01-28-2011 02:42 AM - edited 03-04-2019 11:14 AM
Hi peps
I am need of a little assistance. I am woring on a kludge to get multicast to work over our BT MPLS WAN. BT do not support multicast on our WAN service so I am thinking of using a few GRE tunnels to 'hide' it from them.
We opperate a fully MPLS LAN environment over multiple sites connected by a BT MPLS WAN service. We are not passing lables to the SP or to other sites. Each site is their own MPLS environment opperating their own private AS. The CEs are their own AS.
MPLS LAN -> IP-CE -> MPLS WAN -> IP-CE -> MPLS LAN
65535 -> 64535 -> 2856 -> 64520 -> 65520
The LAN vrfs are already enabled for multicast, using PIM spare-modet. Each site has their own Anycast RP. The application in question is non-deterministic and any unicast host can become the multicast source!
I was thinking of adding a GRE tunnel interface between the two LAN PEs and create an MSDP peering between the LAN RPs.
MTU and QoS issues aside, my question is:
1) How do I get the multicast traffic to go over the tunnel interface and leave the unicast traffic as is?
2) If so, I expect to run into RPF issues, right?
I know I can add static mroutes to get round these issues but is their a scalable way to resolve this, especially as I dont know which machine is source and this can change rapidly?
I hope this all makes sence! I've not had a chance to lab this up yet.
01-28-2011 03:36 PM
James,
If you don't want your mcast flows to follow the unicast, you have 2 options.
Either mroute or BGP Extension for Multicast.
You can configure BGP peering via the GRE tunnel and just active the Multicast extension.
This will prevent learning unicast routes from BGP neighbors while having some kind of dynamic mrouting in your network.
Something like:
router bgp xx
neighbor 1.1.1.1 remote xx
address-family ipv4 unicast
no neighbor 1.1.1.1 activate
address-family ipv4 multicast
neighbor 1.1.1.1 activate
network x.x.x.x (source IP subnet)
Be sure to lab this theory up.
Regards,
Edison
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