Links: Volcanoes

Cisco CCNA / CCNP: How And Why To Build An Etherchannel   by Chris Bryant

CCNA and CCNP candidates are well-versed in Spanning-Tree Protocol, and one of the great things about STP is that it works well with little or no additional configuration. There is one situation where STP works against us just a bit while it prevents switching loops, and that is the situation where two switches have multiple physical connections.

You would think that if you have two separate physical connections between two switches, twice as much data could be sent from one switch to the other than if there was only one connection. STP doesn't allow this by default, however in an effort to prevent switching loops from forming, one of the paths will be blocked.

SW1 and SW2 are connected via two separate physical connections, on ports fast0/11 and fast 0/12. As we can see here on SW1, only port 0/11 is actually forwarding traffic. STP has put the other port into blocking mode (BLK).

SW1#show spanning vlan 10

(some output removed for clarity)

Interface Role Sts Cost Prio.Nbr Type

Fa0/11 Root FWD 19 128.11 P2p

Fa0/12 Altn BLK 19 128.12 P2p

While STP is helping us by preventing switching loops, STP is also hurting us by preventing us from using a perfectly valid path between SW1 and SW2. We could literally double the bandwidth available between the two switches if we could use that path that is currently being blocked.

The secret to using the currently blocked path is configuring an Etherchannel. An Etherchannel is simply a logical bundling of 2 - 8 physical connections between two Cisco switches.

Configuring an Etherchannel is actually quite simple. Use the command "channel-group 1 mode on" on every port you want to be placed into the Etherchannel. Of course, this must be done on both switches if you configure an Etherchannel on one switch and don't do so on the correct ports on the other switch, the line protocol will go down and stay there.

The beauty of an Etherchannel is that STP sees the Etherchannel as one connection. If any of the physical connections inside the Etherchannel go down, STP does not see this, and STP will not recalculate. While traffic flow between the two switches will obviously be slowed, the delay in transmission caused by an STP recalculation is avoided. An Etherchannel also allows us to use multiple physical connections at one time.

Here's how to put these ports into an Etherchannel:

SW1#conf t

Enter configuration commands, one per line. End with CNTL/Z.

SW1(config)#interface fast 0/11

SW1(config-if)#channel-group 1 mode on

Creating a port-channel interface Port-channel 1

SW1(config-if)#interface fast 0/12

SW1(config-if)#channel-group 1 mode on

SW2#conf t

Enter configuration commands, one per line. End with CNTL/Z.

SW2(config)#int fast 0/11

SW2(config-if)#channel-group 1 mode on

SW2(config-if)#int fast 0/12

SW2(config-if)#channel-group 1 mode on

The command "show interface trunk" and "show spanning-tree vlan 10" will be used to verify the Etherchannel configuration.

SW2#show interface trunk (some output removed for clarity)

Port Mode Encapsulation Status Native vlan

Po1 desirable 802.1q trunking 1

SW2#show spanning vlan 10 (some output removed for clarity)

Interface Role Sts Cost Prio.Nbr Type

Po1 Desg FWD 12 128.65 P2p

Before configuring the Etherchannel, we saw individual ports here. Now we see "Po1", which stands for the interface "port-channel1". This is the logical interface created when an Etherchannel is built. We are now using both physical paths between the two switches at one time!

That's one major benefit in action let's see another. Ordinarily, if the single open path between two trunking switches goes down, there is a significant delay while another valid path is opened - close to a minute in some situations. We will now shut down port 0/11 on SW2 and see the effect on the etherchannel.

SW2#conf t

Enter configuration commands, one per line. End with CNTL/Z.

SW2(config)#int fast 0/11

SW2(config-if)#shutdown

3w0d: %LINK-5-CHANGED: Interface FastEthernet0/11, changed state to administratively down

SW2#show spanning vlan 10

VLAN0010

Spanning tree enabled protocol ieee

Interface Role Sts Cost Prio.Nbr Type

Po1 Desg FWD 19 128.65 P2p

SW2#show interface trunk

Port Mode Encapsulation Status Native vlan

Po1 desirable 802.1q trunking 1

The Etherchannel did not go down! STP sees the Etherchannel as a single link therefore, as far as STP is concerned, nothing happened.

Building an Etherchannel and knowing how it can benefit your network is an essential skill for CCNA and CCNP success, and it comes in very handy on the job as well. Make sure you are comfortable with building one before taking Cisco's exams!

About the Author

Chris Bryant, CCIE #12933, owns The Bryant Advantage (http://www.thebryantadvantage.com), home of free CCNA and CCNP tutorials, Pass the CCNA exam with Chris Bryant!

Protect Yourself While Gaming - Tips to avoid eye strain and Proper sitting tips while playing games   by Paul Wilson

Gaming means long hours at the computer. Self absorbent and an obsessive hobby, incorrect habits and posture are detrimental to health. Problems like musculoskeletal injuries, eyestrain, and disabilities of the hands and wrist like, RSI or Repetitive Strain Injury are common. Bad posture causes: pain, stiffness of joints, weakness, bad circulation, as well as swelling. Ensure that: * The desk is designed especially for computers. * While seated, the feet are flat on the floor; arms and thighs are parallel to the ground; back is straight; and the arms don't have to stretch out to reach the keyboard or mouse. * The keyboard height is such that the elbows are parallel to the ground and level with the keyboard. An ergonomic keyboard is recommended. * The spine maintains its 'S' curve when seated, so use an ergonomic chair and if required, a footstool. * The mouse is placed at the same height as the keyboard. Use your whole arm not just the wrist when operating the mouse. * Typing is done with light fingers. The wrists should be flat and not angled to the left or right. To avoid nerve compression the elbow must not be angled more than 90 degrees. * The arms are raised off the keyboard as often as possible. * Tasks are alternated so that you are not typing or clicking the mouse continuously. Another factor is eye strain. Extended computer use can cause: blurred vision, focusing difficulties, as well as headaches. Reduce risk by ensuring that: * The light source is angled from the side. The primary light source must not shine on the face or directly on the screen. Lighting should have a 10:3 ratio screen characters should be 10X brighter than background and room lights should be 3X the screen brightness. Use a shaded copy lamp to avoid screen reflections. * Reflections and glare are eliminated by using an antiglare screen and by tilting the monitor slightly. * The monitor must be centered so that neither the body nor neck is twisted when viewing the screen. * The screen is of good quality. The text should be sharp and nor distorted. Change the resolution to a comfortable font size. * The monitor is a suitable distance away. * The screen is at eye level or lower. * Brightness and contrast are reduced to suitable levels. It is important to: * Break concentration by looking away from the monitor at far away objects at least once every 15-20 minutes. * Pause in between to blink your eyes rapidly. This will lubricate the eyes and prevent dryness. * Schedule regular eye checks. * Monitor blurred vision, headaches, red eyes, or watering eyes. * Splash water and wash your eyes at least 3-4 times a day. Tips: * It is advisable to take frequent breaks, either do stretches or take a short walk once every hour for 10-15 minutes. * Use a well ventilated room. * Reduce emission in laser printers, photocopiers, and scanners. Problems can be eliminated and the risk reduced by inculcating good posture and working habits.

About the Author

Paul Wilson is the content manager for www.1888FreeOnlineGames.com, the premier website to play thousands of free online games including arcade games, action games, card games, flash games, strategy games, puzzle games and more. He also manages content for www.1888softwaredownloads.com.

3D Modeling & Animation, 3D Models, 3D AutoCAD models, 3D character Animation,3D graphic, 3D AutoCAD Drafting, 3D Character Animation   by Bluent CAD

Bluent CAD

3D or Three Dimension which means giving an 3D effect to any image. The image is going to have depth, height, and width.

3D Modeling improves your graphics & gives a better look to your website. 3D modeling or animation is applicable where it is necessary to convey your company's proffesional image .

With the advancement in technology one can offer 3D computer models, 3D AutoCAD® Models, 3D AutoCAD® Drafting, 3D Solid Animations along with CAD services. 3D softwares can offer magical quality and the tools can create high quality 3d character & animations.

3d Art can be used for 3D Character animation, 3D modeling, 3D graphic, 3D background, 3D logo. These days 3D is widely being used along with Computer Design Design. 3D can be used in Architectural, Mechanical or Structural related projects. Very Interactive objects cen be created via 3D which are widely available on the Web. 3D objects are used for dynamic Web marketing and e-commerce related project.

CAD (Computer Aided Design) can convert all your paper documents to digitized format. With the help of CAD, all your paper work gets converted into software format.

3D modeling is done for various objects based on information such as drawings, sketches, design concepts, or other special requirements.

One can turn his ideas into profitable ventures with the use of 3D.

So, go ahead and explore your imagination. http://www.bluentcad.com

About the Author

Computer War Games: How To Estimate Decisions Made By C & C Trainees   by Donald Jones

Now that the Russian military is cash-strapped and can afford only a limited number of field preparation exercises, computer warfare games (CWG) ar of special importance for in operation(p) grooming of C & C agencies and elements because they make it potential to upgrade career-area skills of officers and rehearse modern C & C methods. Estimation of decisions made in the procedure by members of missile forces and artillery (MF & A) C & C authorised personnel department presents the hardest part of it. Modern theory and methods of estimating the results of CWG education numerous on the one hand and, on the other, there no sufficiently studied and in general accepted methods and templates to estimation decisions being interpreted. This can be put down first of all to objective difficulties involved in formalizing the outgrowth of estimating the decisions of commanders (persons in authority): the complexity of initial operating(a)-tactical situations; considerable uncertainty of stimulation information; the numerous criteria used in estimating the trainees' decisions and the need for reducing the -making values to one generalized value.

Moreover, existing methods of processing the results of CWG breeding not quite adequate for dealing with uncertain stimulus ; the many criteria used in estimating decisions made by authoritative personnel office of C & C agencies of MF & A during state of war games either not into history or into chronicle without due thoughtfulness. This, as a rule, reduces estimate objectivity. In order to achieve the main objective of CWG--to train C & C staff office of MF & A and pinpoint their errors--the CWG headquarters should have tools to promptly and objectively approximation the decisions ; to idea the caliber of work by C & C agencies in the main and by person members of its force; to appraisal the performance of trainees on a leg-by-microscope stage basis.

Meeting these requirements calls for careful preparations of CWG, designing appropriate methods of estimating the performance of C & C agencies and someone members of the who undergo . Continued from page 1. Estimation of armed combat employment plans is based on decisions made at the stagecoach of preparation for the functioning of MF & A subsystems: reconnaissance, command and control, effective engagement and support.

To this end, we take indicators of the selected system for stimulant , whereas indicators of the other subsystems selected and normalized to match the computed units. This organization of the modeling cognitive process makes it conceivable a more complete gauge of the calibre of decisions made by C & C trainees in provision the functioning of MF & A subsystems. Thus, comparative approximation of decisions made by C & C and the drafting of recommendations for upgrading these decisions include: the assignment of problem (formulation of basic characteristics of decisions to be made of C & C trainees); for variants of computation experiments (determination of the functional-tactical background, usable-tactical scenarios of MF & A fight trading operations, forecasts of enemy fighting ); the development of an integrated information model ( squad versus supporting team up); determining the values of indicators essential for idea of decisions related to variants of scrap under considerateness; analysis of values of the indicators essential for estimations; of decisions for every of C & C trainees; the selection of the best arrived at by the trainees; analysis of mistakes made by the trainees and the drafting of recommendations for upgrading their decisions.

The suggested methodological approach makes it imaginable to upgrade the timbre (validation and speed) of of decisions made in various forms of useable of C & C agencies, such as games, command post exercises and during the course of solving somebody problems of battle employment of MF & A in army (corps).

About the Author

Donald Jones http://www.newssites.net

1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70 | 71 | 72 | 73 | 74 | 75 | 76 | 77 | 78 | 79 | 80 81 | 82 | 83 | 84 | 85 | 86 | 87 | 88 | 89 | 90 91 | 92 | 93 | 94 | 95 | 96 | 97 | 98 | 99 | 100