These addresses are hardcoded into the hardware by the manufacturer and serve as a permanent identifier for the device within a network segment. ​

Are MAC addresses UNIQUE?

• Privacy and Security:

  • Changing your MAC address can enhance privacy. By using a different address, you make it harder for others to track your device.
  • Some public Wi-Fi networks may restrict access based on MAC addresses. Changing it allows you to bypass such restrictions.

• Network Troubleshooting:

  • If you encounter network issues, altering the MAC address can help diagnose problems.
  • It allows you to simulate a different device on the network, which can reveal whether the issue is specific to your hardware.

• Avoiding IP Conflicts:

  • In some cases, multiple devices on the same network segment might accidentally have the same IP address.
  • Changing the MAC address ensures that your device gets a unique IP address from the DHCP server.

• Testing and Development:

  • Developers and network administrators often need to test network configurations.
  • Changing the MAC address allows them to simulate different devices without physically swapping hardware.

• Spoofing and Anonymity:

  • MAC address spoofing is used for anonymity or to bypass network restrictions

Reasons to change MAC Address

• Device Identification:

  • Each network interface controller (NIC) has a unique MAC address.
  • It acts like a digital fingerprint for devices, allowing them to be identified within a network segment.
  • When data packets travel across a network, routers and switches use MAC addresses to direct them to the correct destination.

• Address Resolution:

  • In local networks, devices communicate using MAC addresses.
  • When a device wants to send data to another device, it first resolves the recipient’s IP address to its corresponding MAC address using the Address Resolution Protocol (ARP).
  • ARP maintains a mapping between IP addresses and MAC addresses.

• Access Control:

  • Wi-Fi routers and switches use MAC addresses for access control.
  • By filtering based on MAC addresses, network administrators can allow or deny specific devices from connecting to the network.
  • This is useful for securing Wi-Fi networks and preventing unauthorized access

Reasons to change MAC Address 

• DHCP and IP Assignment:

  • DHCP servers assign IP addresses dynamically to devices when they join a network.
  • They use the device’s MAC address to ensure consistent IP assignments.
  • This simplifies network management and prevents IP conflicts.

• Troubleshooting:

  • Network administrators use MAC addresses to diagnose issues.
  • By tracking MAC addresses, they can identify faulty devices, monitor network traffic, and troubleshoot connectivity problems.

• Virtualization and Cloning:

  • In virtual environments, virtual machines (VMs) often share the same physical NIC.
  • Each VM has a unique MAC address, allowing them to function independently.
  • Cloning VMs involves changing their MAC addresses to avoid conflicts.

More Reasons to change MAC Address 

ARP CACHING

• Purpose: Dynamic entries are automatically added by the network device (such as a router or switch) and have a limited lifespan in the cache.
• Creation Process:
  • When a device wants to communicate with an IP address, it performs an ARP request.
  • The request broadcasts to the local LAN, asking, “Who has IP address X, and what is your Ethernet MAC address?”
  • The responding device provides its MAC address, and the entry is added to the dynamic ARP cache.
• Lifespan:
  • Dynamic entries remain in the cache as long as they are actively used.
  • If an entry remains unused for a certain period (the ARP cache timeout), it is removed.
• Benefits:
  • Dynamic entries adapt to network changes and are more flexible.
  • They minimize management overhead compared to static entries.

Dynamic

Internetworking

A collection of networks to provide data delivery of host-to-host.

H# are hosts

R# are routers

Store and Forward Packet Switching

IP and Routing

Internet Protocol (IP)

Governs the transmission of data over the internet.

Responsible for Routing data packets.

• Sender

  • Encapsulates segments into datagrams and sends them from the sending host to the receiving host

• Receiver

  • Datagrams are delivered to the transport layer

• Every host and router

  • Network layer protocols that operate at the network, data link, and physical layers

• A router examines the header fields in all IP datagrams that pass through it

Network Layer

Encapsulation

segment

datagram

frame

• Routing Protocols

  • RIP, OSPF, BGP

• IP Protocol

  • Address

  • Datagram Format

  • Packet handling

• ICMP Protocol

  • Error reports

  • Router Signals

• Forwarding Table

Internet network Layer (disassembled) 

• Internet Protocol Address
  • Identification for a device using the Internet Protocol
  • Location identification
• What are they?
  • A 32 bit number (IPv4)
  • A 128 bit number (IPv6)
• Who manages it?
  • Internet Assigned Numbers Authority (IANA)
    • Internet providers
  • Local administrators for a business or YOU at home

IP Address

Address Classes

• IPv4 addresses divided in
  • Network portion
  • Host ID
• At the beginning of IP protocol addresses were designed based on classes:
  • Class A
  • Class B
  • Class C
  • Class D
    • Multicasting
  • Class E
    • experimental

• Class A network range

  • 0-127

  • Really 0-126 as 127 is reserved

• Class B network range

  • 128-191

• Class C network range

  • 192-223

     

Network Ranges

• Class A supports 16777214 hosts
• Class B supports 65534 hosts
• Class C supports 254 hosts
  
   
• What if I only need 50 hosts or even worse 300?
  • IP wastage

SUBNETting

• To avoid IP wastage

• Create smaller networks (sub networks; subnets) inside large networks

• How?

  • Borrow bits from the Host ID

• Still have wastage but a lot more reduced

SUBNETting

• How do we know that 192.168.1.32 is an IP address or a subnet

• Subnet Masks

Class A: 255.0.0.0
Class B: 255.255.0.0
Class C: 255.255.255.0

• Subnet 192.168.1.32 is then represents as :

192.168.1.32  255.255.255.224 (or 192.168.1.32/27)

Network layer

Forwarding

Connects one network to another network

Routing

Determines the best route to the destination before forwarding traffic to the next router along the path

Routers

Responsible for routing traffic between network

Efficient path

Routing table used to determine the most efficient path to reach the destination

Router Architecture

datagrams journey

The concept of net neutrality is based on the idea that the internet should be an open and level playing field, where all users have equal access to information and online resources, regardless of their location, financial resources, or the type of device they use to access the internet.

If network neutrality is not enforced, ISPs could prioritize or block certain types of internet traffic, including specific websites, applications, or services. This could have significant implications for how routers function and how data is transmitted over the internet.

https://www.youtube.com/watch?v=fpbOEoRrHyU

https://worldpopulationreview.com/country-rankings/countries-without-net-neutrality

Network Neutrality