tailieunhanh - CompTIA Network+ Certification Study Guide part 18

CompTIA’s Network+ certification Study Guide part 18 is a globally-recognized, vendor neutral exam that has helped over 235,000 IT professionals reach further and higher in their careers. The 2009 Network+ exam (N10-004) is a major update with more focus on security and wireless aspects of networking. Our new study guide has been updated accordingly with focus on network, systems, and WAN security and complete coverage of today’s wireless networking standards. | 156 CHAPTER 4 Switching is the process of sending data from segment to segment based on the MAC address what happens when data has to be sent to a remote network The data is sent to the default gateway commonly a router which sends the data to its destination. The time spent sending the data from the switch to the router and then the time spent by the router taking the packet off the wire to read it is now eliminated or shortened drastically by implementing a multilayer switch. This is because a Layer 3 switch is built into a Layer 2 switch so data does not have to be sent to a router that is the router is built into the circuitry of the switch so the data is routed as quickly as the switch can send it to itself - much quicker than one device trying to send data to another device. Now consider the speed at which a high-speed switch works. Consider the amount of packets that could be sent across that cable. Now you can start to see the benefits of a multilayer switch having the two devices sandwiched together increases the efficiency of the transmission thus speeding it up drastically as the volume of data increases. CONTENT SWITCHES Because of the success of Layer 3 switching and the performance gains it can provide it was no surprise that switching would climb higher along the OSI s layered model. Content switches use Layers 4 to 7 of the OSI model and rather than looking at the individual packets being transmitted they can use sessions to transmit data between machines. Content switches will also take advantage of caching and load balancing so that the amount of data transmitted across networks and requests processed by a server are reduced. Content switches that use Layer 4 work at the transport layer of the OSI model and have the ability to look at information in the packets it receives to not only identify the MAC address and IP address of the destination computer but also the application protocols being used to send it. The switch can determine if Hypertext .