FreeBSD as multicast router

[Victor Gamov]

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.
=====

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
=====


and

=====
# pimd -r
Virtual Interface Table 
======================================================
Vif  Local Address    Subnet              Thresh  Flags      Neighbors
---  ---------------  ------------------  ------  --------- 
-----------------
   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 
======================================================
----------------------------------- (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.
=====


A.A.A.A is external IP-address.  No multicast trafic must be sended to 
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?


P.S. FreeBSD 11.3-STABLE #0 r351605M

--
CU,
Victor Gamov