Same subnet MPLS connectivity

[Nikhil Patil]

Hello,

           As per following senario;  I want to connect two same subnet (192.168.0.0/16) network using MPLS, Is it possible or not..If possible then please suggest me respective configuration.

Thanks,

Nikhil...

[rsimoni]

I can't see the 2 192.168.0.0/16 subnets in your topology. I could see a 192.168.0.0/16 and a 192.168.44.0/16 which are 2 distinct subnets, but I am unsure whether you were referring to them.

Anyway in general if for MPLS you are referring to MPLS VPN you cannot have overlapping subnets within the same vrf as each PE is supposed to advertise only the subnets which reside behind it, or else routing loops will occurr.

If 2 sites have the same addressing, AND YOU CANNOT ALLOCATE A NEW SUBNET TO ONE OF THEM (this is the best option) you need to use NAT and translate of of them into something else.

If you ar e referring to something else instead please elaborate your post.

Riccardo

[Nikhil Patil]

Hi Riccardo,

                I am using /16 subnet so 192.168.0.x  and 192.168.44.x  are in the same subnet range.

If i am wrong then please clearfy and tell me is it possible to configure on respective subne.

Nikhil.

[rsimoni]

Hi Nikhil,

obviously you are right... for some reason even though I was writing /16 my mind was understanding the mask as /24 (therefore 2 different subnets).

For your problem you either make them /24 subnets, (or equal/bigger than /19) or you use NAT.

In general I don't understand the use of having the same subnet across 2 different sites... are you working on a way to merge 2 existing networks?

Alternetively if you have the resources you can use L2 VPN services to connect the 2 sites and extend the same subnet across the 2 sites (i.e. AtoM).

Riccardo

[Nikhil Patil]

Hi Riccardo,

         I can not change subnet thats why i need configuration for same subnet connectivity.

         You talked about L2 vpn means Lan to Lan vpn (Site to Site). How can i extend same subnet across the 2 sites.

Nikhil.

[rsimoni]

Hi Nikhil,

I was referring to some L2VPN technology which can help you extend your vlans across an IP or MPLS backbone.

L2TPv3 (for IP backbones) or EoMPLS (subset of AtoM) for MPLS.

See for reference:

for L2TPv3 http://www.cisco.com/en/US/docs/ios/12_3t/12_3t2/feature/guide/gtl2tpv3.html

or

for AtoM

http://www.cisco.com/en/US/products/ps6646/products_ios_protocol_option_home.html

You need to match some specific hw/sw requirements for those technologies.

Riccardo

[Nikhil Patil]

Hi Riccardo,

              Thanks for your suggestion.

Nikhil..