Section 7: TCP/IP Fundamentals CSIS 479R Fall 1999 “Network +” George D. Hickman, CNI, CNE

Objectives Describe the IP address structure Identify network classes Obtain a registered IP address Register a Domain name Assign addresses to hosts Describe how host names, host tables, and DNS work

Objectives (con’t) Describe Windows Internet Name Services (WINS) Describe how ports are used Explain the purpose of subnets Define a subnet mask Describe how subnet masks are used Assign subnet addresses

IP Address Structure 4 bytes or 32 bits called a “dotted quad” Comprised of a network ID and a host ID Host is a server, workstation, or other node Routers on Internet route messages to the Network ID portion Once message gets to correct network, it is delivered based on the node address

IP addresses –Base 10 numbers –Binary number system Same address

Network Classes Class A –Network number Class B –Network number Class C –Network number Class D –Network number Class E –Network number

Network Classes Class A Network number –0xxxxxxx.x.x.x 126 networks, 16,777,216 hosts Class B Network number –10xxxxxx.x.x.x 16,384 networks, 65,534 hosts Class C Network number –110xxxxx.x.x.x 2,097,152 networks, 255 hosts Class D Network number –1110xxxx.x.x.x Multicast packets Use is router communications Class E Network number –11110xxx.x.x.x Experimental use and future addressing modes address is to all hosts on this network

Special IP Addresses network –The default route. Used in routing tables network –Loopback is local host All network bits set to 0 –A host on “this” network is host 34 on this class A network

Special IP Addresses (con’t) All host bits set to 0 –Refers to the network refers to network x.x Used within routing tables Network or node address with all bits set to 1 –Refers to all networks or all hosts –Broadcast to all hosts on this network only

Obtain a Registered IP Address InterNIC or Network Solutions ARIN American Registry for Internet Numbers RIPE Reseaux IP Europeans APNIC 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” 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 – –Educational. Now mostly 4 year colleges and Universities – –Government, non military, non educational – –Organizations established by International treaties ??

Domains (con’t).MIL –US Military – –Network providers – –Non-profit and other organizations that don’t fit anywhere else –

Domains (con’t) Country codes Australia –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 to Class B to Class C to If you are connected to the Internet, you must use registered addresses!

Host Tables Internet-Address official-host-name aliases argo pacific pa sales.vax loopback #loopback DNS 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 default Mask is a dotted quad number, logically ANDed with the IP address to identify which bits are network and which are host or node address Any bit that is part of the network address has a “1” value in the subnet mask

Default Masks Default masks do no additional subnetting Class A or FF Class B or FF.FF.0.0 Class C or FF.FF.FF.0

# of Subnet bits Possible subnet addresses (Binary) Byte in corresponding subnet mask Possible subnet addresses * 0* * * * *

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

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 mask Routers within the network apply the subnet mask

Partial bytes as subnets Book Example page 7-40 Class C address, subnet mask of bits left for host

Subnetted Class C Masked bits BinaryDecimalSubnetsHosts

Assign Subnet Addresses Each address must be unique Network and subnet numbers must be the same for all devices on the same network The Host portion of the address cannot be all [1]s or [0]s Plan for growth Don’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 bit Assign hosts from the right most bit This leaves a buffer zone between hosts and subnets, for future use See page 7-46 Subnet Calculator

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

Determine the number of subnets you need Keep in mind growth Book example 6 subnets are needed now, but they reserved the entire third byte for future needs This 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 subnet Class B address, 3 masked bits ( ) –

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 value Add Delta to the previous value to determine the next subnet value Continue until the value is >254 Example on page 7-51/52

Assign IP Addresses to each host Book example page 7-53 All addresses must be x.y X must be [100x xxxx] –Therefore x is between 128 [ ] and 159 [ ] Y can be 0 [ ] – 255 [ ] Exceptions: – and 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