I will give you a simple guide to troubleshoot Vlans and make things work again.

• First check for Layer 1 and Layer 2 issues
• Is the cable plugged into the correct port?
• Is the link light on, and if so, what color is it? (If the led has a green color, it means that the switch port is in the forwarding state, if the port led has a yellow color the port is in the blocking state and if the port has a yellow blinking led, it is in the error state.
• We can use the Switch# show interface command to confirm link state
• Check the duplex mode

• Check the speed of the port
• Avoid autonegotiation
• Check Vlan 1 for IP address
• Check if default gateway is set on the switch
• Verify the trunking configuration
• Check the trunking protocol (802.1Q or ISL)
• If you have more than one vlans that you want to communicate one with the other you must configure intervlan routing.
• Verify that you have add the Vlans to your switch and that you have assigned the correct ports to the correct vlan
• Use the command Switch# Show vlan
• Check the spanning-tree configuration
• Use the command Switch# show spanning-tree
• Check the VTP settings (VTP domain name, mode, password and revision number)

That are the most common mistakes when we try to setup a vlan and i hope i covered most of them. Seems troubleshooting articles are a good source of information that can help a lot of people so, expect some more in the near future.

Before showing you the commands, that are quite simple, I will explain what we will achieve with them.

Enabling an HTTP server on the router allowing the administrator by using any web browser to configure the router by pointing to the IP address of the server.

Syntax of the Commands:

Router(config)#ip http server

Now if you wish to enable the web interface in a non default port (The default port is 80) you can use the following command:

Router(config)#ip http port [port number]

Example configuration:

Router(config)#ip http server

Router(config)#ip http port 8090

Enabling the web interface of the router, will not give us the choices we have when we use telnet to connect to it, but it can automate or at least make changes ages, allowing us to spend more time to serious configuration and not just opening or closing Ethernet ports.

With the VoIP technology we can transmit the analog voice signals of our telephone, through the traditional data network. This technology works by encoding analog voice signals into IP packets. These packets are sent across the data network and reassembled and decoded at the other end back to analog signal.

Tip 1:

Keep in mind that if we wish to have VoIP we need a telephone center that can support VoIP like Cisco Call Manager and IP Phones.

Tip 2:

Now think carefully that the voice packets share the shame bandwidth with all the other network applications and data. But interruptions in voice conversations are not acceptable, so it’s very important to configure the network devices in some way that they will give priority to voice data. The key technology is called QoS (Quality of Service).

VoIP implementations always need a proper configuration of QoS. So, why not, that can be a good article in the future! Stay Netralized

For example if you use the subnet 10.1.1.0 /24 the broadcast address is 10.1.1.255

From privileged mode perform a ping like this:

Router#ping 10.1.1.255

A “list” with all the active nodes should appear.

Another command that you can use to find out with witch hosts has the router communicated is

Router#show ip arp

You can use this useful type of ping for many types of things, for example to check how many computers are connected on a wireless network. Till our next article, stay tuned.

If you are wondering why the router’s clock is important, just think the syslog messages. Every syslog message has the time that the event occurred. Imagine a hacking attempt that has been tracked by your syslog, if the clock of your router is not configured properly, you can’t find out when the attack took place.

Now let’s start with the commands.

Clock set

Clock set hh:mm:ss day month year

This command manually sets the router’s clock. The time is specified in terms of a 24 hour clock and the year must be in a four digit notation for example 2000.

Clock timezone

Clock timezone zone hours [minutes]

This command sets the routers time zone and the number of hours from the UTC.

Clock summer time

Clock summer-time zone recurring [sweek sday smonth shh:mm eday emonth ehh:mm]

This command informs the router for the daylight savings time. The recurring form of the command specifies that daylight savings time should be observed at the given time every year. The syntax format of the command specifies a start date and an end date for daylight savings time.

Don’t underestimate your router’s clock settings. It is a powerful tool to know when, and sometimes given the time, who attempted to bypass your security. It is a crucial setting that can be used as an evidence or as a tool to avoid problems in the future.

Situation is like this: You’re enjoying with your afternoon with your friends having fun. Your cellphone rings and once again it’s the mr. IWontSpendAMinuteFixingMyComputerCauseIKnowPeopleWhoWillDoItForMe, starting once again the usual conversation:

-Mr-Hey there, i have a serious problem!

-You-What’s wrong?

-Mr-I don’t know, i try to open an application and it crashes.

-You-What’s the error it shows you?

-Mr-A Popup screen about an error, i don’t know.

And you’re changing colors trying to hold your temper so you can continue talking… What can you do to avoid helping him? Cause after all people like him are not worth helping. (To make my self clear, i am not implying that whoever calls you, is a pain in the A$$ an should be avoided but people who just call just because they know that you will find the solution so they won’t have to spend 5 minutes or even 10 seconds looking at the error screen should be.)

Possible ways to avoid

• Pretend You’re Driving and can’t talk right now. (One of the most successful methods i use from time to time)
• Act like you’re with a customer so you can freely talk, just hear the problem fast and tell him you’re going to call when you can.
• Tell a woman from your friends, to start calling you like you’re about to leave, or do something. If that doesn’t work and he’s not embarrassed enough to say i
• ll call you later, just tell him to call in ten minutes because you’re about to go. Needless to say that in ten minutes no one will answer the phone…

If that person is more than annoying and less than a friend, you have the following options:

• Tell him that you don’t know how to solve that problem, and the next time, not to mention the next time too
• Just tell him that you can’t continue supporting him because you are very busy in your life.
• Tell him that for the next support he’ll have to donate to your paypal account for support (that will make him run like the wind to find another “friend” to solve his issues)

Most ways have been personally tested and seem to work flawlessly, except some extreme occasions.

Disclaimer: Don’t try this at home

According to a statement made by Mike Schroepfer, vice-president of the department of Mozilla’s engineers, the official publication of Firefox for mobile phones will be released at the end of 2008. He has also announced the development of Firefox 3 for PCs.

The mobile Firefox will probably have the capability of accepting themes and support XUL.

After the iPhone started supporting the Safari web browser, the need for such mobile browsers which open entire web pages increased significantly. The potential usage of Opera would also be an option, but if the Firefox offers all the customization features that gives us in desktop computers, it will have more than enough chances of becoming the number one mobile web browser.

The future will provide us all the necessary answers about the mobile web browsers.

We just have to wait.

I am into computers for more than 10 years and i think many of you reading this blog, would be using computers for more than 5 because after all, you can’t say: Hmm computers might seem something good. Let me start using them! And the next day you’ve come upon a specialized networks blog and start reading it:)

So, i was thinking… What’s the problem with today’s computer users?

I’ve come up to this question because it seems that the average person that uses a computer doesn’t have:

• Patience
• Passion to make things happen
• Appetite for knowledge

I can’t say that the above are absolute but a great percentage of users can’t:

• Have something broken on their computer for more than 5 minutes cause it “Disturbs” them.
• Spend more than 10 minutes on a problem. After 10 minutes the problem becomes unsolved and “mission critical” so what they can do is to pick up the phone and call their “geek” friend and ask him/her.

I can accept it, users nowadays aren’t used to be able to control problems with their computer but for god’s shake why when i ask a friend who calls for support:

- What was the error message when the incident happened?

-I don’t know a message popped up.

- What did it say?

- I don’t know, something about an error!

How does that guy want me to help him when i try to find an error that i don’t know what caused it? I will try and do it once, twice, then i’ll act like I don’t know. That’s how the article’s title was created.

The old days of searching through magazines to find commands to solve your problems and read manuals so you can see what’s wrong belong to the past.

I still can remember a period that i used to do 3 formats a day. Installing windows 3.11 messing with settings and then ruining everything and again installing, till i make it work the way i wanted it to work.

I don’t know why this happens maybe it’s the way we live nowadays that demands everything to be fast

Maybe people today think that a computer is a gaming machine, an mp3 player, a home cinema and nothing else, therefore they think that nothing should go wrong and if it does the problem should be solved with just a click.

And to stop whining, i can’t complain about it, this issue has given work to many many it technicians (including me) who can charge a very good amount of money for a problem that could be solved by the same user in 5 minutes. So after all it’s not a bad thing at all.

I would be very interested to hear your version of the story, your thoughts on the issue and what do you think caused it.

And until our next article… Stay Netralized

But first things first,

Why is an Ip address and default gateway needed in the switch?

After all switches are OSI Layer 2 devices that care only about MAC addresses.

The modern switches are manageable and support extra features than normal old fashion switches. This features include the support of TCP/IP applications like ping, telnet, trace route etc. For example, if you want to telnet or ping a switch, the switch must have an Ip configured. Also, if you want to execute ping or telnet to a device in another subnet the switch must have a default gateway configured.

Now let’s see the configuration for a 2950 series cisco switch.

Ip address

To configure the ip address first you have to enter from global configuration mode to interface vlan 1.

Switch#

Switch#conf t

Switch(config)#int vlan 1

Switch(config-if)#ip address {your ip address} {mask}

Switch(config-if)#no shutdown

Default Gateway

Be careful!!! The configuration of default gateway takes place in the configuration mode and the command does not include the mask for the ip.

Switch#

Switch#conf t

Switch(config)#ip default-gateway {ip address}

Now you can access your switch remotely, you can ping it from another network with different subnet and start “playing” with the settings. Have fun

But is this the most efficient tool for this job?

Surely not.

There is a tool, not quite widespread, called Network Stumbler which is much more effective than the default windows scanner. The network stumbler is a wireless network scanner that supports many different chipsets of wireless network cards as Lucent, Dell True Mobile, Compaq WL 110, Elsa Airlancer and several others.

I guess that many of you are already familiar with it. For those who haven’t heard of it before let’s see why network stumbler is better than the default windows wireless scanner.

With network stumbler we get much more information for access points concerning the following:

• We learn the MAC address of access point
• We learn the SSID of access points
• We discover the number of the channel were the access point works
• We can see the speed by which the access points send and receive information
• We can learn the type of the devices that are scanned, meaning whether they are access points or computers with their network cards configured as adhoc
• Last but not least, with network stumbler we have the opportunity to see information about the quality and the strength of the signal of access points

And not to forget network stumbler is a free application and you can download it from http://www.netstumbler.com/downloads/

Till our next article stay Netralized!!!