Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Internet Protocol Internetworking Lab 1 Why Internet? The Internet Host 1 N1 N2 N3 N4 Host 2 Gateway /Router 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 Classes of IP addresses Identifying class CLASS Range of Values A 0-127 B 128-191 C 192-223 D 224-239 E 240-255 Number of networks and hosts Address Bits in Max # of Bits in Max # of Class Prefix Networks Suffix Hosts/net A 7 128 24 16777216 B 14 16384 16 65536 C 21 2097152 8 256 Specific IP addresses Prefix Suffix Type of Addr Purpose All-0s All-0s This computer Used during bootstrap Identifies a network Network All-0s Network Network All-1s Directed broadcast Broadcast to a All-1s All-1s 127 Any specific network Limited broadcast Broadcast to local net Testing Loopback 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 IP functions Fragmentation in IP Host1 Host2 Network 3 MTU = 1400 Network 1 MTU = 1400 Router Network 2 MTU = 600 Router 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 Fragmentation field ID 16bits FLAGS 3bits Offset 13 bits Fragmentation field Original datagram 33 000 0 0, 1, 2, ………….1400 Fragmented datagram – fragment 1 33 001 0 0, 1, 2, ………….599 Fragmented datagram – fragment 2 33 001 75 600,601, ………….1199 Fragmented datagram – fragment 1 33 000 150 1200, 1201…….1400 IP properties • Unreliable • Connectionless - ? • Best Effort