3 Network layer duties Internetworking : heterogeneous Physical Networks To look Like a single network to he upper layers The address at Network layer must uniquely and universally define the connection of a host (computer) or a router to the internet When there are multiple routes to the destination ROUTERS must choose one route Encapsulate packets from upper layer and makes new packets out of them. Packetizing is made by IP Each ROUTER decapsulate IP datagram from the receiving frame, process it, end encapsulate it in another frame (depend on the protocol used by the physical network)
4 Host-to-Host Delivery: Internetworking, Addressing, and Routing
5 Links in an internetwork 4 LANs and WAN If the host A needs to send a data packet to host D, the packet first needs to go from A to S1 (Switch or Router), then from S1 to S3, and finally from S3 to host D
6 Network layer in an internetwork The Network layer at the source is responsible for creating a packet that carries two universal addresses DESTINATION address and SOURCE address
7 Network layer at the source
8 Network layer at a router
9 Network layer at the destination
11 Datagram approach In the DATAGRAM approach each packet is treated independently of all others. This approach can cause the datagrams of a transmission to arrive at their destination out of order. It is the responsibility of an upper layer to reorder the datagrams. The routing and delivery of the packet are based on the source and destination address included in the packet itself. The switches and routers each have a routing table that can decide on the route based on these two addresses.
12 Switching at the network layer in the Internet is done using the datagram approach to packet switching. Communication at the network layer in the Internet is connectionless.
14 An IP address is a 32-bit address. An IP (Internet Protocol) address is a unique identifier and universal for a node or host connection on an IP network. An IP address is a 32 bit binary number usually represented as 4 decimal values, each representing 8 bits, in the range 0 to 255 (known as octets) separated by decimal points. This is known as "dotted decimal" notation.
15 Example Change the following IP addresses from binary notation to dotteddecimal notation. a b Solution We replace each group of 8 bits with its equivalent decimal number and add dots for separation: a b
16 Example Change the following IP addresses from dotted-decimal notation to binary notation. a b Solution We replace each decimal number with its binary equivalent : a b
17 Every IP address consists of two parts: one identifying the network one identifying the node The Class of the address and the subnet mask determine: which part belongs to the network address and which part belongs to the node address. In classful addressing, the address space is divided into five classes: A, B, C, D, and E.
18 Finding the class in decimal notation A B C D E
19 Finding the class in binary notation
20 Finding the address class Class A addresses begin with 0xxxxxxx, or 1 to 126 decimal. Class B addresses begin with 10xxxxxx, or 128 to 191 decimal. Class C addresses begin with 110xxxxx, or 192 to 223 decimal. Class D addresses begin with 1110xxxx, or 224 to 239 decimal. Class E addresses begin with 1111xxxx, or 240 to 254 decimal. Obs: Addresses beginning with , or 127 decimal, are reserved for loop back and for internal testing on a local machine. [You can test this: you should always be able to ping , which points to yourself] Class D addresses are reserved for multicasting. Class E addresses are reserved for future use. They should not be used for host addresses.
21 Example Find the class of each address: a b Solution a. The first bit is 0; this is a class A address. b. The first 4 bits are 1s; this is a class E address.
22 Example Find the class of each address: a b c Solution a. The first byte is 227 (between 224 and 239); the class is D. b. The first byte is 252 (between 240 and 255); the class is E. c. The first byte is 134 (between 128 and 191); the class is B.
23 Netid and hostid Now we can see how the Class determines, by default, which part of the IP address belongs to the network (N) and which part belongs to the node (n). Class A -- NNNNNNNN.hhhhhhhh.hhhhhhhh.hhhhhhhh Class B -- NNNNNNNN.NNNNNNNN.hhhhhhhh.hhhhhhhh Class C -- NNNNNNNN.NNNNNNNN.NNNNNNNN.hhhhhhhh
24 Blocks in class A Class A is divided into 128 blocks, each block having a different netid. Millions of class A addresses are wasted.
25 Blocks in class B
26 Blocks in class C The number of addresses in class C is smaller than the needs of most organizations.
27 Network address In classful addressing, the network address is the one that is assigned to the organization.
28 There are reserved three blocks of the IP address space for private networks: 1 * Class A Class A network IP address range = For one Class A network: Subnet mask = Network address length = 8 bit ; Computer address length = 24 bit 16 * Class B Class B network IP address range = Class B network IP address range = For each of the 16 Class B networks: Subnet mask = Network address length = 16 bit ; Computer address length = 16 bit Alternatively, 16 * Class B combined Combined Class B networks IP address range = For all 16 Class B networks combined: Subnet mask = Network address length = 12 bit ; Computer address length = 20 bit 256 * Class C Class C network IP address range = Class C network IP address range = For each of the 256 Class C networks: Subnet mask = Network address = 24 bit ; Computer address = 8 bit Alternatively, 256 * Class C combined Combined Class C networks IP address range = For all 256 Class C networks combined: Subnet mask = Network address length = 16 bit; Computer address length = 16 bit
29 Example Given the address , find the network address. Solution The class is A. Only the first byte defines the netid. We can find the network address by replacing the hostid bytes ( ) with 0s. Therefore, the network address is
30 Example Given the address , find the network address. Solution The class is B. The first 2 bytes defines the netid. We can find the network address by replacing the hostid bytes (17.85) with 0s. Therefore, the network address is
31 Example Given the network address , find the class. Solution The class is A because the netid is only 1 byte.
32 A network address is different from a netid. A network address has both netid and hostid, with 0s for the hostid.
33 Sample internet 1 Token ring LAN class C 2 WAN 2 Ethernet LAN class B 4 Point to point WAN T1 line just connect two routers 5 Ethernet LAN class A
34 A network with two levels of hierarchy IP addresses are designed with two levels of hierarchy.
35 Three level of hierarchy( Sub- netted) The network needs to be divided into several sub networks Example : University has one network address The outside world knows the organization by its network address. But needs several sub network addresses for different departments Inside the organization each sub network is recognized by its sub network address In sub netting, a network is divided into several smaller groups with each sub network having its own sub network address.
36 A network with three levels of hierarchy (sub netted) The sub-networks still appear as a single network to the rest of internet
37 Addresses in a network with and without sub netting
38 Hierarchy concept in a telephone number
39 Default masks Class In Binary In Dotted- Decimal Using Slash Prefix A /8 B /16 C /24 The network address can be found by applying the default mask to any address in the block (including itself). It retains the netid of the block and sets the hostid to 0s.
40 Windows IP Configuration Host Name : computer Primary Dns Suffix : Node Type : Hybrid IP Routing Enabled : No WINS Proxy Enabled : No Ethernet adapter Wireless Network Connection: Media State : Media disconnected Description : Intel(R) PRO/Wireless 2200BG Network Connection Physical Address : D-2C Ethernet adapter Local Area Connection: Connection-specific DNS Suffix. : Description : Broadcom NetXtreme Gigabit Ethernet Physical Address : C2-DF-F2-F4 Dhcp Enabled : Yes Autoconfiguration Enabled.... : Yes IP Address : Subnet Mask : Default Gateway : DHCP Server : DNS Servers : Lease Obtained : 9 decembrie :22:01 Lease Expires : 12 decembrie :22:01 Ethernet adapter VPN: Media State : Media disconnected Description : TAP-Win32 Adapter V8 Physical Address : 00-FF-41-B3-55-4F
41 Subnet Masking Applying a mask to an IP address allows you to identify the network and node parts of the address. The network bits are represented by the 1s in the mask, and the node bits are represented by the 0s. Performing a bitwise logical AND operation between the IP address and the subnet mask results in the Network Address or Number. For example, using our test IP address and the default Class B subnet mask, we get: Class B IP Address Default Class B Subnet Mask Network Address
42 Example A router outside the organization receives a packet with destination address Show how it finds the network address to route the packet. Solution The router follows three steps: 1. The router looks at the first byte of the address to find the class. It is class B. 2. The default mask for class B is The router ANDs this mask with the address to get The router looks in its routing table to find out how to route the packet to this destination. Later, we will see what happens if this destination does not exist.
43 Subnetting Subnetting an IP Network can be done for a variety of reasons, including organization, use of different physical media (such as Ethernet, FDDI, WAN, etc.), preservation of address space, and security. The most common reason is to control network traffic. In an Ethernet network, all nodes on a segment see all the packets transmitted by all the other nodes on that segment. Performance can be adversely affected under heavy traffic loads, due to collisions and the resulting retransmissions. A router is used to connect IP networks to minimize the amount of traffic each segment must receive.
44 More Restrictive Subnet Masks Additional bits can be added to the default subnet mask for a given Class to further subnet, or break down, a network. When a bitwise logical AND operation is performed between the subnet mask and IP address, the result defines the Subnet Address (also called the Network Address or Network Number). There are some restrictions on the subnet address. Node addresses of all "0"s and all "1"s are reserved for specifying the local network (when a host does not know its network address) and all hosts on the network (broadcast address), respectively. This also applies to subnets. A subnet address cannot be all "0"s or all "1"s. This also implies that a 1 bit subnet mask is not allowed. This restriction is required because older standards enforced this restriction. Recent standards that allow use of these subnets have superseded these standards, but many "legacy" devices do not support the newer standards. If you are operating in a controlled environment, such as a lab, you can safely use these restricted subnets.
45 A router inside the organization receives the same packet with destination address Show how it finds the subnetwork address to route the packet The router follows three steps: 1. The router must know the mask. We assume it is /19 2. The router applies the mask to the address, The subnet address is The router looks in its routing table to find how to route the packet to this destination. Later, we will see what happens if this destination does not exist.
46 CIDR -- Classless InterDomain Routing CIDR was invented several years ago to keep the internet from running out of IP addresses. The "classful" system of allocating IP addresses can be very wasteful; anyone who could reasonably show a need for more that 254 host addresses was given a Class B address block of host addresses. Even more wasteful were companies and organizations that were allocated Class A address blocks, which contain over 16 Million host addresses! Only a tiny percentage of the allocated Class A and Class B address space has ever been actually assigned to a host computer on the Internet.
47 CIDR notated address Under CIDR, the subnet mask notation is reduced to a simplified shorthand. Instead of spelling out the bits of the subnet mask, it is simply listed as the number of 1s bits that start the mask. Example, instead of writing the address and subnet mask as , Subnet Mask the network address would be written simply as: /22 which indicates starting address of the network, and number of 1s bits (22) in the network portion of the address. If you look at the subnet mask in binary , you can easily see how this notation works. The use of a CIDR notated address is the same as for a Classful address. Classful addresses can easily be written in CIDR notation : (Class A = /8, Class B = /16, and Class C = /24)
50 Class C # bits Subnet Mask CIDR #Subnets #Hosts Nets * Hosts / / / / /
51 Example Say you are assigned a Class C network number of You want to utilize this network across multiple small groups within an organization. You can do this by subnetting that network with a subnet address. We will break this network into 14 subnets of 14 nodes each. This will limit us to 196 nodes on the network instead of the 254 we would have without subnetting, but gives us the advantages of traffic isolation and security. To accomplish this, we need to use a subnet mask 4 bits long. Recall that the default Class C subnet mask is Extending this by 4 bits yields a mask of
52 Example cont This gives us 16 possible network numbers, 2 of which cannot be used: Subnet bits Network Number Node Addresses Broadcast Address Reserved None thru thru thru thru thru thru thru thru thru thru thru thru thru thru Reserved None
Lecture 8 Internetworking and IP Address Motivation of Internetworking Internet Architecture and Router Internet TCP/IP Reference Model and Protocols IP Addresses - Binary and Dotted Decimal IP Address
Classful IP Addressing (cont.) 1 Address Prefix aka Net ID defines the network Address Suffix aka Host ID defines the node In Classful addressing, prefix is of fixed length (1, 2, or 3 bytes)! Classful
Chapter 19 Network Layer: Logical Addressing 19.1 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 19-1 IPv4 ADDRESSES An IPv4 address is a 32-bit address that
CE363 Data Communications & Networking Chapter 6 Network Layer: Logical Addressing TCP/IP and OSI model APPLICATION APPLICATION PRESENTATION SESSION TRANSPORT NETWORK Host-Network TRANSPORT NETWORK DATA
Application Note IP Addressing A Simplified Tutorial July 2002 COMPAS ID 92962 Avaya Labs 1 All information in this document is subject to change without notice. Although the information is believed to
Subnetting Basics You learned previously how to define and find the valid host ranges used in a Class A, Class B, and Class C network address by turning the host bits all off and then all on. This is very
Due to the number of hardware possibilities for a network, there must be a set of rules for how data should be transmitted across the connection media. A protocol defines how the network devices and computers
Computer Network Foundation Chun-Jen (James) Chung 1 Outline Network Addressing Subnetting Classless Inter-Domain Routing (CIDR) Route Aggregation Network Addressing How does the network decide where to
Tutorial (03) IP addresses & Sub netting Dr. Ahmed M. ElShafee ١ Agenda IP Addressing Conventions Original IPv4 Address Classes Subnetting CIDR (Classless InterDomain Routing) ٢ IP Addressing Conventions
Review questions 1 Data information is sent onto the network cable using which of the following? A Communication protocol B Data packet C Media access method D Packages 2 To which TCP/IP architecture layer
CCNA1 V3.0 Mod 10 (Ch 8) 1. How many bits are in an IP C. 64 2. What is the maximum value of each octet in an IP A. 28 55 C. 256 3. The network number plays what part in an IP A. It specifies the network
CS 348: Computer Networks - IP addressing; 21 st Aug 2012 Instructor: Sridhar Iyer IIT Bombay Think-Pair-Share: IP addressing What is the need for IP addresses? Why not have only MAC addresses? Given that
Lecture 8. Internet Network Layer: IP Fundamentals Outline Layer 3 functionalities Internet Protocol (IP) characteristics IP packet (first look) IP addresses Routing tables: how to use ARP Layer 3 functionalities
Module 10 Subnetting Class A, B and C addresses Solutions to the Lab Exercises 10.3.5a, 10.3.5b, 10.3.5c and 10.3.5d 10.3.5a Basic Subnetting Use the following information and answer the following subnet
TCP/IP Protocol Suite HTTP SMTP DNS RTP Distributed applications Reliable stream service TCP UDP User datagram service Best-effort connectionless packet transfer Network Interface 1 IP Network Interface
Internet Protocols Addressing & Services Updated: 9-29-2012 Virtual vs. Physical Networks MAC is the part of the underlying network MAC is used on the LAN What is the addressing mechanism in WAN? WAN is
Future Internet Technologies Traditional Internet Dr. Dennis Pfisterer Institut für Telematik, Universität zu Lübeck http://www.itm.uni-luebeck.de/people/pfisterer Internet Protocol v4 (IPv4) IPv4 Model
CCNA R&S: Introduction to Networks Chapter 9: Subnetting IP Networks Frank Schneemann Chapter 9: Subnetting IP Networks Subnetting IP Networks In this chapter, you will be learning how devices can be grouped
The fundamentals of TCP/IP networking TCP/IP (Transmission Control Protocol / Internet Protocols) is a set of networking protocols that is used for communication on the Internet and on many other networks.
Networking Basics for Automation Engineers Page 1 of 10 mac-solutions.co.uk v1.0 Oct 2014 1. What is Transmission Control Protocol/Internet Protocol (TCP/IP)------------------------------------------------------------
IP Addressing -Internetworking (with TCP/IP) -Classful addressing -Subnetting and Supernetting -Classless addressing Internetworking The concept of internetworking: we need to make different networks communicate
Process Process Process Layer CSCE 515: Computer Network Programming ------ IP routing Wenyuan Xu ICMP, AP & AP TCP IP UDP Transport Layer Network Layer Department of Computer Science and Engineering University
Lab 10.4.1 IP ing Overview Estimated time: 30 min. Objectives: Background: This lab will focus on your ability to accomplish the following tasks: Name the five different classes of IP addresses Describe
Internet Technology Prof. Indranil Sengupta Department of Computer Science and Engineering Indian Institute of Technology, Kharagpur Lecture No #06 IP Subnetting and Addressing (Not audible: (00:46)) Now,
then to a router. Remember that with a Class C network address, the first 3 octets, or 24 bits, are assigned as the network address. So, these are two different Class C networks. This leaves one octet,
Internetworking Problem: There is more than one network (heterogeneity & scale) Hongwei Zhang http://www.cs.wayne.edu/~hzhang Internetworking: Internet Protocol (IP) Routing and scalability Group Communication
TCP/IP Network Essentials Linux System Administration and IP Services Layers Complex problems can be solved using the common divide and conquer principle. In this case the internals of the Internet are
Savera Tanwir Internet Protocol The IP Protocol The IPv4 (Internet Protocol) header. IP Packet Details Header and payload Header itself has a fixed part and variable part Version IPv4, IPv5 or IPv6 IHL,
IP Subnetting Shailesh N. Sisat Prajkta S. Bhopale Vishwajit K. Barbudhe Abstract - Network management becomes more and more important as computer-networks grow steadily. A critical skill for any network
Module 2: Assigning IP Addresses in a Multiple Subnet Network Contents Overview 1 Lesson: Assigning IP Addresses 2 Lesson: Creating a Subnet 19 Lesson: Using IP Routing Tables 29 Lesson: Overcoming Limitations
Indian Institute of Technology Kharagpur IP Subnetting and Addressing Prof Indranil Sengupta Computer Science and Engineering Indian Institute of Technology Kharagpur Lecture 6: IP Subnetting and Addressing
Lab 10.3.5a Basic Subnetting Objective How to identify reasons to use a subnet mask How to distinguish between a default subnet mask and a custom subnet mask What given requirements determine the subnet
IP Addressing To facilitate the routing of packets over a network, the TCP/IP protocol suite uses a 32-bit logical address known as an IP address. This topic introduces the components of an IP address.
Network layer: Overview Network layer functions IP Routing and forwarding 1 Network layer functions Transport packet from sending to receiving hosts Network layer protocols in every host, router application
Computer Networks Introduc)on to Naming, Addressing, and Rou)ng Week 09 College of Information Science and Engineering Ritsumeikan University MAC Addresses l MAC address is intended to be a unique identifier
Unit 3 Let s Route Overview Description This unit contains two lessons: The first lesson introduces the format for addressing data that travels across the Internet. The lesson focuses on the underlying
Mobile IP Bheemarjuna Reddy Tamma IIT Hyderabad Source: Slides of Charlie Perkins and Geert Heijenk on Mobile IP IP Refresher Mobile IP Basics 3 parts of Mobile IP: Outline Advertising Care-of Addresses
IP Addressing Introductory material. A module devoted to IP addresses. Addresses & Names Hardware (Layer 2) Lowest level Ethernet (MAC), Serial point-to-point,.. Network (Layer 3) IP IPX, SNA, others Transport
Chapter 4 IP Addresses: Classful Addressing CONTENTS INTRODUCTION CLASSFUL ADDRESSING OTHER ISSUES A SAMPLE INTERNET 4.1 INTRODUCTION An IP address is a 32-bit address. The IP addresses are unique. Address
TCP/IP Addressing and Subnetting an excerpt from: A Technical Introduction to TCP/IP Internals Presentation Copyright 1995 TGV Software, Inc. IP Addressing Roadmap Format of IP Addresses Traditional Class
1. Introduction to IP... 1 2. IP Networks, IP Hosts and IP Ports... 1 3. IP Packet Structure... 2 4. IP Address Structure... 2 Network Portion... 2 Host Portion... 3 Global vs. Private IP Addresses...3
IP address format: 7 24 Class A 0 Network ID Host ID 14 16 Class B 1 0 Network ID Host ID 21 8 Class C 1 1 0 Network ID Host ID 28 Class D 1 1 1 0 Multicast Address Dotted decimal notation: 10000000 00001011
IP v 1-3: defined and replaced Introduction to IP v6 IP v4 - current version; 20 years old IP v5 - streams protocol IP v6 - replacement for IP v4 During developments it was called IPng - Next Generation
VLSM Static routing Computer networks Seminar 5 IP address (network and host part) Address classes identified by first three bits Subnet mask determines how the IP address is divided into network and host
Subnetting,Supernetting, VLSM & CIDR WHAT - IP Address Unique 32 or 128 bit Binary, used to identify a system on a Network or Internet. Network Portion Host Portion CLASSFULL ADDRESSING IP address space
SUBNET MASK To define the network and host portions of an address, the devices use a separate 32-bit pattern called a subnet mask. We express the subnet mask in the same dotted decimal format as the IPv4
SFWR 4C03: Computer Networks and Computer Security January 19-22 2004 Lecturer: Kartik Krishnan Lectures 7-9 RARP: Reverse Address Resolution Protocol When a system with a local disk is bootstrapped it
Question 3.1.1 Question Answers a. 123 01111011 b. 202 11001010 c. 67 01000011 d. 7 00000111 e. 252 11111100 f. 91 01011011 g. 18.104.22.168 01110100.01111111.01010001.00000011 h. 255.255.255.0 11111111.11111111.11111111.00000000
Chapter 3: IP Addressing and VLSM QUESTION 54 What is the principle reason to use a private IP address on an internal network? A. Subnet strategy for private companies. B. Manage and scale the growth of
CS 43: Computer Networks IP Kevin Webb Swarthmore College November 5, 2013 Reading Quiz IP datagram format IP protocol version number header length (bytes) type of data max number remaining hops (decremented
Networking Test 4 Study Guide True/False Indicate whether the statement is true or false. 1. IPX/SPX is considered the protocol suite of the Internet, and it is the most widely used protocol suite in LANs.
The IP Transmission Process V1.4: Geoff Bennett Contents Communication Between Hosts Through a MAC Bridge Through a LAN Switch Through a Router The tutorial is divided into four sections. Section 1 looks
Guide to Network Defense and Countermeasures Third Edition Chapter 2 TCP/IP Objectives Explain the fundamentals of TCP/IP networking Describe IPv4 packet structure and explain packet fragmentation Describe
IP Addressing & Subnetting Made Easy Working with IP Addresses Introduction You can probably work with decimal numbers much easier than with the binary numbers needed by the computer. Working with binary
IP addressing IP address: 32-bit identifier for host, router interface Interface: Connection between host, router and physical link routers typically have multiple interfaces host may have multiple interfaces
IP Addressing Introductory material. An entire module devoted to IP addresses. IP Addresses Structure of an IP address Classful IP addresses Limitations and problems with classful IP addresses Subnetting
A unified network requires a universal communication service. Host identifiers: Name: identifies what the object is Address: identifies where it is Route: identifies how to get there Copyright Jim Martin
Course Name: TCP/IP Networking Course Overview: Learn the essential skills needed to set up, configure, support, and troubleshoot your TCP/IP-based network. TCP/IP is the globally accepted group of protocols
Network System Design Lesson Unit 1: INTRODUCTION TO NETWORK DESIGN Assignment Customer Needs and Goals Identify the purpose and parts of a good customer needs report. Gather information to identify network
Gary Hecht Computer Networking (IP Addressing, Subnet Masks, and Packets) The diagram below illustrates four routers on the Internet backbone along with two companies that have gateways for their internal
COMP 631: COMPUTER NETWORKS IP Addressing Jasleen Kaur Fall 2014 1 How to Deal With Heterogeneity & Scale? Requirements from IP addressing: Should be globally unique Should facilitate easy mapping to link-layer
Advanced TCP/IP Overview There is one primary set of protocols that runs networks and the Internet today. In this lesson, you will work with those protocols: the Transmission Control Protocol (TCP) and
Chapter 2 TCP/IP Networking Basics A network in your home or small business uses the same type of TCP/IP networking that is used for the Internet. This manual provides an overview of IP (Internet Protocol)
About the Tutorial Internet Protocol version 4 (IPv4) is the fourth version in the development of the Internet Protocol (IP) and the first version of the protocol to be widely deployed. IPv4 is described
Advanced IP Addressing CS-765 A Aspects Of Systems Administration Spring-2005 Instructure: Jan Schauman Stevens Institute Of Technology, NJ. Prepared By: Modh, Jay A. M.S. NIS SID: 999-14-0352 Date: 05/02/2005
IPv4 Addressing Simplified by Ken Foster B.S. IT Information; Security and Forensics Kaplan University January 23, 2011 The concept of IP Addressing is foundational to overall routing in general. Without