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Internetworking. What is internetworking ? Connect multiple networks of one or more organizations into a large, uniform communication system . The resulting system is called an internetwork or internet. What is Internet?
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Internetworking • What is internetworking? • Connect multiple networks of one or more organizations into a large, uniform communication system. • The resulting system is called an internetwork or internet. • What is Internet? • The Internet is the specific global internetwork that grew out of ARPA-NET for communication of between computer located anywhere in the world
Protocols • Each intermediate network must agree to handle transit in exchange for the right to send traffic throughout the internet. • Internetworking protocols • All computers and routers in an internet must agree on a common set of internetworking protocols.
What is a protocol? revisited • A set of syntactic and semantic rules for communication. • details of message formats • How a computer should respond when a message arrives. • How a computer handles errors or. • Independent of lower layers or hardware.
TCP/IP protocol • TCP/IP is the most widely used internetworking protocol suite. • TCP: Transmission Control Protocol. • IP: Internet Protocol. • TCP/IP is now the defacto standard for internetworking protocols.
TCP/IP suite • Here are some of the key features provided by TCP/IP suite: • Packet switching • Logical addressing • Dynamic rooting • Name resolution
Packet switching • The data is divided in small chunks “packets” • The packets are transmitted independently • Possibly by different routes • And reassembled at the other end. • This allows a faster transmission
Logical addressing • Every computer has physical address • Ethernet address 48 bits (MAC address) • 90:AF:F4:CA:BA:03 • Burned into the chip at the factory • Physical addresses are of different formats • With no hierarchical scheme • Uniform format: IP addresses • 32 bits identifying the network and the host. • Two systems can not connect to the Internet with the same address at the same time. • Translation of IP to Ethernet address and vice versa.
Dynamic rooting • Different routes can be taken from source to destination • Router can choose a path for the data depending on present conditions • Path taken
Name resolution • TCP/IP provides a mapping of domain name and numeric addresses • www.doc.gold.ac.uk = 158.223.1.108