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Beginner

Why is mpls required?

Hi, I'm a newbie and currently learning to configure MPLS. I can't find a good explanation why I would use MPLS on my topology. I know there are lots of articles in the internet explaining about what is MPLS & how it works & how to configure it, but I cant find a satisfying explanation about why should I use it.

 

here's the topology i used in my lab:

MPLS.png

  • I've had OSPF configured for IGP between P and PE routers
  • I've had iBGP between PE1 and PE2 and advertise the attached "customer" network each other between PE
  • I've redistribute BGP to OSPF to let the P routers knows where to forward the packet for each "customer" network
  • I've had VRF running on PE to separate between "customer" network

Everything is running fine this way and I can ping between customer CE on each VRF

 

The point is, why would I add MPLS on top of this? 

 

I initially thought that with MPLS enabled I can eliminate one of the activities mentioned above, but the fact is those activities above are required to run MPLS. I know the benefit of label switching on performance perspective that it makes forwarding becomes faster but other than that, from configuration and implementation perspective, what is the benefit of implementing the MPLS command?

 

Please advise

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1 ACCEPTED SOLUTION

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Hall of Fame Guru

Re: Why is mpls required?

 

The key part of your description is where you say you redistribute BGP into OSPF so the P routers know how to get to the customer networks. 

 

The key to an MPLS setup is that you don't do that, only the PE routers need to know about the customer networks and there is no redistribution needed between PE and P routers which means the MPLS setup is far more scalable because in your setup every P router would need to know about every customer network and that was one of the limitations in provider networks before MPLS. 

 

Jon

 

 

5 REPLIES 5
Rising star

Re: Why is mpls required?

i think that is a directly connection between business.
Jaderson Pessoa
*** Rate All Helpful Responses ***
Hall of Fame Guru

Re: Why is mpls required?

 

The key part of your description is where you say you redistribute BGP into OSPF so the P routers know how to get to the customer networks. 

 

The key to an MPLS setup is that you don't do that, only the PE routers need to know about the customer networks and there is no redistribution needed between PE and P routers which means the MPLS setup is far more scalable because in your setup every P router would need to know about every customer network and that was one of the limitations in provider networks before MPLS. 

 

Jon

 

 

Beginner

Re: Why is mpls required?

Hi Jon, this is the kind of answer I need! 

Why didn't I tried this before - I removed the redist BGP command on OSPF and things are working without P router needs to know the information of customer network on its routing table!

Thanks!!! now i can sleep in peace :))

Hall of Fame Guru

Re: Why is mpls required?

 

No problem, I went through the same sort of thing when I was learning about MPLS :) 

 

Happy to have helped. 

 

Jon

Beginner

Re: Why is mpls required?

yeah, on the front page of almost all search engines that i tried, the article related to mpls always making the perception of bgp redist as prereq for the implementation of mpls... and that's where my misconception comes from :(

 

happy that i found the answer here :)

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