On 26/Feb/16 11:33, Yann Lejeune wrote:
It's up to you to choose what mode you want to use: - spt-only: is quite "simple". We only have (s,g) in the core. To validate an os, it's faster. - rpt-spt. We have both (*,g) and (s,g) in the core. the validation is more complex, the protocol is more dynamic...
I've ran both modes, and found SPT-only mode to be a fair compromise between speed and scale. When operating SPT-only modes, we did not witness a noticeable difference in channel-changing times. In SPT-only mode, the (S,G) state is already present on the Receiver PE router even though there is no downstream interest for that state. So when an IGMP Join request comes into the router, it does not have to travel the RPT tree like it would if you ran RPT-SPT mode (which is traditional Multicast). In our case, we had Multicast probes connected to every Receiver PE router to track performance for each channel. So if you have that, you're going to need all the channels present on the router anyway, even though downstream interest is not present. In this case, avoiding the extra steps associated with RPT-SPT mode is what compelled us to run SPT-only mode. But as Yann has mentioned, even in SPT-only mode, the Type 6 routes will exit in the router, but won't really be used. Type 5 routes are more important when operating in SPT-only mode, and those are always present in such a state. My next NG-MVPN operation will be SSM-based, so this should be simpler still. Mark.