TCP/IP Network Protocol Overview

TCP/IP Overview

• TCP/IP is a network protocol suite for packet delivery across networks of any scale
• It handles logical addressing, address resolution, name resolution, dynamic address assignment, and efficient packet delivery
• It includes many other tasks

TCP/IP Components

• Windows computers use TCP/IP as the default network protocol, including IPv4 and IPv6
• TCP/IP related protocols include:
  • Domain Name System (DNS)
  • Dynamic Host Configuration Protocol (DHCP)
  • Transmission Control Protocol (TCP)
  • User Datagram Protocol (UDP)
  • Internet Protocol version 4 (IPv4)
  • Internet Protocol version 6 (IPv6)
  • Address Resolution Protocol (ARP)
  • Internet Control Message Protocol (ICMP)
  • Internet Control Message Protocol version 6 (ICMPv6)

TCP/IP Communication

• DNS resolves website names to IP addresses when a user opens a web page
• The client then determines whether the website is on the same or different network
• General network terms include MAC address (physical layer of a Network Interface Card (NIC)), frame (formatted data ready for transfer), packet (Network layer data unit for IPv4/IPv6), and segment (Transport layer data unit for TCP/UDP)

The Role of TCP and UDP

• TCP/UDP headers determine which application the received data should be sent to
• TCP and UDP use port numbers to specify source and destination application-layer protocols
• The Internet Assigned Numbers Authority (IANA) assigns port numbers for well-known network services
• Some applications use TCP, some use UDP

IPv4 Addresses

• IPv4 addresses are 32-bit numbers divided into four 8-bit octets (values from 0 to 255)
• Subnet masks are also 32-bit numbers to determine network ID and host ID allocation

IPv4 Addresses Example

• Example conversion of 192.168.14.250 to binary
• Example conversion of 255.255.255.0 to binary

Binary Math

• Logical AND operations are used to determine the network ID from IP address and subnet mask
• Example binary AND operations (0 AND 0 = 0, 1 AND 0 = 0, 0 AND 1 = 0, 1 AND 1 = 1)
• Finding the subnet mask: converting example IP address (172.31.100.6) and subnet mask (255.255.0.0) to binary, performing the AND operation, and converting the result back to decimal (172.31.0.0)

Converting Decimal to Binary, and Binary to Decimal

• Conversion tables for decimal to binary, and binary to decimal conversion

IP Address Classes

• IP addresses are categorized into Classes A, B, and C for host assignment
• Class A: First octet is between 1 and 127, IP registry assigns the first octet
• Class B: First octet is between 128 and 191, IP registry assigns the first two octets
• Class C: First octet is between 192 and 223, IP registry assigns the first three octets

Private IP Addresses

• Addresses reserved for private networks (not directly accessible via the internet)
• Class A: Beginning with 10
• Class B: From 172.16 to 172.31
• Class C: From 192.168.0 to 192.168.255

Link-Local Addresses and APIPA

• Another type of private address is a link-local address
• Automatically assigned when a computer needs an IP address but no DHCP service is available (APIPA)
• Range of 169.254.1.0 to 169.254.254.255, with subnet mask 255.255.0.0

Network Address Translation (NAT)

• NAT allows organizations to use private IP addresses while connected to the internet
• The NAT process translates a workstation's private address into a valid public internet address.

Classless Interdomain Routing (CIDR)

• CIDR uses IP addresses without default subnet masks
• Format: A.B.C.D/n, where n is number of 1 bits in the subnet mask
• Example conversion of 172.31.210.10 with subnet mask 255.255.255.0 to CIDR notation (172.31.210.10/24)

Broadcast Domains

• A broadcast domain defines devices that receive a broadcast packet (packet sent to all computers on the network)
• TCP/IP relies on broadcasts for tasks like DHCP and ARP

Subnetting

• Subnetting reallocates bits from the host portion to the network portion of an IP address, creating smaller address spaces
• This is done to divide large networks into smaller subnetworks and conserve IP addresses
• Formula: 2^n, where n is the number of bits reallocated to the network ID

Calculating a Subnet Mask

• To determine the number of host addresses available in a subnet, use the formula 2^n - 2, where n is the number of host bits in the subnet mask

Determining Host Addresses

• Calculate the beginning and ending host addresses for a subnet in binary and decimal formats.

Using command-line tools

• Several command-line tools are available for IP configuration: netsh, PowerShell cmdlets, ipconfig, ping, arp, tracert, nslookup
• Use netsh to set IP address
• Use ipconfig to display IP address settings

IPv6 Overview

• IPv6 is the replacement for IPv4 (due to address space exhaustion)
• IPv6 has a larger address space and a better hierarchical structure

IPv6 Address Structure

• IPv6 uses 128 bits for addresses
• Addresses are written in hexadecimal format, separated by colons
• Consecutive zeros can be represented by a double colon

IPv6-over-IPv4 Tunneling

• A method for sending IPv6 packets through an IPv4 network; encapsulating IPv6 packets in IPv4 headers

Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)

• Protocol that transmits IPv6 packets between dual IP layer hosts through an IPv4 network

6to4 Tunneling

• Protocol that provides automatic IPv6 tunneling over an IPv4 network

Teredo Tunneling

• Solves the problem that 6to4 has needing a publicly addressable IPv4 address
• Allows to traverse NAT (Network Address Translation) routers.

Multihomed Servers

• Enables servers to be accessed by both internal and external clients while providing resources to multiple subnets
• A server connected to multiple IP networks

Configuring Multiple IP Addresses

• Windows operating systems allow configuring multiple IP addresses on a single network connection

Configuring the Default Gateway

• The default gateway's address must share the same network ID as the host's network ID