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Internet Protocol. Internetworking Lab 1. Why Internet?. Protocols for Inter-network. TCP/IP protocol suite TCP /UDP – layer 4 – Transport layer IP network layer Forward packets from network to network Unique address which is globally recognized Why not MAC/Physical addresses
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Internet Protocol Internetworking Lab 1
Protocols for Inter-network • TCP/IP protocol suite • TCP /UDP – layer 4 – Transport layer • IP network layer • Forward packets from network to network • Unique address which is globally recognized • Why not MAC/Physical addresses • Routing ( algorithms, decisions, tables )
Internet Protocol - Goals • Single seamless communication • Physical network details to be hidden from applications • Hardware details • Software details • Addressing mechanism to locate the network/machine (independent of MAC/Phy address)
Internet Protocol Goals • Based on the location of the network – forward the packets • For this purpose use – routing algorithms and tables
Solution – IP functions • Provide an addressing mechanism • IP addresses • IP layer ( network layer) to provide Routing and forwarding mechanisms • Is not Reliable – No guarantees • Best Effort Delivery
IP Address • 32 bits or 4 bytes • Each byte – 255 decimal – FF (hex) • Typical address 129.21.21.3 • Dotted quad, dotted decimal • Two parts – • Network id – locates the network – used in routing • Host id – identifies the host in the network
Classes of IP address • Class A • Network id is in 1st byte, host id in the rest 3 • Class B • Network id is in first two bytes, host id in the last 2 • Class C • Network id is in the first three bytes, host id in the last byte • Class D and E – special cases
Network Mask The network mask (subnet mask) where there are 1’s indicates the network ID where there are 0’s indicates the host ID Examples for a class A address: 255.0.0.0 for a class B address: 255.255.0.0 for a class C address: 255.255.255.0
Fragmentation in IP • Identification • used to determine which fragments belong to each other • Flag • D flag =0– data may be fragmented • =1 data may not be fragmented • Fragment offset • indicates where a fragment belongs in the complete message – measured in octets
IP properties • Unreliable • Connectionless - ? • Best Effort