All things related to multicast

[Marshall Eubanks <>]

First, I said you should use even ports for RTP.

Second, I (and others) use rtpdump etc. for a quick and dirty look at  
all UDP multicast sources, RTP
or not, as at least it will tell you something. AFAICT this software  
expects even ports for the source.
That's a pretty minor issue, but not a zero issue, especially as in  
interdomain multicast you frequently find
yourself relying on the kindness of strangers to debug things.

Regards
Marshall

On Aug 13, 2006, at 7:51 PM, Richard Mavrogeanes wrote:

> Marshall,
>
> I don't wish to be picky, I just want to make sure I understand.   
> Isn't the issue exactly zero, and not just "less" without RTP?  I'm  
> trying to construct any case where it would matter.
>
> Granted, RTP brings other advantages and we support RTP too (for  
> unicasts).
>
> /rich
>
>
>         -----Original Message-----
>         From: Marshall Eubanks 
> [mailto:]
>         Sent: Sun 8/13/2006 7:47 PM
>         To: Richard Mavrogeanes
>         Cc: 
> ;
>  
>
>         Subject: Re: testing
>         
>         
>
>         RTP expects the even/odd RTP / RTCP pairing. True, you can override
>         it, but
>         the standard RTP monitoring tools then won't work well. Of course,
>         this is less of an issue
>         if you don't use RTP.
>         
>         Regards
>         Marshall
>         
>         
>         On Aug 13, 2006, at 7:00 PM, Richard Mavrogeanes wrote:
>         
>         > The MPEG-2 is not RTP, it is MPEG-2TS.
>         > But since the port is associated only with the group, I don't see
>         > why it would matter what port number you select.
>         >
>         > /rich
>         >
>         >
>         >       -----Original Message-----
>         >       From: Marshall Eubanks 
> [mailto:]
>         >       Sent: Thu 8/10/2006 1:16 PM
>         >       To: 
>
>         >       Cc: 
>
>         >       Subject: Re: testing
>         >
>         >
>         >
>         >       Dear Frank;
>         >
>         >       Not seeing it from here :
>         >
>         >       bash-2.05b$ rtpdump -F ascii 233.88.214.137/4444
>         >       <silence>
>         >
>         >       BTW, you should use even ports for RTP.
>         >
> 	>       The whole question of multicast ports is a vexing one. Of  
> course, you
>         >       need to look at
>         >
>         >       http://www.iana.org/assignments/port-numbers
>         >
> 	>       Most multicasters just pick some at random (and, remember,  
> most
>         >       multicast is RTP,
> 	>       so if you pick port X, X should be even, and you will use X 
> +1 for
>         >       RTCP AND if
> 	>       you are sending audio + video, then you will be using X+2  
> and X+3 as
>         >       well.
>         >
> 	>       The trouble with just picking a random one is IANA will  
> eventually
>         >       assign it (unless
>         >       it is up high in the private address space).
>         >
> 	>       AmericaFree.TV currently uses ports from 7500 to 8090, but  
> I am
>         >       intending to switch this to ports in the
>         >       private port space :
>         >
> 	>             The Dynamic and/or Private Ports are those from  
> 49152 through
>         >       65535
>         >
> 	>       I have proposed a number of times that the multicast  
> community pick a
>         >       port range (or ranges) for
> 	>       streaming, either through IANA or just in the private  
> address space,
>         >       but this has never seemed to find favor in Mboned.
>         >
> 	>       My current thinking is that multicast needs at least 1000  
> ports (I
>         >       could see sourcing 1000 SSM channels
> 	>       from one server), and so why not pick, say, 60,000 to  
> 61,000 ? At any
>         >       rate, that is my current thinking for
> 	>       AmericaFree.TV (which currently has 46 channels and thus  
> needs almost
>         >       200 ports now).
>         >
>         >       (I will post this separately to the I2 WG mailing list.)
>         >
>         >       Regards
>         >       Marshall
>         >
>         >       On Aug 10, 2006, at 12:53 PM, 
>
>  wrote:
>         >
> 	>       > We are just getting started with multicasting, wondering  
> if anyone
>         >       > can see our multicast VBrick streams
>         >       >
>         >       > MPEG2 at 233.88.214.138, port 4443
> 	>       > MPEG4 at 233.88.214.137, port 4444 for video and 4644  
> for audio
>         >       >
> 	>       > We are connecting to I2 through the Connecticut  
> Education Network
> 	>       > (CEN). Last spring we could see our SAPs and streams on  
> CEN, but
>         >       > they were not making it to I2 for some reason.
>         >       >
> 	>       > Also, we set up a special subnet just for I2 activities.  
> Just
> 	>       > wondering if most institutions keep the firewall  
> completely open to
> 	>       > all ports for this, or whether there is a set of  
> "mutlicast-
> 	>       > activity" friendly ports suggested be kept open, to  
> specific IPs on
>         >       > the subnet.
>         >       >
>         >       > Thanks,
>         >       >
>         >       > Frank Fulchiero
>         >       > Digital Media Specialist
>         >       > Connecticut College
>         >       >
>         >
>         >
>         >
>         
>