Saturday, March 1, 2008

Cisco CCNP Certification / BSCI Exam Tutorial: Comparing IRDP And HSRP

To pass the BSCI exam, you need to know the difference between IRDP and HSRP. While they have the same basic function, the operation and configuration of each are totally different.

The aim of both is to allow hosts to quickly discover a standby router when the primary router fails. IRDP is commonly used by Windows DHCP clients and several Unix variations, but you do see it in Cisco routers as well. IRDP is defined in RFC 1256.

IRDP routers will multicast Hello messages that host devices hear. If a host hears from more than one IRDP router, it will choose one as its primary and will start using the other router if the primary it's chosen goes down.

HSRP is a Cisco-proprietary protocol that is designed for quick cutover to a secondary router if the primary fails, but the host devices don't "see" either the primary or secondary router. The hosts use a virtual router as their default gateway. This virtual router has its own IP and mac address! All the while, the router chosen as the primary is actually the one doing the routing. If the primary router goes down, the secondary router quickly takes over with no major interruption to network services.

The HSRP routers communicate by multicasting updates to 224.0.0.2, and its through these hellos that the HSRP routers decide which router is primary and which is secondary. HSRP is defined in RFC 2281.

The configuration of each of these will be covered in a future tutorial. In the meantime, I urge you to read the RFCs mentioned in this article, and visit www.cisco.com/univercd to read about the configurations and options available for both of these vital protocols.

Yoga Cl Langhorne

Portable TV - Easy To Handle

The handheld televisions are regarded as the next trend that is gaining momentum in the market nowadays. The users can choose their portable TV from the various brands that are available in the market. The users can easily carry their portable TV with them and watch their favorite shows anywhere. These devises possess crisp, sharp and clear images and superb sound quality. The high quality portable analogue and digital television also comes with a built-in rechargeable battery.

A handheld TV is a device that uses a TFT colour LCD screen as its display. Many of these handheld televisions resemble handheld transistor radios. These devices often come with stereo 1/8" phone plugs for the composite video analog mono audio relay to help them serve as composite monitors. Some of these models also have 1/8" jacks that are required to serve them as composite monitors that are usually relayed through an F connector on standard television models. The screen size of these models varies from 1.3" to 5".

Today, television is regarded as one of the most influential forces that have the ability to make and form opinions of the people. through this device, the user can receive news, sports, entertainment, information and commercials. The portable TV those are available in the market come from various brands. The 9.2" portable LCD Digital and Analogue TV with Stand/Wall Mounting Bracket produces high quality digital and analogue TV that is designed to watch Free view TV where the signal is strong. The August DA104CD is the other model that is available with advanced features.

The model is a 7-in-one portable multi-functional personal entertainment centre. The device comes with Portable LCD TV, digital free view TV receiver, digital radio receiver, and high quality tablet dvd player with slot-in-disc loader, media player from SD/MS/MMC memory cards and from an external hard disc by a usb port, digital photo displayer and high-resolution monitor. Therefore, various models are available in the market that comes with a lot of advanced features. The users now have the option to choose their favorite brand and avail the best.

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