mVPN default to DATA MDT

Unanswered Question
Mar 18th, 2009

Hello ,

I have one confusion on switchover from default to data mdt for mVPN.

Say Singe Multicast source is sending Multicast stream to more than 1 Multicast group.

Now when i configure threshold to swithcover to DATA mdt on VRF at PE and if say traffic from source for one of the multicast stream cross threshold, will it switchover to data mdt for only that Multicast Group and soruce ( S,G) and for second multicast group it will be still default MDT. right ?

so threshold would trigger for each Multicast group not for one source ?

Also i configure threshold for burst traffic and burst could be for some microsecond, will it have switchover to Data MDT ?



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Harold Ritter Wed, 03/18/2009 - 08:03

Hello Chintan,

By default a different data MDT would be started for each (s,g). The threshold therefore applies to each (s,g) individually rather than to all of the multicast streams in a specific VRF.


chintan-shah Wed, 03/18/2009 - 08:10

Hi Hritter,

Thanks. It means that single source sendign traffic to two MC Group and i can still have Default MDT for one group and DATA MDT ( based on threshold) for second group from same source. right ?


shivlu jain Wed, 03/18/2009 - 08:22

Hi Chintan

For mVPN always there will be a one default mdt which is mandid and data mdt will be created on the basics of the threshold.


shivlu jain

chintan-shah Wed, 03/18/2009 - 21:59

Hi Shivlu,

That's correct. I was little confuse on how threshold will trigger, now it is clear to me that it is always (S,G) based as explained by Hritter.



Harold Ritter Wed, 03/18/2009 - 08:47


That is correct. In the same way, you could have two sources sending to the same group and one would be sending via a data MDT and the other via the default MDT. The decision to switch between the default and data MDT is made independently based on (s,g).


chintan-shah Wed, 03/18/2009 - 22:02

Hi Hritt,er,

Thanks for clarification. Now, I am clear on this.

on other note, we have IP MTU 1500 in our core network, do we need to change this across core to take care of 24 byte GRE overhead when MDT is created ?

Because it might happen customer send Packet with 1500 byte, as far as customer has packet with less than 1476 it should be fine.




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