Unit 02: LO 3 - 3.2 - Network Addressing

MAC and IP addresses are both numerical identifiers that help in computer networking, but they're used in slightly different ways and have different number systems.

MAC Address

• Number System: MAC (Media Access Control) addresses are in hexadecimal.

• Example: A MAC address might look like 00:1A:2B:3C:4D:5E.

• Explanation: Each pair of characters represents a byte (8 bits), and the numbers/letters range from 0-9 and A-F. The pairs are separated by colons.

In simpler terms, think of a MAC address like a permanent name tag for a computer's network card. It's written in a language that uses not just numbers, but also some letters (A to F) to be more precise.

Manufacturing factories keep track of the different MAC (Media Access Control) addresses for every unique device they create through a systematic process involving several key steps. Here's a simplified explanation suitable for high school students:

1. Understanding MAC Addresses

A MAC address is a unique identifier assigned to network interfaces for communications on the physical network segment. Think of it like a fingerprint for devices like computers, smartphones, or any device that can connect to a network.

2. Allocation of MAC Addresses

MAC addresses are 48-bit numbers, typically represented in hexadecimal format (e.g., 00:1A:2B:3C:4D:5E). They are usually assigned by the device's manufacturer. The first half of the MAC address (24 bits) is called the Organizationally Unique Identifier (OUI), which identifies the manufacturer, while the second half (24 bits) is unique to each device produced by that manufacturer.

3. Getting a Block of MAC Addresses

Manufacturers obtain blocks of MAC addresses from the Institute of Electrical and Electronics Engineers (IEEE). The IEEE allocates these blocks, ensuring that each block is unique to a specific manufacturer. For example, Apple or Samsung will have their own blocks of MAC addresses.

4. Assigning MAC Addresses in Production

During the manufacturing process, each device is assigned a unique MAC address from the allocated block. This assignment is done through automated systems that ensure no two devices get the same address.

5. Tracking and Management

Manufacturers use databases and specialized software to keep track of which MAC addresses have been assigned to which devices. This helps in several ways:

• Quality Control: Ensuring no duplicate MAC addresses are assigned.

• Customer Support: Helping with device identification and troubleshooting.

• Regulatory Compliance: Some regions require manufacturers to keep records of MAC addresses for security and compliance purposes.

6. Recording and Documentation

When a device is tested and passes quality checks, its MAC address is recorded in the factory's database. This information can be used later for warranty purposes, software updates, and support services.

7. Labeling

The MAC address is often printed on a label attached to the device, or it can be stored in the device’s firmware. This makes it easy to identify the MAC address if needed.

Example

Imagine a factory making Wi-Fi routers. They receive a block of MAC addresses from the IEEE. As each router is assembled, the factory’s computer system assigns the next available MAC address from their block to each router. This assignment is recorded in their database, ensuring every router has a unique identifier.

Given the current rate of device production and the fact that MAC addresses must only be unique within a local network, this space is considered sufficient for the foreseeable future2. On a local network, MAC addresses can be reused as long as they are unique within that network segment2. Additionally, one of the 48 bits is used to designate whether the MAC address is globally or locally administered, which effectively doubles the number of usable addresses for local contexts2.

So, while it’s theoretically possible to run out of unique MAC addresses if every device globally required a unique identifier, in practice, the current system of MAC address allocation and management is designed to prevent such a scenario. The vast number of available addresses, combined with the ability to reuse them on separate networks, ensures that we won’t run out of MAC addresses anytime soon.

If a network engineer encounters a collision due to two devices having the same MAC addresses on the same local area network (LAN), they would typically take the following steps to resolve the issue:

1. Identify the Devices: Determine which devices are causing the collision by examining the network’s MAC address table or using network scanning tools.

2. Isolate the Issue: Temporarily disconnect one of the devices to confirm that the MAC address conflict is the source of the network issues.

3. Address Resolution: If the conflict is due to a manually set MAC address (MAC spoofing), the engineer would change the MAC address on one of the devices to a unique value.

4. Update Network Configuration: In cases where the network devices support port security features, the engineer might configure the network to allow only one MAC address per switch port. This way, if a port detects a different MAC address than the one it learned initially, it can disable the port to prevent the conflicting device from connecting1.

5. Vendor Notification: If the duplicate MAC addresses are due to a manufacturing error, the engineer would notify the device manufacturer to investigate the cause and prevent future occurrences.

6. Documentation: Update network documentation to reflect the changes made and ensure proper tracking of MAC addresses within the network.

7. Monitoring: Continue to monitor the network for any further instances of MAC address conflicts and take proactive measures to prevent them.

It’s important to note that while duplicate MAC addresses can cause network connectivity issues for the hosts involved, they do not cause packet collisions in the traditional sense. Packet collisions are a 

IP Address

• IPv4 Number System: IPv4 addresses are in decimal.

• Example IPv4: An IPv4 address might look like 192.168.0.1.

• Explanation IPv4: The numbers range from 0 to 255 and are separated by periods.

• IPv6 Number System: IPv6 addresses are in hexadecimal.

• Example IPv6: An IPv6 address might look like 1200:0000:AB00:1234:0000:2552:7777:1313.

• Explanation IPv6: Similar to MAC addresses, but longer and separated by colons.

In simpler terms, think of an IP address as a temporary address that your computer gets when it joins a network, like when you go to a hotel and get a room number.

Ports

In computer networking, there are a total of 65,535 TCP/UDP ports available1. These ports are divided into different ranges:

• Well-Known Ports: Range from 0 to 1023 and are reserved for system or standard services2.

• Registered Ports: Range from 1024 to 49151 and are registered for specific services but are not as commonly used as well-known ports2.

• Dynamic/Private Ports: Range from 49152 to 65535 and are reserved for private or ephemeral use2.

Each port serves as a communication endpoint for network services, and the vast number of ports allows for a multitude of services and applications to operate concurrently on a network. 

For example, most of us use https (secure web traffic - this is on port 443. If an application uses http (unsecure), it's on port 80. 

Firewalls by default have most to all ports turned off, except for 80 and 443 as this is the predominant use of a router. Imagine buying or installing one and not having internet?