Summary for T.2, L.4 (cn)
Topic Title: IP SUBNETTING
- It is a logical numerical address that uniquely identified a devices that is part of a TCP/IP on IP network such as a single computer.
- Made up of 32 bits.
- Can be divisible into a network portion and host portion with the help of as subnet mask
- two IP addressing operates: OSI model (network layer) & TCP/IP (internet layer)
- BINARY OCTETS CONVERT TO DECIMAL (below)
-> The octets are broken down to provide an addressing scheme that can accommodate large and small networks.
The first octet is the network portion
Major network address of 1.0.0.0 − 127.255.255.255
Octets 2, 3, and 4 (the next 24 bits) are for the networkmanager to divide into subnets and hosts as he/she sees fit
Used for networks that have more than 65,536 hosts
The first two octets are the network portion
Major network address of 128.0.0.0 − 191.255.255.255
Octets 3 and 4 (16 bits) are for local subnets and hosts
Used for networks that have between 256 and 65,534 hosts.
The first three octets are the network portion
Major network address of 192.0.0.0 − 233.255.255.255
Octet 4 (8 bits) is for local subnets and hosts − perfect for networks with less than 254 hosts.
Helps to know which portion of the address identifies the network and which portion of the address identifies the host
Class A, B and C = default masks = natural masks.
The mask helps you identify the network and node parts of the address, convert the address and mask to binary numbers.
Identifying the network ID and host ID is easier when have the address and the mask represented in binary.
bits set to 1 represent the network ID.
bits set to 0 represent the host ID.
A logically visible subdivision of an IP network
The practice of dividing a network into two or more networks is called subnetting
A subnetwork is a network which covers only part of a project and is linked in relationships with other subnetworks in the same project.
Used the subnetworks to refine and detail the networks as planning progresses. The system treats subnetworks and networks the same, that is, can plan dates, capacities, costs, materials and production resource/tools also with a subnetwork.
It allows you to create multiple logical networks that exist within a single Class A, B, or C network
If you do not subnet, you are only able to use one network from your Class A, B, or C network
Each data link on a network must have a unique network ID
With every node on that link being a member of the same network
If you break a major network (Class A, B, or C) into smaller subnetworks, it allows you to create a network of interconnecting subnetworks
Each data link on this network would then have a unique network/subnetwork ID.
In order to subnet a network, extend the natural mask using some of the bits from the host ID portion of the address to create a subnetwork ID.
Router, subnetworks, IP address.
Each of the router is attached to four subnetworks
One subnetwork is common to both routers
Each router has an IP address for each subnetwork to which it is attached
Each subnetwork could support up to 30 host addresses
The more host bits you use for a subnet mask, the more subnets you have available.
The more subnets available, the less host addresses available per subnet
Variable-Length Subnet Masking (VLSM)
VLSM is a process of dividing an IP network into the subnets of different sizes without wasting IP addresses. When we perform Subnetting, all subnets have the same number of hosts, this is known as FLSM (Fixed length subnet mask). In FLSM all subnets use same subnet mask, this lead to inefficiencies.
Variable Length Subnet Mask (VLSM) extends classic Subnetting. VLSM is a process of breaking down subnets into the smaller subnets, according to the need of individual networks.
Steps for VLSM Subnetting
Find the largest segment. Segment which need largest number of hosts address.
Do Subnetting to fulfill the requirement of largest segment.
Assign the appropriate subnet mask for the largest segment.
For second largest segments, take one of these newly created subnets and apply a different, more appropriate, subnet mask to it.
Assign the appropriate subnet mask for the second largest segment.
Repeat this process until the last network.