Category Archives: Networking

Configuring PVST+ on Cisco Switches

Posted on February 1, 2012 by Humair

Per VLAN Spanning Tree Plus (PVST+) is a flavor of Spanning Tree Protocol (see prior blog, Default STP Behavior on Cisco Switches) which maintains a spanning tree instance for each VLAN in the network. This means certain VLAN trunks (using … Continue reading →

Posted in Cisco, Labs, Networking, Protocols, Technology | Tagged avoid loop, Cisco, Cisco 3560, Cisco 3560 switch, Cisco switch, dot1q, loop, Per VLAN Spanning Tree Plus, prevent loop, PVST+, Spanning Tree Protocol, STP, switch, vlan | 6 Comments

Default STP Behavior on Cisco Switches

Posted on January 31, 2012 by Humair

In a prior blog, Functionality of Layer 2 Switches/Bridges, I discussed the core functionality of layer 2 switches. In this blog, I hit upon the Spanning Tree Protocol (STP) used on layer 2 switches to prevent loops. As mentioned before, … Continue reading →

Posted in Cisco, Labs, Networking, Protocols, Technology | Tagged Blocking, BPDUs, bridge ID, Bridge Protocol Data Units, broadcast storm, change root bridge, Cisco, Cisco 3560, designated port, device priority, Disabled, Forwarding, layer 2, layer 2 loop, Learning, Listening, loop, MAC address, prevent layer 2 loop, prevent loop, redundancy, root bridge, root port, Spanning Tree Protocol, STP | 1 Comment

How to Transfer Your Putty Settings Between PCs Running Windows

Posted on January 8, 2012 by Humair

I can’t tell you how many times I’ve had people ask me how they can export their Putty settings. For those of you who have been completely in the dark for the last decade, Putty is a Telnet and SSH … Continue reading →

Posted in Applications, Hacks, Networking, Operating Systems, Technology, Tips & Tricks, Windows, Windows 7, Windows Server 2008 R2 | Tagged export putty, export putty settings, export windows putty, export windows putty settings, hack, putty, putty hack, putty hack to export settings, putty windows registry hack, regedit, registry hack, Simon Tathamm, ssh client, telnet client, transfer putty settings, transfer putty settings between computers, transfer putty settings between pcs, windows, Windows 7, windows 7 registry hack, windows regedit, windows registry, windows registry hack | 8 Comments

Cisco – Filtering Unwanted Packets with Standard Access Lists

Posted on January 7, 2012 by Humair

Access lists (ACLs) are basically statements that packets are compared against for the purpose of taking some action if a match occurs. After an access list is created, it can be applied to inbound or outbound traffic; in some cases … Continue reading →

Posted in Cisco, Labs, Networking | Tagged access list, access lists, acess-lists, ACL, ACLs, block host, block ip address, block packet, block traffic, Cisco, Cisco 2611, Cisco 2611 router, deny host, deny ip address, deny packet, deny traffic, extended access list, filter, filter host, filter ip address, filter packet, filter traffic, named access list, router, standard access list, standard access-lists | 1 Comment

OSPF Explained and Useful Troubleshooting Commands

Posted on January 4, 2012 by Humair

Open Shortest Path First (OSPF) is an open standard link-state routing protocol that supports multiple equal-cost routes to the same destination (four by default). OSPF constructs a shortest path tree and then updates the routing table with the best paths. … Continue reading →

Posted in Cisco, Labs, Networking, Protocols, Technology, Troubleshooting | Tagged ABRs, adjacency, area 0, Area Border Routers, AS, ASBR, Autonomous System, Autonomous System Border Router, backbone area, Backup Designated Router, BDR, Cisco, Cisco 2126XM, Cisco 2126XM router, Cisco IOS, cisco router, cost, Designated Router, Hello packets, Link State Advertisement, LSA, neighbor, Neighbors, Open Shortest Path First, OSPF, OSPF Adjacencies, OSPF area, OSPF Backup Designated Router, OSPF BDR, ospf cost, ospf database, OSPF Designated Router, OSPF Hello Packets, ospf neighbor, OSPF Neighbors, OSPF process, OSPF Router ID, ospf troubleshooting, router, Router ID, Shortest Path First, shortest path tree, SPF | 5 Comments

Setting-up DHCP with IP Helper-Address on Cisco Routers

Posted on December 29, 2011 by Humair

In a prior lab, Setting-up DHCP on Cisco Routers, I discussed how to setup a Cisco router as a DHCP server. In this lab, I use a DHCP server setup on one subnet to provide DHCP services to two different … Continue reading →

Posted in Cisco, Labs, Networking, Protocols, Technology | Tagged Cisco, Cisco 2126XM, Cisco 2126XM router, Cisco WS-C2950-24, Cisco WS-C2950-24 switch, configure DHCP, dhcp, DHCP broadcasts, dhcp configuration, Dynamic Host Configuration Protocol, ip helper, ip helper-address, Setting-up DHCP with IP Helper-Address on Cisco Routers | 1 Comment

Setting-up DHCP on Cisco Routers

Posted on December 11, 2011 by Humair

The Dynamic Host Configuration Protocol (DHCP) provides the capability to automatically allocate reusable network addresses and configuration options to hosts.

Posted in Cisco, Labs, Networking, Protocols, Technology | Tagged BOOTP, Cisco, Cisco 2126XM, Cisco 2126XM router, cisco dhcp configuration, cisco router, cisco setup dhcp, Cisco switch, Cisco WS-C2960-24TT, Cisco WS-C2960-24TT switch, dhcp, dhcp configuration, Dynamic Host Configuration Protocol, router, switch | 1 Comment

Tech Tips – Check if your E-mail Server is Running [Video]

Posted on December 7, 2011 by Humair

I created and uploaded this video to youtube back in 2009, but I thought it might be helpful for others if I post the link here. It’s just a simple video that shows you how you can use telnet to … Continue reading →

Posted in E-mail, Networking, Servers, Technology, Troubleshooting, Troubleshooting | Tagged Check if your E-mail Server is Running, e-mail, e-mail server, e-mail troubleshooting, email, imap, pop, pop3, smtp, telnet, troubleshooting connectivity and server issues | Leave a comment

Installing the Microsoft Loopback Adapter in Windows 7

Posted on December 5, 2011 by Humair

The Microsoft Loopback Adapter is a logical dummy network card. It can be very useful for testing purposes with a virtual network environment where network access is not available. You can also bind network clients and other network configuration items … Continue reading →

Posted in Networking, Operating Systems, Windows, Windows 7, Windows 7 | Tagged dummy network card, gns, Graphical Network Simulator, Hardware Wizard, Install Microsoft Loopback Adapter in Windows 7, Installing Microsoft Loopback Adapter in Windows 7, loopback, loopback adapter, Microsoft Loopback Adapter, Network adapter, Network adapters, pc loopback adapter, windows, Windows 7, Windows 7 Microsoft Loopback Adapter, windows loopback adapter | 2 Comments

Intel VT FlexMigration and AMD-V Extended Migration – Enabling Dynamic, Agile Data Centers

Posted on December 3, 2011 by Humair

Server virtualization/consolidation is becoming a norm and data centers and enterprises are now looking towards the horizon at how to bring dynamic, agile, and flexible capabilities to their IT infrastructure. What I will focus on here is one specific technology … Continue reading →

Posted in AMD, Intel, Networking, Processors/CPUs, Virtualization and Cloud Computing, VMware | Tagged AMD, AMD CPUs, AMD-V, AMD‐V Extended Migration, CPU, CPUs, Data Centers, Enhanced VMotion Compatibility, ESX, ESX 3.5, ESX 3.5 Update 2, ESXi, EVC, hypervisor, Intel, Intel CPUs, Intel VT, Intel VT FlexMigration, Live Migration, virtual machine, virtual machines, VM, vms, vmware, VMware Enhanced VMotion Compatibility, VMWare ESX, VMware ESX 3.5, VMware ESX 3.5 Update 2, VMware ESXi, vmware vmotion | Leave a comment