multicast over MPLS-core that not support multicast

[tonywen]

Hi Team

I have a question re multicast over MPLS core.The problem is the MPLS core doesn't support multicast but we need to forward multicast anyway.

The MPLS core doesn't support multicast.A customer has 15+ sites and wants to use MULTICAST between the sites.

I thought about GRE tunnel but it will require full mesh tunnels between all the routers, will it not? so for 15 sites only there will be 14 tunnel config and in total it will be too many. and if they add new site it will be a lot of work.

Can we implement hub-and spoke like architecture for multicast and create GRE tunnels from the CPEs to HQ CPE only without going full mesh? is there any limit for the number of GRE tunnels? what impact will it have on the router performance. is PIM capable of working over GRE tunnel?

Thank you very much team!

Regards

Tony

[mheusinger · Accepted solution]

Hi,

Multicast can work over GRE and this seems to be the easiest solution in your case. Make sure your unicast routing is using GRE as well then, otherwise RPF check might fail and no multicast packets will be sent.

You can use a hub-and-spoke like topology but because of RPF check you should be aware of the impacts on unicast routing, delay, bandwidth requirements and the like.

Another option to look into might be dynamic multipoint VPN (DMVPN), which was invented for IPSec tunnel full mesh. It automatically generates the full mesh of tunnels. Some investigation and lab work might be needed to setup a solution in your environment without the encryption part.

In brief: both methods - DMVPN and hub-and-spoke GRE tunnels - need some more considerations or testing and careful design.

Hope this helps! Please rate all posts.

Regards, Martin

[tonywen]

Hi Martin

Thank you so much!You rocks!

Again much appreciate your help.

Tony