uck. Many modules-especially service modules like FWSMs, IDSMs, and CSMs-are densely packed with components. I've seen $40,000 modules ruined by engineers who forced them into slots without properly aligning them. Remember to use a static strap, too. Switches Any time you're working with a chassis or modules, you should use a static strap. They're easy to use, and come with just about every piece of hardware these days. Routing cables When routing cables to modules, remember that you may need to remove the modules in the future. Routing 48 Ethernet cables to each of 7 modules can be daunting task. Remember to leave enough slack in the cables SO that each module's cables can be moved out of the way to slide the module out. When one of your mod- ules fails, you'll need to pull aside all the cables attached to that module, replace the module, then place all the cables back into their correct ports. The more planning you do ahead of time, the easier this task will be. Chapter 2: Hubs and Switches CHAPTER 3 Auto-Negotiation When I get called to a client's site to diagnose a network slowdown or a "slow" device, the first things I look at are the error statistics and the auto-negotiation set- tings on the switches and the devices connected to them. If I had to list the most common problems I've seen during my years in the field, auto-negotiation issues would be in the top five, if not number one. Why is auto-negotiation such a widespread problem? The truth is, too many people don't really understand what it does and how it works, SO they make assumptions that lead to trouble. What Is Auto-Negotiation? Auto-negotiation is the feature that allows a port on a switch, router, server, or other device to communicate with the device on the other end of the link to determine the optimal duplex mode and speed for the connection. The driver then dynamically configures the interface to the values determined for the link. Let's examine these parameters: Speed Speed is the rate of the interface, usually listed in megabits per second