Tag: gns3

Reflexive Access List

Some of my readers commented on my old article about reflexive access-list with issues in the configuration. I tried it in the lab again to be sure I didn’t make any mistake in the configuration example and here I’m sharing the lab and the config used.

About Reflexive Access Lists

Extended ACLs are a special kind of extended access-lists that have limited stateful behaviour technique implemented for TCP sessions. It is better to say that reflexive access-list is simulating stateful behaviour because it, by use of ‘established’ command, is allowing TCP packets that have the ‘ACK’ bit set but not the initial ‘SYN-only’ packet. In this way, we are effectively permitting only the packets that are part of an established session.

In my prior article, I showed how this works by enabling PING from PC1 in VLAN 10 to PC2 in VLAN 20 but not the other way.

I created the lab topology in GNS3:

INE v5 Full-Scale Practice Lab1 TS GNS3 topology

Few days ago I added an article with Config GNS3 topology for newly published INE Routing and Switching Workbook v5 Full-Scale LAB1. Here’s now the topology with starting config of TS section for LAB1.

I will not insert here any of my stories today as the same article was published before but with other topology files so if you would like more info, just go to previous post INE R&Sv5 Workbook Full-Scale Practice Lab1 made in GNS3



INE R&Sv5 Workbook Full-Scale Practice Lab1 made in GNS3

UPDATE on 27 Dec 2016:
This post was updated in order to include Tom’s reply in the comments mentioning opening errors with GNS3 for MAC
UPDATE on 21 Jul 2015:
This post was updated on 21th of July 2015 with GNS3 version 1.3.7 INE  Full-Scale Practice Lab1 download. Just scroll to the bottom for download link..


Yesterday INE finally added a Full-Scale LAB in their new CCIE Route and Switching blueprint 5 workbook.
I realized this morning that you maybe don’t want to spend half of your day (like me) configuring this topology in GNS3. Better to just take it from here and start your lab right away.

In my study process for the last year I made almost all my labs from INE on GNS3. In that way I was able to run the labs for more days in a row and not think about the money I would spent on rack rentals. Of course, you will still need some rack rentals particularly for troubleshooting sessions. For troubleshooting you need preconfigured rack because if you configure those topologies by yourself there is a big chance that you will see ticket answers and that will break the point of troubleshooting study process.

All my config sessions were done on GNS3 and this one in the next few days will be also done in GNS3. If you want to spare some time and get the topology ready, up and running in few minutes you can download it at the end of this article.


Read more and download files!

GNS3 topology for INE Workbook

Now that my topology in GNS3 is exactly as in INE Workbook 1 I can share it with you if you don’t want to do all the basic configurations and connections by yourself.

After spending too much money on different rack rentals in the past few months I decided that I will definitely need to try to use GNS3 for simulating my CCIE labs. It will be the only solution if I didn’t want to spend all my money and then have no more left to pay myself trip to Cisco HQ.

GNS3 BGP topology

After one whole day of struggling with different GNS3 issues I did succeed to configure almost everything. From now I am able to use GNS3 for almost all chapters of my loved INE Workbook VOL.1 and probably VOL.2 also.

There are some things that are not available on GNS3 simulated IOS and I will try to list them below at some point. Other thing that took me some time are that the interfaces are named differently. Cisco Etherswitch Module is added to router in GNS3 order to simulate some basic switch features that is normally not available in GNS3. There is no way to use 0/0 – 0/21 port names on that Etherswitch Module. The interfaces are 1/0 – 1/15 so you cannot do nobrainer paste of config to those “switch” devices. Some serial interfaces are for example Serial 0/0 and in the workbook they are Serial 0/0/0 so this is another one. There are furthermore some other changes to witch interfaces are different devices connected but all the devices now are connected to all other devices exactly as in VOL.1 physical topology. This file down there is prepared for BGP lab chapter of INE Workbook 1. but keep in mind that it can be good for all other parts of the Workbook as the interface configuration is not changed across the Workbook 1 so you just need to modify routing to get started with other chapters.

Do the topology by yourself, you will learn more!