RV042 Multicast VPN Support

Discussion in 'Cisco Small Business Routers and VPN Solutions' started by dvdmih, May 15, 2008.

  1. dvdmih

    dvdmih Addicted to LI Member

    Does anyone know if the RV042 supports multicast over VPN tunnels between RV042s?

    Thank you in advance,
  2. dvdmih

    dvdmih Addicted to LI Member

    I have received 2 replies from Linksys sales on this issue, unfortunately, one stated that it is supported and the other stated it wasn't.

    Does anyone have any experience, good, bad or otherwise with trying to do multicast over VPN using RV042s?
  3. boteman

    boteman Network Guru Member

    I have a pair of RV042 VPN routers that I'm testing here in my lab.

    I checked the box for multicast and saved the config, but it doesn't route my multicast audio packets across the VPN as-is.

    Perhaps I need to do something more, but what I have no idea. I haven't gotten around to asking Linksys (or is it Cisco Small Business Systems?) yet.

    At the very least, the router must transmit IGMP join messages across the VPN so that the multicast source knows to send packets there. Beyond that I don't know what they did.

    In a "real" Cisco router you have a choice of sparse, dense, and sparse-dense modes and you can set up a rendevous point for really serious multicast distribution nets. Normally, IP multicast will not transit a router unless said router is specifically configured to do so.

    Just checking a box to enable it seems suspiciously simple to me, but hey, if it works I'm all for it! I haven't gotten there yet, though.
  4. boteman

    boteman Network Guru Member

    RV042 multicast pass-through is for firewall

    Now that I checked the management screens of the RV042 I now see that the Multicast Pass-Through selection is for the firewall, not the VPN.

    This makes sense, because getting multicast packets through a VPN aint easy or simple.

    I see no practical applications for the RV042 that would need multicast to pass through the firewall to the open Internet, so definitely leave that disabled especially if it slows down the link.

    I did not quantify it, but the RV042 definitely seemed slower on my home DSL connection than my USR 5465. I'll bet the multicast selection was doing that, because I think I had it enabled. I'll take it back home and test it again.

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