Fiber Optic basics

Calin — Thu, 01 Mar 2012 21:50:55 +0000

I think all network engineers touched, if not used / patched, as least one time a fiber optic patch cord. As a network engineer you might not necessarily need to understand HOW fiber optic is working. It’s there and it’s working. You just need to plug the patch cord and that that’s it.

Anyway, for [...]

InterVLAN routing using Private VLANs

Calin — Fri, 23 Sep 2011 13:04:06 +0000

Private VLANs is one possible solutions for service providers to offer secure connections to their customers and avoid inter-vlan communication in the same switched environment.

I’m sure that you heard (and most probably practice already) InterVLAN routing. When it comes to Private VLANs the routing part may be a bit tricky. Keep in mind that [...]

Would you do such things to an ISR 819?

Calin — Fri, 09 Sep 2011 10:03:41 +0000

Lucky there is a big disclaimer at the beginning of this video. Otherwise I would be tempted to test such things and then plug it in to see if it still start (at least) and run.

It’s a nice commercial from Cisco, but to be honest I feel bad for this poor device:

Interface software loop

Calin — Tue, 30 Aug 2011 08:13:13 +0000

If you ever worked in an environment where you have to deal with leased / dedicated lines provider by your SP (service provider) then you know that whenever it’s a problem on the line they request, if possible, to put a loop on the line from one end toward the other end, so they can [...]

Cisco IOS release naming

Calin — Mon, 11 Jul 2011 13:42:26 +0000

Most probably you already know this, but for those who are interested, here is a list of the letter definitions for Cisco IOS release trains. In more human terms, if you have loaded an IOS image like c2900-universalk9-mz.SPA.150-1.M5.bin, what those letters (in this case SPA) mean:

A = Aggregation/Access Server/Dial technology B = Broadband C [...]

How to connect Vyatta to Cisco using VirtualBox and GNS3

Calin — Tue, 17 Aug 2010 10:40:28 +0000

“Vyatta is a software-based, open-source, network operating system that is portable to standard x86 hardware as well as common virtualization and cloud computing platforms. By deploying Vyatta, users benefit from a flexible enterprise-class routing and security feature set capable of scaling from DSL to 20Gbps performance at a fraction of the cost [...]

Cisco 2900 – Interface related chassis modification

Calin — Mon, 09 Aug 2010 11:41:50 +0000

The Cisco Enhanced EtherSwitch Service Modules seen above, expands the router’s capabilities by integrating Layer 2 and Layer 3 switching feature sets identical to those found in the Cisco Catalyst 3560-E and Catalyst 2960 Series Switches.

The new Cisco Enhanced EtherSwitch Service Modules are the first modules to take [...]

Cisco IOS: single user access in CLI configuration terminal

Calin — Wed, 07 Jul 2010 10:00:17 +0000

Usually big companies with large network have a dedicated department which deals with all the network configuration. The problem that I have in mind is when this department is splitted over large geographical areas (e.g. some colleagues in Europe, some in Asia and some in America) it may happen that more than [...]

Cisco: Use TTCP to test together with TTCPW or JPerf

Calin — Tue, 27 Apr 2010 13:27:26 +0000

In one my previous posts, I shown you how to test a connection using a hidden Cisco IOS tool called TTCP. A few days ago I run into an issue. I had to test a TCP connection to [...]

Cisco tips: Track down communication issues – Part 2

Calin — Tue, 16 Mar 2010 11:58:12 +0000

In the 1st Part of this series, I’ve described the most common steps that you should follow to troubleshoot a total lack of communication between a Layer 2 device (Cisco switch) and an end user connected device. As I [...]

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