All things related to multicast

["Greg Shepherd" <>]

On 7/24/08, Stig Venaas <> wrote:

Dan Pritts wrote:

On Thu, Jul 24, 2008 at 08:56:29PM +0200, Stig Venaas wrote:

I don't have any good answers, but I feel it would be problematic to use
SAP if I had to receive 1 Mbit/s of data. Right now the rate seems to be
about 27Kbit/s which is not a problem at all.

Do we expect some form of global SAP to last into an SSM-only world,
which (last i checked) was the goal?

At least I don't. I think we need something else. I still think some
kind of announcement service (or program guide) would be nice, but not
SAP as it is today.

If so, I'm not sure how it would work.

I have some ideas for how it could work, but they are probably not
pursuing. They would just recreate some of the same problems I think.

If not, people should be encouraged not to use SAP for any future
applications, except perhaps within their own domains (e.g., cable
tv systems).

I feel SAP still has some use today, but we need alternatives. I don't
think just putting a link to an SDP file on a web page suffices.

Well, this depends on your goals and target audience. A web link works well for the average user, as long as the content can be found in a search. But if you're trying to target other network engineers who are interested in the transport as much as the content then either we need to be able to search on transport (mcast) to find the content, or we need some central directory service.

But even for the later, SAP doesn't make sense. A flat list of content that requires the source (or something on behalf of the source) to send out periodic announcements was a great bootstrap tool. Remember when Yahoo.com was a list? ;-)

I've spoken with Google about providing additional meta search tags for streaming content (codec, bitrate, transport, etc..). There was interest but nothing more.

Tom Pusateri at one time was working on a content directory web app where sources could push the schedule and users could search. I believe he dropped the work before completion but I've been bugging him to release the source for someone else to pickup the torch. Maybe it's time for a group push? :)

Greg

Stig

In the meantime, I agree that 1Mbit would be too much for normal
circumstances.

danno
--
Dan Pritts, Sr. Systems Engineer
Internet2
office: +1-734-352-4953 | mobile: +1-734-834-7224

Internet2 Workshops
Hands-on. Brains-on.
http://www.internet2.edu/workshops/