Chapter Eleven

Networkingwith TCP/IP

and the Internet

IP Planning

An IP address contains 32 bits or total of 4 octets

i.e. 192.168.0.2

Each bit of the 32 bits can be a member of one and only one of the following sections:

Network Host Subnet

What is the Network section? A group Identifier (compare to area

code number)What is the Host section?

Group of individual PC’s or devices within the same network

IP Planning

How many bits should be under the Network section? Depending on the size of the organization and

potential growth, one of the following classes can be obtained from the ICANN organization: A, B, or C

How many bits should belong to the host section? 32 – # Network bits

How many hosts can a Network have? (2 ^ Number of host bits ) - 2

IP Planning

Why are we loosing 2? Network Identifier Network Broadcast Address

What is a Network Identifier? The first IP address in a network, known as the

“cable identifier”. Represents the entire network. All host bits are turned off (0’s)

Example: 192.168.4.0 What class is it? What is it in binary?

What is a Broadcast Address? The last IP address in a network. Used to

communicate with all the hosts in the network. All host bits are turned on (1’s)

Example: 192.168.4.255 What is it in binary?

IP Planning

Examples: Class A uses the first 8 bits for the network identifier

The address range is only up to 126. The binary equivalent to that is 01111110. The MSB is 0 so we use only the last 7 bits.

Number of networks that can be created = 27 = 128 – 2 = 126. Why?

Number of hosts per Class A network 32 bits – 8 bits = 24 bits 224 = 16,777,216 – 2 = 16,777,214 Class A structure: N.H.H.H

Class B uses the first 16 bits for the network identifier The address range is from 128 - 191. The difference is = 64.

The binary equivalent to that is 00111110.00000000 The first two MSB are 0 so we use only the last 14 bits

Number of networks that can be created = 214 = 16384 Number of hosts per Class A network

32 bits – 16 bits = 16 bits 216 = 65,536 – 2 = 65,534 Class B Structure: N.N.H.H

What would be Class C?

Exercise

Classify the following IP addresses as A, B, or C and label the network and host parts of the IP address: 99.1.1.0 156.1.149.9 171.13.5.233 127.1.1.255 193.4.14.1

IP Planning

What is Subnetting? Process of subdividing a single class of network into multiple,

smaller networks.Why do we need it?

Organization, control, and ease of managementWho does it?

The Network Administrator of the organizationHow is subnetting done?

Borrow bits from the host section and move them to the “subnet” section

How many bits should I borrow?

Depends on how many subnets you want to create

What are some of the problems associated with subnetting?

Loosing IP’s

The outside world does not have any knowledge of our Subnetting plan

IP Planning

What is a Subnetmask? Special 32-bit number that, when combined (Logically

Anded) with a device’s IP address, determines which subnetwork that particular device belongs to

For an external host to communicate with 166.144.63.12, the router will need to interpret the subnetmask information

IP Planning

How is it written? All bits under the network and subnetwork sections are

turned on (1’s).What is default subnetmask?

The subnet mask that will be used if you do not specify one in your TCP/IP Configuration

255.0.0.0 for Class A 255.255.0.0 for Class B 255.255.255.0 for Class C

What is the relation between Subnet Mask and Bit Mask?

Subnet mask is the dotted decimal notation of the number of network and subnetwork bits

Bit Mask is the count of the number of network and subnet bits

Default bit mask for class A is 8 Default bit mask for class B is 16 Default bit mask for class C is 24

IP Planning

What are the rules? Number of subnets created =

2 ^ (Number of bits borrowed from the host

section)

Number of subnets Available = 2 ^ (Number of bits borrowed from the host

section) – 2 Number of hosts created per

subnet = 2 ^ (Number of bits remaining under the host

section)

Number of hosts available per subnet =

2 ^ (Number of bits remaining from the host

section) – 2

Agenda

Attendance, and Review of subnetting rulesSubnetting Class C -- Case StudyBuilding the topology and Interconnecting Networking Devices Using real Cisco routers and switchesGateways – What are they???Packet Tracer– A quick introduction, and simulating how a packet traverses a simple WAN (How a packet goes from one LAN to another through routers)Subnetting Class C– Group ExerciseLogical And

Example

Say you are assigned a Class C network number of 200.133.175.0 (apologies to anyone who may actually own this domain address:). You want to utilize this network across multiple small groups within an organization. You can do this by subnetting that network. Break this network into 8 subnets of 32 IP addresses each. How many subnets can be used? How many nodes can be in each subnet?

Building the Topology

Now, we will use real Cisco routers and switches to connect two LANs (Let’s say, the HR department LAN and the IT department LAN)During this lab make sure that you take the time to do the following:

Check the different types of interfaces that a router can have

Know what each type of an interface is used for Know what type of cable is used with each interface Ask Questions

Default Gateway

The role of Routers in connecting subnetsWhat is a Gateway?

Combination of software and hardware that enable two different network segments to exchange data

Examples: Cisco Routers, Linksys routes, Linux servers with multiple NICs and routing services installed, windows 2000 server with multiple NICs and RRAS installed.

The IP address of a router’s port through which a network is connected to the router

Every device has to have a default gateway to communicate with other devices outside its network

iMac iMac iMac iMac iMac iMac iMac iMac

Rules1. Each router’s interface has to be on a separate network ( You can’t have two differentinterfaces on the same network)2. Each interface on the router has to be assigned an ip address and a subnet mask3. Routers’ interfaces usually take the first available IP address on a network4. Switches are layer 2 devices and do not need an IP address to work5. Each PC on the network must be configured with the correct IP properties. Your PC will needan IP address and a subnet mask to be able to communicate with other hosts on the samenetwork. Your PC will need a default gateway to be able to communicate with other hosts on adifferent network6. PCs and their Default Gateway must belong to the same network.

Building The Topology with Packet Tracer

Interconnect Devices Simulate how a Packet traverses a simple WAN

Group Exercise

Do number 2 from the IP Addressing/Subnet Masking Problems

Agenda

Attendance and questions from last week’s meetingGroup discussion about the homework ExerciseLogical AND and group exerciseCase 1, and 2 (To be studied at home)Sockets, well-known port numbers, DNS, BOOTP, DHCP, and WINSTools: netstat, nbtstat, snlookup, and tracero

Logical And – Why

Why: The logical AND function is used to extract the subnet ID from a host IP address and its subnet Mask Question: With out using the table

from the previous group exercise, can you tell to which subnet the host 200.133.175.199 belongs???

Logical And – How

Host IP Address (in binary format)AND

Subnet Mask (in binary format)= Subnet ID

1 And 1 = 11 And 0 = 00 And 0 = 00 and 1 = 0Short cut: X And 255 = X

X And 0 = 0

Logical AND Exercise

Given the IP Address: 199.10.10.110/248 What is the subnet mask? How many bits were borrowed? How many subnets were created What is the number of theoretical hosts per

subnet? Using the Logical And function, find the subnet

ID where the host resides What is the broadcast address for this subnet?

Case 1

1. Suppose you are given the IP address 195.5.5.0 and wish to connect Springfield and Bedrock to Southpark. Create an IP addressing scheme that will meet the following requirements:

A: Each subnet must support between 25 and 30 devices.

B: You must have enough subnets to address each network.

i. What is the subnet mask for this network?

ii. What is the broadcast address of the 3rd subnet?

iii. On the diagram, assign a subnet address to each network and give each router interface an appropriate IP address for that network.

Case 1 AnswerSouthpark

Springfield Bedrock

--

192.5.5.33/27

192.5.5.34/27

192.5.5.65/27

192.5.5.66/27

192.5.5.97/27 192.5.5.129/27

IP:192.5.5.98/27SM: 255.255.255.224

GW: 192.5.5.97

IP:192.5.5.130/27SM: 255.255.255.224

GW: 192.5.5.129

List of networks for the 195.5.5.0 network with the subnet mask 255.255.255.224

Hosts Network

from to Broadcast Address

195.5.5.0 195.5.5.1 195.5.5.30 195.5.5.31 195.5.5.32 195.5.5.33 195.5.5.62 195.5.5.63 195.5.5.64 195.5.5.65 195.5.5.94 195.5.5.95 195.5.5.96 195.5.5.97 195.5.5.126 195.5.5.127 195.5.5.128 195.5.5.129 195.5.5.158 195.5.5.159 195.5.5.160 195.5.5.161 195.5.5.190 195.5.5.191 195.5.5.192 195.5.5.193 195.5.5.222 195.5.5.223 195.5.5.224 195.5.5.225 195.5.5.254 195.5.5.255

Rules1. Each router’s interface has to be on a separate network ( You can’t have two differentinterfaces on the same network)2. Each interface on the router has to be assigned an ip address and a subnet mask3. Routers’ interfaces usually take the first available IP address on a network4. Switches are layer 2 devices and do not need an IP address to work5. Each PC on the network must be configured with the correct IP properties. Your PC will netan IP address and a subnet mask to be able to communicate with other hosts on the samenetwork. Your PC will net a default gateway to be able to communicate with other hosts on adifferent network6. PCs and their Default Gateway must belong to the same network.

Case 2

Given the IP address 199.199.199.172 with a subnet mask of 255.255.255.192. Answer the following:

a. How many bits were borrowed? b. How many subnets have been created? c. How many host address per subnet? d. What is the subnet address of the network containing

the given IP address? e. What is the broadcast address of the network

containing the given IP address?

Case 2 Answer

List of networks for the 199.199.199.0 network with the subnet mask 255.255.255.192

Hosts Network

from to Broadcast Address

199.199.199.0 199.199.199.1 199.199.199.62 199.199.199.63 199.199.199.64 199.199.199.65 199.199.199.126 199.199.199.127 199.199.199.128 199.199.199.129 199.199.199.190 199.199.199.191 199.199.199.192 199.199.199.193 199.199.199.254 199.199.199.255

A: 2

B: 4

C: 64

D: 199.199.199.128

E: 199.199.1299.191

Sockets and Ports

Socket Logical address

assigned to a specific process running on a computer

Sockets and Ports

Virtual circuit for the Telnet service

Host Names and Domain Name System (DNS)

Host name Symbolic name that describes a TCP/IP device

Domain Group of computers that belong to the same

organization and have part of their IP addresses in common

Domain name Symbolic name that identifies an organization Must be registered with the Internet Naming Authority. Must be available (not already taken by another

organization)

Domain Names

Fully qualified domain name (FQDN) Name of a host that includes the full domain name

as well as the host name Example: You work at the library of congress and

named your machine PeggySue. Your fully qualified hostname is PeggySue.loc.gov

Top-level domains (TLDs) Highest-level category used to distinguish domain

names A certain suffix that applies to an organization

according to the nature of business it conducts.

Domain Names

Domain naming conventions

What other domains are now available?

Host Files

Text file that associates TCP/IP host names with IP addresses (was used when we had 1000 hosts on the web)

Alias Nickname for a node’s host name

Example: host file

This file is called lmhosts in Windows and /etc/hosts on a UNIX-based computer

Domain Name System (DNS)

Database that is distributed over several key computers across the Internet.Hierarchical way of tracking domain names and their addresses, devised in the mid-1980sExample: How does the DNS request is processed?

From Local, Regional, National To National, Regional, Organizational (local)

DNS server hierarchy by geography

Domain Name System (DNS)

Resolvers Hosts on the Internet that need to look up domain

name information Example, type the command telnet

support.novell.com and your Telnet client software will kick off the resolver service to find the IP address for support.novell.com

Name servers are servers that contain databases of names and their associated IP addresses

Each name server manages a group of devices, collectively known as a zone

Configuring DNS

To view or change the name server information on a Windows 2000PC

Right-click My Network Places, then right-click appropriate Network Adapter.

Select Properties, Select TCP/IP, Select Properties.

In the TCP/IP Properties box, click the DNS tab.

DNS Configuration properties tab

DNS Name Space

Name space Database of Internet IP addresses and their associated

names distributed over DNS name servers worldwide (every name server holds a piece of that database)

Root server DNS server maintained by InterNIC and acts as the

ultimate authority on how to contact the top-level domains (how to get from .edu to .com)

Resource record One record for each host Element of a DNS database stored on a name

server that contains information about TCP/IP host names and their addresses

Bootstrap Protocol (BOOTP)

Service that simplifies IP address management.Requires network administrators to enter every IP and MAC address into the BOOTP table

• This situation is ideal for Diskless workstations: workstations that do not contain any hard disks

Dynamic Host Configuration Protocol (DHCP)

Automated means of assigning a unique IP address to every device on a network

Reasons for implementing DHCP Reduce the time and planning spent on IP address

management Reduce the potential for errors in assigning IP

addresses Enable users to move their workstations and printers

without having to change their TCP/IP configuration Make IP addressing transparent for mobile users

DHCP Leasing Process

Lease Agreement between DHCP server and client on how

long the client will borrow a DHCP-assigned address

NetBIOS Names Defined

Each Windows-based host receives a NetBIOS name during the installation of the operating system. This name is used to uniquely identify the machine on the network However the NetBIOS name is not used itself to identify a host: it is used by NetBIOS applications and processes to establish communication with other NetBIOS applications on remote hostsA NetBIOS name consists of 15 alphanumeric characters If a NetBIOS name does not contain 15 characters to fill the name out to the required 15 characters, Windows will add the necessary number of null characters to fill the name out to the required 15 charactersA sixteenth character , which is not usually visible, is added to each NetBIOS name to indicate the type of name, service, or group that the NetBIOS name represents

Registration, Discovery and Release of NetBIOS Names

Process Broadcast WINS

Registration(defending a NetBIOS name)

Sent to every machine within the same LAN (subnet) to see if any machine is already using the name being requested

No broadcast. The name registration request is sent directly to WINS to see if the requested name is available.

Discovery A broadcast will be sent to all hosts to request the IP associated with the NetBIOS name. When obtained results will be registered in cache.

No Broadcast. Request is sent directly to WINS, which can resolve names of hosts on the entire Network (different subnets)

Release During proper shutdown, NetBIOS host sends a broadcast to release its name

Release request is sent directly to WINS

LMHOSTS File

Standard Text file used to resolve NetBIOS names to IP addresses.The LMHOSTS file should be located in:%systemroot%\system32\drivers\etc directory

Example: 192.168.0.1 BONGO #PRE # DOM: Resource

The LMHOSTS file is read from top to bottom. So would the order of entries matter???

NetBIOS Node Types

B-Node: relies completely on broadcast for name registration, discovery and release. Creates great deal of traffic on the network

Cache, Broadcast, EndP-Node: Point-to-point communication with a WINS server for NetBIOS name services

Cache, WINS, EndH-Node: default configuration in windows machine

Cache, WINS, Broadcast up to 3 requests, LMHOST if exist, End

NetBIOS Names and Browsing The Network Resources

How do I get to see all these network resources when I click on My Network Places???What is a browse List? A list of available NetBIOS network resources for a particular network segment.How are the lists built and who keep them?

NetBIOS machines announce their presence at the start up then once every 12 minutes. Those announcements will be used by the following special hosts to built the browse lists:

Master Browser: One per segment Backup Master Browser: Future Master browser Domain master Browser : Pulls the master browser to

get a list of the resources on this particular segment, then sends a complete list with all the resources on the entire network to each Master Browser

NetBIOS Switches

Windows Internet Naming Service (WINS)

Provides a means of resolving NetBIOS names with IP addressesWhat are NetBIOS names?How are DNS names different from NetBIOS?Make sure that you can differentiate between TCP/IP host names and NetBIOS namesRemember that NetBIOS is used primarily with Windows-based systemsWINS offers several advantages

Guarantees a unique NetBIOS name is used for each computer on a network

Support for DHCP Better network performance (eliminates NetBIOS

broadcast)

TCP/IP Troubleshooting

Packet Internet Groper (PING) Troubleshooting utility that

can verify TCP/IP is installed, bound to the NIC, configured correctly, and communicating with the network

How does it work? It uses ICMP to send echo request and echo replay messages.

What is an Echo Request? An echo request is a signal sent out to another computer

What is an Echo Replay? An echo reply is the other computer’s response signal

Process of sending this signal back and forth is known as pinging

Netstat and Nbstat

Netstat Displays statistics and the state of current TCP/IP

connectionsNbstat

Provides information about NetBIOS names and their addresses

Nslookup and Traceroute

Nslookup Allows you to look up the DNS host name of a

network node by specifying its IP address, or vice versa. Used to troubleshoot problems related to the DNS server.

Tracert Uses ICMP and TTL to trace the path from one

networked node to another What is TTL? Numeric measure used to determine

how many more network hops a datagram can make. When TTL expires a datagram returns to the source with the identity of the destination.

How is it done? By transmitting a series of UDP to a specified destination

Next Meeting (After Spring Break)

Take Chapter 11 Test (Read the chapter first)Take The Midterm Exam (Make sure that you study both case 1, and 2 before you take the testDownload the Project and start working on it; It is due two weeks before the final exam!Make sure that you have the cable kitRead Chapter 6 (Network Hardware)Enjoy your break