Tag Archive

CCIE Lab Tip: Multicast Troubleshooting using mtrace

Published on February 24, 2012 By Daniel Rodriguez

We are going to start doing some quick post about tips for the CCIE lab, to start with the series of post, I’m going to describe the use of one command that I found very useful and indispensable for the troubleshooting of multicast networks but one that not too much people know or use: mtrace. […]

Scale Fail

Published on May 4, 2011 By Jose Leitao

This is a presentation from Josh Berkus called Scale Fail given at the O’Reilly MySQL CE 2011 that goes into detail on how building “scalable” applications and services can go very wrong (thanks Ivan for the link) Jose LeitaoJose has been working in the IT industry for the last 10 years, he holds the following certifications: CCNP, […]

How to use Perl to connect to your devices and save the day

Published on April 25, 2011 By Daniel Rodriguez

Today I want to write a little bit a about a non-CCIE topic, but a useful one if you are into the network administration arena, and that is “how perl (or scripting in general) can save your neck/network” Almost a year ago I had a problem, it was a Cisco IOS bug that made the […]

Troubleshooting GRE Recursive Routing

Published on February 7, 2011 By Jose Leitao

Imagine you have to troubleshoot a couple of routers that constantly show the following messages: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 192.168.0.3 (Tunnel13) is up: new adjacency %TUN-5-RECURDOWN: Tunnel13 temporarily disabled due to recursive routing %LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel13, changed state to down %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 192.168.0.3 (Tunnel13) is down: interface down The key […]

Review :: Routing-Bits Handbook for Routing and Switching (formerly RS Short Notes)

Published on January 24, 2011 By Jose Leitao

Preparing for the CCIE or just going through our day-to-day work, we all tend to write notes, some better than others. I know folks who have pages and pages filled with notes on things like docs.google.com, notepad, flash cards or Gmail drafts. Why do we write them? The notes allow us to recall quickly and […]

Troubleshooting OSPF network type mismatches against a Backbone device

Published on January 9, 2011 By Daniel Rodriguez

I’m going to start with an interesting troubleshooting scenario that can be very tricky to diagnose. Let’s imagine a ticket that is worded like this: “R2 lost the prefixes to the networks behind the backbone, find the problem and fix it. At the end of this ticket, R3 should be able to ping BB1 redistributed […]