Archive for November, 2011

Cisco VLAN Trunking Protocol (VTP)

Wednesday, November 23rd, 2011

VLAN Trunking Protocol (VTP) is a Cisco proprietary protocol that reduces administration in a switched network. When you configure a new VLAN on one VTP server, the VLAN is distributed through all switches in the domain. This prevents you from having to configure the same VLAN everywhere. The goal is to manage all configured VLANs across a switched internetwork and to maintain consistency. (more…)

Twitt

Address Resolution Protocol (ARP)

Sunday, November 20th, 2011

Address Resolution Protocol (ARP) is used by IP devices to locate the hardware addresses of other devices on the local network. RFC 826 introduced ARP as a method for IP devices to locate other IP devices on the same local network by Ethernet hardware address. RFC 1122 clarified RFC 826 further,and a correct ARP implementation needs to incorporate both RFC 826 and RFC 1122. (more…)

Twitt

Cisco – Spanning VLANs across Switches via Trunking

Sunday, November 20th, 2011

In this lab I use two Cisco WS-C2960-24TT [IOS 12.2(25)FX] switches to demonstrate how to span VLANs across switches via 802.1q trunking. I avoid using VTP by using “VTP transparent mode”; as a result, I have to configure the VLANs on both switches. Also, the Cisco 2960 switch only allows you to use 802.1q encapsulation. However, on some other Cisco switches the default encapsulation is a Cisco proprietary protocol called Inter-Switch Link (ISL). If you are using one of these switches and you want to use 802.1q instead of ISL, you will have to manually change the encapsulation type. (more…)

Twitt

Setting-up Tomcat 7 on Windows 7

Saturday, November 19th, 2011

Apache Tomcat 7Apache Tomcat 7 is unique compared to prior releases as it supports the Servlet 3.0, JSP 2.2, and EL 2.2 specifications. However, make note that Tomcat 7 requires Java 1.6 or higher. (more…)

Twitt

Perl – merging files

Friday, November 18th, 2011

Below I demonstrate a quick method of merging two files into a third file using Perl. The program merges two files together into a third file by writing one line from file one to file three and then writing one line from file two to file three; this pattern is then repeated until all contents from both file one and file two
have been written to file three. (more…)

Twitt

Recover from a Forgotten Console Password on Dell Force10 E-Series Switches

Friday, November 18th, 2011

Dell Force10 E600i Dell Force10 E600i

In this lab I will use a Dell Force10 E600i chassis [FTOS 8.3.1.1] to demonstrate how to recover if you forget your console password. The first thing to do to prepare for this lab is to log on through the console, set a console password, and reload the chassis as demonstrated below. (more…)

Twitt

Linux – tar command

Thursday, November 17th, 2011

The linux ‘tar’ program (name derived from tape archive) is a useful utility for archiving/transmitting files. A ‘.tar’ file does not represent compressed files; it is a collection of files within a single uncompressed file. If the file is a ‘.tar.gz’ (also called ‘tarball’) or ‘.tgz’ file, it is a collection of files that are compressed. In the below examples, I always compress/decompress with the ‘z’ flag. (more…)

Twitt

Perl – Initial Values and Context Based Evaluation

Wednesday, November 2nd, 2011

It’s important to remember that in Perl all scalar variables have an initial value of the null string, “”. You do not need to define a value for scalar variables unless you are using “strict” mode. Knowing this, what do you think the output of the below code will be? (more…)

Twitt