Introduction to MPLS

(Nyein C) #15

Hi Rene,

Please some posts for L2VPLS on IOS-XR and XE.


(John S) #16

Hi Rene,

Thank you for the great lesson. I am only confused about what are the benefits of using MPLS over GRE tunnel?




(Rene Molenaar) #17

Hi John,

It has many advantages, this will become more clear once you have seen some of the other MPLS PE-CE lessons.

One issue with GRE tunneling is that it’s not a scalable solution. You have to create static tunnels between each pair of PE routers that we use…not a good idea.


(John S) #18

Thank you Rene!!! well explained!!



(Praveen Kumar K) #19

Hi Rene,

what ever we do with the MPLS VPNs and IPSEC VPNs and SSL VPNs is it same.

little confused though I did not understand the security VPNs clearely. need to go through again

(Rene Molenaar) #20

Hi Praveen,

These are different topics with different solutions. First of all, keep in mind that VPN is often used to talk about encryption / authentication / security but this is not always the case. Even a VLAN could be considered a VPN, it’s “virtual” and a “private network”.

Let me give you a quick overview in a nutshell:

  • MPLS VPN: we use this for connectivity. service providers offer MPLS for remote connectivity. For details, check the MPLS material. The "VPN" part of MPLS is that we use VRFs to separate customer routing information and we create unique VPN routes.
  • IPsec VPN: There is no security at all on the network layer, IPsec is a framework that takes care of this.
  • SSL VPN: This is a VPN on the application layer, it's typically used with web browsers so that you don't need any client software on your computer. Take a look at this example that I created with the ASA firewall.


1 Like
(Praveen Kumar K) #21

Thanks a lot for the great info


(bridget e) #22

Good stuff, Rene’. I’m still working through deciphering the forwarding-table output, but we’ll see…

(Akram E) #23

After using mpls instead of GRE do we still need IGP since mpls already use ip in the network layer. Is it possible to use mpls without igp.

Thank you for your support.

(Rene Molenaar) #24

Hi Akram,

I think you refer to the PE-CE scenarios? In that case, you can’t:

  • We use MP-BGP to advertise VPN routes between the PE routers.
  • We establish the iBGP neighbor adjacency with loopback interfaces.
  • We use an IGP to advertise the loopback interfaces.

We still need an IGP there.


(elbert s) #25

Hi Rene,

I am getting the same result but the output format was a bit different than yours in this lab, may I know what is the router platform and version you use?


(Rene Molenaar) #26

Hi Elbert,

I used IOS routers in Cisco VIRL for this. These run IOS 15.x, it’s possible that routers running IOS 12.4 will have a different output for some show commands.


(Nasim S) #27

Hi Rene,

1st question, PE router is connected with a P router. We always talk about redundancy. Now, in this case, if P router is down then PE router can’t reach to it. How does SP solve this issue?

2nd question, do you have any plan for Nexus DC lessons?

Thanks and regards,


(Rankit T) #28

Hi Rene,

These are very good but do you think you can create some videos as well and put it here so that its easier to listen while driving back home and understand the concepts. Thank you.


(Rene Molenaar) #29

Hi Nasim,

In a real MPLS network, you will find redundant P routers in the core. In my examples, I try to use the minimum number of routers to explain something, to keep it simple. Nexus material is definitely something I am going to work on.

@Rankit I will add more videos yes.


(Surinderpal S) #30

hii Rene …your lessons are awesome…can you please add topics like
1)route-reflectors in MPLS network
2)hub and spoke topology in mpls
3)Ways of internet access in VRF’s

(Rene Molenaar) #31

These are good topics indeed. I’ll add them in the future.

(Garrett F) #32

Hi, Rene

I had some issues with the first GRE tunnel configuration. I even inputted a static route on PE1 and 2 for traffic to use tunnel. Trace route would then work, but not ping. The MPLS config worked perfectly and you had great explanations above for it. Thank you!

(Garrett F) #33

Why does MPLS help so much with reliability and latency?

(Rene Molenaar) #34

Hi Garrett,

Theoretically, label switching is faster than IP forwarding. About ~15 years ago that might have made a difference but nowadays, this doesn’t matter much.

When you use MPLS, you use a private network from the service provider which is far more reliable compared to a “regular” Internet broadband connection.

Internet connections don’t offer any QoS, it’s all best effort. MPLS does support QoS which ensures that delay sensitive traffic (like VoIP) is forwarded before other traffic.