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New Member

Inter-AS or CSC

Hi All,

I have a probelm on hand, can someone here advise.

Am designing a medium size MPLS network. And the MPLS service is spread in different regions.Now this SP doesnt own a MPLS backbone. So need a Transit MPLS service provider. Now the question is what is the best method of recommending a solution. Whther Inter-AS transit service method or CSC method.

Typical Topology,

SPA - PoP1 <=====>Transit MPLS<====> SPA - POP2

This transit MPLS should be via CSC or inter=AS method.

can someone help me with the pros and cons for each method.

Thanks in advance,



Re: Inter-AS or CSC

I would suggest CSC, simply because for any VPN's you configure the transit provider is totally transparent to you as it is an overlay VPN.

Re: Inter-AS or CSC

Hi Jasvinder,

1) The deciding factor would be what Transit support the provider in your region is currently offering. Having said that technically the options can be evaulated.

2) CSC Restrictions:


Carrier supporting carrier traffic engineering

Carrier supporting carrier class of service (CoS)

RSVP aggregation

VPN Multicast between the customer carrier and the backbone carrier network


So you can verify what are your client requirements, based on that keeping in line the restrictions as per point 1 and 2 you can go ahead with an appropriate option.



New Member

Re: Inter-AS or CSC

yes i agree too, before the technical comaprision, first thing which is important is what transit the existing providers are giving.

then also i have to consider the mcast part as well, as it is a important service.

thanks for your time all...




Re: Inter-AS or CSC

you have a few other issues as well. What IGP are you running? Hope its OSPF as ISIS is a no no in a vrf (apparently it is there but i still havent seen code that supports it). Also on the multicast front - MVPN within a CSC environment is fine - i tested that a good few years ago and works absolutely no problems.


Remember that with CSC the routing table that the SP takes is your IGP, that is it the SP has no knowledge of the thousands of vrfs. ALSO some SPs will not do such an interface due to the inability to hide their core hops (the no mpls ip propogate-ttl command has no affect in CSC envronment - this is being sorted tho).


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