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CIS 1140 Network FundamentalsChapter 10 – In Depth TCP/IP Networking
Collected and CompiledBy JD WillardMCSE, MCSA, Network+, Microsoft IT Academy AdministratorComputer Information Systems InstructorAlbany Technical College
Attention: Accessing Demos
• This course presents many demos. • The Demos require that you be logged in to the Virtual
Technical College web site when you click on them to run.
• To access and log in to the Virtual Technical College web site:– To access the site type www.vtc.com in the url window– Log in using the username: CIS 1140 or ATCStudent1– *Enter the password: student
• If you should click on the demo link and you get an Access Denied it is because you have not logged in to vtc.com or you need to log out and log back in.
*Remember that passwords are case sensitive so enter it in all lower case letters.
Objectives• Understand methods of network design
unique to TCP/IP networks, including subnetting, CIDR, and address translation
• Explain the differences between public and private TCP/IP networks
• Describe protocols used between mail clients and mail servers, including SMTP, POP3, and IMAP4
• Employ multiple TCP/IP utilities for network discovery and troubleshooting
Designing TCP/IP-Based Networks• TCP/IP protocol suite use
– Public Internet connectivity– Private connection data transmission
• TCP/IP fundamentals– IP: routable protocol
• Interfaces requires unique IP address• Node may use multiple IP addresses
– Two IP versions: IPv4 and IPv6• IPv4: older; more common
• IPv4 addresses– Four 8-bit octets
• Binary or dotted decimal• Network host name assignment
– Dynamic using DHCP– Static
• Network classes: A, B, C, D, E – Class D, E addresses reserved– Node’s network class provides information about segment network node belongs to
IP Addressing Demo
Subnetting• Separates network
– Multiple logically defined segments (subnets)• Geographic locations, departmental boundaries,
technology types
• Subnet traffic separated from other subnet traffic
• Reasons to separate traffic– Enhance security– Improve performance– Simplify troubleshooting
• First, simplest IPv4 addressing type
• Adheres to network class distinctions
• Recognizes Class A, B, C addresses
• Fixed network ID size ultimately limits number of hosts a network can include
• Difficult to separate traffic from various parts of a network
Address Classes Demo
Classful Addressing in IPv4
Classful Addressing in IPv4
IP addresses and their classes
• Network information (network ID)– First 8 bits in Class A address– First 16 bits in Class B address– First 24 bits in a Class C address
• Host information– Last 24 bits in Class A address– Last 16 bits in Class B address– Last 8 bits in Class C address
Subnet Masks• Subnetting depends on subnet masks to identify
how a network is subdivided– Indicates where network information is
located in an IP address– “1” bits indicate corresponding bits in IP
address contain network information– “0” bits indicate corresponding bits in IP
address contain host information• To calculate host’s network ID given IP address
and subnet mask, perform ANDing
Defining a Subnet MaskConvert the Number of Segments to Binary
Count the Number of Required Bits
Convert the Required Number of Bits to Decimal (High Order)
11
22
33
Example of Class B Address
Number of SubnetsNumber of Subnets
Binary ValueBinary Value
Convert to DecimalConvert to Decimal
6
0 0 0 0 0 1 1 0
= 6
(3 Bits)
4+2
255 . 255 . 224 . 0
11111111 11111111 11100000 00000000
Subnet MaskSubnet Mask
Subnet Masks Demo Solutions for Masks Demo
Determining the Destination of a Packet (ANDing)
10011111 11100000 00000111 10000001
11111111 11111111 00000000 00000000
10011111 11100000 00000111 10000001
11111111 11111111 00000000 00000000
10011111 11100000 00000000 0000000010011111 11100000 00000000 00000000
IP Address
Subnet Mask
IP Address
Subnet Mask
ResultResult
• Local and Destination Host’s Subnet Masks Are ANDed• ANDing
– Combining bits• Bit value of 1 plus another bit value of 1 results in 1• Bit value of 0 plus any other bit results in 0
– ANDing logic• 1: “true”, 0: “false
– If ANDed results of source and destination hosts match, the destination is local. – If ANDed results of source and destination hosts do not match, the destination
is remote and the packet is sent to the default gateway.
ANDing Demo
Reserved Addresses• Certain types of IP addresses reserved for special
functions• Cannot be assigned to node network interface; used as
subnet masks• Network ID
– Bits available for host information set to 0– Classful IPv4 addressing network ID ends with 0 octet– Subnetting allows network ID with other decimal
values in last octet(s)• Broadcast address
– Octet(s) representing host information equal all 1s– Decimal notation: 255
Addressing Rules; the Logical AND Operator Demo
IPv4 Subnetting Techniques• Subnetting breaks classful IPv4
addressing rules– Some bits that in classful addressing would
represent host information are changed to represent network information
– Reduces the number of usable host addresses per subnet
– Hosts, subnets available after subnetting related to host information bits borrowed
Subnetting Shortcuts Demo Borrowing Bits Demo Subnetting Demo Borrowing Bits Demo Solutions for Borrowing Demo Subnet Numbers Demo
Implementing Subnetting• Determine the Number of Required
Network IDs– One for each subnet– One for each wide-area
network connection• Determine the Number of Required
Host IDs per Subnet– One for each TCP/IP host– One for each router interface
• Define One Subnet Mask Based on Requirements
• Define a Unique Subnet ID for Each Physical Segment Based on the Subnet Mask
• Define Valid Host IDs for Each Subnet Based on the Subnet ID
Table 1 : Class B subnet masks
Table 2 : Class C subnet masks
Calculating IPv4 Subnets• Formula for determining how to modify a default subnet mask: 2n-2=Y
– n = number of bits in subnet mask that must be switched from 0 to 1
– Y = number of subnets that result• Extended network prefix: Additional bits used for subnet information
plus existing network ID• Class A, Class B, and Class C networks
– Can be subnetted• Each class has different number of host information bits usable
for subnet information• Varies depending on network class and the way subnetting is
used• LAN subnetting
– LAN’s devices interpret device subnetting information– External routers
• Need network portion of device IP address
Defining Subnet IDs255 255 224 0
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0
00000000 = 000100000 = 3201000000 = 6401100000 = 9610000000 = 12810100000 = 16011000000 = 19211100000 = 224
11
22 33
Address Ranges Demo
Solutions for Ranges Demo
Shortcut to Defining Subnet IDsList the Number of Bits (High Order) Used for Subnet Mask
Convert the Bit with the Lowest Value to Decimal
Increment the Value for Each Bit Combination
1100000011000000
6464
0+ 64= 64+ 64= 128+ 64
192
w.x.64.1 w.x.127.254
w.x.128.1 w.x.191.254
11
22
33
Defining Host IDs for a SubnetSubnet IDsSubnet IDs Host ID RangeHost ID Range
Invalidx.y.32.1 – x.y.63.254x.y.64.1 – x.y.95.254x.y.96.1 – x.y.127.254x.y.128.1 – x.y.159.254x.y.160.1 – x.y.191.254x.y.192.1 – x.y.223.254Invalid
Invalidx.y.32.1 – x.y.63.254x.y.64.1 – x.y.95.254x.y.96.1 – x.y.127.254x.y.128.1 – x.y.159.254x.y.160.1 – x.y.191.254x.y.192.1 – x.y.223.254Invalid
00000000 = 000100000 = 3201000000 = 6401100000 = 9610000000 = 12810100000 = 16011000000 = 19211100000 = 224
00000000 = 000100000 = 3201000000 = 6401100000 = 9610000000 = 12810100000 = 16011000000 = 19211100000 = 224
• Each Subnet ID Indicates the Beginning Value in a Range• The Ending Value Is One Less Than the Beginning Value
of the Next Subnet ID
Calculating Subnets
Practice 1 Demo Solutions for Practice 1 Demo
Practice 2 Demo Solutions for Practice 2 Demo
A router connecting several subnets
CIDR (Classless Interdomain Routing)
• Also called classless routing or supernetting• Provides additional ways of arranging network and
host information in an IP address• Not exclusive of subnetting
– Provides additional ways of arranging network and host information in an IP address
– Conventional network class distinctions do not exist
• Supernet– Subnet created by moving subnet boundary left
Classless Internet Domain Routing Demo
CIDR• CIDR notation (or slash notation)
– Shorthand denoting subnet boundary position– Form
• Network ID followed by forward slash ( / ), followed by number of bits used for extended network prefix
– CIDR block• Forward slash, plus number of bits used for extended
network prefix• Example: class C range of IPv4 addresses sharing network ID
199.34.89.0– Need to greatly increase number of default host addresses
Calculating a host’s network ID on a supernetted network
Subnetting/Supernetting Demo
Internet Gateways• Gateway
– Combination of software and hardware– Facilitates communication between different networks, subnets
• Default gateway– Every device on a TCP/IP-based network has a default gateway– First interprets its outbound requests to other subnets– Then interprets its inbound requests from other subnets– Each node on network has one default gateway– May be network interface on a router
• Must maintain routing tables as well• Core gateways make up the Internet backbone• Network nodes
– Allowed one default gateway• Assigned manually, automatically (DHCP)
Internet Gateways• Gateway interface on router
– All data not meant for the local subnet is sent to this router
– Advantages• One router can
supply multiple gateways
• Gateway assigned own IP address
• Default gateway connections– Multiple internal networks– Internal network with
external networks• WANs, Internet
– Router used as gateway• Must maintain routing
tables
The use of default gateways
Address Translation• Public network
– Any user may access• Little or no restrictions
• Private network– Access restricted
• Clients, machines with proper credentials– Hiding IP addresses
• Provides more flexibility in assigning addresses• NAT (Network Address Translation)
– Gateway replaces client’s private IP address with Internet-recognized IP address
• Reasons for using address translation– Overcome IPv4 address quantity limitations– Add marginal security to private network when connected to public
network– Develop network addressing scheme
NAT Demo
Address Translation
SNAT (Static Network Address Translation)
• SNAT (Static Network Address Translation)– Client associated with
one private IP address, one public IP address
• Never changes– Useful when operating
mail server• DNAT (Dynamic Network
Address Translation)Also called IP
masqueradingInternet-valid IP address
might be assigned to any client’s outgoing transmission
Address Translation• PAT (Port Address Translation)
– Each client session with server on Internet assigned separate TCP port number
• Client server request datagram contains port number
– Internet server responds with datagram’s destination address including same port number
• NAT– Separates private, public
transmissions on TCP/IP network• Gateways conduct network translation
– Most networks use router• Gateway might operate on network host
– Windows operating systems• ICS (Internet Connection
Sharing)
Internet Connection Sharing Demo
The Concepts of NAT & PAT Demo
TCP/IP Mail Services• E-mail
– Most frequently used Internet services– Functions
• Mail delivery, storage, pickup
• Mail servers– Communicate with other mail servers– Deliver messages, send, receive, store
messages
• Mail clients – Send messages to; retrieve messages from mail
servers
SMTP (Simple Mail Transfer Protocol)
• Protocol responsible for moving messages– From one mail server to another
• Over TCP/IP-based networks• Operates at Application layer
– Relies on TCP at Transport layer• Operates from port 25• Provides basis for Internet e-mail service
– Relies on higher-level programs for its instructions• Services provide friendly, sophisticated mail interfaces• Simple subprotocol
– Transports mail, holds it in a queue• Client e-mail configuration
– Identify user’s SMTP server• Use DNS: Identify name only
– No port definition• Client workstation, server assume port 25
MIME (Multipurpose Internet Mail Extensions)
• SMTP drawback: 1000 ASCII character limit• MIME standard encodes, interprets binary files,
images, video, non-ASCII character sets within e-mail message– Identifies each mail message element
according to content type• Text, graphics, audio, video, multipart
• Does not replace SMTP– Works in conjunction with it
• Encodes different content types– Fools SMTP
POP (Post Office Protocol)
• Application layer protocol– Retrieve messages from mail server
• POP3 (Post Office Protocol, version 3)– Current, popular version– Relies on TCP, operates over port 110– Store-and-forward type of service
• Advantages– Minimizes server resources
• Mail deleted from server after retrieval• Disadvantage for mobile users
– Mail server, client applications support POP3
IMAP (Internet Message Access Protocol)• More sophisticated alternative to POP3• IMAP4: current version• Advantages
– Replace POP3 without having to change e-mail programs– E-mail stays on server after retrieval
• Good for mobile users• Features
– Users can retrieve all or portion of mail message– Users can review messages and delete them
• While messages remain on server– Users can create sophisticated methods of organizing messages on server– Users can share mailbox in central location
• Disadvantages– Requires more storage space, processing resources than POP servers– Network managers must watch user allocations closely– IMAP4 server failure
• Users cannot access mail
Additional TCP/IP Utilities
• TCP/IP transmission process– Many points of failure
• Increase with network size, distance• TCP/IP comes with complete set of utilities that can help to
track down most TCP/IP-related problems– Help discover information about node, network– e.g., Ping, Telnet, ARP
• Nearly all TCP/IP utilities can be accessed from command prompt on any type of server or client running TCP/IP– Syntax may differ depending on OS– Options may differ according to OS
Ipconfig• TCP/IP administration utility for use with Windows NT, 2000, XP, and
Server 2003 OSs– Provides information about network adapter’s IP address, subnet mask, and
default gateway• Commonly used switches:
– /? displays list of available switches– /all displays complete TCP/IP configuration information for each network
interface on device– /release releases DHCP-assigned addresses for all network interfaces– /renew renews DHCP-assigned addresses for all network interfaces
IPConfig, Ifconfig,Winipcfg Demo
Ifconfig• Utility used on UNIX and Linux systems
– Modify TCP/IP network interface settings, release and renew DHCP-assigned addresses, check TCP/IP setting status
– Runs at UNIX, Linux system starts
• Establishes computer TCP/IP configuration
• Used alone or with switches
– Uses hyphen ( - ) before some switches
– No preceding character for other switches
Detailed information available through ifconfig
Netstat
• Displays TCP/IP statistics and details about TCP/IP components and connections on a host– Port on which a particular TCP/IP service is running– Network connections currently established– Number of packets handled by network interface since
activation– Number of data errors
NETSTAT Demo
Nbtstat• NetBIOS
– Protocol runs in Session and Transport layers
– Associates NetBIOS names with workstations
– Not routable• Can be made routable by
encapsulation• Nbtstat utility
– Provides information about NetBIOS statistics
– Resolves NetBIOS names to IP addresses
– Useful on Windows-based operating systems and NetBIOS
• Limited use as TCP/IP diagnostic utility
NBTSTAT Demo
Hostname, Host
• Hostname utility– Provides client’s host name
• Administrator may change
• Host utility– Learn IP address from host name– No switches: returns host IP address or host
name
Nslookup• Query DNS database from any network computer and
find host name of a device by specifying its IP address, or vice versa– Provides host’s IP address, primary DNS server
name, and address holding record for this name– Many options (switches)– Verify host configured correctly; troubleshoot DNS
resolution problems
Using NSLOOKUP Demo
Dig
Using DIG in Unix Demo
• Domain information groper• Similar to nslookup
– Query DNS database– Find specific IP address host name
• Useful for diagnosing DNS problems• Dig utility provides more detailed information
than nslookup• Flexible: two dozen switches• Included with UNIX, Linux operating systems• Windows system: must obtain third party code
Whois• Query DNS registration database and obtain information about a
domain• Troubleshoot network problems• Syntax
– whois xxx.yy•xxx.yy is second-level domain name
– Who is domain registered to?– Technical person responsible for domain?– Hosting entity?– DNS Server addresses?
• Must install software to use on Windows systems• Web-based alternatives exist
– e.g., www.arin.net
WHOIS Demo
Traceroute (Tracert)• Windows-based systems: tracert
• Linux systems: tracepath• Uses ICMP to trace path from one node to another
– Identifies all intermediate hops– Useful for determining router or subnet connectivity problems– Transmits series of UDP datagrams to specified destination
– Using either IP address or host name
• To identify destination• Increases TTL as path is discovered
• Traceroute may stop before completing– Device problem on path– Device does not accept ICMP transmissions
• Often indicates firewall
Using TraceRT Demo
Mtr (my traceroute)• UNIX, Linux operating systems
– Route discovery, analysis utility– Combines ping, traceroute functions
• Output: easy-to-read chart• Simplest form
– mtr ip_address or mtr host_name• Run continuously• Stop with Ctrl+C or add limiting option to command
• Number of switches refine functioning, output• Results misleading
– If devices prevented from responding to ICMP traffic
Mtr (my traceroute)• Windows XP, Vista, Server 2003, Server 2008
– Pathping program as command-line utility
– Simile switches as mtr– Pathping output differs slightly
• Displays path first
• Then issues hundreds of ICMP ECHO requests before revealing reply, packet loss statistics
Route• Route utility
– Allows viewing of host’s routing table• UNIX or Linux system
– Type route and press Enter• Windows-based system
– Type route print and press Enter• Cisco-brand router
– Type show ip route and press Enter
• Route command– Add, delete, modify routes
• Route command help– UNIX or Linux system
• Type man route and press Enter– Windows system
• Type route ? and press EnterThe Route Command Demo
Summary
• This chapter covered:– Designing TCP/IP-Based Networks– Subnetting– CIDR– Internet gateways– Address translation– TCP mail services– Utility commands