Question on Multicast VPN

[chintan-shah]

Hi,

In service provider to provide Multicast VPN to customer, they run PIM-SM or PIM-SSM. PIM-SM for default MDT.

PIM-SM require RP and i learnt that best to use Anycast RP.

Now, I have 13 locations having P route connected to form core. Do i need to run Anycast RP on each core local to location and run MSDP between them to exchange SA?

What should be best solution to support PIM-SM in Core for Multicast VPN on MPLS network ?

I guess, Custoemr RP,MSDP would be under VRF instance for each customer.

Please correct me if i am wrong , can suggest any good document.

Regards,

Chintan

[chintan-shah]

Hi,

Thanks for clarifiation. So only advantage i get is i dont need to use any RP, MSDP etc on P router..

Any other benefit of SSM (default MDT) vs. SM ( default MDT) ??

[Harold Ritter]

Chintan,

This is the only advantage as far as I can think of. But in my view, the fact that you don't need to support an RP infrastructure simplifies things quite a bit.

Regards

[chintan-shah]

Hi Hritter,

I agree that It would at least simplifies RP Infrastrcture...

BTW,Is there any SP who only runs DATA MDT ? I would doubt because that will require loads of number (S,G)states on Core , almost = Number of VPN X Number of MC per VPN X Number of PE Per MC reciver unlike Number of VPN X Number of PE for Default right ?

Thanks agian.

Regards,

Chintan

[shivlu jain]

hi hritter

thanks for your links.

chintan:- What i think if we ssm instead of sm one major advantage which we get in ssm is that no more flooding of join or register for PE which really save lot of processes. Another adavantage is that in case of Anycast msdp flooding occurs every 180 sec whether it is having new sa or not but in case of ssm it doesnot happen.

In ssm what i feel bad is that you cannot use ip pim spt thrashold infinity because there is no *,G entry. As per me if you are desiging a proposal for financial trading company which is having lot of groups then you might go with anycase becasue in that you use ip pim spt threshold infinity.

regards

shivlu jain

[Harold Ritter]

Shivlu,

Even if you are designing a proposal for a financial customer with thousands of states, these states will not be seen in the SP core (P-Domain), which is really the upside of mVPN.

Regards

[Harold Ritter]

Shivlu,

One more thing, you are correct about the register messages but the periodic PIM join messages are still being used in SSM mode.

Regards

[shivlu jain]

Hritter

As per me there should not be periodic pim join messgages in the SSM mode. In SSM source is my MP-BGP loopback address and groud will be mdt.

Correct me if i am wrong.

regards

shivlu jain

[Harold Ritter]

Shivlu,

SSM uses PIM-SM with a few modifications. RFC4601 section 4.8.1 defines the modifications to the PIM SM protocol to support SSM. Beyond these modifications, all normal PIM SM functionality and messages are required, including periodic join messages.

http://tools.ietf.org/html/rfc4601

Regards

[shivlu jain]

thanks hritter; Now I am more cleared about SSM.

regards

shivlu jain

[Harold Ritter]

Chintan,

The default MDT is required for control plane communication between the PEs (PIM messages between the PEs). It is also through that the more data MDT you have, the more states as well. There is a trade-off between the more efficient of multicast traffic and the number of states.

Regards

[chintan-shah]

Hi Hritter, Sivlu,

Thanks for your extensive help. It might be possible that we go with PIM-SM( Default MDT) and PIM-SSM( DATA MDT) due to multivendor enviroment.

We also have one requirment to have Inter-AS mVPN as we are already running Inter-AS VPN.

Now, we run RP on our some of few coure router. In case we want to go with Option B for Inter-AS mVPN , we will need to do MSDP with our partner to share SA message.

Question is : Since we plan to run MSDP on Core, how do we establish MSDP with Partner ?

We will use one ASBR to connect to partner so can we get all MSDP from core to ASBR and then run MSDP with partner ?

I also see in opton-B they talk about SSM and BGP MDT SAFI but in case i don't run PIM-SSM in core for default , will option B supported with PIM-SM ??

Thanks in advance for your help,

Regards,

Chintan

[chintan-shah]

Hi,

I could find out from other thread where you guys have given your feedback on inter-AS.

I understood that it is better to go with Option-A -back to back VRF if i don't ahve PIM-SSM in Core for default & data MDT both this is due to fact that still mutlivendor support for PIM-SSM in core not avilable.

Please correct me , If I'm wrong.

Regards,

Chintan

[Harold Ritter]

Chintan,

This is correct. For interoperability between vendors you need to go with either option A or C. A is the simples by far.

Regards

[Harold Ritter]

Chintan,

Option B means no ipv4 route exchange between the two ASes (except for the MDT SAFI), only VPNv4. Again, I will not be able to get option b to work in a multi-vendor context. You will need to go to either option A or C.

Regards

[Mohamed Sobair]

Hi,

Cisco Highly recommend the use of Data-mdt to optimize multicast traffic and 2 support high bandwidth multicast application uses SSM.

Multicast using NBMA Access:

This solution creates MTI , unlike GRE tunnel , this is not a point to point tunnel, this tunnel Tracks the remote PE and unicast the multicast packet to the remote PE.

PEs Signal the Use of Data-mdt via udp port 3232 , Only CEs intend receipent of Data Join the group.

The Default-mdt is used to forward pim control messages.

a Unique Group per each customer is required, a unique Source is also requires , this Source recommended to be the Looback address of the Origination BGP Session ID.

Only a Single Mvrf per customer is supported.

The Provider facing customer Interfaces should be configured with (Pim Sparse-dense mode) , This will make sure all customer Pim Control messages and bootstrap messages are forwarded.

The PE facing P Interfaces should be configured with (Pim Sparse-mode) since its the only Pim mode supported , Pim Bidirectional will be supported once it proves stability.

The RPF check is performed a gainst the MTI (The Origination BGP session Id).

The Provider Network is completely transparent to the customer multicast traffic.

So, a customer can use any Pim mode, Only PEs has to be a customer CE pim neighbors.

For the Provider Network (P or PE) devices, you dont need to run Anycast RP or MSDP, since its a single AS.

Anycast RP would provide redundancy and loadsharing capability for the Provider Network.

HTH

Mohamed