MPLS L2 or L3

[Bekzod Fakhriddinov]

Hi people . Stupid questions but my excuse I am not familiar with MPLS too close :) .  

1 we have 2 sites located in 2 diff countries and MPLS between them . How to detect is it MPLS level 3 or level 2 ?  

I am trying to find out do ISP see our internal ip range, as I know if its L3 so they route it too and will see on L2 they will not see . In my case i have bgp running between my and isp router and also ibgp inside.  

I saw somewhere that MPLS l2 can be deployed with  BGP too ... 

Thank you 

[Mark Malone]

Hi

mpls would be layer 2 in the core of the ISP mpls domain where its switching packets , but at the CE to PE side there would be MP-BGP shifting traffic between the PE routers and then they would speak to the P routers where it be layer 2 only , see pic below PE routers layer 3 using the MP-BGP then in core where P routers are its layer 2 switching , this is how mpls is setup as standard

you can use is-is either as below , the pics just a good physical example

• P (provider) routers are ISP core routers which don't connect to customer routers and typically run only MPLS
• PE (provider edge) routers connect to customer sites and form the edge of a VPN
• CE (customer edge) routers exist at the edge of a customer site; they have no VPN awareness
• an IGP running among all P and PE routers is used to support LDP and BGP adjacencies within the provider network
• MP-BGP is run only among PE routers
• an IGP (typically) is run between each CE router and its upstream PE router

[Bekzod Fakhriddinov]

label switching is just switching, I agree , I was meaning connection from our network to the network of the ISP , I was not sure is it L3 or L2.  The thing is if it's L3 I'd need to have SBC to run sip trunk  between sites, if L2 I don't. 

It's not clear yet.  Anyone can clear it up ? 

[Mark Malone]

usually its layer 3 using BGP CE - PE but it could be l3 wrapped in a layer 2 tunnel , that section has nothing to do with MPLS , whats your config setup on the CE side , you will be able to tell from that , you haven't supplied enough information to be able to tell you , each ISP has there own setups and design , whats your wan setup currently in cli ?

[Bekzod Fakhriddinov]

on my port connected  just public ip address and description , it connects to the 3945 I think its PE because we don't have access to it.  And I have bgp running on my router with redistributed subnets from ibgp. 

[Mark Malone]

That's a layer 3 setup then from your sidec if there is no tunnelling involved on the interface or your definitely not setting a tag under the same interface to wrap it in layer 2 , if not you have a standard Layer 3 CE  - PE BGP setup 

[Bekzod Fakhriddinov]

so it's L3  and ISP routes our internal subnets .  So i will need to have SBC to hide voice infr. 

Thank you

[Mark Malone · Accepted solution]

Yes from what you have described its a standard MPLS connection L3 between CE - PE , sorry I cant answer the voice part I don't work on SIP/voice at all so I don't want tell you the wrong thing there

[Adam Vitkovsky]

Mark,

That is actually a very incorrect conclusion.

Correct way of determining whether your SP is involved with you internal IP routing is as follows:

If on both sites you have the same subnet on the link to SP and you run BGP session directly between your CEs, then that means SP is not involved with your routing and is connecting your two sites via L2VPN service.

If you have unique subnet on the link to SP at each site and you run BGP session from CE to your SP’s PE router, then that means SP is involved with your routing and is connecting your two sites via L3VPN service.

adam

netconsultings.com

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