NetCom Mod1 NetworkBasics12!21!04

8/12/2019 NetCom Mod1 NetworkBasics12!21!04

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NetCom Training Course 1: Networking & NetCom

Unit 1 - Networking Basics

Unit 1 - Network BasicsUnit 1 - Network Basics


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Objectives

After successfully completing this unit, you will be able to:

Define basic networking terms Describe network configurations, architecture, LANs, and

common network hardware

Define what is meant by the term protocol and provide 3

examples

Identify the classes of IP networks and explain differences

between them

Describe an IP address and explain its purpose

Explain subnetting and the two major problems it solves

Explain why both MAC and IP addresses are needed

Describe the purpose and use of ARP, Telnet, and Ping



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Topics

General Networking

IP Networks

Using ARP, Telnet and Ping

More Resources



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General

Networking

General

Networking


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Example

Terms you need to know1. Bandwidth

2. Packet

3. Digital

4. Host computer

5. Port numbers

6. Encapsulation

7. Hardware address

8. Internet address

9. T-1

10. Datagram

11. Routing table

12. Default gateway

May we have volunteers to complete each of the

definitions in the workbook?



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5th Floor = Data Center

4th Floor = 200 Clients

3rd Floor = 244 Clients

2nd Floor = 225 Clients

LAN Dallas

WAN

TelephoneServiceProvider

INTERNET

or GAN

New York

Detroit

Types of Networks


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Architecture


Peer-to-Peer Network

One Server, one or more PCs

Server, a.k.a. back end, provides

services, while clients, a.k.a. front end,

provides processing

Most networks built around a domain

structure

Client/Server

No Server

Computers share all resources

Only practical for 12 users or less


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Types of LANs


Developed by Xerox Corp in 1976

Original rate of 10 Mbps

Current version data rate 100 Mbps

and now 1000 Mbs or Gigabit

Computers share cabling by using a

technique called Carrier Sense

Multiple Access (CSMA),

listening before they transmit

Ethernet

Older, archaic network configuration

Messages transferred in one direction

along a ring

Each message is viewed by every

device and viewed as a token

After message is read, token is returned

to sender and marked as received

Sender frees token

Token Ring


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Hub

Connects networks together

Contains at least 2 network devices

Analyzes packets, and perhaps modifies

them, so they can be redirected,

if necessary

Router

Like Smart Hubs

Switches data from one port to another

Results are faster with fewer errors

Can associate IP addresses to

MAC addresses

Switch

Network Interface Card

Generally located in a PC

Interface between PC and Network

NIC

Hardware

Connects all ports

Adds some logic for error detection

Moves data in and out of systems

Sends packets to every system


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What is a protocol?


Network communication is provided through a predetermined

set of rules by which network operations are conducted. These

rules are called protocols.

Protocols come in nearly endless varieties; some with common

features, some are hybrids with more than one function.

Network professionals have attempted to classify them

according to the OSI model.


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Protocols


Transmission Control Protocol

/ Internet Protocol

Allows dissimilar computers to talk

Really two protocols in one

Basis for the Internet

Routable protocol

Very flexible for large networks

TCP/IP

Similar to an optimized TCP/IP

Like TCP/IP, it is also routable

Quicker access than TCP/IP

IPX/SPX

Designed for small LANs

Fast

Not a routable protocol

NetBEUI


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Other protocols


Dynamic Host Configuration Protocol

Device on network broadcasts requestfor IP along with its network cards

Ethernet address (MAC)

DHCP server furnishes IP for an

amount of time specified by server

DHCP

User Datagram Protocol

Used for messages of one datagram

Delivery is responsibility of hardware;

not network

Fast transmission

UDP

Terminal emulation

protocol

Allows communication

with Host computer

More on Telnet later

Telnet

Packet Internet Groper

Tests the accessibility of

network device

More on PING later

ARP

Address Resolution

Protocol

Lookup table that ties an

IP to MAC temporarily

More on ARP later

ARPPing


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IP

Networks

IP

Networks



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Classes of IP networks


Decimal Value from 224 to 239

Used to support multicasting

Class D

Decimal value 192 to 223

First 3 octets identify network, remaining

identify host within network

Example: 192.168.212.226,

192.168.212 = network, 226 = host

Class C

Decimal value between 128 and 191 127 reserved for loopback

First 2 octets identify network, remaining

identify host within network

Class B

Decimal value 1 to 126

First octet network, remaining identifies

host. Example: 102.168.212.226,

102 = network, 168.212.226 = host

Used for governments, large

institutions, major ISPs

Class A

Decimal Value 240 to 255

Used strictly for experimentation

Class E


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IP protocol stack

Network File System (NFS) Redirector

TCP-aware Applications

(browser, IRC, News Reader, etc.)

Remote FileService (RFS)

Internet MessageAccess Protocol

(IMAP)

Internet MessageAccess Protocol

(IMAP)

Simple MailTransfer Protocol

(SMTP)

Simple MailTransfer Protocol(SMTP)

File TransferProtocol

(FTP)

File TransferProtocol

(FTP)

Terminal

EmulationProtocol(TELNET)

Terminal

EmulationProtocol(TELNET)

Network FileSystem (NFS)

Server MessageBlock (SMB)

Transmission ControlProtocol (TCP)

Transmission ControlProtocol (TCP) User Datagram Protocol (UDP)

User Datagram Protocol (UDP)

Internet Protocol (IP)Internet Protocol (IP)

Packet Driver

Protocols

Product Specific

Driver

Link Access

Protocol Balance(LAPB)

Application Layer

Each has its own portnumber.

Transport Layer

Responsible for delivery of

traffic over the network.Network Layer

Manages traffic to and

from individual devices.

Physical Layer

Communicates directly with

hardware, like an Ethernet

adapter or modem.



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Classroom discussion

Using the IP Protocol Stack diagram, which layer utilizes unique

identifiers called port numbers?

Answer: Application layer protocols.

Which layer is responsible for the actual delivery of traffic and

for error checking to ensure data is received correctly betweencomputers?

Answer: The transport layer.

Which layer provides information needed to route networktraffic?

Answer: The network layer.


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TCP and UDP comparison


Two types of network traffic with different uses; TCP and UDP. Both are classified as

part of the transport layer within the IP protocol stack.

TCP - competitors UDP - NetCom

Conclusion:

Connection-oriented protocol

Reliable; server will re-request lost

data

Message order is checked and

maintained

Requires more bandwidth to

furnish reliability

Simpler, message-basedconnectionless protocol bandwidth

is smaller.

Has a perception for being unreliable

Not ordered; but in the case of

NetCom this is a non-issue

Lack of ordering, tracking of

connections, requirement from thenetwork, UDP is fast

Although TCP is more widely-used, UDP provides acceptable reliability suitable

for NetComs needs, with the added benefit of being extremely fast


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IP addressing


Every computer that communicates over the Internet is assigned

an IP address that uniquely identifies the device and

distinguishes it from other computers on the Internet An IP address consists of 32 bits, often shown as 4 octets of

numbers from 0-255, represented in decimal form instead of

binary form

For example, the IP address 168.212.226.204 in binary form is

10101000.11010100.11100010.11001100


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Routing calculations are based on

operations on binary numbers

Binary operations are the key to

understanding how default and

custom subnet masks are

determined

Having a basic understanding of

subnetting will help you to

understand how NetCom packets

are routed on a given network

Why it is helpful to know about binary conversions?



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Binary is a base 2 numbering system Each consecutive place, moving from right to left, has a value of

the previous place, times the base (which, again, is 2)

Start with the Least Significant Bit (LSB) of 1 and double the

value with each place

Chalk talk on binary to decimal conversions

1 1 1 1 1 1 1 1

128 64 32 16 8 4 2 1

One of 4 octets. Placement in the octet determines value.

Sum of the values equals decimal.


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Binary to decimal conversion exercise


Manually calculate and convert the following binary addresses to

decimal form.

01100100

11100000

11111111.11111111.11110000.00000000

01100100.01100100.00000010.00000001

01111111.00000000.00000000.00000001

1 1 1 1 1 1 1 1

128 64 32 16 8 4 2 1

= 100

= 224

= 255.255.240.0

= 100.100.2.1

= 127.0.0.1


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Subnetting


Subnetting is the division of a single Class A, B, or C network

number into smaller pieces

Subnetting was introduced to overcome some of the problemsthat parts of the Internet were beginning to experience with the

classful two-level addressing hierarchy:

Internet routing tables were beginning to grow

Local administrators had to request another network numberfrom the Internet before a new network could be installed at

their site


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Subnetting


Solution: Reduces growth of the Internet routing table

Ensures subnet structure is never visible outside of the

subnets private network

Route from Internet to any subnet is the same, regardless of

location of host

Only private organization subnet can differentiate

between individual subnets

As far as Internet router is concerned, all of an organizations subnetsare under a single routing table entry

Solution: Overcame the delay associated with obtaining

registered network numbers Organizations are assigned one network number from IPv4 address

space

Allows organizations to deploy several subnets


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Subnet Mask


Routers Internet

Registered IP:12.10.0.0

12.10.32.10

Node IP:

192.168.1.15

Subnet Mask:255.255.0.0

Default Gateway:

12.10.0.0

Router12.10.64.0

12.10.96.0

12.10.32.20

12.10.32.30

12.10.96.10

12.10.96.20

12.10.96.30

12.10.64.10

12.10.64.20

12.10.64.30

Subnet 1

Subnet 2

Subnet 3

Subnet 1


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Subnet Mask


A site with several networks might use subnet addressing with a

single /16 (Class B) network address

The router accepts all traffic addressed 12.10.1.0 and forwards

to appropriate subnetworks based on the 4th octet

A subnet mask is applied to addresses so that larger (class)

address populations can be broken down into smaller groups for

efficiency or economy purposes

In many cases, default subnet masks are used:

255.0.0.0

255.255.0.0 255.255.255.0


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Classroom discussion

What would the router do with a packet with the destination

address of 192.168.1.128?

It belongs on the same subnet as the router. It would be routed

within the subnet.

What would be done with a packet addressed to 192.167.1.128?

It is not within the subnet. It would be sent out of the subnet.

What about a packet addressed to 12.45.6.80?

It is not within the subnet. It would be sent out of the subnet.


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The routers NAT table


Network Address Translation conceals the internal IP addresses

from the Internet and uses non-routable addresses (10.x.x.x,

172.16.x.x or 192.168.x.x)

A company needs only one live Internet address

NAT uses port numbers in the complete IP address

NAT records outgoing source address and port number so whendata is returned, can use the port number as reference to look

up the real internal address for routing the data


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Why do we need MAC addresses if we have IP addresses?


MAC addresses are like occupants of a location, IP addresses

are the location

MAC addresses are used to verify delivery to correct occupant

The MAC address and IP address are stored together in the

ARP table in the NIM or on the PC

ARP tables change frequently

Joe Smith

340 El Camino Real

Boise, Idaho 83701

Mary Beth Miller

130 Perinton Parkway

Fairport, NY 14450

Occupants name = MAC Address

Street Number = IP Inside the Network

Street & City = Network

ompare an IP Network to the Postal Service


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U it 1 N t ki B i


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Using ARP,

Telnet and Ping

Using ARP,

Telnet and Ping


U it 1 N t ki B i


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Using ARP


ARP - Address Resolution Protocol

A lookup table that associates an IP address to a MAC

address for a temporary amount of time

Used so that you can telnet to the device to give it a

permanent address or program it

The ARP table resides in the local device and it has noeffect on the device holding the MAC address, or any other

networked device

U it 1 N t ki B i


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Using ARP


To add IP address 192.168.0.2 to the ARP tablewith a MAC address of 00-20-4a-12-34-f4,

do the following:

arp s 192.168.0.2 00-20-4a-12-34-f4

To verify that an address is in the ARP table do the following:

arp gYou would see the following:

Must be programmed.

Always consistent.

Unit 1 Networking Basics


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Using ARP


After performing the previous ARP command, you will be able to telnet

to the network device (Note: sometimes using Ping after arp but before

telnet forces a refresh of the arp table)

The IP Address that you are going to ARP and the PC you are using

need to be on the same subnet



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Using ARP


If you are trying to setup a device on your network that is going to be

used outside of your subnet:

ARP an IP Address that is within your subnet Telnet to that address

After you are connected to the device through telnet, freely

program the unit (more on programming in the next unit)

NOTE: This is also useful if you dont know what is programmed in a

unit and want to check



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Using Telnet


Telnet provides a text based connection to a network device to

perform functions such as programming, information lookup, etc.

Telnet uses port 23 by default when connecting to other devices

(However, Lantronics products listen to telnet on port 9999)

You can also manually select the port

Telnet comes in several interfaces, most commonly:

GUI version on Windows 9x/Me

Command line version in Windows NT/2000/XP



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Using Telnet


REMEMBER:

ARP does NOT change any settings in the unit

It only allows you to link an IP Address to a MAC Address

temporarily, normally for the purpose of performing a TELNET

session

Dont confuse this with the actual IP settings that are in a unit.

After Arp and Telnet, you can use Ping to verify that the device isconnected to the network



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Command line hints and tips


To avoid Windows problems, be sure to avoid leading an octet with a

zero when choosing an IP

Example: 192.169.020.1 is interpreted as 192.169.16.1

To repeat the previous command, press F3. You can then backspace

to change the command

At command line, enter help to see a listing of commands and the one-

letter shortcut



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Additional resources


Online courses:

www.learntcpip.com

www.learntosubnet.com

For good PC info:

www.dansdata.com



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Thank you for your attention!Thank you for your attention!

NetCom Mod1 NetworkBasics12!21!04

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