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CCNA

vtp modes

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VLAN Trunking Protocol (VTP) Server Mode

VLAN Trunking Protocol (VTP) server mode is the default VTP mode for all Catalyst switches. At least one server is required in a VTP domain to propagate VLAN information within the domain. We can create, add, or delete VLANs on a VTP domain VTP Server and change VLAN information in a VTP Server. The changes made in a switch in server mode are advertised to the entire VTP domain.

VLAN Trunking Protocol (VTP) Client Mode

VLAN Trunking Protocol (VTP) client mode switches listen to VTP advertisements from other switches and modify their VLAN configurations accordingly. A network switch in VTP client mode requires a server switch to inform it about the VLAN changes. We CANNOT create, add, or delete VLANs in a VTP client.

VLAN Trunking Protocol (VTP) Transparent Mode

VLAN Trunking Protocol (VTP) transparent mode switches do not participate in the VTP domain, but VTP transparent mode switches can receive and forward VTP advertisements through the configured trunk links.

Submarine Cables in India

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There are now 9 Submarine Cables in India, with three respectively in Mumbai and Chennai, and each in Cochin,?Tuticorin and Digha.

Submarine cables in India

Tata Communications owns three cable landing stations, each in Mumbai, Chennai and Cochin.
Reliance Globalcom owns the Versova Cable Landing Station in Mumbai.
Bharti Airtel owns three cable landing stations, two in Chennai and one in Mumbai.
BSNL owns its first international submarine cable connecting India and Sri Lanka and its cable landing station in Tuticorin. The Digha Cable Landing Station in West Bengal is newly approved in May 2011 by the department of telecommunication (DoT) of India for a submarine cable project between India and Southeast Asia. BNSL is expected to own the Digha Cable Landing Station.

  • Mumbai Cable Landing Station
  • Bharti Airtel Chennai Cable Landing Station
  • Tata Chennai Cable Landing Station
  • Bharti Airtel Mumbai Cable Landing Station
  • Cochin Cable Landing Station
  • Versova Mumbai Cable Landing Station
  • Digha Cable Landing Station
  • Tuticorin Cable Landing Station

CROSSOVER CABLE VS STRAIGHT CABLE

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CROSSOVER CABLE VS STRAIGHT CABLE

Hello Everyone , ?today we discuss about the cables used in LAN network .

we have many devices in a network , like routers , switches , hubs , pc’s , but which cable is used to connect those devices

Category 5 cable?(Cat 5) is a?twisted pair?cable?for carrying?signals. This type of?cable?is used in?structured cabling?for?computer networks?such as?Ethernet

SAME DEVICES – CROSSOVER CABLE

DIFFERENT DEVICES -?STRAIGHT CABLE

router to router….crossover

PC to PC….crossover

switch to switch…..crossover

PC to router….crossover

PC to switch, Router to switch, PC to Hub….straight-through

But there is an exception ROUTER TO PC connect via cross cable , Bcoz they both have same?components?that’s?why they use crossover.

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There are two standards adopted for Cabling EIA/TIA 568A & EIA/TIA 568B.

When you use single standard (either EIA/TIA 568A or EIA/TIA 568B) on both the end of cable then the resulting cable is?STRAIGHT CABLE.

On the other hand if you use different cabling standard on the ends of cable then the resulting cable is?CROSS CABLE

You can check the image for the colour coding of standars

Thanks !

Null Interface

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What is a Null Interface ?

By Atul Sharma

What is a Null Interface ?

Null interface is not a physical interface. Its a virtual interface where you can route traffic, but want packets destined for a particular network to be dropped. Directing packets to the null0 interface will prevent the router from sending an Internet Control Message Protocol (ICMP) network unreachable message when it receives a packet with an unknown destination. A situation in which you might want to use the null0 interface is when you have configured a default network, but want packets destined for a particular network to be dropped.

If a static route is configured for the network to the null0 interface, the packets will be dropped without the ICMP message or without having to configure an access list. This interface is always up and can never forward or receive traffic; encapsulation always fails. The null interface provides an alternative method of filtering traffic. You can avoid the overhead involved with using access lists by directing undesired network traffic to the null interface.

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Introduction to Null Interface

Null interfaces are completely software-like logical interfaces. Null interfaces are always up. However, they can neither forward data packets nor have IP addresses and link layer protocols configured on them. With a null interface specified as the next hop of a static route to a specific network segment, any packets routed to the network segment are dropped. Null interface provides you a way to filter packets. That is, you can simply transmit unwanted traffic to a null interface rather than applying ACLs.

For example, by executing the?ip route-static 92.101.0.0 255.255.0.0 null 0?command (which configures a static route leading to a null interface), you can have all the packets destined to the network segment 92.101.0.0/16 discarded.

Configuring a Null Interface

Follow these steps to configure a null interface:

To do?

Use the command?

Remarks

Enter system view

system-view

?

Enter null interface view

interface null 0

Required

Null0 interface is the default null interface on a switch. It can neither be created nor removed.

Configure a description for the null interface

description?text

Optional

By default, the description of a null interface is its interface name followed by the word?interface, for example,?Null0 Interface.

Display information about the null interface

display interface null?[??]