Thursday, November 8, 2012

What is MAC Address? Part 1

What is MAC Address? MAC address (Media Access Control) is assigned by manufacturer to identify the device and it's not like a IP address but each device has unique MAC ID to identify the device.

MAC Address = 48 Bits Hexadecimal Mode
 Example : oqwo.asdf.ghjk

Ok, Let's take a example with a switch device,

48 Switch Port  = 49 MAC Address

You have to listen to this carefully,  make sure in 48 Switch ports probably 48 Ports as per device, So 48 Ports = in to 48 MAC Address, They produces each port as 1 MAC Address, Now you recognized the way to realize ports MAC Address but how did you get 49 MAC Address, Let's See Below Simple Diagram.

48 Switch Port Device = 48 Ports (48 MAC Address) + Switch Device (1 Mac Address)

48 Ports MAC + 1 Switch Device = All 49 MAC Addresses. 

12 Switch Port Device = 13 MAC Address (12 Port MAC Addresses + Switch Device) 

What is Class A, B, C IP Address and Default Subnet Masks

What is an IP mostly known as Internet protocol but you have to know the other word too (Internet Networking Protocol), Some how as we learned There is a two kind of IP specifies IPV4 and IPV6

IPV4 - 32 Bits in Numerical Mode and IPV6 128 Bits Hexadecimal Mode.

IPV4 there is a separate list as "Private IP" and "Public IP",
Private IP Called as we can assign for our private local area network, In other words you can use it for you home, office and cafes but Public IP is except private ip ranges others all are public ip and specially use it for in internet.

Check it out his Ranges here
Private Ranges

Class A - - ---> You can use this IP ranges in to a large area network.
Class B - - ---> You can use this IP ranges in to a medium area network
Class C - - ---> you can use this IP Ranges in to a small area network

Except these above IP ranges other all IP's are considered as Public IP

Class A Default subnet mask -
Class B Default subnet mask -
Class C Default subnet mask -

Saturday, November 3, 2012

What is Half Duplex and Full Duplex

Hmmm well let's we learn about Half duplex and full duplex actually we are going to learn the key points also known as useful notes only so this post would be very helpful to you to learn the Duplexes.

Half Duplex

  • Half Duplexes running on 10 Mbps speed probably 10BaseT Type of Ethernet.
  • In here one can send or one can receive (You can't send or receive at the same time in network)
  • Using CSMA/CD (Collision Detection)
  • You'll able to see in Walkie-Talkie - using the half duplex method to conversation with destination. once you talk "hello" it should be send to destination probably destination should not able to send at the same time which send "Hello" by a host. after destination got the message from the host "Hello" destination will answer to it "hello"... Simple na..

Full Duplex

  • Full Duplexes are running at 100 Mbps speed probably 100BaseTX (UTP and STP) Type of ethernet
  • In here you can send and receive at the same time.
  • using Free way because there are no data can be collide unless a error. 
  • You'll able to see this method on mobile or mobile conversation between host and destination. :D

Wednesday, October 31, 2012

[Useful Notes] Broadcast Domain and Collision Domain

1. In switch every port has own a collision domain because switches direct traffic to only correct port.
2. Collision domain broken up by Bridges,Switches and routers
3. Every end device would be plugged to switch port would be 1 collision domain.
4. Broadcast domain depends on how you segmented a network.
5. 1 Hub = 5 Hosts There is only one collision domain. because hub has 1 collision domain and 1 broadcast     domain
6. Collisions are resolved using CSMA/CD (Collision Detection) For retransmit.
7. Mostly collision found on Wifi Network also known as wireless network. (and also in Ethernet Hub environment)
8. Modern wired network uses a network switch to eliminate collisions
9. Separating VLANs divides broadcast domain as well.

Router Benefits

  • Routers by default breakup broadcast domain and it is helps to connect to WAN (Wide-Area-Network),
  • Routers are using something called a serial interface for WAN Connection (V.35 physical interface on a cisco router)

Why we need to breakup broadcast domain?

Breaking up a broadcast domain is very important because now you have to send a "Network Broadcast" to a another host on a network, Some how you have sent the network broadcast to the host in other words every hosts in a network read and process the particular network broadcast message. 

  • Routers are not only breaking up the broadcast domain but also collision domain as well. 

2 Main advantages of using a router

  • They don't forward broadcast domain by default. 
  • They can filter the network based on Layer 3 (We will talk about Layer functions and OSI layers later)

4 Functions of a Router

  1. Packet Switching - Router also defined as "layer 3 Switches". use for logical addressing that's why we called as packet switching.
  2. Packet Filtering and Internetworking - Router also packet filtering to using access list.when two or more routers in a networks together use logical addressing  (IP -IPV4 Or IPV6 ) What is called Internetwork
  3. Path Selection - Routers are using a Routing table (map of the internetwork) to make path selections and forward packets to remote network. 
( I just gave you 3 on the above list but in the 2nd option you'l lsee packet filtering and internetworking, i just combined two options as one)

Maybe You have a Question Like This - How much broadcast needs to a network? 

Actually this is question when i asked in forums when i'm newbie still i'm newbie- I'm taking CCENT so this blog is very helpful to provide the useful notes for your cert exams indeed. so this is the answer,

Always keep in mind - Broadcast domains on how you segmented a network.. 

Tuesday, October 30, 2012

Network Segmentation?

What is a HUB?

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HUB (Layer 1 of OSI Model)  is a device which helps you to connect a LAN (Local -Area- Network) and it's very inexpensive mostly uses in Home networks and troubleshooting perhaps using in some small offices because of budget summary. Hub is provides 10mbps speed and it has 1 Collision domain and 1 Broadcast domain, Called as "Multi Repeater" too.

A normal Ethernet Hub

This is a Dual Speed Hub We will talk about this later