[Twisted-Python] Source specific multicasting (SSM) example?
rlott at evertz.com
Fri Apr 4 13:49:50 EDT 2008
Thanks for the information, Phil.
I believe the 2.6 kernels are supposed to have IGMP setup. Not sure about the PIM-SSM, though.
My Python setup (Debian etch, python 2.4.4-2) shows similar to yours re. the socket module.
Yeah. I sent a post here because my Googling for this stuff wasn't going anywhere. Oh, well. Not the end of the world. I will just use separate IGMP groups and switch on the separate addresses.
From: twisted-python-bounces at twistedmatrix.com
[mailto:twisted-python-bounces at twistedmatrix.com]On Behalf Of Phil
Sent: Friday, April 04, 2008 12:41 PM
To: Twisted general discussion
Subject: Re: [Twisted-Python] Source specific multicasting (SSM)
Rodney Lott wrote:
> Hi, there.
> I was wondering if there is any information or examples on how to use
> Twisted to perform a SSM operation. I am new to Twisted and to Python.
> In C, I believe one would use the setsocketopt() to specify the joining
> to a multicast group (G) to a specific source (S):
> setsockopt(sock,…, IP_ADD_SOURCE_MEMBERSHIP, (S, G, iface), …)
...provided your OS has IGMPv3 support (and the underlying network has
IGMPv3 and PIM-SSM setup).
> I believe that Python itself has analogous socket calls and could do
> this using a UDP socket.
At least on my version of Python (2.5.1, Fedora 8) there's no constant
in the "socket" module for that:
>>> [x for x in dir(socket) if 'member' in x.lower()]
['IP_ADD_MEMBERSHIP', 'IP_DROP_MEMBERSHIP', 'IP_MAX_MEMBERSHIPS']
Google for "python igmpv3" does not look promising... It seems as if
this support isn't there yet.
> I read the Multicast UDP example on Twisted here:
> This shows how to do a normal multicast UDP situation with Twisted (i.e.
> a process will receive UDP traffic from ALL sources registered to the
> IGMP group).
> So, if there were UDP three sources (e.g. A, B, and C) registered to the
> IGMP group, I would like to find a way for my client to only receive
> data from source B.
> I believe that I can get information using a SDP/SAP using a simple UDP
> server listening on the appropriate port. So, the only thing that I am
> missing is how to register to a group for a specific source. I am not
> sure if the joinGroup() method will allow for this.
> -Rodney Lott
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