Cisco Routers for the Desperate: Router and Switch Management, the Easy Way
Michael W. Lucas
Format: PDF / Kindle (mobi) / ePub
Cisco routers and switches are the cornerstones of many networks. But when things break, repairs can intimidate even the most competent administrator. Luckily, just knowing the "in case of emergency" basics will take you far.
Just like the original, this second edition of the highly acclaimed Cisco Routers for the Desperate is written for the administrator in crisis mode. Updated to cover switches and the latest Cisco terminology, with a tighter focus on the needs of the small network administrator, this second edition gives you what you need to know to provide reliable network services and fix problems fast. You'll find coverage of:
- Installation—how to get your router and network connections up and running right the first time
- Troubleshooting routers and switches, so that you can determine whether your hardware or the Internet is broken
- Security concerns, like how to keep your network equipment safe from hackers and install a private network between two offices
- How to implement basic network redundancy to reduce the risk of network downtime
Cisco Routers for the Desperate, 2nd Edition is designed to be read once and left alone until something breaks. When it does, you'll have everything you need to know in one easy-to-follow guidebook.
standard of B8ZS). This meant that the circuit could not pass large all-zero packets. The .gif image format uses a lot of large all-zero packets, as do the Windows network protocols. Note Other physical problems generate different symptoms; this particular example is just the one that seems destined to haunt me. Your data circuit should accept whatever sort of data you want to transmit, even if it is a whole lot of nothing! To perform an extended ping test, enter enable mode and just type
choice, we will use it in our examples. Use the FTP variant of the commands if necessary. Note Before using SCP, you must configure your device to support SSH. See Chapter 9 for instructions on setting up SSH. Copying Your Configuration to a File Server Before an upgrade, back up your router's configuration in case the upgrade goes really, really badly and the router loses its memory. You can use a text file backup if you wish, or you can actually copy the startup configuration to an FTP or
SCP server. router# copy startup-config scp://mwlucas@scpserver/startup-config When you have backed up your current system, you are finished until your maintenance window begins. * * *  This is, of course, an acronym for "You really think I would use a real password here?" Performing the Upgrade An IOS upgrade requires a router reboot, which interrupts service. If all goes well, the router will only be down for a few minutes. If the new IOS image does not work, you must reload
For example, while your switch might support 100Mb/s full duplex today, if one cable has a problem and must fall back to half-duplex, your hard-coded duplex setting will bring the circuit down. It's better to run in a degraded mode than to go down entirely! Your best bet, if possible, is to allow your router to autonegotiate its duplex setting unless you already understand the issues involved. If two devices have trouble autonegotiating, however, you probably must hard-code speed and duplex.
network. For example, to set the IP address to 192.168.1.1, with a netmask of 255.255.255.128, you would use the following command. router(config-if)# ip address 192.168.1.1 255.255.255.128 After you have this basic configuration, you can go on to a variety of other settings. Description While entering a description is almost pointless for a simple router with a single T1 port and a single Ethernet, the description field is very useful when your router has multiple interfaces of each type.