MPLS configuration process with ISP

ajay kondapalli · ‎01-05-2011

Hi,

Can any one clarify my doubts regarding MPLS config generally done for corporate networks.

Generally if a corporate company takes MPLS from any service provider, I heard that mostly we use BGP as routing protocol for mpls which is called MP -BGP. We need to work with service provider for completing configuration part and establishing neighbor relationships with ISP routers.

I think , ISP will give us some AS numbers to be configured on our routers. we need to configure that AS number and IP addresses on our routers in BGP processes. Later my doubt is do we have to configure MPLS commands on our router interfaces ? or will ISP do that part assuming their routers as Edge routers.

Does Label assignments start at ISP routers or at corporate routers ?

How are the labels allocated to customer networks by ISP in MPLS?

Don't we need to bother about MPLS config part, is it sufficient if we configure BGP part and map our exit path to ISP .

Please explain.

Thanks,

Ajay.

Peter Paluch · ‎01-05-2011

Ajay,

Generally if a corporate company takes MPLS from any service provider, I
 heard that mostly we use BGP as routing protocol for mpls which is 
called MP -BGP.  We need to work with service provider for completing 
configuration part and establishing neighbor relationships with ISP 
routers.

That is one way of doing that. Another possibility is to use any existing IGP protocol - RIP, OSPF, EIGRP, even IS-IS. That depends on what the ISP decided to do.

I think , ISP will give us some AS numbers to be configured on our 
routers. we need to configure that AS number and IP addresses on our 
routers in BGP processes.

Yes. You will need to configure your routers according to data your ISP gives you, including BGP AS number (it is possible that the number will be from the private range 64512-65535).

Later my doubt is do we have to configure MPLS commands on our router 
interfaces ?  or will ISP do that part assuming their routers as Edge 
routers.

You are not going to run MPLS. The MPLS is used and seen only on ISP routers. Your routers will not use MPLS. Also, no MPLS will be run between your and ISP's edge routers. The MPLS is purely the stuff of your ISP and you do not need to care about it at all.

Does Label assignments start at ISP routers or at corporate routers ?

On ISP routers.

How are the labels allocated to customer networks by ISP in MPLS?

By an automated process not manually controlled by the ISP - usually as a sequential numbering of routes received from a customer.

Don't we need to  bother about MPLS config part, is it sufficient if we configure BGP part and map our exit path to ISP .

Yes, you do not care about MPLS at all. You just configure the BGP to make a BGP peering with your ISP and advertise your corporate networks to the ISP. Everything else is your ISP's business.

Best regards,

Peter

ajay kondapalli · ‎01-05-2011

Thanks Peter for your quick response.

Why are we allocated AS number in the private range. Is it not a problem for routing private AS numbers over internet. Generally if we take leasedlines also, ISP will give a public ip to configure on our routers . (point to point) Then what is the exception here coming to BGP. Why are we getting private AS numbers ?

If we use OSPF or EIGRP as IGP, does ISP redistribute our routes at his end?

You said that some automated process will take care of Label assignment for customer routes . Where does it happen ? on ISP router ? If so in what form ? is it VRF ? can you give me more info on this ?

Like other connectivities, does ISP give us any means of checking tool for MPLS working efficiency for customer, i mean any graphs or such things to monitor links how they are functioning ?

Thanks,

Ajay

Peter Paluch · ‎01-05-2011

Ajay,

Why are  we allocated  AS number in the  private range

It is because you do not need any unique AS. You are not a standalone AS, rather, you are simply a part (a customer) of your ISP. You will either use your ISP's AS number, or you will be assigned a private AS. If you are assigned a private AS number, your ISP will take care of removing that private AS when - and if - it advertises your company networks to other providers and out to public internet. If you are purchasing only an MPLS VPN service then your company routes won't probably be advertised to public internet, in which case having a unique AS number would be completely useless.

If we use OSPF or EIGRP as IGP, does ISP redistribute our routes  at his end?

Yes, the ISP takes care of redistributing the IGP into his BGP.

You said that some automated process will take care of Label assignment 
for customer routes .  Where does it happen ? on ISP router ?   If so in
 what form ?  is it VRF ? can you give me more info on this ?

Yes, the ISP will create a VRF on his PE routers where your company is connected. Each network learned from your company and stored in the VRF will be assigned a unique label value and advertised to other PE routers via BGP. This unique enumeration of entries in different VRFs is performed by the IOS running on the PE router.

Like other connectivities,  does ISP give us any means of checking tool 
for MPLS working efficiency for customer, i mean any graphs or such 
things to monitor links how they are functioning ?

I do not know about this. You have to ask your ISP.

Best regards,

Peter