Network Terminology and Explanation

ARP(Address Resolution Protocol)

Change IP address to !MAC address!

I have this MAC address and which IP is assigned to it?(Broadcast)

 

ARPing with a host in different network(subnet)

1. Get default gateway(router)'s MAC by ARP.

2. Host A sends a packet to gateway with Host D's IP address

3. Gateway sends ARP with the IP address that Host A notified.

4. Get Host D's MAC address and sent the packet to D.

 

DHCP(Dynamic Host Configurations Protocol)

Acutally assign IP address to the MAC address by referring to ARP table.

 

[While communicating, plz note that the IP is not assigned yet so MAC is the only way to destine.]

Client: I am broadcasting my MAC and IP request hey DHCP server, plz unicast me free IP!(Broadcast)

DHCP: Okay. I will unicast assign-able IP address.(Unicast)

Client" Thanks. Let me ARP to see if this is unique. Alright. can i lease this IP?(Broadcast)

DHCP: sure! this is the lease period. If you want to extend, plz broadcast DHCP Request again. If you want to releave, plz unicast me DHCP Release

 

For real communication, outside to inside network, MAC address is needed. Phsycal address

This Discover Packet(from DHCP Client, Client computer) contains the client’s computer name and Media Access Control (MAC) address so the DHCP servers can respond to it.

 

Subnetting

By using subnet mask, divide Host ID into Network ID

ex) Network ID(The sequence of 1)/Host ID(The sequence of 0)
Default 0.0.0.0 (Host ID) ->to  1.1.0.0 (Network ID/Host ID) 
 

Supernetting

By using subnet mask, add Network ID into Host ID

 

Subnet Mask

A concept that 'devide network area' by changing the assigned area of Network ID and Host ID in IP address

 

Why we use Subnetting?

The network communication in general operates as broadcasting. To boost up efficency of data flow through network, it divides into sub-network to group highly interact hosts.

 

Available number of Hosts

2 squre of "the number of 0" - 2(Broadcast address and Network Name Address)

ex) 255.255.255.(240) = 255.255.255.(1111 0000)

= 2^4 -2 = 14

 

Subnet Mask from (Subet + Prefix)

Prefix: the number of bits of subnet mask
194.133.10.124/27

/27 is a prefix which is the number of '1' ,network range -> [1111 1111]. [1111 1111]. [1111 1111]. [1110 0000]

                                                                      ->[2^8=256]. [256]. [256]. [256-2^5(Amount of '0', Hosts)]

So subnet mask would be 256.256.256.224

 

The number of additional subnet

When default subnet mask is 255.255.0.0

It becomes to 255.255.(255).[240] > 255.255.(1111 1111).[1111 0000]

'1' is added 12x times = 2^12 = 4094 = additional subnet

 

Subnet Break Down to figure host IDs and network IDs

Example -> Subnet: 193.192.10.114/28, Subnet Mask: 255.255.255.[240]

(1)0~15 (2)16~31 (3)32~47 (4)48~63 (5)64~79 (6)80~95 (7)96~111 (8)112~127 (9)128~143 (10)144~159 (11)160~175 (12)176~191 (13)192~207 (14)208~223 (15)224~239 (16)240~255

16x hosts by 16x network ranges  = 256 in total

 

 

http://korean-daeddo.blogspot.com/2016/01/blog-post_26.html

서브넷 마스크와 서브넷팅 계산법

https://m.blog.naver.com/sbd38/50194591607

[네트워크] 서브넷 마스크(subnet mask)에 대해서 알아보자

The definition of IP classes

https://blog.naver.com/aufcl856/221051405287

IP에도 클래스가 존재한다? IP 클래스, 클래스풀(Classful) 방식에 대해 알아보자!