Thaiio.com

Thaiio is the best of PC interfacing Electronic Hardware and Devices resource.

Today , 2007
January 14th, 2008

CCNP BSCI Exam Tutorial Route Summarization And The OSPF Null Interface

CCNP exam success, particularly on the BSCI exam, demands you understand the details of route summarization. This skill not only requires that you have a comfort level with binary conversions, but you have to know how and where to apply route summarization with each individual protocol.

You also have to know the “side effects” of route summarization. With OSPF, there will actually be an extra interface created at the point of summarization, and this catches a lot of CCNP candidates by surprise. Let’s take a look at the null0 interface and how it relates to OSPF summarization.

On R1, the following networks are redistributed into OSPF, and then summarized.

interface Loopback16

ip address 16.16.16.16 255.0.0.0

interface Loopback17

ip address 17.17.17.17 255.0.0.0

interface Loopback18

ip address 18.18.18.18 255.0.0.0

interface Loopback19

ip address 19.19.19.19 255.0.0.0

R1(config)#router ospf 1

R1(config-router)#redistribute connected subnets

R1(config-router)#summary-address 16.0.0.0 252.0.0.0

The summary address appears on R2, a downstream router.

R2#show ip route ospf

O E2 16.0.0.0/6 [110/20] via 172.12.123.1, 00:00:05, Serial0

Let’s go back to R1 and look at its OSPF table.

R1#show ip route ospf

O 16.0.0.0/6 is a summary, 00:01:51, Null0

Where did the null0 interface come from, and why is it there? Packets sent to the null interface are dropped, and in this case, that’s a good thing.

When you configure summary routes in OSPF, a route to null0 will be installed into the OSPF routing table. This helps to prevent routing loops. Any packets destined for the routes that have been summarized will have a longer match in the routing table, as shown below…

C 17.0.0.0/8 is directly connected, Loopback17

C 16.0.0.0/8 is directly connected, Loopback16

C 19.0.0.0/8 is directly connected, Loopback19

C 18.0.0.0/8 is directly connected, Loopback18

O 16.0.0.0/6 is a summary, 00:01:51, Null0

.. and packets that do not match one of the summarized routes but do match the summary route will be dropped.

Preventing routing loops when performing route redistribution and summarization is vital. OSPF gives us a little help in that regard in this situation, and as you study more complex redistribution scenarios on your way to the CCNP and CCIE, you’ll realize that we’ll take all the help we can get!

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage, home of free CCNP and CCNA tutorials, The Ultimate CCNA Study Package, and Ultimate CCNP Study Packages.

You can also join his RSS feed and visit his blog, which is updated several times daily with new Cisco certification articles, free tutorials, and daily CCNA / CCNP exam questions! Details are on the website.

For a FREE copy of his latest e-books, “How To Pass The CCNA” and “How To Pass The CCNP”, just visit the website! You can also get FREE CCNA and CCNP exam questions every day! Get your CCNP certification with The Bryant Advantage!

January 14th, 2008

Review of Popular Wireless Headphones

Just about everyone would I agree, I think, that wires on headphones are just about the most annoying wires associated with any electronic device. When you listen to music you don’t want to have to stay in anyone one place, and you don’t want to have to worry about cords tripping you are pulling your headphones down. The answer to this problem is wireless headphones, many of which allow you to listen to music over 100 feet away. They, like all wireless devices, give you a sense of freedom, an ability to move, work, and play wherever you want. You will find here a list of some of the most popular wireless headphone devices, with important information about each.

RCA WHR120 Infrared Wireless Stereo Headphones

Manufacturers Description: Experience the freedom that RCA Infrared Wireless Headphones can provide. You don’t have to be chained to your stereo when you put on a pair of headphones. With the infrared, line-of-sight transmission, you have 23 feet to roam as you please. Also, the base doubles as a convenient charger and stand. And the lightweight design and adjustable band make for a comfortable, snug fit. Enjoy life with RCA technology.

Key Features:

- Provides convenient listening privacy in the same room

- Low cost infrared technology operates up to 20 ft. from transmitter

- Adjustable headband provides comfort for hours of listening pleasure

- Horizontal style transmitter is compact, saves shelf space

- Operates on Two “AAA” size rechargeable batteries (connect to transmitter for recharging)

Price: $25

RCA WHR150 Wireless Stereo Headphones

Manufacturers Description: Hear your stereo outside your house without disturbing the neighbors. With RCA Wireless 900 MHz Headphones, you don’t even have to be in the same room with your stereo. The 900 MHz signal can pass through walls, floors, and carry outside of your home up to 125 ft. That means you have the freedom to work or relax wherever you wish without the problem of being connected to cords or carrying around a portable system. The lightweight design and adjustable headband make the fit so comfortable that you will hardly notice you have them on, as you move freely about your home. Also, the unique compact base serves as both a charger and a stand. Add some freedom to your life with this innovation from the RCA brand.

Key Features:

- Transmits 900MHz stereo signal up to 125 ft.

- Goes through walls and floors

- Unique compact base serves as both a charger and a stand

- Lightweight design with adjustable headband

- Soft earpads for comfortable listening

Price: $75

Sony MDRRF920RK 900 MHz Wireless Headphones

Manufacturers Description: Tired of tripping over cords, and accidentally ripping out headphone jacks? Go wireless, and listen to the freedom. Sony’s MDR-RF920RK 900 MHz RF Wirless Headphones have a transmission range of 150 feet, allowing you to roam your house or yard without missing a beat (or word). The 900 MHz radio frequency delivers high quality sound, and the 30mm driver units provide deeper bass, lower distortion and a wider dynamic range. These lightweight headphones are easily recharged by placing them on the transmitter, and the package includes rechargeable NiMH batteries.

A powerful ARM processor lets you listen to MP3s while looking up an address or scheduling an appointment. Watch the latest movie trailer or a new sales video. Carry digital photo albums of friends and family, students and co-workers, even the latest real estate listings. Plus it’s expandable, and with 32MB of memory there’s plenty of room to customize from more than 18,000 applications (sold separately).

Key Features:

- Wireless Design lets you move inside and outside your house and still enjoy music and TV sound, and lets you turn up the volume late at night without disturbing others.

- 150 Foot Transmission Range for listening enjoyment upstairs, downstairs, virtually everywhere in your home and outside in your backyard.

- 900 MHz Radio Frequency (RF) Transmission provides better sound quality and greater range.

- 30mm Diameter Driver Units are larger than many portable headphones for deeper bass, lower distortion and wider dynamic range; low frequency response extends down to 20Hz.

- PET Diaphragms ensure high rigidity for minimum distortion, and low mass for excellent high-frequency response.

- Ferrite Magnets combine high energy and small size for ample sound output.

- Comfortable Open-Air Type Supra-Aural Headphones fit securely for maximum frequency response reception.

- Double Headband with self-adjusting mechanism conforms to the curve of your head for a fit.

- Easy Rechargeable Battery System automatically charges the headphones when placed onto the transmitter.

- 3 Transmission Channels Available helps ensure optimum signal reception; convenient sliding selector control on the side of the transmitter.

- Automatic Power On/Off for both headphones and transmitter conserves battery life; transmitter turns on when it senses an input signal; headphones turn on when you place them on your head.

- Complete Kit is supplied, which includes transmitter, headphones, connecting cord, UniMatch plug adapter and AC power supply.

- Supplied Connecting Cord goes directly to headphone output of your high fidelity system for easy connection to hi-fi system, TV or VCR.

- FM Transmission System resists static and distortion for higher fidelity.

- Included Rechargeable NiMHBatteries provide up to 18 hours of playback when fully charged.

Price: $50

Sennheiser RS-65 Hi-Fi Stereo Wireless Headphones

Manufacturers Description: The RS-65 wireless RF headphone system with open, circumaural headphones features an integrated, switchable SRS processor for impressive surround sound. The system has very transparent and balanced sound reproduction and comes equipped with Center-Lock TM Auto-Tuning. This feature allows you to automatically adjust to the transmitter with a simple touch of a button (and can simply be returned with a second touch if it locks on to your neighbor’s transmitter).

Features:

- Supra-aural, hi-fi stereo headphones for superb audio quality

-Volume and transmission channel can be set individually on the headphones

- Expand with an additional set of headphones for multiperson use

- Soft, cloth-covered earpads and headband cushion for comfortable extended use

- Transmission range: 300 feet

- Extremely lightweight - less than 6 ounces

Price: $180

Sennheiser RS-85 Hi-Fi Stereo Wireless Headphones

Manufacturers Description: The RS-85 wireless RF headphone system with open, circumaural headphones features HiDyn Plus noise reduction for wide dynamics and superb sound quality, ensuring a very natural and detailed sound reproduction. The RS-85 comes equipped with Center-Lock TM Auto-Tuning, which allows you to automatically adjust to the transmitter with a simple touch of a button (and can simply be returned with a second touch if it locks on to your neighbor’s transmitter). The RS-85 headphones feature reception up to 300 feet from the transmitter, through walls and ceilings, even outside the home. A second battery pack is also provided for near limitless use; simply charge one as the other is being used.

Price: $250

Bradley James is a senior editor at SciNet.cc, a website containing many helpful consumer electronics review articles. For more information on wireless headphone technology, please visit our wireless headphones webpage.

Tags: plc
pac
pc
port
vb
vc
c#
parallel
serial
com
usb

|
Interior Accessories Shop free xxx cheapest viagra in uk cheap viagra viagra rise levitra alternative levitra vs viagra soft tabs cheapest online cialis 24 hour delivery canadian rx drugs bigtits i made free pornstars drunken asian girls BIGNATURALS big fat booty lessons in blow jobs porn fuck free porn videos free anal old mom video milfs amateur blowjob cheapest online diazepam 24 hour delivery cheap levitra rx pills buy lorazepam cheap cialis buy cheapest generic valium purchase new report female zyban order oxazepam prescription cheapest generic xanax viagra order herbal klipal for woman levitra buy drugs online buy herbal tramadol cialis soft tabs levitra cialis best herbal viagra soft tabs uk cialis buy viagra on line viagra levitra women buy cialis online without prescription natural levitra substitutes cheapest generic viagra cyber pharmacy propecia viagra soft tabs studies women
Close
E-mail It