TCP/IP Overview and Components

TCP/IP Overview

• TCP/IP is a network protocol designed to deliver data packets to computers on any scale
• It's a suite of protocols for tasks like logical addressing, address resolution, name resolution, dynamic address allocation, efficient packet delivery, and sequencing
• TCP/IP is the default protocol on Windows computers, both IPv4 and IPv6 are included

TCP/IP Components

• TCP/IP includes related protocols like DNS (Domain Name System), DHCP (Dynamic Host Configuration Protocol), TCP (Transmission Control Protocol), UDP (User Datagram Protocol), IPv4 (Internet Protocol version 4), IPv6 (Internet Protocol version 6), ARP (Address Resolution Protocol), ICMP (Internet Control Message Protocol), and ICMPv6

TCP/IP Communication

• When a user opens a web page, DNS converts the website name (e.g., google.com) into its IP address
• The client then determines if the website is on the same network or a different one

General Network Terms

• MAC address: the unique physical address of a network interface card (NIC)
• Frame: a formatted data unit ready for transfer on the network medium
• Packet: the Network layer data unit, used by IPv4 and IPv6
• Segment: the Transport layer data unit used by TCP and UDP

The Role of TCP and UDP

• The TCP or UDP header gives information about which application receives the data
• TCP and UDP use port numbers to specify the source and destination of application-layer protocols
• IANA (Internet Assigned Numbers Authority) assigns a port number to each well-known networked service

IPv4 Addresses

• IPv4 addresses are 32-bit numbers divided into four 8-bit octets (values range from 0 to 255)
• Subnet masks are also 32-bit numbers to allocate bits for network and host IDs

IPv4 Addresses - Example

• 192.168.14.250 is an example of an IPv4 address in dotted decimal notation
• 255.255.255.0 is an example of a subnet mask

Binary Math

• Computers use logical AND operations to determine the network ID using the IP address and subnet mask
• Logical AND operations result in 0, 0, 0, or 1

Converting Decimal to Binary

• Tables are provided to convert decimal numbers (e.g., 125) into their binary equivalent using powers of two

Converting Binary to Decimal

• Tables are provided to convert binary numbers (e.g., 11010011) into their decimal equivalent using powers of two

IP Address Classes

• IP addresses are categorized in classes A to E, but only A, B, and C are commonly used
• Each class has a specific range for the first octet, and different bits are assigned for network and host IDs depending on the class

Private IP Addresses

• Private IP addresses are reserved for internal networks and cannot be directly accessed on the public internet directly

Private IP Addresses (continued)

• Class A private addresses begin with 10
• Class B private addresses range from 172.16 to 172.31
• Class C addresses range from 192.168.0 to 192.168.255

Private IP Addresses (further continued)

• Link-local addresses are automatically assigned if no DHCP service is available
• They range from 169.254.1.0 to 169.254.254.255

Network Address Translation (NAT)

• NAT allows organizations to use private IP addresses while connected to the internet
• It translates private addresses to public addresses when packets leave a corporate network

Classless Interdomain Routing (CIDR)

• CIDR represents IP addresses with their subnet masks, avoiding the classes A, B, and C
• It uses the format A.B.C.D/n, where 'n' specifies the number of bits in the subnet mask

Broadcast Domains

• A broadcast domain defines devices that receive broadcast packets
• Broadcast packets are destined for all computers on a network

Subnetting

• Subnetting divides a large network into smaller ones by reallocating bits from the host portion to the network portion of an IP address
• It is often used to conserve IP addresses

Calculating a Subnet Mask

• The formula 2ⁿ - 2, where 'n' is the host bits in the subnet mask, determines the number of host addresses

A Pattern Emerges

• The calculation process for subnet networks generates a sequential pattern.

Determining Host Addresses

• Calculating the starting and ending host addresses for each subnet generates a sequential pattern

Supernetting

• Supernetting aggregates smaller subnets into larger ones, streamlining routing tables

Configuring IPv4 Addresses

• Every IP configuration must include a subnet mask
• All hosts on the same physical network must share the same network ID
• Host IDs must be unique

Configuring Multiple IP Addresses

• Windows operating systems allow multiple IP addresses to be assigned to a single network connection

Configuring the Default Gateway

• Almost every IP configuration uses a default gateway
• A default gateway's address must have the same network ID as the host's network ID

Using Multihomed Servers

• Multihomed servers have two or more network interface cards (NICs), each connected to different IP networks

Use the Route Command

• Typing 'route print' displays the routing table on the computer; the results are separated into five columns (Network Destination, Netmask, Gateway, Interface, and Metric)

IP Configuration Command-Line Tools

• Command-line tools can assist with IP configuration (e.g., netsh, PowerShell cmdlets, ipconfig, ping, arp, tracert, nslookup)

Using netstat

• Display and modify network settings on a computer

Using PowerShell Cmdlets

• PowerShell cmdlets are used to view and configure IP address settings (e.g., Get-NetIPConfiguration, Get-NetIPAddress, Set-NetIPInterface, Set-DnsClientServerAddress)

Using ipconfig

• Displaying IP address settings; it can also perform other actions (e.g., /all, /release, /renew, /displaydns, /flushdns, /registerdns)

Using ping

• Testing connectivity between two computers using ICMP echo requests; ICMP echo replies are used for response verification

Using arp

• Displays or modifies the ARP cache, which contains IP addresses and MAC addresses

Using tracert

• Displaying the route that packets take between two computers

Using nslookup

• Testing and troubleshooting DNS operation; typing 'nslookup host' in command mode queries the host address

Internet Protocol Version 6 (IPv6)

• IPv6 is replacing IPv4 as the newer and larger internet protocol
• It expands the address space compared to IPv4

IPv6 Overview

• IPv6 provides a large address space, hierarchical addressing, and support for Quality of Service (QoS), security, mobility, and extensibility to address the limitations of IPv4

IPv6 Address Structure

• IPv6 addresses are 128-bit hexadecimal numbers separated by colons

Transitioning from IPv4 to IPv6

• Both IPv4 and IPv6 use a dual IP layer architecture where both protocols coexist
• Using IPv6-over-IPv4 tunneling, ISATAP, 6to4, Teredo technologies help the transition

Dual IP Layer Architecture

• A dual IP architecture means computers can communicate with both IPv4 and IPv6 devices using their respective native packet types

IPv6-over-IPv4 Tunneling

• IPv6-over-IPv4 tunneling allows IPv6 packets to be encapsulated in IPv4 headers for transmission over IPv4 networks

Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)

• ISATAP transmits IPv6 packets over IPv4 networks for dual-IP layer hosts

6to4 Tunneling

• 6to4 provides automatic tunneling for IPv6 traffic over IPv4 networks

Teredo Tunneling

• Teredo solves the limitations of 6to4 by allowing traversal of NAT routers and enabling IPv6 communication over IPv4 networks when a public IPv4 address is required or not available