MP-BGP and Address Families

CCNA Batch-12 – New ONLINE Batch – CTech Academy

Sticky Post Posted on April 1, 2019 by in Networking

CCNA New ONLINE Batch – CTech Academy (JULY-2019)

Sticky Post Posted on April 1, 2019 by in Networking

CCNA New ONLINE Batch – CTech Academy (1st July 2019)

Sticky Post Posted on April 1, 2019 by in Networking

CCNA New ONLINE Batch is starting on 1st of July 2019. Register NOW!

CCNA Routing
CCNA New ONLINE Batch – CTech Academy (1st July 2019)


Start Date: 1st July 2019
Cost: Pay $9 & start classes (Total Cost $49)

Instructor Led Online Interactive Training SESSIONS
Course Schedule & Contents are attached

Course Schedule & Contents

OSI Model

OSI Model (Open Systems Interconnection Model) is simply a reference tool, a standardised Reference Framework for conceptualising data communications between networks.OSI Model

OSI was the first conceptual model that characterized and standardized the communication functions of a Network system without regard to its underlying internal structure and technology.

OSI is a Vendor Neutral Model. Before OSI Model, each vendor used to use its own network model to manufacture Network equipment. So, one vendor’s equipment & network was not compatible with another vendor’s equipment. Buyers were bound to buy only from one vendor.

For example, if you were buying IBM Computers then you were now bound to buy all Network Equipment from IBM as well in the future. Because IBM Computers couldn’t be connected by other vendor Switches or Routers. You must buy IBM Switches to connect them. They will not work with HP Server or Cisco Switches.

OSI Model

To resolve this problem, the idea of a standardised Network Model emerged. International Organization for Standardization (ISO) started working on it, different network models were proposed and finally the OSI Model was chosen & released in 1984 by ISO. OSI provided brought in the flexibility along with standardization.

In simple words, OSI reference model describes how information from a software application in one computer moves through a network medium to a software application in another computer.

*An important point worth of mentioning here is that: Although OSI is the standard today but we never find it on real equipment. The model in action today is TCP/IP. OSI is used only for standardization & reference purposes.


Layers in OSI Model

OSI Model divides the network communication processes into seven layers in order to simplify it. Each layer performs specific functions to support the layers above it … which we will discuss in detail later. OSI Model has 7x Layers starting from Physical till Application level as in below:OSI Model

Physical Layer standardises the Physical medium. For example, signal level, voltage, radio, cabling standards & so on…. It simply, standardises everything which you can touch & feel. Physical layer is responsible for ultimate transmission of digital data bits in the form of electrical, optical or radio signals from the Physical layer of the source or sending device over network communications media to the Physical layer of the receiving of destination device.  Data Link Layer standardizes the Physical Addressing. It is responsible for Data Switching. Physical addressing includes MAC Address & Ethernet Frames. Network Layer deals with Logical Addressing. It is responsible for Data Routing. Transport Layer ensures the error free data transmission across networks. It mainly focuses on data delivery. Transport Layer mainly uses two protocols called TCP & UDP which we will discuss in detail in later sections.  Session Layer is responsible for session control. In simple words, it manages on how to start, control, and end conversations between two hosts or computers.  Presentation Layer is responsible for data organization & conversion so that it is readable by Application layer of all hosts/applications involved in the data communication.  Application Layer is responsible for end-user processes or applications. It supplies network services to end-user applications.


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TCP 3-way Handshake Summary Cheatsheet

Network Topology Types

“The layout pattern & connectivity scheme between the devices in a network is called network topology”. It is a virtual shape or structure of the network. Devices on the network are called as nodes. The most common nodes are computers and peripheral devices. Network topology is a virtual illustration of these nodes and their connections using physical cabling. There are a number of different types of network topologies which are broadly divided into two types:

  • Physical Network Topology: Actual Connectivity/Layout as per real cabling & connections
  • Logical Network Topology: Virtual view of the network that member devices see

Physical Network Topology Types

There are many types of Physical Network Topology, out of which, most common 7xtypes include Point-to-Point, Ring, Mesh, Star (Hub/Spoke), Bus, Tree and Hybrid.

Network Topology Types Atech Waqas Karim (0)_

Let’s discuss each type one by one.

1. Point-to-Point Network Topology

Point-to-point topology is the simplest of all network topologies. The network simply consists of a direct link between two computers for a faster and more reliable connection. Using circuit-switching or packet-switching technologies, a point-to-point circuit can be set up dynamically and dropped when no longer needed. Switched point-to-point topologies are the basic model of conventional telephony.

This is fastest network topology because there is a direct connection so no broadcast is required on such network types. p-p topology is the most reliable than all other types of the connections because there is a direct connection. But p-p topology can only be used for small areas where computers are in close proximity & short distance. Below figure shows a Point-to-Point Network Topology along with its Advantages & Disadvantages:


Point-to-Point Network Topology

2. Ring Network Topology

In Ring topology, the devices in the network are connected in a circle. Each device has two paths to send & receive data. If one link goes down, data could be sent from the other side. A ring topology is similar to a bus topology in a closed loop. In this type of topology, data travels around the ring in one direction. When one node sends data to another, the data passes through each intermediate node on the ring until it reaches its sink or destination. The intermediate nodes simply repeat the data to keep the signal strong.

Ring Network Topology is more secure because if one link is broken in the Ring, data can travel from the side. It is easy to Troubleshoot and easy to Install. However, in Ring Network Topology, Scalability and expansion in existing network is a bit difficult & requires more skill. Below figure shows a Ring Network Topology along with its Advantages & Disadvantages:

Ring Network Topology


3. Mesh Network Topology

In Mesh network topology, every device is interconnected to every other device in the network. Nodes are connected to each other in a redundant fashion with multiple connections. There are two types of mesh topologies, Partial Mesh and Full Mesh. Mesh Network Topology is the most stable & fault tolerant. It is cable fault & device fault tolerant. However, it is the most expensive as it requires more cabling & infrastructure. Below figure shows a Mesh Network Topology along with its Advantages & Disadvantages:

Mesh Network Topology


4. Star Network Topology

In a Star Topology every device is connected to a central device such as a switch. Star topology requires more cable as compared to other topologies but it mode robust as a failure in one cable will only disconnect the specific connected computer via that cable to the central device. Star Network Topology is easier to manage. It is easier to locate node and cable problems in it and it is well suited for expansion into high-speed networking. However, it contains single point of failure and requires more network cable.

Below figure shows a Star Network Topology along with its Advantages & Disadvantages:

Star Network Topology


5. Bus Network Topology

It is an old topology. In this type of topology, one main trunk is chosen a backbone & all devices connect to it using T connectors or taps. It is cheap as it requires less cabling. Bus Network Topology doesn’t need any special equipment and it is less complex. However, Network down time is required whenever devices are added/removed. It is more prone to problems. If once cable goes down then whole network is disturbed. A signal from the source travels in both directions to all machines connected on the bus cable until it finds the intended recipient. If the machine address does not match the intended address for the data, the machine ignores the data. Alternatively, if the data matches the machine address, the data is accepted. Below figure shows a Bus Network Topology along with its Advantages & Disadvantages:

Bus Network Topology


6. Tree Network Topology

It is a topology in which network devices are connected in a tree manner. A tree network is also called star-bus network. Tree network topology is basically a combination of Star & Bus. It is a hybrid network topology in which star networks are interconnected via bus networks. Tree networks are hierarchical in nature and each node can have multiple no. of child nodes.


An important point to not here is that: in a tree topology, there can be only one connection between any two connected nodes

Tree Network Topology is a loop free topology & is used mostly in Layer2 Networks. It is an easy to scale network. We can simply continue adding devices on branches with no down time required. However, there is a Single Point of Failure in case the Backbone goes down. Below figure shows a Tree Network Topology along with its Advantages & Disadvantages:

Tree Network Topology


7. Hybrid Network Topology

Hybrid network is simply a combination of more than one network topology types. e.g. Ring & bus combine together. With Hybrid Network Topology, we can achieve combined advantage of individual member topologies if properly designed. However, it becomes complex if the network is no properly designed. Below figure shows a Hybrid Network Topology along with its Advantages & Disadvantages:

Hybrid Network Topology