII and MIME)

Inverse ARP

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IP Host A IP Host B

3 33 3 IP

M M

3 3

Layer 3 Protocol = IP Layer 3 Routing Protocols = RIP, OSPF, EIGRP, BGP

IP and OSI Network Layer 3

Router 1 Router 2IP IP

23(C) Herbert Haas 2005/03/11

IP Introduction (4)

IP over anything: Overlay Technique IP can be easily integrated upon layer 2 technologies Open development quickly adapts to new transport and switching methods

End-to-end principle Only hosts must be intelligent (TCP) Routers remain simple

24(C) Herbert Haas 2005/03/11

IP Introduction (5)

TCP cares for reliability Connection oriented Error recovery Flow control Sequencing

IP is the router's language No idea about applications Best effort delivery

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4 4

Layer 4 Protocol = TCP (Connection-Oriented)

M M

TCP/UDP and OSI Transport Layer 4

IP Host A IP Host B

Router 1 Router 2

Layer 4 Protocol = UDP (Connectionless)

TCP/UDP Connection (Transport-Pipe)

26(C) Herbert Haas 2005/03/11

IP Introduction (6)

Request for Comments (RFCs) De fact