Re: [manet-dlep-rg] Multicast destination

[Teco Boot <[e-mail]>]

Op 11 nov. 2013, om 02:08 heeft Stan Ratliff (sratliff) <[e-mail]> het volgende geschreven:

> Maybe I'm being dense here, but….. 
> 
> Multicast addresses "come with" Layer 2 MAC addresses. Yes, they are derived. Yes, they might collide. But DLEP already supports (at least spec-wise) the notion of one MAC address having multiple Layer 3 addresses associated with it.

We have to discuss the address TLVs at a next teleconf. Personally, I think the address TLVs deserve a separate RFC. Let's do it right. I'm willing to put energy in it. 


> So, in my little (maybe weird??) world, either
> 
> 1. The radio is "PIM snooping"

Could be. There is more than PIM.


> , sees Multicast traffic, and peels the MAC/Layer 3 address off. The "DLEP smarts" in the modem generates a "Destination Up" message, with the MAC and Layer 3 address.

Why would it do so? If it is a bridge, it floods multicast (unless IGMP/PIM snooping of RGMP). And multicast has same metrics as broadcast.

If it supports some kind of smart multicast forwarding, shouldn't we first describe what it is? And as a next step define signaling between router and modem, if we need such?

If it is for traffic management, why not use the Traffic Flow Template? Much more powerful and implemented in millions of devices already.


> Oh, and it puts metrics on that, too. If the characteristics of the multicast transmission change (bandwidth, etc), a "Destination Update" is used, just like for any other destination in the network. 
> 
> *OR* 
> 
> 2. The "Destination Up" is supplied by the router, when the appropriate PIM information is received. Again, the "Destination Up" (this time, from router to modem), will have the MAC and Layer 3 information. The modem takes note of the new Destination MAC (I assume that's the only thing the modem is interested in), and can then respond with a "Destination Update" that gives the router metrics.

This is RGMP, I believe (rfc3488).


> 
> After the initial exchange, there's really no difference between the modem-initiated and the router-initiated case.

If two mechanisms result in same outcome, let's skip one.

But maybe they are different, I don't know. An "Order" message from router to modem looks different to me than a "Report" message from modem to router.


Teco