Router Overview - Router Packaging
(Page 12 of 15 )
Three major categories of modules can be configured into Cisco routers to support either LAN or WAN connectivity:
▼ Ethernet modules To support any of the many Ethernet LAN variants on the market, including Novell NetWare, Banyan VINES, and AppleTalk.
■ Token Ring modules IBM’s LAN technology, which is well established in banks, insurance companies, and other Fortune 1000 corporate environments.
- ▲ WAN connectivity modules To support a wide variety of WAN protocols, some old and some new. Example WAN technologies include newer protocols such as ISDN, Frame Relay, Asynchronous Transfer Mode (ATM), and legacy protocols such as SDLC and X.25.
Configuration options depend mainly on the specific Cisco router:
- ▼ Lower-end routers tend to be “fixed configuration” in that the modules are factory integrated only (preconfigured).
■ Midrange routers, such as the Cisco 3600 Series, are “modular” in that they can accept a variety of modules, often packaging different protocols in the same box. Interface modules are plugged into this class of routers’ motherboards.
▲ High-end routers, the Cisco 7300 Series and Cisco 12000 Series, have buses (also called backplanes). Bus-based routers accept larger modules—usually referred to as bladesor cards—that are effectively self-contained routers (they have their own CPUs, memory units, and so on).
Figure 4-10 is a view of the back of a Cisco 4500 configured with two Token Ring modules (Ring A and Ring B) and four serial ports. Notice that an empty slot is available on the right. It’s a common practice to purchase a router model with room for adding an interface as network traffic grows.
 This chapter is from Cisco: A Beginner's Guide, by Velte and Velte (McGraw-Hill/Osborne, 2004, ISBN: 0072256354). Check it out at your favorite bookstore today.
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