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Cisco CCNA CCNP BCMSN Exam Review Trunking And Trunking ProtocolsTo earn your CCNA or CCNP certification, you've got to understand the basics of trunking. This isn't just a CCNA topic - you must have an advanced understanding of trunking and etherchannels to pass the BCMSN exam and earn your CCNP as well. Before we address those advanced topics, though, you need to master the fundamentals! The Brief History of Cisco Certifications The Brief History of Cisco Certifications Even young people can remember the old days when network administrators were more often associated for being the person sitting next to a computer system rat.. ISL is a Cisco-proprietary trunking protocol, making it unsuitable for a multivendor environment. That's one drawback, but there are others. ISL will place both a header and trailer onto the frame, encapsulating it. This increases the overhead on the trunk line. You know that the default VLAN is also known as the "native VLAN", and another drawback to ISL is that ISL does not use the concept of the native VLAN. This means that every single frame transmitted across the trunk will be encapsulated. The 26-byte header that is added to the frame by ISL contains the VLAN ID; the 4-byte trailer contains a Cyclical Redundancy Check (CRC) value. The CRC is a frame validity scheme that checks the frame's integrity. In turn, this encapsulation leads to another potential issue. ISL encapsulation adds 30 bytes total to the size of the frame, potentially making them too large for the switch to handle. (The maximum size for an Ethernet frame is 1518 bytes.) IEEE 802.1q differs substantially from ISL. In contrast to ISL, dot1q does not encapsulate frames. A 4-byte header is added to the frame, resulting in less overhead than ISL. If the frame is destined for hosts residing in the native VLAN, that header isn't added. Since the header is only 4 bytes in size, and isn't even placed on every frame, using dot1q lessens the chance of oversized frames. When the remote port receives an untagged frame, the switch knows that these untagged frames are destined for the native VLAN. Do Computer Repair Classes Make Sense for You Do Computer Repair Classes Make Sense for You? There is a lot to know if you plan on repairing computers for a living. Even if you simply plan on moonlighting with a computer repair business, the amo.. Knowing the details is the difference between passing and failing your CCNA and CCNP exams. Keep studying, get some hands-on practice, and you?re on your way to Cisco certification success! Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage, home of freeCCNP andCCNA 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! Pass theCCNP exam with The Bryant Advantage!
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