Eagle Computer Services

Static versus dynamic routing

Darrel — Mon, 13 Feb 2012 15:47:16 +0000

Static versus dynamic routing.
A router requires a ROUTE to a remote network if it is to send traffic there.
A route specifies how the network can be reached.
Routes are stored in a route table.
The route table can consist of static, dynamic or a combination of routes.
We can examine the route table by issuing the show ip route command.
In static routing the route table is constructed manually by the router programmer.
In dynamic routing the route table is learnt by the router itself.
There are advantages and disadvantages to each method.

Cisco Routers Ports, Interfaces and the IOS

Darrel — Sun, 12 Feb 2012 20:40:38 +0000

External ports and interfaces
Routers can be purchased with different ports and interfaces.
Typical interfaces include:-
-Console port
-Auxiliary port
-Serial port

The CONSOLE port
-Starting point for configuration.
-Allows terminal connection (hyperTerminal in windows) via a PC and a cable.
-Typically basics like IP addresses will be assigned through the connection.
-Once basic configuration is in place further configuration can be done via telnet across the network.

The AUXILIARY port
-Allows a modem to be connected to the router.
-This can then be used to dial into the router for remote troubleshooting or configuration.
-Its main use is for remote configuration since troubleshooting and minor changes can be done via a telnet connection.

Cisco Routers Networking Overview

Darrel — Sun, 12 Feb 2012 20:33:00 +0000

Network devices
There are three key devices you need to be aware of in order to understand internet-working:-
-HUB
Used as the central connection point within the star topology.
-SWITCH
Used to reduce collision domains within a star network.
-ROUTER
Used to link network segments together

HUB
All devices on a star network plug into the hub.
Hence it forms the central connection point of the whole network.
If a hub receives a signal on a port it will propagate that signal to the whole network.
This means that collisions can result.
The more collisions on a network the slower the network will run.

SWITCHES
Switches are sophisticated hubs.
They learn what machines are connected to each port.
They only propagate the signal on the port the device is connected to.
Switches reduce collision domains.

How do switches learn?

Windows XP – System Utilities Part 3

Darrel — Fri, 23 Dec 2011 14:56:05 +0000

Memory Usage.
By default more memory is given to the running of local programs.
This is typical for a workstation, If the system shares a lot of data on a network it may offer better performance if more memory is given to the system cache.
This allows more files to be cached in RAM meaning the system can share data faster.
Virtual Memory.
Virtual memory is an area of the hard disk that is set aside to store running programs and files it is sometimes referred to as the swap file or the page file, It is used when the system is running out of proper RAM.
When RAM becomes full the system will move the oldest data stored to the swap files, This is done in 4k chunks called pages.
This frees up system RAM fir new data to be stored, If the data moved to virtual memory is required later it can be pulled back from the swap file.
The size and location of the swap file can make a big difference to performance,
Generally the system will be responsible for managing the size of the page file, This can cause a slowdown as the system will have to monitor and change the size of the page file.

Windows XP – System Utilities Part 2

Darrel — Wed, 14 Dec 2011 12:27:14 +0000

Task Manager.
The applications tab is useful if a program has crashed we can end and tasks that are listed as ‘not responding’
Processes show the software running at present and the resources they are using.
The only process that should be near 100% is the system idle process.
The svchost is running more than once, This is normal as svchost looks after DLL (direct library link) based software, Each instance manages a number of software services.

Performance Tweaks.
The best way to keep your system running satisfactorily is basic maintenance.
1. Defrag hard disks regularly
2. Clean out temporary files periodically
3. Ensure you have up to date anti-virus and anti-spyware utilities running
There are also some more advanced tweaks that can be made.

Windows XP – System Utilities Part 1

Darrel — Mon, 12 Dec 2011 14:15:00 +0000

Performance Monitoring.
One of the most common complaints from end user is “my computer is running slowly”.
Since speed is highly speculative it can be a difficult thing to trouble shoot.
It is therefore important that performance monitoring be carried out in a structured way rather than on an ad-hoc basis.

Monitoring Strategy.
When a System is running a baseline should be created .
This shows the ‘Normal’ level of activity for key performance areas.
This baseline should be stored away from the system for future use,
it should also be updated regularly since the way a system is utilised will change over time
The performance tab is perhaps the most commonly used screen,
It shows basic information about CPU utilisation and memory usage.
The network tab allows us to see the current amount of traffic going across our networks connections.

Tune up your computers

Darrel — Thu, 08 Dec 2011 16:20:48 +0000

1. Keep your PC up to date

One of the best things you can do to protect your PC is also one of the easiest: Make sure you are set up to get automatic updates from Microsoft. If you use Windows and other Microsoft software, such as Microsoft Office or Windows Live Essentials, then you should use the Microsoft Update service. You'll also get notices about new Microsoft software that you can download for free.
So how do you turn on automatic updates? Simple: Go to the Microsoft Update website. If you don't have automatic updates turned on, we'll help you through the process.

2. Performance

Wireless Networks

Darrel — Wed, 07 Dec 2011 21:16:21 +0000

The easiest, least expensive way to connect the computers in your home is to use a wireless network, which uses radio waves instead of wires. The absence of physical wires makes this kind of network very flexible. For example, you can move a laptop from room to room without fiddling with network cables and without losing your connection. The downside is that wireless connections are generally slower than Ethernet connections and they are less secure unless you take measures to protect your network.
If you want to build a wireless network, you'll need a wireless router. Signals from a wireless router extend about 100 feet (30.5 meters) in all directions, but walls can interrupt the signal. Depending on the size and shape of your home and the range of the router, you may need to purchase a range extender or repeater to get enough coverage.

Wired Networks

Darrel — Wed, 07 Dec 2011 21:15:01 +0000

Ethernet and wireless networks each have advantages and disadvantages; depending on your needs, one may serve you better than the other. Wired networks provide users with plenty of security and the ability to move lots of data very quickly. Wired networks are typically faster than wireless networks, and they can be very affordable. However, the cost of Ethernet cable can add up -- the more computers on your network and the farther apart they are, the more expensive your network will be. In addition, unless you're building a new house and installing Ethernet cable in the walls, you'll be able to see the cables running from place to place around your home, and wires can greatly limit your mobility. A laptop owner, for example, won't be able to move around easily if his computer is tethered to the wall.

Building A Home Network

Darrel — Wed, 07 Dec 2011 21:13:18 +0000

The two most popular home network types are wireless and Ethernet networks. In both of these types, the router does most of the work by directing the traffic between the connected devices. By connecting a router to your dial-up, DSL or cable modem, you can also allow multiple computers to share one connection to the Internet.
If you're going to connect your network to the Internet, you'll need a firewall. A firewall is simply a hardware device or software program that protects your network from malicious users and offensive Web sites, keeping hackers from accessing or destroying your data. Although they're essential for businesses looking to protect large amounts of information, they're just as necessary for someone setting up a home network, since a firewall will secure transactions that might include Social Security numbers, addresses, phone numbers and credit card numbers. Most routers combine wireless and Ethernet technology and also include a hardware firewall.