Section 7: TCP/IP Fundamentals

CSIS 479R Fall 1999“Network +”George D. Hickman, CNI, CNE

Objectives

Describe the IP address structureIdentify network classesObtain a registered IP addressRegister a Domain nameAssign addresses to hostsDescribe how host names, host tables, and DNS work

Objectives (con’t)

Describe Windows Internet Name Services (WINS)Describe how ports are usedExplain the purpose of subnetsDefine a subnet maskDescribe how subnet masks are usedAssign subnet addresses

IP Address Structure

4 bytes or 32 bits called a “dotted quad”Comprised of a network ID and a host IDHost is a server, workstation, or other node

Routers on Internet route messages to the Network ID portionOnce message gets to correct network, it is delivered based on the node address

IP addresses

172.16.4.2– Base 10 numbers

10101100.00010000.00000100.00000010– Binary number system

Same address

Network Classes

Class A– Network number 1-127

Class B– Network number 128-191

Class C– Network number 192-223

Class D– Network number 224-239

Class E– Network number 240-255

Network ClassesClass A Network number 1-127 – 0xxxxxxx.x.x.x 126 networks, 16,777,216 hosts

Class B Network number 128-191– 10xxxxxx.x.x.x 16,384 networks, 65,534 hosts

Class C Network number 192-223– 110xxxxx.x.x.x 2,097,152 networks, 255 hosts

Class D Network number 224-239– 1110xxxx.x.x.x Multicast packets Use is router communications

Class E Network number 240-255– 11110xxx.x.x.x Experimental use and future addressing modes

address 255.255.255.255 is to all hosts on this network

Special IP Addresses

network 0.0.0.0– The default route. Used in routing tables

network 127.0.0.0– Loopback. 127.0.0.1 is local host

All network bits set to 0– A host on “this” network. 0.0.0.34 is host 34 on this

class A network

Special IP Addresses (con’t)

All host bits set to 0– Refers to the network. 145.67.0.0 refers to network

145.67.x.x Used within routing tables

Network or node address with all bits set to 1– Refers to all networks or all hosts

255.255.255.255– Broadcast to all hosts on this network only

Obtain a Registered IP Address

InterNIC or Network SolutionsARIN American Registry for Internet NumbersRIPE Reseaux IP EuropeansAPNIC Asia Pacific Network Information Center

Addresses are given to major ISPs, who assign numbers to their customers

Register a Domain Name

My business name is “Technology Trainers”I “own” www.technologytrainers.com

Registered the name, pay InterNIC a fee for a “business card” at that location to hold the name.Renew every 2 years

Domains

.COM– Commercial entities – www.novell.com

.EDU– Educational. Now mostly 4 year colleges and Universities– www.uvsc.edu

.GOV– Government, non military, non educational– www.whitehouse.gov

.INT– Organizations established by International treaties ??

Domains (con’t)

.MIL– US Military– www.army.mil

.NET– Network providers– www.pacbell.net

.ORG– Non-profit and other organizations that don’t fit anywhere else– www.lds.org

Domains (con’t)

Country codesAustralia– AU

Brazil– BR

Canada– CA

Dominican Republic– DO

Country Domains

Egypt– EG

France– FR

Germany– DE

Hong Kong– HK

Country Domains (con’t)

India– IN

Japan– JP

Kuwait– KW

Malaysia– MY

Country Domains (con’t)

New Zealand– NZ

Oman– OM

Portugal– PT

Great Britain– UK

Private Network Addresses

Filtered out by Internet routers (RFC 1918)Class A 10.0.0.0 to 10.255.255.255Class B 172.16.0.0 to 172.31.255.255Class C 192.168.0.0 to 192.168.255.255

If you are connected to the Internet, you must use registered addresses!

Host Tables

Internet-Address official-host-name aliases132.132.87.176 argo132.132.12.45 pacific pa132.132.19.42 sales.vax127.0.0.1 loopback #loopbackDNS server resolves names by referring to table

Subnets

A way of overcoming the limitations of a single or limited number of networks, by making sub-networks.– To extend the network (overcome physical limits)– To reduce congestion– To reduce CPU use (less broadcasts)– To isolate network problems– To improve security– To use multiple media

Subnet mask

“Borrow” bits from the host (or node) address to create sub-networks All IP Addresses MUST have a subnet mask, even if it is the defaultMask is a dotted quad number, logically ANDed with the IP address to identify which bits are network and which are host or node addressAny bit that is part of the network address has a “1” value in the subnet mask

Default MasksDefault masks do no additional subnettingClass A 11111111.00000000.00000000.00000000 255.0.0.0 or FF.0.0.0Class B 11111111.11111111.00000000.00000000 255.255.0.0 or FF.FF.0.0Class C 11111111.11111111.11111111.00000000 255.255.255.0 or FF.FF.FF.0

# of Subnet bits

Possible subnet addresses (Binary)

Byte in corresponding subnet mask

Possible subnet addresses

1 1 000 00000 000 0000

1 000 0000 128*0*

2 11 00 000010 00 000001 00 000000 00 0000

11 00 0000 192*128640*

3 111 0 0000110 0 0000101 0 0000100 0 0000011 0 0000010 0 0000001 0 0000000 0 0000

111 0 0000 224*1921601289664320*

Subnet addresses from Mask

Subnets of all [0]s or all [1]s are reserved in TCP/IP networks. NetWare (and most other industry implementations) will allow their use, but be sure all your routers and other NOSs will support it first !That means the number of available subnets is

2 2n

Classful and Classless Hierarchies

Classful Hierarchy– Uses default masks, no subnets

Classless Subnet Hierarchy– Network address, Subnet address, Host address

Internet routers route by the default maskRouters within the network apply the subnet mask

Partial bytes as subnets

Book Example page 7-40Class C address, subnet mask of 255.255.255.2245 bits left for host

hosts30)2)32(()2)2(( 5

Subnetted Class C

Masked bits

Binary Decimal Subnets Hosts

1 1000 0000 128 2 1282 1100 0000 192 4 643 1110 0000 224 8 324 1111 0000 240 16 165 1111 1000 248 32 86 1111 1100 252 64 47 1111 1110 254 128 2

Assign Subnet Addresses

Each address must be uniqueNetwork and subnet numbers must be the same for all devices on the same networkThe Host portion of the address cannot be all [1]s or [0]s

Plan for growthDon’t use reserved addresses

Plan for Growth

How many subnets do I need today?How many subnets will be needed in the future?What is the maximum number of hosts on the largest segment?How many hosts will there be on the largest segment in the future?

Assigning Addresses

Assign subnets from the left most bitAssign hosts from the right most bitThis leaves a buffer zone between hosts and subnets, for future useSee page 7-46Subnet Calculator www.net3group.com/download.html-ssi

Steps for creating subnetsDetermine the number of subnets you needDetermine your subnet mask and subnet addressesAssign IP addresses to each host on a subnetFormulas (page 7-49)– n=number of masked address bits– m=number of unmasked address bits

hosts

subnetsm

n

22

22

Determine the number ofsubnets you need

Keep in mind growthBook example 6 subnets are needed now, but they reserved the entire third byte for future needsThis gives growth possibility of 254 subnets

Determine Subnet Mask and Subnet Addresses

Determine the number of available subnet address values and the number of available host address values per subnetClass B address, 3 masked bits (255.255.224.0)–

hosts

subnets

819022

62213

3

Calculate the subnet address values

Calculate the Delta (the decimal value of the rightmost mask bit) Add Delta to the original network address to obtain the first subnet address valueAdd Delta to the previous value to determine the next subnet valueContinue until the value is >254Example on page 7-51/52

Assign IP Addresses to each hostBook example page 7-53All addresses must be 132.132.x.yX must be [100x xxxx]– Therefore x is between 128 [1000 0000] and 159

[1001 1111]Y can be 0 [0000 0000] – 255 [1111 1111]Exceptions:– 132.132.128.0 and 132.132.159.255 are invalid– Invalid because all node bits are set to either 0 or 1

Exercises

Do exercises 7-3 and up beginning on page 7-54