All things related to multicast

[Frank Fulchiero <>]

Stig, Thanks for the informative stats.
Our SAP server is on 136.244.96.106, and we are sending out SAPs for  
3 programs. In the future, we may send out some for even more.
Our SAP Announcement interval is 30 seconds, but the average shown is  
9.8 secs, as we are sending out 3 in one program group.

I recall University of Canberra, in the "glory days" of multicast,  
announcing about 36 international channels.
There is a tradeoff between being net-friendly and giving viewers the  
convenience of not waiting to long to see what's playing on VLC, and  
with other SAP listeners.
Don't some set-top boxes have these?
How long after you turn on your TV do you want to see the channel  
listings?

What is considered good etiquette? We will gladly decrease our  
announce frequency to meet that criteria.

The RFC has a formula for computing announce frequency, but I have  
never tried to compute it. Just using common sense, and 30 seconds  
seemed a good compromise.
I believe in some cases the RFC formula gives an announce frequency  
of 5 minutes, which seems too long in this day and age.

How would the stats below differentiate between someone sending one  
SAP/second for one stream, and someone sending 30 SAPS for 30 streams  
with an announce interval of 30 seconds?

Glad you are doing this analysis, seems like it's needed.

Frank Fulchiero
Digital Media Specialist
Connecticut College


On [Jul 24], at 9:24 AM, Stig Venaas wrote:

> We've tried to collect some statistics for sources currently  
> sending to
> the IPv4 SAP group. See attachment if you like.
>
> Right now (when we checked), there was one source (193.10.29.5)  
> sending
> 10 pps to SAP, which is rather high.
>
> Next up there are a handful of sources sending announcement 1pps which
> also is rather high. Many others at about one packet every 10s which
> still is rather high.
>
> Anyway, see attachment for details.
>
> Stig
>
>
> Date 2008-07-24             packet        loss          size 
> (byte)                      packet gap(ms)                thrust 
> (bps)                 source
> time       span  setup    numb   dup late lost  avg  sdv    avg   
> sdv  min  max      numb   avg   sdv   min   max      avg    1s  
> 100ms             file
>
> 14:01:53  610.0    0.0       63    0    0    0    0    0    796    
> 90  669  862         62  9.8s  6.9s   0.0 27.9s     658  7.0K  
> 63.6K  136.244.96.106:1473->224.2.127.254:9875