Date: Tue, 05 Nov 2019 20:41:39 -0600 From: Mike Karels <mike@karels.net> To: Victor Gamov <vit@otcnet.ru> Cc: freebsd-net@freebsd.org Subject: Re: FreeBSD as multicast router Message-ID: <201911060241.xA62fd40065707@mail.karels.net> In-Reply-To: Your message of Wed, 06 Nov 2019 00:41:33 %2B0300. <a789de99-00ce-f12c-f698-9594cf4c9fe7@otcnet.ru>
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> On 05/11/2019 09:09, Mike Karels wrote:
> >> On 03/11/2019 08:22, Mike Karels wrote:
> >>>>>>> Hi All
> >>>>>>>
> >>>>>>> I have (noob) questions about multicast routing under FreeBSD.
> >>>>>>>
> >>>>>>> I have FreeBSD box with two (or more) multicast enabled interfac=
es (e.x.
> >>>>>>> vlan750 and vlan299). vlan750 connected to multicast source.
> >>>>>>>
> >>>>>>> Then pimd installed and only this two interfaces enabled in pimd=
config.
> >>>>>>> Multicast routes successfully installed by pimd and listed by `n=
etstat
> >>>>>>> -g -f inet`
> >>>>>>>
> >>>>>>> Then client on vlan299 send IGMP-Join (this Join received by Fre=
eBSD on
> >>>>>>> vlan299)
> >>>>>>>
> >>>>>>> The question is: who will forward muilticast from one interface
> >>>>>>> (vlan750) to another (vlan299)? Is it kernel specific job or I =
need
> >>>>>>> additional software?
> >>>>>
> >>>>>> Please read the manpage multicast(4) "man 4 multicast",
> >>>>>> you should need to build a custom kernel with the "options MROUTI=
NG"
> >>>>>> to enable the multicast forwarding in the kernel.
> >>>>>
> >>>>> If "netstat -g" shows routes, the kernel must have been built with=
"options
> >>>>> MROUTING".
> >>>
> >>>> Indeed.
> >>>
> >>>>>
> >>>>> The kernel does the forwarding, according to those routing tables =
installed
> >>>>> by pimd or another multicast routing program. Is it not working? =
It sounds
> >>>>> like you are very close.
> >>>
> >>>> Could it be sysctl net.inet.ip.forwarding? Does that still apply t=
o mroutes?
> >>>
> >>> No, they are separate. The test is just whether MROUTING is enabled=
, and
> >>> whether a multicast router like pimd is active.
> >>>
> >>> One other thing to check would be "netstat -gs" (multicast stats).
> > =
> >> Oops!
> > =
> >> =3D=3D=3D=3D=3D
> >> # netstat -f inet -gs
> >> No IPv4 MROUTING kernel support.
> >> =3D=3D=3D=3D=3D
> > =
> > This looks like a bug in netstat; it is doing a test that is wrong for
> > the loadable module.
I don't know how much the stats might help, but if you let me know what
version you are running, I can build a fixed netstat. Or I can send
a source patch.
> >> But I have ip_mroute.ko loaded and netstat -g shows something like
> > =
> >> =3D=3D=3D=3D=3D
> >> # netstat -f inet -g
> > =
> >> IPv4 Virtual Interface Table
> >> Vif Thresh Local-Address Remote-Address Pkts-In Pkts-Ou=
t
> >> 0 1 A.A.A.A 0 0
> >> 1 1 B.B.B.19 0 0
> >> 2 10 10.199.199.102 0 =
0
> >> 3 15 10.200.200.6 77440 =
0
> >> 4 1 A.A.A.A 0 77440
> > =
> >> IPv4 Multicast Forwarding Table
> >> Origin Group Packets In-Vif Out-Vifs:Ttls
> >> 10.200.200.5 232.232.8.33 1844 3 4:1
> >> 10.200.200.5 232.232.8.171 1843 3 4:1
> >> 10.200.200.5 232.232.8.58 4609 3 4:1
> >> 10.200.200.5 232.232.8.154 1844 3 4:1
> >> 10.200.200.5 232.232.8.170 1844 3 4:1
I missed this before. Looks like the last column should include 2:1 in
each case if pimd saw the join. The multicasts are only being sent to
Vif 4, the register-vif (see below); the Pkts-Out for it is the same
as the input on 3. I'm not familiar enough with pimd to guess what is
wrong.
> >> =3D=3D=3D=3D=3D
> > =
> > =
> >> and
> > =
> >> =3D=3D=3D=3D=3D
> >> # pimd -r
> >> Virtual Interface Table
> >> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D
> >> Vif Local Address Subnet Thresh Flags Neighbor=
s
> >> --- --------------- ------------------ ------ ---------
> >> -----------------
> >> 0 A.A.A.A A.A.A.A/25 1 DR NO-NBR
> >> 1 B.B.B.19 B.B.B 1 DR NO-NBR
> >> 2 10.199.199.102 10.199.199.100/30 10 DR PIM
> >> 10.199.199.101
> >> 3 10.200.200.6 10.200.200/29 15 DR NO-NBR
> >> 4 A.A.A.A register_vif0 1
> > =
> >> Vif SSM Group Sources
> > =
> >> Multicast Routing Table
> >> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D
> >> ----------------------------------- (S,G)
> >> ------------------------------------
> >> Source Group RP Address Flags
> >> --------------- --------------- ---------------
> >> ---------------------------
> >> 10.200.200.5 232.232.8.33 SSM CACHE SG
> >> Joined oifs: ....j
> >> Pruned oifs: .....
> >> Leaves oifs: .....
> >> Asserted oifs: .....
> >> Outgoing oifs: ....o
> >> Incoming : ...I.
> >> =3D=3D=3D=3D=3D
> > =
> > =
> >> A.A.A.A is external IP-address. No multicast trafic must be sended t=
o
> >> this interface.
> >> 10.200.200.6 -- vlan750, multicast comes from here
> >> 10.199.199.102 -- vlan299, multicast must be forfarded here after
> >> IGMP-Join received from 10.199.199.101/30
> > =
> > =
> >> So, kernel with MROUTING options must be configured/installed or
> >> ip_mroute.ko is enough?
> > =
> > A kernel with MROUTING would let you see stats, but ip_mroute.ko shoul=
d
> > be enough to function (although I haven't tested that).
> > =
> > I'm not familiar with the pimd output, but it seems plausible. I am
> > assuming that the multicasts are not getting to the vlan299 network?
> > Have you looked at the incoming traffic with tcpdump? Use the -p
> > option to avoid promiscuous mode to see that the input NIC is receivin=
g
> > those multicasts, and check the TTL of the incoming multicast packets.
> > (If it is 1, the packets will not be forwarded.)
> Yes, multicast packets arrived to FBSD via vlan750 and TTL is 20. But =
> no packets forwarded to vlan299 after IGMP-Join received:
> =3D=3D=3D=3D=3D
> 00:39:30.484901 IP (tos 0xc0, ttl 1, id 13571, offset 0, flags [none], =
> proto IGMP (2), length 36, options (RA))
> 10.199.199.102 > 224.0.0.1: igmp query v3
> 00:39:31.356732 IP (tos 0xc0, ttl 1, id 0, offset 0, flags [DF], proto =
> IGMP (2), length 56, options (RA))
> 10.199.199.102 > 224.0.0.22: igmp v3 report, 3 group record(s) =
> [gaddr 224.0.0.22 is_ex { }] [gaddr 224.0.0.2 is_ex { }] [gaddr =
> 224.0.0.13 is_ex { }]
> 00:39:33.091330 IP (tos 0xc0, ttl 1, id 0, offset 0, flags [DF], proto =
> IGMP (2), length 40, options (RA))
> 10.199.199.101 > 224.0.0.22: igmp v3 report, 1 group record(s) =
> [gaddr 232.232.8.33 to_ex { }]
> 00:39:35.166091 IP (tos 0xc0, ttl 1, id 0, offset 0, flags [DF], proto =
> IGMP (2), length 40, options (RA))
> 10.199.199.101 > 224.0.0.22: igmp v3 report, 1 group record(s) =
> [gaddr 232.232.8.33 to_ex { }]
> =3D=3D=3D=3D=3D
> -- =
> CU,
> Victor Gamov
Mike
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