IP addresses 32 bit address written as four decimal numbers One per byte of address(e.g, 155. 34.60.112) Hierarchical address structure Network iD/ Host ID/ Port iD Complete address called a socket Network and host id carried in IP Header Port ID(sending process)carried in TCP header iP Address classes: Net ID Host ID Class A Nets Net iD Host ID Class B Nets 110 Net ID Host Id Class C Nets Class d is for multicast traffic
IP addresses • 32 bit address written as four decimal numbers – One per byte of address (e.g., 155.34.60.112) • Hierarchical address structure – Network ID/ Host ID/ Port ID – Complete address called a socket – Network and host ID carried in IP Header – Port ID (sending process) carried in TCP header • IP Address classes: 8 32 Net ID Host ID Net ID Net ID Host ID Host ID 0 10 110 16 32 24 32 Class A Nets Class B Nets Class C Nets Class D is for multicast traffic Eytan Modiano Slide 11
Host Names Each machine also has a unique name Domain name System: a distributed database that provides mapping between IP addresses and Host names E.g., 155. 34.50.112=> plymouth. I mit. edu
Host Names • Each machine also has a unique name • Domain name System: A distributed database that provides a mapping between IP addresses and Host names • E.g., 155.34.50.112 => plymouth.ll.mit.edu Eytan Modiano Slide 12
Internet Standards Internet Engineering Task Force (IETF Development on near term internet standards Open body Meets 3 times a year Request for Comments(RFCs) Official internet standards AvailablefromIetFwebpagehttp://www.ietf.org y°
Internet Standards • Internet Engineering Task Force (IETF) – Development on near term internet standards – Open body – Meets 3 times a year • Request for Comments (RFCs) – Official internet standards – Available from IETF web page: http://www.ietf.org Eytan Modiano Slide 13
The Internet Protocol (P Routing of packet across the network · Unreliab| e service Best effort delivery Recovery from lost packets must be done at higher layers Connectionless Packets are delivered(routed) independently Can be delivered out of order Re-sequencing must be done at higher layers Current version v4 Future v6 Add more addresses(40 byte header! Ability to provide Qos
The Internet Protocol (IP) • Routing of packet across the network • Unreliable service – Best eff ort delivery – Recovery from lost packets must be done at higher layers • Connectionless – Packets are delivered (routed) independently – Can be delivered out of order – Re-sequencing must be done at higher layers • Current version V4 • Future V6 – Add more addresses (40 byte header!) – A bility to provide QoS Eytan Modiano Slide 14
Header fields in IP Header er length type of service Total length(bytes) 16-bit identification Flags13-bit fragment offset TTL Protocol Header checksum Source iP address Destination IP Address Options(if any) Note that the minimum size header is 20 bytes TCP also has 20 byte header y6"°
Header Fields in IP 1 4 8 16 32 Protocol Note that the minimum size header is 20 bytes; TCP also has 20 byte header Ver Header length type of service Total length (bytes) 16 - bit identification Flags 13 - bit fragment offset TTL Header Checksum Source IP Address Destination IP Address Options (if any) Data Eytan Modiano Slide 15