Wednesday, October 10, 2018

ICND1 100-101 Dumps


Free Cisco CCNA Cisco Certified Network Associate 200-125 Latest & Updated Exam Questions for candidates to study and pass exams fast. 200-125 exam dumps are frequently updated and reviewed for passing the exams quickly and hassle free! You can pass your 200-125 Cisco Exam Fast 


Friday, October 5, 2018

What is a VLAN ?

What is a VLAN?

VLANs (Virtual Local Area Networks) are a logical grouping of devices in the same broadcast domain. VLANs are typically configured on switches by placing specific interfaces in one broadcast domain and some interfaces in a different broadcast domain. VLANs can be distributed through a variety of switches, with each VLAN being treated as its own subnetwork or broadcast domain. This means that the frames transmitted in the network are only exchanged between the ports of the same VLAN.


A VLAN acts as a physical LAN, but it allows hosts to be grouped in the same broadcast domain, even if they are not connected to the same switch. Here are the main reasons why you should use VLANs on your network:


  • VLANs increase the number of broadcast domains and reduce their size.

  • VLANs reduce security risks by reducing the number of hosts receiving copies of frames flooded by switches.

  • You can keep hosts that contain sensitive data on a separate VLAN for added security.

  • You can create more flexible network designs that group users by department rather than physical location.

Network changes can be made simply by configuring a port in the appropriate VLAN.

The following topology shows a network with all hosts in the same VLAN:



Topology without VLAN

Without VLAN, a broadcast sent by Host A would reach all devices on the network. By arranging the Fa0 / 0 and Fa0 / 1 of the two switches in a separate VLAN, a broadcast host A can only reach host B, where each VLAN is a separate broadcast domain and only the host B entities in the same VLAN as the host A. The hosts in VLAN 3 and VLAN 5 will not even realize that communication was taking place. This is shown in the picture below:



Topology with VLAN

NOTE

To reach hosts in another VLAN, a router is needed.

Access and network ports

Each port of a switch can be configured as an access port or trunk port. An access port is a port that can be assigned to a single VLAN. This type of interface is configured on switch ports that are attached to devices with a standard network adapter, such as a network adapter. To a host on a network. A trunk interface is an interface that connects to another switch. This type of interface can transfer traffic from multiple VLANs.

In the network example shown above, the connection between SW1 and SW2 would be configured as a trunk interface. All other switch ports are connected to end-user devices. They must therefore be configured as access ports.

Tuesday, October 2, 2018

Configuring VLANs

Configuring VLANs

By default, all ports on a switch are in VLAN 1. We can verify this by entering the show vlan command from the IOS activation mode of a switch:



Default VLAN

In the picture above, you can see that all 24 switch ports are in the same VLAN, ie VLAN 1.

To create a VLAN and assign a switch port to the VLAN, two steps are required:

Create a Vlan with the global mode control VLAN NUMBER

Link a port to the VLAN by using two interface subcommands. The first command is the access command for switchport mode. This command indicates that the interface is an access interface. The second command is the switchport access vlan NUMBER command. This command assigns the interface to a VLAN.

Here is an example of the assignment of VLAN 2 to the interface:

Create a Vlan

The first command (vlan 2) created VLAN 2. We then called the Fa0 / 1 subinterface mode and configured the interface as an access interface to VLAN 2. To verify this, we can use the show vlan command:




You can Check out Video :



You can Download Project File Pkt From here for version 7.1



Inter-VLAN routing

Inter-VLAN routing

Introduction

In the previous chapters, we learned how VLANs segment broadcast traffic on a switch and segment a switched network into different LANs. We also learned to avoid layer 2 loops by using the STP protocol. ,

As a network administrator, you must create and assign different users to the VLANs in your network, with three main departments being logically segmented using VLANs, VLANs - FINANCE, VLANs - SALES, and VLANs. 30 - HR.

The use of VLANs means that users would not be able to communicate between services; H. That a FINANCE user can not send a message to a user in SALES because they are in different broadcast domains.

In many companies you will find that sharing information between services is a necessity. The question then arises of how to communicate with the users of the Sales and Finance department, but with different VLANs.

In this chapter we discuss the role that inter-VLAN routing plays in communication between different VLANs. We'll learn how it works, look at the different ways it can be implemented, configure inter-VLAN routing using a router and traditional inter-VLAN routing, compare the two implementation styles, and then check and fix that Inter-VLAN routing.

Introduction to Inter-VLAN Routing

When we learned about the existence of VLANs, we said that each VLAN is normally located on its own subnet, that the switches mainly operate on layer 2 of the OSI model and therefore do not examine logical addresses. Therefore, user nodes in different VLANs can not communicate by default. In many cases, we may need to connect users in different VLANs. This can be achieved by inter-VLAN routing.

In this course we'll look at a kind of inter-VLAN routing that uses a router.

Definition

Inter-VLAN routing can be defined as a way to transfer traffic between different VLANs by implementing a router on the network. As we have already learned, VLANs logically segment the switch into different subnets. When a router is connected to the switch, an administrator can configure the router to transfer traffic between the different VLANs configured on the switch. The VLAN user nodes transmit traffic to the router, which routes the traffic to the destination network, regardless of the VLAN configured on the switch.


You can Check out Video :



You can Download Project File Pkt From here for version 7.1



Monday, September 24, 2018

Half duplex and full duplex

Half duplex and full duplex

In telecommunications, a two-sided communication system is a point-to-point system of two devices that can communicate with each other in both directions. Both types of duplex communication systems are available in Ethernet environments:


Half duplex - A port can send data only if it does not receive data. In other words, it can not send and receive data at the same time. Network hubs operate in half-duplex mode to avoid collisions. Because hubs are rare in modern LANs, the half-duplex system is no longer widely used in Ethernet networks.
Full duplex - all nodes can send and receive simultaneously on their port. There is no full-duplex collision, but the host network adapter and the switch port must support full duplex mode. Ethernet full duplex uses two pairs of cables instead of a single pair of cables, such as half duplex.


Each network adapter and switch port have a duplex setting. All connections between hosts and switches or between switches must use full duplex mode. However, all connections connected to a LAN concentrator must use half-duplex mode to avoid duplex incompatibility, which can affect network performance.

On Windows, you can specify duplex settings in the Network Adapter Properties window:



Friday, September 21, 2018

OSI Model Interview Questions


OSI Model Interview Questions

The Open Systems Interconnection Model (OSI) was created by the International Organization for Standardization (ISO), the international standardization body. It was designed as a reference model for describing the functions of the communication system. The OSI model provides the basis for creating and implementing network standards and devices and describes how network applications on different computers can interact through networked media. It has seven levels, each layer describes another function of the data passing through the network.



Cisco three-layer hierarchical model

Cisco three-layer hierarchical model


Because networks and different multi-protocol technologies can be extremely complex, Cisco has developed a hierarchical hierarchical model for designing a reliable network infrastructure. This three-layer model lets you design, implement and maintain a scalable, reliable and cost-effective network. Each layer has its own features and functions that reduce the complexity of the network.

An example of the Cisco hierarchical model:




Cisco Three-Level Hierarchical Model

Here is a description of each layer:


Access - controls the access of users and workgroups to network resources. This layer typically includes Layer 2 switches and access points for post-to-server connections. You can manage access control and policy, create separate collision domains, and implement port security at that level.


Distribution - serves as a point of communication between the access layer and the kernel. Its main functions are to provide routing, filtering and WAN access and to determine how packets can access the database. This layer determines the fastest way to access network service requests - e.g. B. as file request is transmitted to a server - if necessary, and transmits the request to the core layer on. This layer typically includes routers and multilayer switches.
Basic - also called the backbone of the network, this layer is responsible for the rapid transport of large amounts of data. The core layer provides the interconnection between devices in the distribution layer that typically consists of high-speed devices such as high-end routers and switches with redundant connections.