Computers have increased in computational power and this power has been integrated into network devices, with network switches being the product of this integration. Before we had network switches, we had network hubs that could only repeat and segment what was said on a network segment. Along came DEC Network …
Read More »Router Stuck in ROMmon Mode
If you have ever experienced the ROMmon mode problem, you probably came across one of the following: configuration register forced the router to go to ROMmon mode during the boot process corrupt image (IOS) on Flash (indicated by bad_checksum message) router was unable to find the IOS (either on Flash …
Read More »Understanding Access Control Lists (ACL)
Defining an access control list may seem a challenging and complex task, especially to those that have just delved into the world of computer networking and network security. The aim of this article is to explain the role of access control lists and basic concepts used to understand them. The …
Read More »Understanding Ethernet Jumbo Frames
There seems to be a growing argument lately over network optimization and the use of Jumbo Frames. With the cost of Gigabit networking continuing to go down, and 10 Gigabit (and greater) networks becoming more affordable, the impact of this decision is becoming more and more important. Knowing how and …
Read More »Meet the ARP Family – ARP, inARP, GARP and RARP
What is ARP? ARP or Address Resolution Protocol is a simple communications protocol used primarily today in IP and Ethernet networks. It’s main purpose is to discover and associate IP addresses to physical MAC hardware addresses. How does ARP work? When a computer needs to send data across a network …
Read More »Errdisabled – Taking Ports OFFLINE Like the MCP from TRON
Everyone remembers the original movie TRON where the character Flynn, played by Jeff Bridges, is sucked into the microscopic world of computer games. In the movie the villain was the Master Control Program or MCP who would take programs OFFLINE if they misbehaved. Switches have their own MCP (of sorts) …
Read More »Important Safety Tips and Alternatives to Cisco’s FabricPath Switches
Entering the Nexus If you have a data center or if you have any services running in a data center then at some point you may have considered Cisco’s Nexus switching platform. Rightly so, Cisco’s Nexus platform promises and delivers huge flexibility and scalability gains within the data center. FabricPath To provide this next …
Read More »There can be only one – Root Bridge
Spanning Tree and Switches are a lot like the Highlander – “there can be only one” (root bridge in your spanning tree). The process of electing a root bridge is very similar to Highlander in that switches will battle it out until one bridge is the root. And all designated …
Read More »Top Five Most Interesting Network Virtualization Technologies of 2010
Author: Andres Villalva Attending our weekly data center project meeting the other day, one of the network engineers was confronted with an incomplete action item against his name. He responded light heartedly by declaring that we were speaking to a ‘virtual instance’ of himself and that this particular instance had …
Read More »EtherChannel Configuration – Cisco WS-X6148A-GE-TX Over-Subscription
Here’s an issue than can occur when configuring EtherChannel on a 6500 series switch. So here’s the scene. You have an uplink that is constantly getting saturated due to backups (or whatever) and you need more than a Gigabit of throughput so that your network won’t be congested. No worries, …
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