Traceroute/mtr in MPLS networks

This post is not meant to be an introduction to traceroute in MPLS. There are many good resources on this topic already.

It is meant to provide a quick reference how a traceroute should look like in a healthy network and how different features might influence the outputs. Most of …

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Quick EVE-NG and Ansible lab setup tutorial

In this post I'll outline the steps required to set up a lab to play with network automation. Although it's pretty straightforward, I've had some headaches, so I thought to leave a note for future reference, and maybe it will help you, too.

Prerequisites:

  1. VMWare ESXi host
  2. Virtual machine running …
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L2 protocol tunelling (ASR920)

Sometimes when we purchase a L2 service from a service provider, we need to have our L2 protocols tunneled.

ASR920 platform gives the operator three option to choose from:

  • l2protocol tunnel
  • l2protool peer
  • l2protocol forward

Although I've been working with ASR920s for a while, I didn't have the time to …

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Constrained Route Distribution

I write this post as I go through Route Target Constraint (RFC 4364) feature. I'll try to answer below questions:

  • What problem does it solve?
  • How vendor support does look like?
  • What are deployment considerations?

Before looking into the feature, let's think for a moment how typical network involving route …

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IS-IS authentication

Here are my notes about how IS-IS deals with authentication. I'll be working on a simple network consisting of IOS XE, IOS XR and Junos based routers.

Here is reference diagram:

Reference lab diagram

Some initial checks

First, I'll start off by verifying IS-IS adjacencies on R6.

R6#sh isis neighbors

Tag 1 …
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BGP best path selection in MPLS/IP BGP VPNs

Recently a friend of mine asked a question which can be summarized as

does the Route Distinguisher of Route Target play any role in BGP best path selection in MPLS BGP VPNs?

I'll try to answer this question based on the following scenario:
Reference lab diagram
We have two PE routers running IOS …

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Service Provider multicast part 1 - Draft-Rosen mVPN

This is one of the oldest methods of implementing multicast in Service Providers core. Quite popular, but unfortunately has some serious limitations.

We will see the operation of Draft-Rosen deployment model in practice by building sample lab topology and looking how particular pieces of technology fit together. Let’s look …

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Got my CCIE number!

I'm happy to announce that on 26th Jan 2015 I passed the R&S lab in Brussels. This was a long road, but definitely worth it!

Getting to Brussels

Because my 1st attempt went smooth in terms of travel arrangements I decided not to make any changes on my 2nd …

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CCIE RS lab exam - summary of attempt 1

Introduction

After long months of study the big day has came. To be honest, I didn't feel 100% prepared, but I finally wanted to see what I'm up against. I was traveling with a friend, also 1st timer. As our lab day was Monday, we chose to leave on Friday …

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Notes on multicast - PIM Dense Mode

Overview

The shortest statement describing PIM-DM behavior is "flood and prune". We assume that every host on every network segment wants multicast traffic. Later routers can signal that they aren't interested anymore in receiving particular multicast group.

High level overview of PIM-DM operation is as follows:

  • Source starts sending multicast …
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