HumairAhmed.com

Cisco Port Security with Dynamic MAC Address Learning

Posted on May 31, 2011 by Humair

In 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. Continue reading →

Posted in Cisco, Labs, Networking, Technology | Tagged Cisco, Cisco Catalyst 3560 switch, Cisco Catalyst WS-C3560G-24TS, Cisco Port Security, Cisco Port Security with Dynamic MAC Address Learning, Dynamic Port Security, MAC address, Port Security, router, switch, switchport port-security, switchport port-security violation | 4 Comments

How to Fix – Force10 S4810 Switch Stuck in Boot Loop

Posted on May 27, 2011 by Humair

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 8.3.7.0], 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”. Continue reading →

Posted in Force10 Networks, Networking, Technology | Tagged boot loop, boot variables, Force10, Force10 S4810, FTOS, S4810, TFTP | 2 Comments

pNIC, vNIC, and vmNIC Confusion

Posted on May 26, 2011 by Humair

I 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). Continue reading →

Posted in Networking, Technology, Virtualization and Cloud Computing | Tagged ESXi, ESXi Server, hypervisor, physical NIC, pNIC, remote connection, Remote Desktop, virtual machine, virtual NIC, virtualization, VM, vmNIC, vmware, vNIC, vSphere Client | 2 Comments

Functionality of Layer 2 Switches/Bridges

Posted on May 26, 2011 by Humair

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. Continue reading →

Posted in Networking, Technology | Tagged Address Learning, application specific integrated circuits, ASICs, bridges, bridging technologies, broadcasts, Cisco, collision domain, collision domains, datalink layer, filter table, Forward/Filter Decisions, frame, frame filtering, frames, layer 2 broadcasts, Layer 2 Switching, Loop Avoidance, MAC, MAC address, MAC address table, MAC database, Media Access Control, Media Access Control Address, multicasts, network, network layer, network loops, networking, packet, packets, routers, slow convergence, Spanning Tree Protocol, STP, switches, switching | 1 Comment

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

Posted on May 25, 2011 by Humair

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 “http://www.cnet.com” site has been “shared” on Facebook. Simply type in the following as the URL address in a browser: “http://graph.facebook.com/http://cnet.com”. The syntax to use to check any site is “http://graph.facebook.com/[website_address]”. See below snapshots for examples. Have fun! Continue reading →

Posted in Data Mining, Hacks, Social Networking, Technology | Tagged Facebook, Facebook Hack, Facebook Shares, hack, shares, website shares | Leave a comment

Windows Server 2008 R2 Remote Desktop

Posted on May 21, 2011 by Humair

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. Continue reading →

Posted in Operating Systems, Technology, Windows Server 2008 R2 | Tagged Administration mode, RDC, RDC Client, RDP, Remote Desktop, Remote Desktop Connection, Remote Desktop Connection Client, Remote Desktop Protocol, Terminal Services Client Access License, Virtual session mode, Windows Server 2008, Windows Server 2008 R2 | 1 Comment

Setup SSH Access on Cisco Switches

Posted on May 20, 2011 by Humair

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: Continue reading →

Posted in Cisco, Labs, Networking, Technology | Tagged Catalyst, Cisco, Cisco Catalyst 3570, Cisco Catalyst WS-C3750G-24TS, default route, router, SSH, switch | Leave a comment

VMware vSphere 4 Step-through

Posted on May 17, 2011 by Humair

VMware vSphere 4 VMware 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. Continue reading →

Posted in Technology, Virtualization and Cloud Computing | Tagged Cisco Nexus 1000V, Cloud Computing, Consolidated Backup, Distributed Resource Scheduler, enterprise level virtualization, enterprise virtualization, ESX, ESXi, Fault Tolerance, High Availability, Hot Add, hypervisor, SMP, Storage VMotion, Thin Provisioning, vCenter Orchestrator, Virtual Symmetric Multi-Processing, VirtualCenter, virtualization, VMDirectPath, vMotion, vmware, VMWare ESX, VMware ESXi, VMware vSphere, vNetwork Distributed Switch, vShield Zones, vSphere, vSphere 4 | Leave a comment

Setup Telnet Access on Force10 Switches

Posted on May 14, 2011 by Humair

I am going to use a Force10 S60 switch [FTOS 8.3.3.4] 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. Continue reading →

Posted in Force10 Networks, Labs, Networking, Technology | Tagged Force10, Force10 Networks, mamangement port, managementethernet, router, S60, switch, telnet | Leave a comment

Creating a Link Aggregation Group (LAG) in FTOS

Posted on May 9, 2011 by Humair

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.). Continue reading →