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,

I still have one doubt on PIM-SSM for Default MDT. It was calrified by Hritter and shivlu that if we use PIM-SSM for default MDT, there will be still flodding.

But now say i have 5 P E part of VPN, and use Default MDT so i will have 5 (S,G) entry where source will be each 5 PE loopback and G will one Default MDT Multicast group.

Now i still fail to understand that say PE1 send join (S,G) to PE2 or it is alwasy that PE1 will send (S,G) to all reset PE in Default MDT and Multicast traffic will be flooded. If there is an still traffic flodded , it would be tradeoff to maintain so many (S,G) entry. right ?

Regards,

Chintan

[Harold Ritter]

Chintan,

You will have one (s,g) per PE whether you use ASM or SSM for the default MDT. With ASM, PEs will first join the RPT (*,g) but will switch over to the SPT (s,g) right after by default.

If you use SSM, then PE1 for instance will send a (s,g) towards all sources that have been learned via BGP MDT SAFI for a specific VPN (specific RT).

The multicast control traffic is always flooded to all PEs that have joined the default MDT.

Multicast streams are sent to all PEs that have joined the default MDT by default.

Multicast streams are sent to PEs with interested receivers if data MDT is configured and that the threshold has been reached.

This is regardless of whether you use SSM or ASM.

Regards

[chintan-shah]

Hi Hritter,

Thanks for very good explanation on Multicast control and stream flooding in Default MDT regardless of SSM or ASM.

As you told by default with ASM, Recevier PE will switchover to STP (S,G) and i think that can again creat loads of (s,G) so i belive that it would be recommonded to keep SPT threshold infinity for ASM and keep (*,G) only state and for higher traffic switchover to DATA-MDT by configuring apprporiate threshold to defind higher traffic.

Do you agree ?

Chintan

[Harold Ritter]

Chintan,

Disabling SPT switchover might be a way to scale. If you really have lots of PEs, a better way might be to use PIM Bidir for the default MDT. PIM Birdir will require one (*,G) per default-MDT (per VPN), which can help tremendously when trying to scale to a very high number of VPNs and PEs.

Regards

[chintan-shah]

Hi Hritter,

Thanks. PIM Birdir is supported on all platform ? like 7600, 12K,7200. These are the platform used by PE and CRS & 12 K as P router in network.

I read some of documents but still PIM-Birdir is not being used most extensively in SP network considering reliability. What is your opinion on this ?

Regards,

[Harold Ritter]

Chintan,

PIM Bidir is supported on all platforms you mentioned. It has been available for quite a while now. Again, bear in mind that JUNOS doesn't support it.

Regards

[chintan-shah]

Hi Hritter,

Thanks for clarification and further information on Juniper. It is really pitty that Multicast is quite tough in multivendor enviroment as other vendor like juniper doesn't support best one..like PIM-BIR, PIM-SSM ..

But any way thanks for clarification. It is good Info.

Regards,

Chintan

[chintan-shah]

I mean Juniper doesn't suport PIM-SSM for Default MDT and BGP MDT SAFI so that SP can have PIM-SSM in Core :-).

[Harold Ritter]

Chintan,

Well, as it is always the case when working with multiple implementations, you need to determine what the lowest common denominator is and make the best of it.

Regards

[chintan-shah]

Hi Hritter,

You are very true that have to determine lowest common denominator and make the best of it.

I was going through one white paper of Juniper mVPN and they proposed NGMVPN ( Next Gen MVPN) and also explain benefit of NGMVPN over draft-rosen implementation. I think NGMVPN is driven by IETF. Does cisco support that ?

What is RFC/Draft for NGMVPN mentioned by Juniper ??

Here is white paper, I am talking about :

http://www.juniper.net/solutions/literature/white_papers/200291.pdf

Regards,

Chintan

[Harold Ritter]

Chintan,

This is currently at the draft level and there seems a lot of divergent opinions on where that should go. It might take a while before we get interoperable implementations. Meanwhile, draft Rosen is interoperable and widely deployed. I think the choice is clear, at least for now.

Regards

[Mohamed Sobair]

The Data-mdt has been introduced to support High Multicast Bandwidth by creating Groups On demand based On a Bandwidth threshhold.

Cisco recommends using 232.239/16, Once a customer reach certain threshhold and there still bandwidth in demand, then another Group is dynamically created from the Range.

and Yes, Since its not a point to point Multicast tunnel interface, There will be 5 Sources entry for each PE. Think of it like mGRE. Why? it will provide redundancy within the provider Network to carry multicast traffic and it has to track each PE in the (P Network).

HTH

Mohamed

[shivlu jain]

Chintan

I want to add one more point in the mohamed post. The data mdt groups are limited to 256 if you are having data mdt customers PE more than 256 at that time the the least used group will be replaced.

During design process it should be considered.

regards

shivlu jain

[chintan-shah]

Hi Shivlu,

Do you mean 256 group per customer ( i.e mVRF ?) or per PE ( i.e number of customer)?

Regards,

Chintan

[chintan-shah]

Hi Guys,

I have one question. In case i use anycast, i understood that i don't need MSDP as per RFC4610.

How does each RP knows source from other RP ?

REgards,

Chintan