Setting up a network
Mark writes in with a networking question
Q. 1. I am in need of a suggestion on how to handle this network project for my school project. The network currently consists of 40 clients, including some laptops, some desktop PCs, and some peripherals, such as printers. Many of the laptops are used by employees at home also, so they have been configured for use with a dial up internet connection. At headquarters, a router connects the LAN to the company's ISP through a T-1 link. Connected to the router a are five switches positioned at different locations throughout the building. Each network client connects to its nearest switch. Every client is assigned a static IP address based on the group of addresses the company leases from its ISP. The IT staff complains that maintaining these static IP addresses has become burdensome, and will only grow more difficult as the company tries to expand. What steps should the company take to simplify its client IP assignment process? What measures could the company take to help conserve IP addresses as the company grows?
2. Months later, the IT manager calls and complains the network is experiencing
such heavy traffic that performance across the LAN is suffering. They suspect that one device is issuing a barrage of requests, perhaps due to a software application malfunctioning or a virus. They are unable to locate the node in question. Using TCPIP utilities what command would you use to identify the troublesome computers IP address? After discovering the IP address, what command would you use to identify the computers host name?
A. 1. Using static IP address is not too difficult if you keep track of what is used where and plan it out before hand and keep track of it in a spreadsheet or building/computer layout mapping. You should base your IP scheme on your current and future needs. Certain class IP addresses will get you a certain number of maximum hosts and subnets. Here is a breakdown of the 3 main IP classes and their maximum hosts and subnets.
Class A max networks 126
Class A max hosts 16,777,214
Class B max networks 16,384
Class B max hosts 65,534
Class C max networks 2,097,152
Class C max hosts 254
When you say "Every client is assigned a static IP address based on the group of addresses the company leases from its ISP" that shouldn’t be the case since you are most likely using internal private IP addresses for your network hosts (or at least you should be). You should only be using your public ISP assigned addresses for external connections for remote clients.
If you are running out of public addresses or its getting too expensive you can consider a Terminal Server for your remote clients assuming you have a Windows based network. This will allow multiple users to log onto one computer at the same time and use it as if they were sitting in the office on a local machine.
http://www.microsoft.com/windowsserver2003/techinfo/overview/termserv.mspx
If you do not want to have to manage static IP addresses you can have them assigned dynamically using DHCP. This is where a DHCP server assigns the IP address, subnet mask, gateway and other IP information to your client computers when they boot up. You assign the DHCP server a pool of addresses to hand out to clients as they boot. All you need to do for the clients is set them to obtain an IP address automatically. If all your computers are on the same subnet then this is a simple process. If you use multiple subnets then you will have to install a DHCP relay agent, which can assign IP addresses across routers. Just make sure to assign your servers and IP printers with static IP addresses since you want them to be the same at all times or else clients will have trouble finding them.
http://www.microsoft.com/technet/network/dhcp/default.mspx
2. If you are using Windows servers you can use Network Monitor to capture and analyze traffic on your network.
http://support.microsoft.com/?kbid=812953
You may need to invest in a network packet sniffer or protocol analyzer to narrow the problem down. These issues can be tough to find without serious trial and error without one. There are many hardware and software solutions that you can purchase. Many will have free trials or be free themselves. I suggest you try a few of them to find the best one for your network. Here is a listing of that I pulled from one of my favorite support forums that you can check out.
*****Hardware*****
Fluke Gear
One Touch (approx $5000)
http://portweb.flukenetworks.com/storage/efulfillment/.....pdf
NetTool (approx $1400)
http://portweb.flukenetworks.com/storage/efulfillment/.....pdf
OptiView (approx $17000)
http://portweb.flukenetworks.com/storage/efulfillment/.......pdf
Optiview Workgroup analyzer
http://portweb.flukenetworks.com/storage/efulfillment/.....pdf
DSP-4300 Tester (approx $5000)
https://myvision.flukenetworks.com/edocs/efile.asp?oid=1626542
Wave Runner Wireless Tester (For Compaq Ipaq) (approx $4000)
http://portweb.flukenetworks.com/storage/efulfillment/.....pdf
*****Software*****
Netflow
http://www.ntop.org
Fluke Optiview (Network Inspector) (approx $8000)
http://portweb.flukenetworks.com/storage/efulfillment/....pdf
http://tomshardware.bizrate.com/Fl...9426,rf--wgg.html
Ethereal (FREEWARE) - Best for sniffing traffic in and out of an interface
http://www.ethereal.com/
Sniffer Pro - Investigator (approx $5000)
http://www.snifferpro.co.uk/
Sniffer Basic (approx $1000)
http://www.networkassociates.com/us/products/sniffer/field/sniffer_basic.htm
Solarwinds Engineers Toolkit (price £688.00 sterling)
http://www.solarwindsuk.co.uk/products/engineers.htm
MTRG (Multi Router Traffic Grapher) (FREEWARE)
http://people.ee.ethz.ch/~oetiker/webtools/mrtg/users.html
IPERF (FREEWARE)
http://dast.nlanr.net/Projects/Iperf/
NetworkActiv Scanner 4.0 (FREEWARE)
http://www.networkactiv.com/Scanner.html
NetIQ (FREEWARE)
http://www.ixiacom.com/enterprise/Qcheck.php
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