Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

1Ch1. Protocols and Architecture

1.1 ProtocolsUsed for communications between entities in a system

Must speak the same language

Entities

User applications

e-mail facilities

terminals

Systems

Computer

Terminal

Remote sensor

Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

21.2 Protocol Architecture

Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

3 1.3 TCP/IP Protocol Suite

An Internet According to TCP/IP

TCP/IP considers all of the hosts to be connected to this larger logical network rather to their individual physical networks.

Dominant commercial protocol architectureSpecified and extensively used before OSIDeveloped by research funded US Department of DefenseUsed by the Internet

Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

4TCP/IP and OSI

TCP/IP and the OSI ModelEncapsulation

Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

5TCP/IP Protocol Architecture

Application Layer

Communication between processes or applications

End to end or transport layer (TCP/UDP/…)

End to end transfer of data

May include reliability mechanism (TCP)

Hides detail of underlying network

Internet Layer (IP)

Routing of data

Network Layer Logical interface between end system and network

Physical Layer Transmission medium Signal rate and encoding

Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

61.3.2 Network Layer

IP Datagram

variable-length packet (up to 65,536 bytes)

two parts: header(20-60 bytes) and data

Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

71.3.3 Addressing

Physical address: local jurisdiction, easy to change.

Internet address: universe jurisdiction, cannot change.

Internet Address

Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

8

Class Ranges of Internet Addresses

IP Addresses in Decimal Notation

Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

9Nodes with more than one address

Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

101.3.4 Subneting

Two Levels of Hierarchy

Three Levels of Hierarchy

Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

11Addresses with and without Subnetting

Masking

Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

12Example. Find the class, netid and hostid for each address:

Class Netid Hostid

a. 4.23.145.90 A 4 23.145.90

b. 227.34.78.7 D N/A N/A

c. 246.7.3.8 E N/A N/A

d. 129.6.8.4 B 129.6 8.4

e. 198.76.9.23 C 198.76.9 23

Boundary-Level Masking Nonboundary-Level Masking

IP Addr: 45. 23. 21. 8 213. 23. 47. 37

Mask 255.255. 0. 0 255.255.255.240

Subnet addr: 45. 23. 0. 0 213. 23. 47. 32

Bit-wise AND

Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

131.3.5 Other Protocols in Network Layer

ARP: find physical address from IP address

RARP: find IP address from physical address.

ICMP: send notification back to the sender

IGMP: identify the hosts that are members of a group.

Unicasting Multicasting Broadcasting

One-to-one one-to-many one-to-all

Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

141.3.6 Transport Layer TCP and UDP(User Datagram Protocol)

Port Addresses

IP: host-to-host, deliver a packet from one physical device to another

TCP: port-to-port, (Buffer used by a particular process)

IP addr: 32 bits-- in IP datagram

Port addr: 16 bits—in TCP datagram

Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

15UDPUDP Datagram Format

UDP only provides basic functions:port addr, checksum, length.

It does not provide any sequencing or reordering functions, can not soeccify the damaged packet

Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

16TCP Segment Format

TCP is a reliable stream transport port-to-port protocol.

TCP generates a virtual circuit between sender and receiver that is active for the duration of a transmission.

connection establishment and connection termination alert.

Sequence number. position of the data in the original data stream.

Header length (HLEN): 4 bits, TCP head length:20—60 bytes

Control(6 bits) :independently.

Window size: size of the sliding window used in ARQ.

Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

171.4 Application Layer

1.4.1. Client-Server Model: (many-to-one)Client:a program running on the local machine requesting service from a server. A client program is finite.

Server: a program running on the remote machine provides services to the clients. A server program is infinite.

Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

181.4.2 BOOTP and DHCP

Attach to a TCP/IP internet, must know:

Its IP address, its subnet mask, the IP address of a router and the IP address of a name server which stored in a configuration file.

BOOTP: provide information for a diskless or first time boot computer.

DHCP: provide dynamic configuration. Moving, temporary IP addr.

1.4.3 Domain name system(DNS) – map name and address

Generic Domains: first level 7 possible 3-character labels: com, edu, gov, int, mil, net, org. a few more labels have been proposed: arts, firm, info, nom(personal nomenclatures), rec(recreation), store, web.

Country Domains: 2-character country abbreviations.

Inverse Domain: used to map a address to a name.

Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

191.4.4 TELNET

Remote Login

Network Virtual Terminal(NVT):universal interface between different OSs.

Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

201.4.5 File Transfer Protocol (FTP)Two connections (Date, Control). Which use different strategies and different port numbers.

1.4.6 Trivial File Transfer Protocol (TFTP) – copy files

1.4.7 Simple Mail Transfer Protocol (SMTP)

•User Agent (UA)

•Mail Transfer Agent (MTA)

•Relaying

•Mail gateway

Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

21Figure 25-16

The Entire E-mail System

Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

22Multipurpose Internet Mail Extensions(MIME)

SMTP: ASCII format

MIME: extend SMTP to non-ASCII

Post Office Protocol (POP) – download mail from server

Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

231.4.8 Hypertext Transfer Protocol (HTTP) -- www

HTTP Transaction

Uniform Resource Locator (URL): method, host, port, path

Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

24

PDUs in TCP/IP

Some Protocols in TCP/IP Suite

Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

25Exercise: A site with a given network address and mask. The administration has divided the site into several subnetworks. Choose appropriate subneaddresses, host addresses, and router addresses

(a) (b)

Ya Bao School of Engineering, SBUACS Ch1 Protocol and Architecture

26Solutions

(a) (b)