ieg 3310 b chapter #2 - internet and tcp page 1. page 2 outline tcp/ip architecture access network...

IEG 3310 B

Chapter #2 - Internet and TCP

Outline TCP/IP Architecture Access Network IP, TCP and UDP Socket API

TCP/IP architecture OSI TCP/IP

Application

Presentation

Session

Transport

Network

Data Link

Physical

Application

Transport

Internet

Network Interface(Ethernet, ADSL, ATM, etc.)

Telnet &

RloginSNMPPing FTP SMTP

Trace-route

DNS TFTPBOOTP

& DHCP

TCP UDP

IPICMP IGMP

Data Link

ARP RARP

Physical Media

TCP/IP protocol graph

UserDatagramprotocol

Transmission ControlProcedure

Network Cabling Cable – allows you to connect devices Connector – standard interface

for making connections.Note: We need different cables & connectors

for different links.

Repeater and Hub

1. Repeater

2. Hub – multiple port repeater

<100m<100m

Signal regenerationSignal regeneration

<100m<100m<100m<100m

<100m<100m<100m<100m

The signal is regenerated on all segments

uplinkuplink

Switches and Hub

Number of ports: 8/16/24/…

Nature: Hub or Switch (access/core)

Speed: 10/100/1Gbps

Interfaces: Fiber/Copper

Backplane bus: stackability

Uplink: connecting to core switch

Management: SNMP and web

Others:

redundant supply

control console

…

Using a Hub or Switch

Straight Through Cable

Computer Hub

1 Tx+ 1 Rx+

2 Tx- 2 Rx-

3 Rx+ 3 Tx+

6 Rx- 6 Tx-

Other lines: unused.

Direct ConnectionWe need a cross over cable – one side uses

568A and the other side uses 568B.

WOGBN – Write: Orange Green, bluish brown

How to wire many computers?

Structured Cabling and Patch Panels

Ethernet Transmissions• The address of a node as defined by its LAN.

• The address in included in an Ethernet frame of data.

•Ethernet uses a six-byte physical address which is imprinted on the network interface card (NIC)

Ethernet FramesData is divided into frames. 64-1518 bytes Src address: 6 bytes Dst address: 6 bytes

LAN addressingEvery Ethernet node has a built-in, unique MAC

(medium access control) address. It represents the address of the node on a shared Ethernet network.

Finding your MAC address: winipcfg or ipconfig /all

IP Addressing

The Internet (IP) addressing. Each address is represented by4 bytes, denoting(1) Network address(2) Host address

11001010 00101101 10110111 00000001

202.45.183.1

Network-ID Host-ID

Host address=0 the network, host address=1s broadcast.

IP Addresses

1 1 1 1 Reserved for future use0

1 1 1 0 Multicast address

1 1 0 netid hostid

1 0 netid hostid

0 netid hostid

Class

A

B

C

D

E

24 bits (16777214)7 bits

14 bits 16 bits (65534)

21 bits 8 bits (254)

CUHK : 137.189.X.X (dotted decimal notation) -> a Class B network

1st Octet netid hostidA 1 - 126 p q.r.sB 128 - 192 p.q r.sC 192 - 223 p.q.r s

Internet Domains

IGS1.IE.CUHK.HK

adnetpc0

137.189.96.37

137.152.96.253

137.152.96.254

137.154.96.250

137.148.96.252

AGS.PWH.HK

IGS2.STH.HK137.150.96.252

137.189.96.131

T-1

137.189.96.252

137.154.96.251

137.148.96.47

137.150.96.48

magnet2.pwh.hk

magnet3.sth.hk

adnet1

IP Packet Format

PADDING

SOURCE IP ADDRESS

DESTINATION IP ADDRESS

IP OPTIONS (IF ANY)

FRAGMENT OFFSET

TOTAL LENGTH

IDENTIFICATION

0 8 16 31

HLENVERS SERVICE TYPE

FLAGS

HEADER CHECKSUMPROTOCOLTIME TO LIVE

DATA

...

PacketHeader

PacketData

How are IP packets routed?

magnet2.pwh.hk

IGS1.IE.CUHK.HK

137.152.96.253

137.152.96.254

137.154.96.250

137.148.96.252

AGS.PWH.HK

IGS2.STH.HK137.150.96.252

137.189.97.37

T-1

137.189.96.252

137.154.96.251

137.148.96.47

137.150.96.48

magnet3.sth.hk

adnetpc0

(1)

(2)

(3)

(4)

IP addresswith net_id routing137.152.0.0 directly137.154.0.0 directly137.148.0.0 directly137.150.0.0 137.154.96.250137.189.0.0 137.152.96.254

Routing table for AGS.PWH.HK

IP Routing AlgorithmRoute_IP_Datagram(datagram, routing_table)

Extract destination address, I-d, from datagramCompute IP address of destination network, I-n

If I-n matches any directly connected network addresssend datagram to destination over that network;

else if I-d appears as a host-specific routeroute datagram as specified in the list;

else if I-n appears in routing tableroute datagram as specified in the table;

else if a default route has been specifiedroute datagram to the default gateway;

else declare a routing error;

IP net_id routing137.152.0.0 directly137.154.0.0 directly137.148.0.0 directly137.150.0.0 137.154.96.250137.189.0.0 137.152.96.254

IP net_id routing137.152.0.0 directly137.154.0.0 directly137.148.0.0 directly137.150.0.0 137.154.96.250137.189.0.0 137.152.96.254

TCP and UDP

End-to-End Transport Protocola. Connectionless packet delivery service (UDP)b. Reliable Stream Transport service (TCP)

It featuresa. Network technology independenceb. Universal interconnectionc. End-to-end acknowledgmentsd. Application protocol standards

Its major applicationsa. e-mail (SMTP)b. file transfer (FTP)c. remote login (TELNET)d. web (HTTP)

physicalnetwork

router orgateway

Relationship of layers and addresses in TCP/IP

End-to-end TransportApplication

Transport

Internet

Interface

Internet

Interface

Physicalnetwork 1

Physicalnetwork 1

Application

Transport

Internet

Interface

Gateway G

frame

packet

datagram or transport segment

Frame Data AreaFrame Header

Packet Header Packet Data Area

Header

Kernal

User

H/W

Internet Connection via TCP

TCP Segment Format

. . .

DATA

DESTINATION PORTSOURCE PORT

0 16 31

OPTIONS (IF ANY)

Segments for connection management, data transfer, andreception acknowledgements.

SEQUENCE NUMBER

ACKNOWLEDGEMENT NUMBER

WINDOWHLEN RESVD CODE BITS

4 10

PADDING

URGENT POINTERCHECKUM

24

UDP CHECKSUM

. . .

DATA

UDP MESSAGE LENGTH

UDP DESTINATION PORTUDP SOURCE PORT

UDP Datagram Format 0 16 31

UDP Message length in bytes (Minimum: 8)UDP Checksum is optional (16-bit 1-complement of 1-complement sum)

To be transferred independently by IP packets.

How can a server serves multiple clients?

binding: 23-204

1048

TELNET client

23

TELNET Server

7 21

magnet1137.189.96.31

iestp10137.189.96.210

204

TELNET Client

9 208

TCP assigns some well-known ports for communications- server port defines the application.- client port defines the client.

Solution: Connection is identified by a pair of end-points

E.g., (137.189.96.31, 23) and (137.189.96,210, 204)

TCP Port numbers

Decimal Keyword Description015791113202123253742537980103104113117119139

--TCPMUXRJEECHODISCARDUSERSDAYTIMEFTP-DATAFTPTELNETSMTPTIMENAMESERVERDOMAINFINGERHTTPX400X400SNDAUTHUUCP-PATHNNTPNETBIOS-SSN

ReservedTCP multiplexerRemote job entryEchoDiscardActive usersDaytimeFile transfer protocol-dataFile transfer protocolTerminal connectionSimple mail transfer protocolTimeHost name serverDomain name serverFingerWeb serverX.400 Mail ServiceX.400 Mail SendingAuthentication ServiceUUCP Path ServiceUSENET news transfer protocolNETBIOS session service

UDP Port numbers

Decimal Keyword Description

079111315171937424353676869111123161162513514

--ECHODISCARDUSERSDAYTIME--QUOTECHARGENTIMENAMESERVERNICNAMEDOMAINBOOTPSBOOTPCTFTPSUNRPCNTP--------

ReservedEchoDiscardActive UsersDaytimeWho is up or NETSTATQuote of the DayCharacter GeneratorTimeHost Name ServerWho isDomain Name ServerBootstrap Protocol ServerBootstrap Protocol ClientTrivial File TransferSun Microsystems RPCNetwork Time ProtocolSNMP net monitorSNMP trapsUnix rwho daemonSystem log

FTP: File Transfer Protocol

userinterface

user protocol

interpreter

user data transfer

function

serverprotocol

interpreter

serverdata transfer

functionfile systemfile system

user at aterminal

ServerClient

controlconnection

dataconnection

21

20

Commands 3 or 4 bytes NVT ASCII w/wo arguments

Replies 3-digit numbers, optional messages ASCII

FTP commands (NVT ASCII)

ABOR

LIST filelist

PASS password

PORT n1,n2,n3,...,n6

QUIT

RETR filename

STOR filename

SYST

TYPE type

USER username

abort previous FTP command and any data transfer

list files or directory

password on server

client IP address (n1..n4) and port (n5x256+n6)

logoff from server

retrieve (get) a file

store (put) a file

server returns system type

specify file type:A (for ascii) I (for image)

username on server

Name Meaning

FTP commands and replies

/data/staff/pcwong> ftp -d magnet1Connected to magnet1.220 magnet1 FTP server (SunOS 4.1) ready.Name (magnet1:pcwong): pcwong---> USER pcwong331 Password required for pcwong.Password:---> PASS rachel41230 User pcwong logged in.ftp> dir cantoni.1---> PORT 137,189,96,21,11,33200 PORT command successful.---> LIST cantoni.1150 ASCII data connection for /bin/ls (137.189.96.21,2849) (0 bytes).-rw-r--r-- 1 pcwong staff 1953 Nov 10 18:16 cantoni.1226 ASCII Transfer complete. �remote: cantoni.165 bytes received in 0.11 seconds (0.56 Kbytes/s)ftp> get cantoni.1---> PORT 137,189,96,21,11,34200 PORT command successful.---> RETR cantoni.1150 ASCII data connection for cantoni.1 (137.189.96.21,2850) (1953 bytes).226 ASCII Transfer complete.local: cantoni.1 remote: cantoni.12009 bytes received in 0.051 seconds (39 Kbytes/s)

User clicks on http://www.singtao.com/ Ethereal network analyzer captures all frames observed

by its Ethernet NIC Sequence of frames and contents of frame can be

examined in detail down to individual bytes

How do the layers work together?

Internet

Top Pane shows

frame/packet sequence

Middle Pane shows

encapsulation for a given frame

Bottom Pane shows hex & text

TCP Segment

GET HTTP Request

Outline TCP/IP Architecture IP TCP and UDP Socket API

Socket API API (Application Programming Interface)

Provides a standard set of functions that can be called by applications

Berkeley UNIX Sockets API Abstraction for applications to send & receive data Applications create sockets that “plug into” network Applications write/read to/from sockets Implemented in the kernel Facilitates development of network applications Hides details of underlying protocols & mechanisms

Also in Windows, Linux, and other OS’s

Communications through Socket Interface

Client Server

descriptor

port number

descriptor

port number

• Application references a socket through a descriptor• Socket bound to a port number

Application 1

Socket

Socket interface

User

Kernel

Application 2

User

Kernel

Underlying communication

protocols

Underlying communication

protocols

Communications network

Socket

Socket interface

Socket Streams - mode of serviceConnection-oriented First, setup connection

between two peer application processes

Then, reliable bidirectional in-sequence transfer of byte stream (boundaries not preserved in transfer)

Multiple write/read between peer processes

Finally, connection release Uses TCP

Connectionless Immediate transfer of one

block of information (boundaries preserved)

No setup overhead & delay

Destination address with each block

Send/receive to/from multiple peer processes

Best-effort service only Possible out-of-order Possible loss

Uses UDP

Client & Server Differences Server

Specifies well-known port # when creating socket May have multiple IP addresses (net interfaces) Waits passively for client requests

Client Assigned ephemeral port # Initiates communications with server Needs to know server’s IP address & port #

DNS for URL & server well-known port # Server learns client’s address & port #

socket()

bind()

listen()

read()

close()

socket()

connect()

read()

write()

close()

blocks until server receivesa connect request from client

data

data

Server

Clientaccept()

write()

connect negotiation

Figure 2.17

Connection Stream

Java TCP Server import java.io.*; import java.net.*; class TCPServer { public static void main(String argv[]) throws Exception { String clientSentence; String capitalizedSentence; ServerSocket welcomeSocket = new ServerSocket(6789); while(true) { Socket connectionSocket = welcomeSocket.accept(); BufferedReader inFromClient = new BufferedReader(new InputStreamReader(connectionSocket.getInputStream())); DataOutputStream outToClient = new DataOutputStream(connectionSocket.getOutputStream()); clientSentence = inFromClient.readLine(); capitalizedSente

nce = "Welcome "+ clientSentence.toUpperCase() + '\n'; outToClient.writeBytes(capitalizedSentence); } } }

import java.io.*; import java.net.*; class TCPClient { public static void main(String argv[]) throws Exception { String sentence; String modifiedSentence; String hostName= “localhost"; // or the server hostname BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in)); Socket clientSocket = new Socket(hostName, 6789); DataOutputStream outToServer = new DataOutputStream(clientSocket.getOutputStream()); BufferedReader inFromServer = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); sentence = inFromUser.readLine(); outToServer.writeBytes(sentence + '\n'); modifiedSentence = inFromServer.readLine(); System.out.println("FROM SERVER: " + modifiedSentence); clientSocket.close(); } }

Java TCP Client

socket()

bind()

sendto()

close()

socket()

bind()

recvfrom()

sendto()

close()

blocks until serverreceives data from client data

data

Server

Client

recvfrom()

Figure 2.18

Datagram Stream

import java.io.*; import java.net.*; class UDPServer { public static void main(String args[]) throws Exception { DatagramSocket serverSocket = new DatagramSocket(9876); byte[] receiveData = new byte[1024]; byte[] sendData = new byte[1024]; while(true) { DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length); serverSocket.receive(receivePacket); String sentence = new String(receivePacket.getData()); InetAddress IPAddress = receivePacket.getAddress(); int port = receivePacket.getPort(); String capitalizedSentence = sentence.toUpperCase(); sendData = capitalizedSentence.getBytes(); DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, port); serverSocket.send(sendPacket); } } }

Java UDP Server

import java.io.*; import java.net.*; class UDPClient { public static void main(String args[]) throws Exception { BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in)); DatagramSocket clientSocket = new DatagramSocket(); InetAddress IPAddress = InetAddress.getByName(localhost"); byte[] sendData = new byte[512]; byte[] receiveData = new byte[512]; String sentence = inFromUser.readLine(); sendData = sentence.getBytes(); DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, 9876); clientSocket.send(sendPacket); DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length); System.out.println("Length " + receiveData.length); clientSocket.receive(receivePacket); String modifiedSentence = new String(receivePacket.getData()); System.out.println("FROM SERVER:" + modifiedSentence); clientSocket.close(); } }

Java UDP Client

Thank You

ieg 3310 b chapter #2 - internet and tcp page 1. page 2 outline tcp/ip architecture access network...

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