Date: Mon, 11 Oct 1999 20:47:07 +0200 From: "Jose M. Alcaide" <jose@we.lc.ehu.es> To: freebsd-net@FreeBSD.org Subject: problem with multicast routing, PPP, and shared subnets Message-ID: <380230AB.BF7A96C5@we.lc.ehu.es>
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Hello, I am doing some experiments with IP multicast. In particular, I am interested in "multicast@home", i.e., bringing IP multicast services to home PCs connected to our LAN with PPP. I set up a FreeBSD (3.3-RELEASE) PPP server, which has MROUTING configured and runs mrouted. The addresses assigned to the PPP clients belong to our LAN's IP subnet, and routing is solved with proxy ARP. When any PPP client adds (or deletes) itself to a multicast group, the membership information is sent through the "tun" interface to the server/router. However, a "netstat -g" shows that these group memberships are associated to the VIF 0 (ethernet) rather than to the VIF 1 (tun), as they would be: Virtual Interface Table Vif Thresh Rate Local-Address Remote-Address Pkts-In Pkts-Out 0 1 0 157.228.6.111 0 0 1 1 0 192.168.6.111 0 0 Multicast Forwarding Cache Origin Group Packets In-Vif Out-Vifs:Ttls 157.228.6.224 224.2.230.125 0 0 <---- BAD 157.228.6.224 224.2.127.254 0 0 <---- BAD (The server's ethernet interface IP address is 157.228.6.111. The PPP client I am using in this example has the IP address 157.228.6.224; the local address of the "tun" point-to-point interface is 192.168.6.111.) Obviously, that multicast forwarding table is wrong, and the consequence is that multicast forwarding does not work. I think that this problem is related to the IP subnet sharing I mentioned above, so that I reconfigured the PPP server in order to use a different subnet: then, MC forwarding worked fine. But I do not want to use another IP subnet for the PPP clients. Anyway, I think that multicast forwarding _should_ work even with the LAN and the PPP clients sharing the same subnet. I read the mrouted(8) man page and I tried a "phyint tun0 netmask 32" to no avail... Am I doing anything wrong? If the cause is a bug I will fill a PR. BTW, I have another problem: mrouted detects the multicast-capable interfaces at startup, and it does not notice when other interfaces go up or down. This behavior is not appropriate for PPP connections, because the "tun" devices go up when a connection is opened (the ppp process is started), and down when it is closed (ppp terminates). I could send a SIGHUP to mrouted whenever a PPP connection is established, but this would flush the multicast forwarding cache. Please accept my apologies for this long message. Saludos, -- JMA ----------------------------------------------------------------------- José Mª Alcaide | mailto:jose@we.lc.ehu.es Universidad del País Vasco | mailto:jmas@FreeBSD.ORG Dpto. de Electricidad y Electrónica | http://www.we.lc.ehu.es/~jose Facultad de Ciencias - Campus de Lejona | Tel.: +34-946012479 48940 Lejona (Vizcaya) - SPAIN | Fax: +34-946013071 ----------------------------------------------------------------------- "Keyboard not present -- Press F1 to resume" To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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