network problems

[Kai Chen]

At 01:49 PM 6/23/99 -0500, Robert Olson wrote:

>Off the top of my head, the statistics that I find myself wanting are
>per-site, per-stream bandwidth/loss/latency/jitter statistics for the media
>streams. This is information that can be gleaned from the RTP/RTCP headers
>and sender/receiver reports. rtpmon provides some of this information, but
>not all. 

That's a very differnt requirement than the general network weather map.
The current rtpmon forks off from vic/vat and monitors a single RTP
session. Are you interested in monitoring ALL sesssions? It looks straight
forward to run a daemon program which grabs all the sdr announcements, and
taps into all the RTCP channels to gather information. Per-site monitoring
is needed if you are interested in local RTP sessions (with small TTL).

The rtpmon may not be doing this, but it seems to me that estimating the
receiver bandwidth is possible just by looking and combining the sender
reports and receiver reports. (RFC 1889 Session 6.3.4).

>It would also be nice to be able to identify the critical paths
>thru the network between sites, and the amount of bandwidth we are using on
>them. 

I haven't used it, but "pathchar" by Van Jacobson is the one that is close
(http://www.ncne.nlanr.net/tools/performance.html). 

-Kai


--
Kai Chen                Research Programmer
217-265-4078            NLANR Application Support
kchen at nlanr.net         NCSA - U of Illinois at Urbana-Champaign