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Ip address subnetting and supernetting (2. Subnet,subnet mask and routing,…
Ip address subnetting and supernetting
Binary Number System
2 ^ 10 = 1024 (k)
2^30 = Giga
2^40 = Tera
2. Subnet,subnet mask and routing
Subnet mask: 1's - NID + SID, 0's - HID, 0's tell how many Ip adreses in the subnet
usage of subnetmask
Bitwise ANDing given IP adres with subnetmask gives subnet ID address
incoming ip adres is ANDed with all interfaces masks. If no one matches it is anded with default entry: 0.0.0.0
If the match comes with more than one interface, then the interface which has more 1's or the longer one is chosen
when sizes of subnets same its aka:
fixed length subnet maskin
So here subnet masks are same for all interfaces
Variable length subnet masking
(VLSM). Here subnet masks will be different for different length subnets
if ex: SID = 8, numof subnets = 2^8
Remember : 1000 0000 - 128, 1111 0000 - 240, 1111 1111 - 255
Provides security
being able to contain and target threats, subnetting can prevent users from hopping around and landing in areas of the network they don’t belong in.
Information is valuable, so all the important information should be separated from possible perpetrators.
Subnetting is the practice of dividing up a network into two or more networks.
enhancing routing efficiency
network management control
when there is a problem with a device on a subnetted network, it’s much easier to locate the issue because the devices are grouped together.
Class less inter domain routing(CIDR)
Here we buy part of network as much as needed. Part bought is aka
BLOCK
Like: 20.10.50.100/20, Num after slash is NID or Block ID
CIDR rules for block
all ip adres are contiguous
Block size of order 2^n
First Ip adres must be evennly divisible by size of block
subnetting , VLSM in CIDR
20.30.40.0/25 in two parts: 20.30.40.0/26, 20.30.40.64/26. Note increment of BID by 1.
Supernetting or Aggregation
Rules for agregatin networks
Net shud be contiguous
Net's size should be of order 2^n
First NID shud be divisible by entire Block
Super net ID :
NID of first agregated network
SuperNet mask=
32 - bits for total size of SuperNet
; those many bits will be 1
We always combine
2^n
number of networks.
IP address and subnetting
ClassFull Ip addressing
Class A
NID : 8 bits
HID : 24 bits
range : 1- 126
Default subnet mask: 255.0.0.0
LEADING BITS : 0
ip adress format
0NNNNNNN.HHHHHHHH.HHHHHHHH.HHHHHHHH
num of networks = 2^7 - 2
Class B
NID: 16 bits
HID: 16 bits
range: 128 - 191
Default subnet mask: 255.255.0.0
LEADING BITS : 10
ip adress format
10NNNNNN.NNNNNNNN.HHHHHHHH.HHHHHHHH
2^14 network addresses
Class C
NID : 24 bits
HID: 8 bits
range: 192- 223
Default subnet mask: 255.255.255.0
LEADING BITS : 110
ip adress format
110NNNNN.NNNNNNNN.NNNNNNNN.HHHHHHHH
(2^21) Network addresses
Class D and E
No specific range
CLASS D
LEADING BITS : 1110
Loopback Ip adreses
The IP range 127.x.x.x is reserved for loopback IP addresses.
parts of an IP address
NID
HID
2. Types of Casting
Unicasting
(One host to only one other host)
Broadcasting
(One to many)
Limited broadcasting adres (LBA): one host to all other host of network
Like: 255.255.255.255 (for all classes)
Direct Broadcasting address (DBA)
One host to all hosts of some other network
like: 120.255.255.255 (for a class a network)
Variable length subnet masking
(VLSM). Here subnet masks will be different for different length subnets