Part 4: Internetworking Using TCP/IP

Transcription

1 Part 4: Internetworking Using Internet architecture Addressing Binding Encapsulation protocol suite Internetworking and IP Addressing Gail Hopkins 1

2 Introduction Motivation Architecture Introduction to protocols IP Addressing Motivation A large organisation will use several networking technologies Inter-organisational communication is significant Universal service - any two computers should be able to communicate However, different network technologies cannot just be wired together 2

3 Internetworking Interconnect heterogeneous networks and provide universal service Hardware: routers connect different networks Internet protocols: provide universal service by creating a single virtual network Internet Architecture Although a single router can connect many networks, most organisations use multiple routers 3

4 Part 34 Internetworking Using Virtual Network The illusion that there is a single universal network Internetworking Protocols The Internet Protocols begun in the 1970s The Internet has emerged into the public domain in the 1990s Controlled by the Internet Engineering Task Force (IETF) 4

5 Internet Reference Model Host Computers used the term host computer to refer to any system that connects to an Internet and that runs applications Both hosts and routers use protocol software 5

6 IP: Internet Protocol Addresses Introduction Uniform addressing The IP address hierarchy Address classes Dotted decimal notation Special addresses Routers and addresses Address resolution 6

7 Uniform Addressing Internet protocols deal in packets and provide uniform addressing The addressing scheme is defined in software and is used transparently by applications Internet addressing is specified in the IP protocol Each host is assigned a unique 32 bit address The IP Address Hierarchy Each 32 bit address is divided into two parts: prefix: physical network to which the host is attached - the network number suffix: a host attached to a given physical network Prefixes are coordinated globally and suffixes locally 7

8 Classes of IP Address Size of prefix and suffix determines maximum number of networks and maximum number of hosts per network IP defines different classes of address with different sized prefixes and suffixes The first four bits of the address specify its class The Five Classes of IP Address 8

9 Dotted Decimal Notation Makes it easier to for humans to use addresses (names are also possible) Examples: = = = = 255 9

10 Classes and dotted decimal Part 34 Internetworking Using Division of the Address Space Public Internet network numbers are assigned by Internet Service providers (ISPs) and these are coordinated by the Internet Assigned Number Authority 10

11 Part 34 Internetworking Using An Addressing Example Classless Addressing The Internet is running out of addresses Allow division between prefix and suffix to appear at an arbitrary boundary Consider network with only 9 hosts Only need four bits for host suffix Class C (smallest) address uses 8 bits for host suffix Can subdivide a class C address into 16 addresses with a 28 bit prefix and 4 bit suffix Extend dotted decimal notation /16 11

12 Special IP Addresses Routers and IP addressing Routers are assigned two or more IP addresses So are multi-homed computers 12

13 Internetworking Summary Concepts, Architecture and Protocols IP Addressing Dotted Decimal Notation and Address Classes Classless Addressing Special IP Addresses 13