The Internet Protocol (IP) The Blood of the Internet (C) Herbert Haas 2005/03/11
"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
The Internet Protocol (IP) � Introduction � IP Addressing � IP Header � IP Address Format � Address Classes � Class A - E � Subnetting, VLSM � IP Fragmentation 3 (C) Herbert Haas 2005/03/11
Need of an Inter-Net Protocol (1) Host 3 Host 2 Host 1 No interconnection Host 2 possible !!! Host 3 Host 1 � Different Data-Link Layer Host 2 � Different frames Host 3 � Different protocol handling � Different Physical Layer � Different hardware Host 1 � Different signals 4 (C) Herbert Haas 2005/03/11
Need of an Inter-Net Protocol (2) 3.3 3.2 Network 3 Network 2 3.1 Gateway 2.2 3.4 2.3 Gateway 2.1 2.4 1.2 � Common internetworking layer � One packet type 1.3 Network 1 � Gateways terminate layer 1 and 2 � Layer 3 addresses identify � Not only Host � But also Network 1.1 5 (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 6 (C) Herbert Haas 2005/03/11
Packet Switching Principle T1 T1 TA T2 T2 T4 T4 T3 User A2 Address Information T3 T1 T4 T4 TB • Each switch must analyze address information User B5 • "Store and Forward" 7 (C) Herbert Haas 2005/03/11
IP packet forwarding is based on routing tables only (Connectionless PS, Best-Effort Service, Datagram Service) B A time t6 time t0 A B A B time t4 time t2 time t5 A B PS2 PS3 PS4 A B forwarding decision of PS4 time t1 to next hop forwarding decision time t3 to next hop of PS2 B local forwarding decision B PS3 C PS5 of PS3 C PS3 D PS3 to next hop Routing Table D PS3 B PS4 of PS 4 C PS5 D PS6 D C ... Packet payload A B ... Source Address / Destination Address 2005/03/11 8
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) local Virtual Call Setup 1 A connection B identifier packet type 14 CR A B unique Switching Table addresses PS4 of PS 4 PS2 PS3 to next hop from to from to B PS3 C PS3 A :14 E PS3 from to Routing Table of PS 2 E C CR ... Call Request 2005/03/11 9
Virtual Call Setup 2 1 B A 14 2 4 3 from to from to from to 23 CR A B A :14 3:23 2 :23 to next hop B PS4 C PS5 E PS6 E C 6 5 CR ... Call Request 2005/03/11 10
Virtual Call Setup 3 1 B A 14 from to 3:07 23 2 4 3 from to to next hop 07 CR A B B local A :14 3:23 C PS5 E PS3 from to 2 :23 4:07 E C 6 5 CR ... Call Request 2005/03/11 11
Virtual Call Setup 4 Virtual connection A - B: 1 B 14-23-07-44 A 14 44 CR A B 07 2 4 3 from to 23 from to A :14 3:23 3:07 B:44 from to 2 :23 4:07 E C 6 5 CR ... Call Request 2005/03/11 12
Virtual Call Setup 5 Virtual connection A - B: 1 B 14-23-07-44 A 44 14 A B CA 44 07 2 4 3 to from 23 to from A :14 3:23 3:07 B:44 to from 2 :23 4:07 E C 6 5 CA ... Call Accepted 2005/03/11 13
Virtual Call Setup 6 Virtual connection A - B: 1 B 14-23-07-44 A 44 14 A B CA 14 07 2 4 3 to from 23 to from A :14 3:23 3:07 B:44 to from 2 :23 4:07 E C 6 5 CA ... Call Accepted 2005/03/11 14
Data Transfer 1 Virtual connection A - B: 1 B 14-23-07-44 A 44 14 D 14 07 2 4 3 from to 23 from to A :14 3:23 3:07 B:44 from to 2 :23 4:07 E C 6 5 D ... Data Packet … payload 2005/03/11 15
Data Transfer 2 Virtual connection A - B: 1 B 14-23-07-44 A 44 14 D 23 07 2 4 3 from to 23 from to A :14 3:23 3:07 B:44 from to 2 :23 4:07 E C 6 5 D ... Data Packet … payload 2005/03/11 16
Data Transfer 3 Virtual connection A - B: 1 B 14-23-07-44 A 44 14 07 2 4 3 from to 23 D 07 from to A :14 3:23 3:07 B:44 from to 2 :23 4:07 E C 6 5 D ... Data Packet … payload 2005/03/11 17
Data Transfer 4 Virtual connection A - B: 1 B 14-23-07-44 A 44 14 D 44 07 2 4 3 from to 23 from to A :14 3:23 3:07 B:44 from to 2 :23 4:07 E C 6 5 D ... Data Packet … payload 2005/03/11 18
IP Datagram Service IP Host IP Router Destination Next Hop A R1 B R4 C R3 R1 R2 R3 ..... ..... A2 B5 A2 B5 Destination Next Hop Destination Based Routing User A.2 A local B R2 C R2 ..... ..... IP Routing Destination Next Hop A2 B5 Table of R1 A R4 B local C R4 IP address ..... ..... R4 R5 (structured address Net-ID:Host-ID) Destination Next Hop A2 B5 A R2 A2 B5 B R5 C R2 ..... ..... User B.5 2005/03/11 19
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 20 (C) Herbert Haas 2005/03/11
IP Introduction (3) OSI TCP/IP Protocol Suite 7 Layer Model Application HTTP FTP SMTP Telnet DNS DHCP TFTP etc. (US-ASCII and MIME) Presentation Routing Protocols Session UDP RIP, OSPF, TCP Transport (User Datagram BGP, EGP (Transmission Control Protocol) Protocol) ICMP Network Internet Protocol (IP) RARP ARP Inverse ARP IP over Link ATM IEEE 802.2 X.25 Frame Relay PPP Physical RFC 1483 RFC 1042 RFC 1356 RFC 1490 RFC 1661 21 (C) Herbert Haas 2005/03/11
IP and OSI Network Layer 3 Layer 3 Protocol = IP Layer 3 Routing Protocols = RIP, OSPF, EIGRP, BGP IP Host A IP Host B Router 1 Router 2 IP IP IP 3 3 3 3 3 3 M M 2005/03/11 22
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 23 (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 24 (C) Herbert Haas 2005/03/11
TCP/UDP and OSI Transport Layer 4 Layer 4 Protocol = TCP (Connection-Oriented) Layer 4 Protocol = UDP (Connectionless) IP Host A IP Host B TCP/UDP Connection (Transport-Pipe) 4 4 M M Router 1 Router 2 2005/03/11 25
IP Introduction (6) � Request for Comments (RFCs) � De facto standards for the Internet � Initially posted by snail mail � IETF (Internet Engineering Task Force) reviews and confirms them � RFCs are numbered in sequence of publishing � Everybody may write an RFC (!) 26 (C) Herbert Haas 2005/03/11
Internet Organizations RARE ISOC (Reseaux Associes pour la (Internet Society) Recherche Europeen) IAB IETF IRTF 27 (C) Herbert Haas 2005/03/11
The IP Header (Address Fields) 0 4 8 12 16 20 24 28 32 Vers HLEN TOS Total Length Identification Flags Fragment Offset TTL Protocol Header Checksum Source IP Address Destination IP Address Padding Options (variable length) PAYLOAD (Encapsulated Higher Layer Packets) 28 (C) Herbert Haas 2005/03/11
The IP Address � Dotted Decimal Notation Binary IP Address: 1100000010101000000000100000001 Decimal Value: 3232235777 Decimal Representation per byte : 1 1 0 0 0 0 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 192 168 1 1 192 . 168 . 1 . 1 29 (C) Herbert Haas 2005/03/11
IP Address Classes � Net-ID? Host-ID? � 5 Classes defined! � A (1-127) � B (128-191) � C (192-223) � D (224-239, Multicast) � E (240-254, Experimental) � Classes define number of address- bits for net-id 30 (C) Herbert Haas 2005/03/11
IP Address Classes Classes are defined by „first octet rule“ Class A 0 Net-ID Host-ID Class B 1 0 Net-ID Host-ID Class C 1 1 0 Net-ID Host-ID Class D 1 1 1 0 Multicast Addresses Class E 1 1 1 1 Experimental Use 31 (C) Herbert Haas 2005/03/11
Broadcasts and Networks � All ones in the host-part represents „network-broadcast“ (10.255.255.255) � All ones in the net-part and host-part represents „limited broadcast in this network” (255.255.255.255) � All zeros in the host-part represents the „network-address“ (10.0.0.0) 32 (C) Herbert Haas 2005/03/11
Reserved Addresses � Address range for private use � 10.0.0.0 - 10.255.255.255 � 172.16.0.0 - 172.31.255.255 � 192.168.0.0 - 192.168.255.255 � RFC 1918 � Network 127.x.x.x is reserved for "Loopback" 33 (C) Herbert Haas 2005/03/11
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