Archive for May, 2011

Cisco Port Security with Dynamic MAC Address Learning

Tuesday, May 31st, 2011

Port SecurityIn this lab I used a Cisco Catalyst WS-C3560G-24TS switch [IOS Version 12.2(40)SE]. Using Cisco Port Security it is possible to associate a static MAC address to a physical port on a switch. This only allows one host with that specific MAC address to connect physically to the specified port. (more…)


How to Fix – Force10 S4810 Switch Stuck in Boot Loop

Friday, May 27th, 2011

In this blog I discuss how to fix a common boot loop problem. A boot loop can occur if you change the boot variables for a switch and accidentally put in incorrect information. You may also make a typo when telling the switch which FTOS image to load. Then when the switch reloads, it will attempt to load the non-existent FTOS image. On the S4810 [FTOS], if the “primary_image” fails to load, it will try the “secondary_image” and lastly the “default_image”. If all three boot variables fail to load an image, the switch goes into a boot loop where it keeps retrying to load the images from “primary_image” to “default_image”. (more…)


pNIC, vNIC, and vmNIC Confusion

Thursday, May 26th, 2011

pNIC, vNIC, and vmNIC ConfusionI have been using both remote desktop and vSphere Client quite often lately. Yesterday, I had a remote desktop session with a Windows Server 2003 physical server and also had vSphere Client (connected to an ESXi server) open with a console window of a Windows Server 2003 virtual machine (VM). Sometimes it’s easy to get confused, but, it’s important to remember that the vSphere Client and the remote connection to Windows Server 2003 are both using the physical NIC card adapter (pNIC). (more…)


Functionality of Layer 2 Switches/Bridges

Thursday, May 26th, 2011

Layer 2 Switching

Layer 2 Switching (STP Needed)

Layer 2 switches and bridges switch frames on a network while layer 3 routers route packets between networks. I once heard a network engineer being asked if a network can be made faster if the network is optimized to use more switches than routers. The network engineer answered that it shouldn’t matter. Of course, this is wrong. Think about it, if your network is just switching, the switches do not have to concern themselves with looking at the network layer; this significantly cuts down on the overhead since there is no need to decode the network header information at every stop like is done by a router. There are some concerns to keep in mind if your network starts to get too big which I discuss near the end of the blog. (more…)


Facebook Hack – How “shared” is your website on Facebook?

Wednesday, May 25th, 2011

In this blog I describe a cool little data mining hack you can use to determine how “shared” a specific website is on Facebook. Let’s say you want to determine how often the “” site has been “shared” on Facebook. Simply type in the following as the URL address in a browser: “”. The syntax to use to check any site is “[website_address]“. See below snapshots for examples. Have fun! (more…)


Windows Server 2008 R2 Remote Desktop

Saturday, May 21st, 2011

This blog explains how to use Windows Server 2008 R2 Remote Desktop. The Remote Desktop technology allows a user to connect remotely to a Windows server using a thin client to display the Windows graphical user interface (GUI). In Windows 2008 Server, Terninal Services runs on the remote system and the Remote Desktop Connection (RDC) client (formerly called Terminal Services Client) runs on the local system. Terminal Services can be run in two different modes – “Administration” or “Virtual Session”. “Administration mode” enables full administration functionality and is equivalent to working locally on the system’s console. “Virtual session mode” has more limitations such as the restriction of not being able to install applications and not seeing console notification messages. Some applications are not Terminal Services aware and display warnings/errors only in the console session. (more…)


Setup SSH Access on Cisco Switches

Friday, May 20th, 2011

The Cisco Catalyst WS-C3750G-24TS [IOS 12.2(25)SEE3] switch provides both layer 2 and layer 3 functionality. In this lab I’m going to demonstrate how to setup SSH access to the switch. The first thing I do is set a hostname and assign an IP address to an interface: (more…)


VMware vSphere 4 Step-through

Tuesday, May 17th, 2011

VMware vSphere 4VMware vSphere is an industry leading virtualization platform. Basically it is a software suite composed of applications directed towards managing datacenters through the use of virtualization technology. I’m going to briefly discuss some of the major/core components of vSphere 4. This will give you a clear idea of some of the power behind vSphere 4 and virtualization technology in general. For more information/documentation and a full list of benefits offered by vSphere 4, you should check VMware’s website. (more…)


Setup Telnet Access on Force10 Switches

Saturday, May 14th, 2011

I am going to use a Force10 S60 switch [FTOS] to demonstrate how to setup telnet access. To setup telnet access you first need to set an IP address on either a data port or a managment port so you can access it with telnet. Since the S60 has a management port, I’m going to use that. (more…)


Creating a Link Aggregation Group (LAG) in FTOS

Monday, May 9th, 2011

This lab demonstrates how to create a Link Aggregation Group (LAG) in FTOS on Force10 switches. A LAG in Force10′s FTOS is called a port channel and in Cisco’s IOS is called an EtherChannel. As described by IEEE 802.3ad, LAG is a mechanism for combining the bandwidth of multiple physical ports in a switch into one logical link. Therefore, a port channel can be treated as an individual port and can be configured as such (ex: can be set as Layer 2 or Layer 3, can be part of a VLAN, etc.). (more…)