From 0230531575d0756d63759c692792f16ee1514171 Mon Sep 17 00:00:00 2001 From: Joachim Wiberg Date: Thu, 7 Jan 2021 05:12:47 +0100 Subject: [PATCH] Mention the 'static-group' setting, and warn about TTL, in README Signed-off-by: Joachim Wiberg --- README.md | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/README.md b/README.md index c679936..05555ca 100644 --- a/README.md +++ b/README.md @@ -45,14 +45,21 @@ Running ------- mrouted does not require a `.conf` file. When it starts up it probes -all available interfaces and, after an initial 10s delay, starts peering -with any DVMRP capable neighbors. +all available interfaces and starts peering with any DVMRP capable +neighbor. Multicast is forwarded to end-devices that *join* a group +using IGMPv1, IGMPv2, or IGMPv3. For LANs where there may be hosts that +do not speak IGMP, or where certain groups should always be forwarded, a +`static-group` setting is available in `mrouted.conf`. Use [mgen(1)][], [mcjoin(1)][], or [iperf](https://iperf.fr/) to send IGMP join packets and multicast data on the LAN to test your multicast routing setup. Use the `mroutectl` tool to query a running `mrouted` for status. +> **NOTE:** Beware of the TTL value in the IP header of your multicast +> data. It defaults to 1 on most operating systems, which +> means nothing will be routed by default! + For the native mrouted tunnel to work in Linux based systems, you need to have the "ipip" kernel module loaded or as built-in: