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Benefits of VLAN ?

Benefits of VLAN :

Assume we have three VLANs:

For Faculty- VLAN 10

For Student-  VLAN 20

For Guest- VLAN 30

There are several benefits of VLAN mentioned below :

Security – Groups that have sensitive data are separated from the rest of the network, decreasing the chances of confidential information breaches. Faculty computers are on VLAN 10 and completely separated from student and guest data traffic.
Cost reduction – Cost savings result from less need for expensive network upgrades and more efficient use of existing bandwidth and uplinks.
Higher performance – Dividing flat Layer 2 networks into multiple logical workgroups (broadcast domains) reduces unnecessary traffic on the network and boosts performance.
Broadcast storm mitigation – Dividing a network into VLANs reduces the number of devices that may participate in a broadcast storm.  LAN segmentation prevents a broadcast storm from propagating to the whole network.

Improved IT staff efficiency – VLANs make it easier to manage the network because users with similar network requirements share the same VLAN. When we provision a new switch, all the policies and procedures already configured for the particular VLAN are implemented when the ports are assigned. It is also easy for the IT staff to identify the function of a VLAN by giving it an appropriate name.
Simpler project or application management – VLANs aggregate users and network devices to support business or geographic requirements. Having separate functions makes managing a project or working with a specialized application easier, for example, an e-learning development platform for faculty. It is also easier to determine the scope of the effects of upgrading network services.

VLAN : A VLAN is a logically separate IP subnetwork. VLANs allow multiple IP networks and subnets to exist on the same switched network. For computers to communicate on the same VLAN, each must have an IP address and a subnet mask that is consistent for that VLAN.

The switch has to be configured with the VLAN and each port in the VLAN must be assigned to the VLAN. A switch port with a singular VLAN configured on it is called an access port. Remember, just because two computers are physically connected to the same switch does not mean that they can communicate.

Devices on two separate networks and subnets must communicate via a router (Layer 3), whether or not VLANs are used. We do not need VLANs to have multiple networks and subnets on a switched network, but there are definite advantages to using VLAN.

show commands of a cisco router

In privilege exec mode we execute each show command :

View version information show version
View current configuration (DRAM) show running-config
View startup configuration (NVRAM) show startup-config
Show IOS file and flash space show flash
Shows all logs that the router has in its memory show log
View the interface status of interface e0 show interface fa0/0
Overview all interfaces on the router show ip interfaces brief
View type of serial cable on s0 show controllers 0 
Display a summary of connected cdp devices show cdp neighbor
Display detailed information on all devices show cdp entry *
Display current routing protocols show ip protocols
Display IP routing table show ip route
Display access lists, this includes the number of displayed matches show access-lists
Check the router can see the ISDN switch show isdn status
Check a Frame Relay PVC connections show frame-relay pvc
show lmi traffic stats show frame-relay lmi
Display the frame inverse ARP table show frame-relay map

For remote login you can set password, for this just put simple commands on router’s global mode :


Router(config)#line vty 0 4
Router(config-line)#password cisco



If you want to set a console password to the cisco router then follow the commands mentioned below :

First go to the Global Mode, then type

Router(config)#line con 0
Router(config-line)#password cisco

Here we have several fields in a packet mentioned below 🙂

1. Version – Version number (4 bits); predominant version is IP version 4 (IPv4)
2. IP header length – Header length in 32-bit words (4 bits)
3. Precedence and type of service – How the datagram should be handled (8 bits); the first 3 bits are precedence bits (this use has been superseded by Differentiated Services Code Point [DSCP], which uses the first 6 bits [last 2 reserved])
4. Packet length – Total length (header + data) (16 bits)
5. Identification – Unique IP datagram value (16 bits)
6. Flags – Controls fragmenting (3 bits)
7. Fragment offset – Supports fragmentation of datagrams to allow differing maximum transmission units (MTUs) in the Internet (13 bits)
8. Time to Live (TTL) – Identifies how many routers can be traversed by the datagram before being dropped (8 bits)
9. Protocol – Upper-layer protocol sending the datagram (8 bits)
10. Header checksum – Integrity check on the header (16 bits)
11. Source IP address – 32-bit source IP address (32 bits)
12. Destination IP address – 32-bit destination IP address (32 bits)
13. IP options – Network testing, debugging, security, and others (0 or 32 bits, if any)

We have three major routing principal :


1. Every router makes its decision alone, based on the information it has in its own routing table.

2. The fact that one router has certain information in its routing table does not mean that other routers have the same information.

3. Routing information about a path from one network to another does not provide routing information about the reverse, or return, path.

There are several dynamic routing protocols for IP. Here are some of the more common dynamic routing protocols for routing IP packets:
1. RIP (Routing Information Protocol)
2. IGRP (Interior Gateway Routing Protocol)
3. EIGRP (Enhanced Interior Gateway Routing Protocol)
4. OSPF (Open Shortest Path First)
5. IS-IS (Intermediate System-to-Intermediate System)


6. BGP (Border Gateway Protocol)

Use following command mentioned in a photo for basic configuration of  a  cisco router.

When configuring a router, certain basic tasks are performed including:
1. Naming the router
2. Setting passwords
3. Configuring interfaces
4. Configuring a banner
5. Saving changes on a router
6. Verifying basic configuration and router operations


These steps should be done for basic configuration of router.