clude the serial number of the device in the hostname, either (yes, I've really seen this). Of course, everyone has their own opinions on host- names, but my advice is to keep them as simple as possible. That being said, Lauren is not a good name for a router either. It's a pretty name, but it doesn't give any indication of the router's function! Once I have my hostnames figured out, I prepend interface names to the hostnames for DNS. For example, Serial 0/0/0:1 on LAX-WAN-1 would have the DNS hostname of s0-0-0-1-lax-wan-1 (because DNS can only use hyphens, I replace each slash and colon with a hyphen). This makes traceroutes very readable, because each node and IP interface within the node is clearly labeled: [gad]$traceroute switch9.mydomain.com traceroute to switch9.mydomain.com (10.10.10.10), 30 hops max, 40 byte packets 1 s0-0.router1.mydomain.com 9.854 ms 10.978 ms 11.368 ms fo-1.switch2.mydomain.com 2.340 ms 1.475 ms 1.138 3 g0-0-12.switch9.mydomain.com 1.844 ms 1.430 ms 1.833 ms Chapter 35: Designing Networks Network Designs I can't tell you how you should design your network. I can, however, show you some of the more common corporate and ecommerce network designs out there and explain why I've chosen to focus on these designs. Corporate Networks Most networks are designed along the lines of the classic three-tier model. The three- tier model has core, distribution, and access levels. These levels are clearly delineated and served by different devices. Traditionally, routing was the slowest, most expensive process. For these reasons, routing was done in the core. All the other levels were usually switched. With the advent of inexpensive Layer-3 switching, the three-tiered model is now often collapsed for corporate networks. We'll look at the traditional model as it might be used today, as well as a couple of collapsed-core models. Three-tiered architecture The three-tiered architecture that is most commonly seen in textbooks is still widely used in the industry. Physical separation of the three levels us