Network Class: Difference between revisions
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== IP Routing == | |||
Networks in the internet are connected to each other via routers. Routers carry traffic from one network/subnet to another. Routers maintain a routing table to decide how to route the IP packets. Each routing entry consists of the destination address, subnet mask and "route to" field. When a message needs to be routed to an IP address | |||
== References == | == References == | ||
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Revision as of 09:00, 6 July 2023
IP Address Classification
There are five classes: A, B, C, D and E in the IPv4 IP address space. Primarily, class A, B, and C are used by the majority of devices on the Internet. Class D and class E are for special uses. Each class has a specific range of IP addresses.[1]
The IP Address Classification figure shows different classes of IP addresses. These addresses differ in the number of bits assigned to the network and host ids.
Within each network class, there are designated IP address that is reserved specifically for private/internal use only. Private IP address cannot be used on Internet-facing devices as they are non-routable - not allowed to be routed outside of your internal network.
| Class | Public IP Range | Private IP Range | Special IP Range | Subnet Mask | Number of Networks | Number of Hosts per Network |
|---|---|---|---|---|---|---|
| A | 1.0.0.0 to 127.0.0.0 | 10.0.0.0 to 10.255.255.255
CIDR[2] example (10.0.0.0/8) |
255.0.0.0 | 126 | 16,777,214 | |
| B | 128.0.0.0 to 191.255.0.0 | 172.16.0.0 to 172.31.255.255
CIDR example, (172.16.0.0/16) |
Automatic Private IP Addressing (APIPA) is a feature with Microsoft Windows-based computers to automatically assign itself an IP address within this range if a Dynamic Host Configuration Protocol (DHCP) server is not available on the network. | 255.255.0.0 | 16,382 | 65,534 |
| C | 192.0.0.0 to 223.255.255.0 | 192.168.0.0 to 192.168.255.255
CIDR example, (192.168.0.0/24) |
127.0.0.1 to 127.255.255.255
**network testing addresses (also referred to as loop-back addresses). |
255.255.255.0 | 2,097,150 | 254 |
| D | 224.0.0.0 to 239.255.255.255 | Multicasting | ||||
| E | 240.0.0.0 to 255.255.255.255 | Research/Reserved/Experimental |
Network prefix vs Host ID
The internet, as the name implied, is a network of networks. Thus to uniquely identify a host on the internet, one needs to know the network's id and the host's id in the network. Thus IP address consist of two components, the network id and the host id. The network id is the number assigned to a network in the internet. Host id represents the id assigned to a host in the network.
Network prefix describes the specific location on the network to find where that IP addresses are located on. Network prefix portion is being used by Router to send packets through an internetwork becuase Routers are not concerned about host addresses.
Two type of routing
- Classless routing : the practice of assigning different size masks on your network—does not work unless you run a routing protocol that supports prefix routing. RIP version 2, OSPF, and EIGRP are examples of routing protocols that can support classless routing.
- Classful routing : means that all hosts have the same size mask. RIP version 1 and IGRP are classful routing protocols, and neither will work in a classless environment.
Subnet
To create smaller networks (sub networks) out of a Class A network ID, you’d borrow bits from the host portion of the mask. The more bits you borrow, the more subnets you can have, but this means fewer hosts per subnet. following lists all the available Class A subnet masks:[3]
Subnetting applies equally whether you working with either private or public addresses. It becomes even more important when you’re working with globally routed IP space.[4]
Subnet defines the specification of bits that should be used for routing is specified by associating a subnet mask with a routing entry.Once define a subnet mask for subclassing large network to small network by assign subnet mask and validate subnet address, to valid subnet address ipcalc would be simplest way to
| Mask | Prefix | Subnets | Hosts |
| 255.0.0.0 | (/8) | 1 network | with 16,777,214 hosts |
| 255.128.0.0 | (/9) | 2 subnets | with 8,388,606 hosts each |
| 255.192.0.0 | (/10) | 4 subnets | with 4,194,302 hosts each |
| 255.224.0.0 | (/11) | 8 subnets | with 2,097,150 hosts each |
| 255.240.0.0 | (/12) | 16 subnets | with 1,048,574 hosts each |
| 255.248.0.0 | (/13) | 32 subnets | with 524,286 hosts each |
| 255.252.0.0 | (/14) | 64 subnets | with 262,142 hosts each |
| 255.254.0.0 | (/15) | 128 subnets | with 131,070 hosts each |
| 255.255.0.0 | (/16) | 256 subnets | with 65,534 hosts each |
| 255.255.128.0 | (/17) | 512 subnets | with 32,766 hosts each |
| 255.255.192.0 | (/18) | 1,024 subnets | with 16,384 hosts each |
| 255.255.224.0 | (/19) | 2,048 subnets | with 8,190 hosts each |
| 255.255.240.0 | (/20) | 4,096 subnets | with 4,094 hosts each |
| 255.255.248.0 | (/21) | 8,192 subnets | with 2,046 hosts each |
| 255.255.252.0 | (/22) | 16,384 subnets | with 1,022 hosts each |
| 255.255.254.0 | (/23) | 32,768 subnets | with 510 hosts each |
| 255.255.255.0 | (/24) | 65,536 subnets | with 254 hosts each |
| 255.255.255.128 | (/25) | 131,072 subnets | with 126 hosts each |
| 255.255.255.192 | (/26) | 262,144 subnets | with 62 hosts each |
| 255.255.255.224 | (/27) | 524,288 subnets | with 30 hosts each |
| 255.255.255.240 | (/28) | 1,048,576 subnets | with 14 hosts each |
| 255.255.255.248 | (/29) | 2,097,152 subnets | with 6 hosts each |
| 255.255.255.252 | (/30) | 4,194,304 subnets | with 2 hosts each |
IP Routing
Networks in the internet are connected to each other via routers. Routers carry traffic from one network/subnet to another. Routers maintain a routing table to decide how to route the IP packets. Each routing entry consists of the destination address, subnet mask and "route to" field. When a message needs to be routed to an IP address