CSE 2207 Data Communication Assignment-2
IPv4 Address Classes - Calculation Summary
Introduction to IPv4 Address Classes
IPv4 (Internet Protocol version 4) addresses are 32-bit binary numbers divided into network and host portions. The classful addressing system divides IPv4 addresses into five classes (A, B, C, D, E) based on the first few bits of the address.
Class A Networks
Range Calculation:
- First octet range: 0-127 (binary: 0xxxxxxx)
- First bit is always 0
- Calculation: 2^7 = 128 possible values (0-127)
- Reserved addresses: 0 (network address) and 127 (loopback)
- Usable range: 1-126
Network and Host Calculations:
- Default subnet mask: 255.0.0.0 (/8)
- Network bits: 8 (first octet)
- Host bits: 24 (last three octets)
- Number of networks: 2^7 - 2 = 126 networks
- Hosts per network: 2^24 - 2 = 16,777,214 hosts
Mathematical Breakdown:
- Total addresses in Class A: 2^7 × 2^24 = 2^31 = 2,147,483,648
- Network portion: N.H.H.H (N=Network, H=Host)
- Example: 10.0.0.0 to 10.255.255.255
Class B Networks
Range Calculation:
- First octet range: 128-191 (binary: 10xxxxxx)
- First two bits are always 10
- Calculation: 128 + (2^6 - 1) = 128 + 63 = 191
- Usable range: 128-191
Network and Host Calculations:
- Default subnet mask: 255.255.0.0 (/16)
- Network bits: 16 (first two octets)
- Host bits: 16 (last two octets)
- Number of networks: 2^14 = 16,384 networks
- Hosts per network: 2^16 - 2 = 65,534 hosts
Mathematical Breakdown:
- Total addresses in Class B: 2^14 × 2^16 = 2^30 = 1,073,741,824
- Network portion: N.N.H.H
- Example: 172.16.0.0 to 172.31.255.255
Class C Networks
Range Calculation:
- First octet range: 192-223 (binary: 110xxxxx)
- First three bits are always 110
- Calculation: 192 + (2^5 - 1) = 192 + 31 = 223
- Usable range: 192-223
Network and Host Calculations:
- Default subnet mask: 255.255.255.0 (/24)
- Network bits: 24 (first three octets)
- Host bits: 8 (last octet)
- Number of networks: 2^21 = 2,097,152 networks
- Hosts per network: 2^8 - 2 = 254 hosts
Mathematical Breakdown:
- Total addresses in Class C: 2^21 × 2^8 = 2^29 = 536,870,912
- Network portion: N.N.N.H
- Example: 192.168.1.0 to 192.168.1.255
Class D Networks (Multicast)
Range Calculation:
- First octet range: 224-239 (binary: 1110xxxx)
- First four bits are always 1110
- Calculation: 224 + (2^4 - 1) = 224 + 15 = 239
- Range: 224-239
Purpose and Calculations:
- Used for multicast addressing
- No subnet mask (not divided into network/host)
- Total addresses: 2^28 = 268,435,456
- No host calculation as it's for group communication
- Example: 224.0.0.1 (All Systems Multicast)
Class E Networks (Experimental)
Range Calculation:
- First octet range: 240-255 (binary: 1111xxxx)
- First four bits are always 1111
- Calculation: 240 + (2^4 - 1) = 240 + 15 = 255
- Range: 240-255
Purpose and Calculations:
- Reserved for experimental and future use
- Not available for general use
- Total addresses: 2^28 = 268,435,456
- No practical network/host division
Summary Table of Calculations
| Class | First Octet | Binary Pattern | Networks | Hosts/Network | Subnet Mask |
|---|
| A | 1-126 | 0xxxxxxx | 126 | 16,777,214 | 255.0.0.0 |
| B | 128-191 | 10xxxxxx | 16,384 | 65,534 | 255.255.0.0 |
| C | 192-223 | 110xxxxx | 2,097,152 | 254 | 255.255.255.0 |
| D | 224-239 | 1110xxxx | Multicast | N/A | N/A |
| E | 240-255 | 1111xxxx | Reserved | N/A | N/A |
Key Mathematical Formulas
For any class:
- Number of networks = 2^(network bits) - 2
- Number of hosts = 2^(host bits) - 2
- Total addresses = 2^32 = 4,294,967,296
Subnet Calculations:
- Network address: First address in range
- Broadcast address: Last address in range
- Usable addresses: Total - 2 (network and broadcast)
Practical Examples
Class A Example (10.0.0.0/8):
- Network: 10.0.0.0
- First host: 10.0.0.1
- Last host: 10.255.255.254
- Broadcast: 10.255.255.255
Class B Example (172.16.0.0/16):
- Network: 172.16.0.0
- First host: 172.16.0.1
- Last host: 172.16.255.254
- Broadcast: 172.16.255.255
Class C Example (192.168.1.0/24):
- Network: 192.168.1.0
- First host: 192.168.1.1
- Last host: 192.168.1.254
- Broadcast: 192.168.1.255
Limitations of Classful Addressing
- Address Wastage: Fixed class sizes don't match actual requirements
- Routing Table Size: Large routing tables in internet routers
- Inflexibility: Cannot efficiently allocate addresses based on actual needs
Modern Solutions
- VLSM (Variable Length Subnet Masking): Allows different subnet sizes
- CIDR (Classless Inter-Domain Routing): Eliminates class boundaries
- NAT (Network Address Translation): Allows private address reuse
- IPv6: Provides much larger address space
Note: This assignment requires handwritten submission with appropriate diagrams. Include binary representations, network diagrams, and calculation examples for each class.