Showing results for 
Search instead for 
Did you mean: 
Join Customer Connection to register!

MPLS for dummies:)


I have a couple of simple questions regarding MPLS and would be appreciate to every help:

question is:

Is it stricly necessary that CE and PE (in MPLS terms) routers are directly connected? Or is it possible to create CE-PE interconnection via Internet connection?

what I mean is, let say we have an ISP provider for datacenter network (our responcibilty) and second ISP provider for office (office's ISP responcibility). ISP provider for office will sell us MPLS services and will interconnect all our offices (may be a good idea). The question is how we should connect our datacenter network to the office MPLS network? should office ISP install new physical link to our datacenter network or we can use public ip addresses to establish a CE-PE connection?


If you have an MPLS in your WAN/LAN and your provider have MPLS for you as a service, and you want to transit your MPlS, you are looking into a CSC (Carrier Supporting Carrier) MPLS scenario. In such scenario, you will control your MPLS interconnections.

The terms PE, CE, P are more from the perspective and functionalities you are look at your devices. For example, what might be a PE for you, will be a CE from your providers perspective.

If your provider is going to interconnect all your offices on MPLS, they might be offering L3VPN services or L2VPN services. In such scenario, your datacenter, if it is in a different location as any of your offices, will be just another "office" for your provider. Now, if your datacenter is within one of your offices, a single connection might be enough for both. Maybe with more bandwidth than the others.

Hope this helps.


(BTW, there is an MPLS forum)

rate posts


>In such scenario, your datacenter, if it is

>in a different location as any of your

>offices, will be just another "office" for

>your provider.

Datacenter network is completly separate instance from office network, uses different ISP (I'm not sure if it can provide us with any MPLS service) and under different management and should use MPLS only for connection from offices.

as I understand CE is one of our routers which has some kind of connection to PE router of office's MPLS provider and don't know anything about MPLS cloud.

PE router is a router which is placed on the edge of MPLS cloud, takes "normal" traffic form CE's routers, place it into different VRF's and then sent into MPLS cloud.

If I correctly undestood you, we should ask office provider to give us something like L3VPN between one of our datacenter's router and provider's router and thus we can include datacenter into MPLS cloud?

what is L3VPN? is it e.g. GRE tunnel?


MPLS L3 VPN is a way in which the service provider do routing with the CE. This routing can be static routes, RIPv2, OSPF, BGP and EIGRP.

The provider then take this routes from the CE and tag them with the RD of the VPN instance. This allows for this routes to "travel" over the providers MPLS cloud without ever interfering with any other route from any other client or the providers network.

From the client perspective, you will see just another hop for your routing.

When a provider gives you L3VPN your routers will run regular routing with the provider and every office int the same L3VPN will receive the routes. (This is when configured in full-mesh or single import/export extended community at the provider level)



but as I said, our datacenter's provider doesn't have MPLS service. How office's provider can get our routing information?

BTW, where I can find the MPLS forum? :)



Since you are the customer you shouldn't really be to concerned about the MPLS network. Rather think of this as a point to multi point links from your office router (CE) to your other office routers (CEs). The MPLS, PEs and P routers just acting as transport medium for your data. Now that said the question is how does your datacentre currently connect to your office network?




currently datacenter has completly separate ISP, we have a VPN router and it is connected to offices's VPN router with help of GRE-IPSec.

The thing is that we want to change as less as possible in datacenter network, the best solution were to put one router and configure it as part of office's MPLS-VPN and that's all.