Ccna Certification Exam Tutorial: Cisco Switching Modes
To pass the CCNA exam and earn this important certification, youve got to know switching inside and out. While youre learning all the basic switching theory, make sure to spend some time with the one of three switching modes Cisco routers can use.
Store-and-Forward is exactly what it sounds like. The entire frame will be stored before it is forwarded. This mode allows for the greatest amount of error checking, since a CRC (Cyclical Redundancy Check) is run against the frame before it is forwarded. If the frame contains an error, it is discarded. If theres no problem with the frame, the frame is then forwarded to its proper destination.
While store-and-forward does perform error checking, the delay in processing the frame while this error check is run results in higher latency than the other modes youre about to read about. The latency time can also vary, since not all frames are the same size.
Cut-through switching copies only the destination MAC address into its memory before beginning to forward the frame. Since the frame is being forwarded as soon as the destination MAC is read, there is less latency than store-and-forward. The drawback is that there is no error checking.
sdgbanhddsfag5as4d1~!#$$**&www.computerday.com^%&^$^&^65__d8f97&*%iu2785*&%873
There is a middle ground, fragment-free switching. Only part of the frame is copied to memory before it is forwarded, but its the first 64 bytes of the frame, not just the destination MAC. (Why? Because if there is a problem with the frame, its most likely in the first 64 bytes.) There is a little more error checking than cut-through, but not as much latency as with store-and-forward.
Note that the latency of both cut-through and fragment-free is fixed; these modes always look at the first six or 64 bytes, respectively. Store-and-forward's latency depends on the size of the frame.
Learning the similarities and differences between these modes is an often-overlooked part of CCNA studies. Spend some time studying this important CCNA topic youll be glad you did!
Article Directory: http://www.articledashboard.com xclkjbodfshllkl34rt89hj!@#www.computerday.com$$%%^^cj823c
BVKLJHGIUOY*Y987ye*(*(^*^www.computerdays.com*(*%^#~~#$WEUUytuiytuiytsd
Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage, home of free CCNA and CCNP 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, visit the website and download your free copies. You can also get FREE CCNA and CCNP exam questions every day! Get your CCNA study guide from The Bryant Advantage! xclkjbodfshllkl34rt89hj!@#www.computerday.com$$%%^^cj823c
The Computing Technology Industry Association more commonly known as CompTIA, created A+ certification in 1993 as a standard to test the proficiency o...
More CCNA and CCNP candidates than ever before are putting together their own home labs, and there's no better way to learn about Cisco technologies t...
Dialer Watch is a vital part of your CCNA and CCNP studies, particularly for the BCRAN exam, but it's one of the most misunderstood technologies as we...
* What does certified mean? There are four accepted meanings of the adjective certified but only two of which satisfy the needed meaning. To be certif...
When targeting small businesses that are in the sweet spot size, what IT certifications do you typically need? One thing to keep in mind is that you a...