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FAQ.md

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Mini FAQ

  • Q: My RP is a Cisco router, but it doesn't work with pimd?

    If your Cisco is running PIM-SMv1, it won't work with pimd which implements only PIM-SMv2. You need to upgrade/configure your Cisco to run PIM-SMv2.

    If your Cisco is indeed running PIM-SMv2, and it is the RP, you need to run the pimd configure script with --enable-broken-crc defined. See the beginning of the configure script, or the output from the command configure --help. Note that this will then likely cause the PIM Register messages to not be accepted by some other vendors, but pimd-to-pimd should still be OK.

    Note: This is a very old FAQ and this issue is exteremly likely to be rather reversed in 2015 ...

  • Q: Do I need to re-configure my Linux kernel to run pimd?

    Maybe, most major GNU/Linux distributions today ship with multicast capable Linux kernels. However, do make a habit of verifying that you have at least the following:

      CONFIG_IP_MULTICAST
  CONFIG_IP_PIMSM_V2
  CONFIG_IP_MROUTE

    You may enable CONFIG_IP_PIMSM_V1 as well, but it is likely not required to interop with any active equipment anymore. What may cause you to have to recompile Linux in 2015 is the lack of multiple multicast routing tables. My Ubuntu 15.04 lists the following in its /boot/config-3.19.0-23-generic:

      # CONFIG_IP_MROUTE_MULTIPLE_TABLES is not set

    Also, make sure to check that NETLINK related settings are enabled, because that is the interface pimd uses on Linux, not routing sockets anymore. Again, very likely to be default in 2015.

    Make sure that those options are set to "y" to include the relevant code in the kernel; if you enable them as modules, then you may have to load that module after you boot with the new kernel. One way to find-out if multicast routing is not working, is to use command cat /proc/sys/net/ipv4/conf/eth0/mc_forwarding after you have started pimd (you may use other interface name instead of eth0). If it returns zero, multicast forwarding on that interface is not working.

  • Q: I tried pimd on Linux, but I get the following error message:

      netlink socket: Address family not supported by protocol

    You need to enable the NETLINK related stuff in the kernel and recompile it.

  • Q: pimd compiled and is running on a single machines, but when I run it on 2+ machines, the multicast packets do not reach the receivers.

    Without detailed debug information I cannot answer this question. Please send to the pimd maintainer a scheme (topology map) of your network, and the debug output from each router (pimd -dall), that may help.

  • Q: How do I debug my multicast routing?

    Check README-debug.md for some hints.

  • Q: How do I use pimd with GRE tunnels?

    See the file README-config.md for examples.

  • Q: How do I run pimd but without configuring it as a Cand-RP and/or a Cand-BSR?

    See the file README-config.md for details.

  • Q: I have set the phyint dr-priority to 10, but another router is still elected as DR, why?

    This happens when not all routers on a LAN advertise the DR Priority option in PIM Hello messages. Check with tcpdump or wireshark to find the culprit. Versions of pimd older than v2.3.0 did not support the DR Priority option.

  • Q: How do I configure pimd to do FOO?

    See file README-config.md. If the answer is not there, send an email to the current pimd maintainer, or file a bug report at the GitHub issue tracker.