Service Provider Implementation - MPLS vs. VLAN

[CSCO12801420]

Hi All,

Thanks for the great forum !!

I'm currently in a small size ISP and is studying MPLS and the implementation thereof. Apologies if I ask a simple
questions, but I want to be able to understand the concepts/implementation of MPLS in the ISP infrastructure.

MPLS is as I understand it 'node' (site so site) tunneling (VRF), which is switched through using labels that are inserted in packet headers
encapsulating each packet respectively with unique identifier. This allows different clients using same subnets without causing routing
problems within the ISP infrastructure.

My questions are as follows:
1) Why would one use MPLS for site to site VPN services and not use a VLAN from one site to another (either through QinQ or single) ?

2) If L3 VPN is required why not just implement a IPSec Tunnel from local to remote or vice versa ?

3) If MPLS is implemented with VRF's but they not only require inter site connectivity but also /26 public addresses to be routed out, how would
an respective ISP implement this ?

Thanks !!!

P

[Julio E. Moisa · Accepted solution]

Hi

It will be a pleasure to assist you with the questions.   :-)

1) Why would one use MPLS for site to site VPN services and not use a VLAN from one site to another (either through QinQ or single) ?

MPLS is a protocol to transport packets from one node to other or between multiple nodes using labels, it is not a static site to site VPN, MPLS is flexible and scalable mechanism to transport data. It can transport many kind of services over the same infrastructure. You can implement MPLS Layer 3 (Using MPBGP) or Layer 2 VPN (EoMPLS, VPLS, H-VPLS) 

2) If L3 VPN is required why not just implement a IPSec Tunnel from local to remote or vice versa ?

IPSec is just a secure method to protect data. MPLS L3 VPN like MPLS L2 VPN are mechanism to transport information between one to one nodes or between multiples nodes. Is important to understand the components and the function of each component of a MPLS Layer 3 VPN.

3) If MPLS is implemented with VRF's but they not only require inter site connectivity but also /26 public addresses to be routed out, how would
an respective ISP implement this ?

Please correct me if I understand wrong the question, basically VRF is to create separate virtual instances, you could have 2 clients using the same networks and being routed on your devices, VRF will isolate them and not overlapping will be generate because each client will have different routing tables. The client prefixes size are independent of the ISP. If the client just want connection between 2 sites only, you could implement EoMPLS but if the client will growth and have multiple site I recommend evaluate use VPLS or HVPLS or include them into your MPLS Layer 3 VPN. 

This link provide more details about MPLS Layer 3:

http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/mp_l3_vpns/configuration/15-mt/mp-l3-vpns-15-mt-book/mp-cfg-layer3-vpn.html

Also I recommend a the following book: 

http://www.ciscopress.com/store/mpls-fundamentals-9781587051975

Hope it is useful

:-)

[CSCO12801420]

Thanks so much Julio Moisa

Hopefully I will also contribute on these forums in the future :)

[Julio E. Moisa]

It was a pleasure my friend  :-)

I'm sure you will 

Have a great day.

:-)