Date: Thu, 7 Nov 2019 17:17:48 +0300 From: Victor Gamov <vit@otcnet.ru> To: mike@karels.net Cc: freebsd-net@freebsd.org Subject: Re: FreeBSD as multicast router Message-ID: <3334fa50-8a88-17b6-7e91-c09d22e11f7e@otcnet.ru> In-Reply-To: <201911060241.xA62fd40065707@mail.karels.net> References: <201911060241.xA62fd40065707@mail.karels.net>
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On 06/11/2019 05:41, Mike Karels wrote: >> 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 interfaces (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 `netstat >>>>>>>>> -g -f inet` >>>>>>>>> >>>>>>>>> Then client on vlan299 send IGMP-Join (this Join received by FreeBSD 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 MROUTING" >>>>>>>> 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 to 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! >>> >>>> ===== >>>> # netstat -f inet -gs >>>> No IPv4 MROUTING kernel support. >>>> ===== >>> >>> 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 >>> >>>> ===== >>>> # netstat -f inet -g >>> >>>> IPv4 Virtual Interface Table >>>> Vif Thresh Local-Address Remote-Address Pkts-In Pkts-Out >>>> 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. I still have misunderstood here. Pimd installs multicast routes and this routes displayed by `netstat -g`. So, the system knows interface where multicast received. When Join received via interface 2 (vlan299) who must resend multicast from input interface 3 (vlan750) to output interface 2 (vlan299)? I guess it kernel-specific task and kernel must resend multicast without any other helpers. Is it wrong? P.S. I rebuild kernel with MROUTING option but ===== # netstat -gs -f inet No IPv4 MROUTING kernel support ===== still here -- CU, Victor Gamov
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