MPLS QOS EXPERIMENTAL BITS
September 7, 2013 2 Comments
Hi All,
After the first unsuccessful CCIE R&S lab attempt in Belgium in my last post I said I was having a little trouble with the MPLS VPN configuration and it most certainly was not because I did not know what ingredients were necessary in order to configure the tunnel between the sites but because the way Cisco asked me to configure it and manipulate the traffic , it made me think really hard for a long while during the exam (almost 1hr) and it cost me very dearly in the end ! 
Below topology is from INE SPv3 (Service Provider) video series with Brian McGahan who I’m sure we all know and love to listen to.
This is how it is presented to us in GNS3
GNS3_NET_FILE : MPLS_QOS_NET_FILE
GNS3 INITIAL CONFIGS : impls_initial_configs
Cisco 12000 series router’s XR_1 and XR_2 are simulated by 3745 routers – these devices are not supported in GNS3 so rack rental is a must. 
Some of you might be asking yourself right now why would I create a post that revolves around MPLS QOS ?? Well , short answer is “be prepare to get stuck in your lab exam ” because even if you get really simple MPLS requirements , they will definitely confuse you with something else. CCIE lab as we all know is not about best practises and myself having finally experienced it , it is miles away from there , it is about whether you can accomplish given task and meet the requirements or not !
One more thing , make sure you experiment with as many commands as possible (some of the I’ve listed below) and understand how they work and affect the network because even if you manage to get your MPLS VPN Tunnel up and running but you do it not how they asked you to , you will fail the whole section !
mpls ldp router-id Loopback0
mpls ip propagate-ttl
mpls ldp autoconfig
bgp default ipv4-unicast
address-family vpnv4
address-family ipv4 vrf
redistribution within MPLS backbone – especially when you have two different IGPs running inside where you first have to correctly redistribute between them in order to make you BGP/MPLS operational then most likely you will need to do some more redistribution between PE-CE to make it all work !
In summary – MPLS is intense , it is great fun though !
Enjoy !
Tom
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Tom G CCIE Blog 
Hi Tom,
I am a subscriber to your blog and definitely get regular mails regarding your posts.
I am impressed with your skill and especially hard work that you put in to learn the technology from its root up. I feel bad you could`t clear the exam.
But you know for clearing it, you need to know the content beforehand. Practice it and perform in the exam. Thats how it is supposed to be. You can go to a number of websites where people discuss the content of the exam.
Its good to know the concept in detail (like you) but still better to know it and clear the exam also.
Thanks
Hello Ashwani,
Thanks so much for the comment, much appreciated.
The thing about the CCIE lab is that as soon as you leave the exam centre you start thinking to yourself “how the hell did I manage to fail this?”
What I mean by that is , you never know what questions you are going to get in your lab but the exam is more than doable.
In my case it definitely was mpls that took me way to long resolve. I was expecting some simple mpls vpn tunnel to be configured but Cisco went way beyond that and it seems like literally “expect an unexpected”.
On the other hand the other candidate who was taking the R&S exam same day as I did , after the exam he told me that he did not get mpls at all but instead they grilled him on spanning tree and bgp where in my lab these topics where pretty simple so the point is we’ve got to know it all !
The best thing about failing is that you push yourself to practise and learn more what in the end will help you become the best !
Best Regards
Tom