Problem with multicast on 4.8-RELEASE

[Andrew Degtiariov]

Hello.
I have got a strange problem with multicast on my NAS. 
Right after start (no dialup users connected) all working fine. But ospf 
has stopped work correctly when the first ppp0 went up.
The reason it does not work because system stops  to send multicast packets via
rl0 interface and start sends its via ppp0 after ones goes up.   
Ospf has been recovered when a dialup user disconnected (ppp0 down).
This problem has been observed with gated and zebra software.
On 4.3 and 4.4 systems such does not occur.

PS. pppX interfaces has been configured as passive (does not enable OSPF on it).

System:
root at nas1-Kiev:~>uname -a
FreeBSD nas1-Kiev.astral-on.net 4.8-RELEASE FreeBSD 4.8-RELEASE #1: Fri Aug 15 13:13:37 EEST 2003     root at test_vh.astral-on.net:/usr/src/sys/compile/NAS0-KIEV  i386
root at nas1-Kiev:~>

List of interfaces before ppp connection:
root at nas1-Kiev:~>ifconfig -au
rl0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        inet 192.168.0.1 netmask 0xffffff00 broadcast 192.168.0.255
        ether 00:00:21:cb:e9:6b
        media: Ethernet autoselect (10baseT/UTP)
        status: active
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
        inet 127.0.0.1 netmask 0xff000000
root at nas1-Kiev:~>

List of interfaces after ppp connection:
root at nas1-Kiev:~>ifconfig -au
rl0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        inet 192.168.0.1 netmask 0xffffff00 broadcast 192.168.0.255
        ether 00:00:21:cb:e9:6b
        media: Ethernet autoselect (10baseT/UTP)
        status: active
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
        inet 127.0.0.1 netmask 0xff000000
ppp0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1500
        inet 192.168.0.1 --> 192.168.1.2 netmask 0xffffffff
root at nas1-Kiev:~>

tcpdump listings:
On 16.38 ppp connections has been established
On 16:38:19 host has been stoped sending multicast via rl0.
On 16:40:00 ppp connections has been breaked off and multicast on rl0 recovered.
root at nas1-Kiev:~>tcpdump -i ppp0 -pn proto ospf
tcpdump: listening on ppp0
16:38:03.693818 192.168.0.1 > 224.0.0.6: OSPFv2-ls_ack 104: backbone [ttl 1]
16:38:04.613847 192.168.0.1 > 224.0.0.5: OSPFv2-hello 80: backbone dr x.x.x.x bdr y.y.y.y [ttl 1]
16:38:04.703817 192.168.0.1 > 224.0.0.6: OSPFv2-ls_ack 44: backbone [ttl 1]
16:38:13.784001 192.168.0.1 > 224.0.0.6: OSPFv2-ls_ack 164: backbone [ttl 1]
16:38:14.624030 192.168.0.1 > 224.0.0.5: OSPFv2-hello 80: backbone dr x.x.x.x bdr y.y.y.y [ttl 1]
16:38:23.894139 192.168.0.1 > 224.0.0.6: OSPFv2-ls_ack 144: backbone [ttl 1]
16:38:24.634133 192.168.0.1 > 224.0.0.5: OSPFv2-hello 80: backbone dr x.x.x.x bdr y.y.y.y [ttl 1]
16:38:24.904164 192.168.0.1 > 224.0.0.6: OSPFv2-ls_ack 84: backbone [ttl 1]
16:38:25.584201 192.168.0.1 > 224.0.0.6: OSPFv2-ls_upd 64: backbone [ttl 1]
16:38:25.914200 192.168.0.1 > 224.0.0.5: OSPFv2-ls_ack 44: backbone [ttl 1]
16:38:26.604230 192.168.0.1 > 224.0.0.5: OSPFv2-hello 80: backbone dr 192.168.0.1 bdr 192.168.0.1 [ttl 1]
16:38:30.594416 192.168.0.1 > 224.0.0.5: OSPFv2-ls_upd 64: backbone [ttl 1]
16:38:31.494278 192.168.0.1 > 224.0.0.5: OSPFv2-hello 80: backbone dr x.x.x.x bdr 192.168.0.1 [ttl 1]
16:38:36.604510 192.168.0.1 > 224.0.0.5: OSPFv2-hello 80: backbone dr x.x.x.x [ttl 1]
...

root at nas1-Kiev:~>tcpdump -i rl0 -np '(proto ospf && host 192.168.0.1)'
tcpdump: listening on rl0
16:37:59.680379 y.y.y.y > 192.168.0.1: OSPFv2-ls_upd 244: backbone [ttl 1]
16:37:59.681411 192.168.0.1 > y.y.y.y: OSPFv2-ls_ack 144: backbone [ttl 1]
16:37:59.693798 192.168.0.1 > y.y.y.y: OSPFv2-ls_upd 64: backbone [ttl 1]
16:37:59.723788 192.168.0.1 > x.x.x.x: OSPFv2-ls_upd 64: backbone [ttl 1]
16:38:09.700343 y.y.y.y > 192.168.0.1: OSPFv2-ls_upd 208: backbone [ttl 1]
16:38:09.701285 192.168.0.1 > y.y.y.y: OSPFv2-ls_ack 124: backbone [ttl 1]
16:38:19.720448 y.y.y.y > 192.168.0.1: OSPFv2-ls_upd 280: backbone [ttl 1]
16:38:19.721611 192.168.0.1 > y.y.y.y: OSPFv2-ls_ack 164: backbone [ttl 1]
16:40:06.695706 192.168.0.1 > 224.0.0.5: OSPFv2-hello 80: backbone dr 192.168.0.1 [ttl 1]

-- 
Andrew Degtiariov 
DA-RIPE