[Cerowrt-devel] Multicast

Dave Taht dave.taht at gmail.com
Wed Apr 24 13:16:05 EDT 2013

On Wed, Apr 24, 2013 at 5:06 AM, William Katsak <wkatsak at gmail.com> wrote:
> It seems that a lot of people are interested in IGMP proxying in order to
> watch multicast IPTV streams from their ISP.
> In my case, I am using the router to run two subnets, one for actual stuff,
> another for non-trusted people to use the Internet.
> I would like to be able to do Ghost imaging (Ghost is running in the primary
> subnet) of the machines in the non-trusted subnet, but it seems that the
> multicast traffic isn't going through properly. I CAN do this within the
> primary subnet.
> I got igmpproxy running and can see the route announcements in the log, but
> I assume I have it mis-configured. Maybe I will go back to pimd and play
> with that.
> I guess if all else fails, I can always switch the VLAN of the port that
> serves that segment when I want to do imagine and switch it back later :)
> ... I just thought this might be a good opportunity to try and see if I can
> get multicast to run properly.
> Thanks,
> Bill

The issues with multicast and firewalling are complex and legion.

It does sound like a src or dst address 224 dot 0 dot 0 dot 0/4 subnet
(the bufferbloat spam filter blocks numeric urls) needs to be
explicitly allowed across the wan, guest and secure lans in cerowrt in
order for this to work (on ipv4), and similar rules for ipv6 generated as

I note that std openwrt doesn't do pim in the first place (thus the need
for the igmp proxy) and enabling pimsm version 1 and 2 is one of the few
remaining differences between cerowrt and openwrt, and it's obviously a
not-so-well-tested area, generally!

Is there a multicast IPTV server out there that could be used as a test
base? vlc?

I have long included uftp as a means of testing multicast but it would be
better to test an actual IPTV application.

While I'm talking about this, I note that I have given up on multicast
rates for wifi of 1mbit in the campground testbed and default everything to
6mbit currently. Battlemesh used even higher values. It violates the spec
for wifi but I figure I will make this change in a future release...

> P.S. This router is still running Sugarland...should that be an issue?
> On 04/24/2013 05:30 AM, Dave Taht wrote:
>> On Wed, Apr 24, 2013 at 12:25 AM, Mikael Abrahamsson <swmike at swm.pp.se>
>> wrote:
>>> On Tue, 23 Apr 2013, Dave Taht wrote:
>>>> pimd is included by default.
>>> But does pimd really do IGMP-proxying?
>> No, it does real IGMP. :)
>> There may be some firewall issues with it.
>>> I can't find any mention of IGMP
>>> proxying in the pimd manual I found. ISPs generally do not allow
>>> residential
>>> customers to talk PIM with the network, they expect an IGMP join, which
>>> is
>>> what an IGMP proxy would do.
>> Sample application?
>>> --
>>> Mikael Abrahamsson    email: swmike at swm.pp.se
>>> _______________________________________________
>>> Cerowrt-devel mailing list
>>> Cerowrt-devel at lists.bufferbloat.net
>>> https://lists.bufferbloat.net/listinfo/cerowrt-devel
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Dave Täht

Fixing bufferbloat with cerowrt: http://www.teklibre.com/cerowrt/subscribe.html

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