GlobalKnowledgePresents_SwitchingEssentials(交换必读白皮书).pdf

Expert Reference Series of White Papers Switching Essentials 1-800-COURSES Switching Essentials Dheeraj (Raj) Tolani, CCSI, CCENT, CCNA, CCDA, CCNP, CCDP, CCIP, CCVP Introduction In every introductory class we teach we get students who are either puzzled about router essentials or switch- ing essentials or both. This switching essentials white paper will give you the basics that will make learning about switching a little less painless when you sit in a course like ICND1, ICND2, CCNA Boot Camp or BCMSN. Switching is an interesting topic. It could be an easy thing in your network, or it could be something that keeps you up nights. Switching can be simple, allowing us to connect our users from various systems (host sys- tems and phones), or it can be a complicated system with various advanced topics. In this white paper, we will address the basics of this Layer 2 technology and help you get your switch up and running. For our examples, we will use Cisco’s 2950 switch. In the past, some switches, such as the Cisco 1900 series, have given us the ability to configure the basics of switching using menus. I prefer to have more control over my switches, so I like the current switches that allow me to configure various components using the Cisco commands. Same as a router, the switch allows us to configure some of the basic things using a set-up script. This set-up script is simply a yes/no interactive questionnaire that allows any novice to get the switch up and running. We will not be using the set-up script for our discussion. When we say “no” to the set-up script, we’re left in a basic mode (user EXEC mode, discussed in the previous router articles): Switch At this mode, we don’t have much power to do anything. In order to be able to configure anything, we need to be in privilege EXEC mode (a.k.a. enable mode). The command that takes us to the privilege exec mode is “enable”: Switchenable Switch# Yo