Videoconferencing update
A. Flavell, Glasgow Univ.
For HEPSYSMAN meeting
Apr 2003
Overview
Technologies
•
H.323/IP, vic/rat, unicast/multicast; H.320/ISDN; Point-topoint, multipoint; data sharing (several offerings)
Services
•
JVCS services bundle (mostly studio-class)
•
UK campuses (sketchy...)
•
ESnet (DCS, ECS) services bundle (USA AUP)
•
VRVS services bundle
•
Access Grid (AG) (sketchy, this time)
•
GDS Global dial(l)ing Scheme
Kit, and client software
Technologies: protocols
• H.323: industry standard for v.c. over IP, seeing
increasing deployment, from low-end up to studio
class.
• Vic/rat: early apps from Mbone, still being used
and developed by VRVS and by AccessGrid;
unicast and multicast-capable.
• H.320/ISDN: the traditional v.c; is fading in our
community, incurs per-use charges. Guaranteed
bandwidth of ISDN was useful back when IP was
congested – it's different now!
Technologies: contd.
• All clients can make point to point calls without
additional help (but gatekeepers and directory
servers may be useful; and you may need a gateway
past a campus firewall)
• In general, multipoint calls require the use of an
MCU (some higher-end clients can act as a mini
MCU): MCUs are expensive and can be
troublesome, not something you can buy and forget.
• Data sharing seems a most valuable service for our
community, and seems as yet under-used: there are
several offerings, maybe it's perceived as too
complicated and confusing...
Services: JVCS
• New H.323/IP service offering (piloted as
JIPVCS) is now in production as JVCS-IP.
• JVCS = JVCSS (ISDN) + JVCS-IP (H.323)
• http://www.jvcs.video.ja.net/docs/jvcsip.shtml
• Booking system is much as before, but now
includes H.323/IP-based stations.
• H.323 Kit was purchased centrally and deployed
to sites. This is 2Mb/s studio-quality kit. Kit
includes local gatekeepers.
• Users with own kit (e.g Zydacron) may join via
their campus v.c administration and gatekeeper.
JVCS continued
• Kit must pass their QA tests. Our Zydacron was tested at
768k (with side-comments implying that anything less
would be unwelcome) and was near their threshold of
acceptability. It gets a fair bit of use – from a rather small
user base as yet.
• Mixed messages about if and when desktops e.g ViaVideo
will be accepted. But the service does include ratematching, so this should be feasible if policy allows it.
JVCS also offers a quite separate data-sharing service, which
they told me they're happy for anyone to use. This uses the
data sharing component of Windows NetMeeting. See
http://jvcsbook.ja.net/docs/datash/
UK Campuses
Various campuses have own v.c arrangements
additional to JVCS, but I have only limited details.
Examples only:
• Glasgow has MCU facilities (heavily committed
for teaching); also an H.323/ISDN gateway permits H.323 clients to make or receive
H.320/ISDN v.c and voice-only (phone) calls.
• UCL has an H.323 MCU, which Grid project users
regularly make use of (by arrangement, of course).
ESnet
• N.B ESnet AUP requires USA participation in
principle (some special cases e.g DESY)
• Traditional offering: DCS bookable H.320/ISDN
conferences. Also voice-only conferences.
• Experimental H.323 link (801234) was implemented
but died. Temporary arrangements now, until ECS
bookable service operational: each H.323 user books
a GUEST slot and uses ESnet ISDN gateway to call it
from H.323.
• New offerings under the "ECS" banner,
http://www.ecs.es.net/
ESnet ECS
• Ad-hoc H.323-only conferences: NOW. Currently
approves only hardware-based codecs.
• Audio conferences: NOW (replaces old audio bridge
service).
• Data sharing: NOW – it works (via proprietary browser
applet, but claims to be T.120 compatible – details unclear)
• Integrated bookable H320/ISDN + H.323/IP sessions to
replace DCS: new booking system being trialled now,
actual service seems to be some months off yet.
Users of ECS services must in general register for use
beforehand. Unregistered users cannot simply walk up
and get service (there seem to have been some
misunderstandings in the recent past.)
ESnet user experience
• Our CDF users have used DCS successfully via H.323
gateway for a long time.
• They are also early adopters of the ECS ad-hoc H.323
facility and use it frequently.
• This with our Zydacron, or with ViaVideo (software
version 2.2, NOT version 3.0).
• Also gets used from laptop on wireless LAN
• The ad hoc MCU does NOT have rate matching, and
requires G.711 64k for audio: it works well from a
colleague's home 256k cable connection, but from another
member's nominal 128k cable it was pretty much unusable.
Note about DESY and ESnet
• DESY manage their video room bookings via the
ESnet system
• DESY/HH rooms are H.323-capable (the IP
addresses are on the room's DCS page)
• Zeuthen (? I got mixed messages ?)
• When booking for a point to point connection to
DESY, the DESY contact will book the room in
the DCS booking system: take care not to reserve
unnecessary H.320 MCU slots at ESnet (this has
happened several times due to misunderstanding).
VRVS
• VRVS enhanced and expanded: VRVS3.0
• Users must now register and assign a password
• Several dedicated communities. Users outside
those communities register in Universe
• Service offerings as before: browser-based control
panel, vic/rat, H.323 etc., chat window, data
sharing via VNC.
• Browser compatibility improved for a wider range
of modern browsers.
• ViaVideo users still need viavideo software
version 2.2 NOT 3.0
VRVS user experience
• Experience with the new VRVS version seems pretty good.
• Chief problem with VRVS is folks using random PC
hardware. Every PC seems to come with a different audio
card, webcam, different drivers, bringing new bugs and
glitches.
• Using ViaVideo (v.v software version 2.2) gives more
predictable results.
• Also, VRVS users tend to be occasional, and will teardown their setup after use, then forget which plug goes
where the next time. Reckon on at least 10 minutes –
sometimes a lot more - for setup time before productive
meeting starts, unless users are experienced, or willing to
take time for a pre-test session.
AccessGrid
• An ambitious continuous-presence studio-based
offering.
• Based on IP multicast (this still causes some
problems at the edges. There exist multicast
relays, but they don't seem ideal).
• Our users seem much more interested in the lowend desktop offerings that allow informal day to
day contacts without having to book and go to a
special room.
• So I haven't much to add to the previous report on
this mode, sorry.
GDS: Global Dialling Scheme
• A world-wide dialling scheme for H.323 analogous to
international telephone dialling, see
http://www.jvcs.video.ja.net/docs/jvcsip.shtml#010 or
http://www.unc.edu/video/videnet/faq/
• JVCS-IP participates in the scheme and uses it itself, and
I've tested it successfully via the campus gatekeeper
• Example 004401158215454: 00 = international prefix,
44=GB/UK, 01158 is JVCS->Glasgow Univ., and 215454
is our Zydacron (while registered to the campus GK)
• ESnet doesn't use the scheme internally, but is connected to
it and can call with appropriate prefix (I've tested this
successfully also).
An apology (again)
• Videoconferencing options are complicated
• This is not of my making: I'm doing my best
to show ways through the maze
• Conferencing is working well for some
groups of users. And it's cheaper than the
telephone, once you have the kit. So why
not give it a try?
• Don't overlook the benefits of data
sharing…
H.323 configuration Tip
• We need to configure to different gatekeepers (campus,
ESnet, UCL) according to usage;
• Each gatekeeper wants a different E.164 identity and/or
alias;
• Damned nuisance to reconfigure via the client GUI every
time we need to change.
• Take copies of the relevant configuration file for each
configuration, and write a script (batch file etc.) to plug the
desired one into place and fire up the client software.
• The file is typically (also for Zydacron) called "Config.val"
in the same folder as the installed application, e.g
C:\Program Files\Polycom\Viavideo
• Create entries on your start menu for the various configs.
Kit and software
• There are no new purchase recommendations this
time.
• ViaVideo can be recommended as before: but use
software version 2.2: version 3 causes problems
with VRVS and with ESnet ad-hoc H.323.
• Zydacrons are still in productive use, but we don't
recommend purchase now.
• Thus there is no concrete recommendation for
group-sized gear. Ask your campus support about
calling-off from the JVCS-IP procurement
contract? (Tandberg)
Purchase (2)
• If only VRVS is required then anything which supports
vic/rat will do (webcam etc) but beware of kooky audio.
• For H.323, find out whether software codecs (e.g
NetMeeting or GnomeMeeting) are acceptable to your
MCU provider, or not. (Usually "not").
• ESnet H.323 saturation test (USA) showed that the vast
majority use ViaVideo.
• It's looking as if GnomeMeeting might be accepted by
ESnet ad-hoc later, but for now only hardware codecs are
approved (e.g viavideo).
• Hardware codecs generally support only Windows OSes.
• ViaVideo security alert.
Purchase (3)
• Software is either bundled, or comes free
from the service provider (VRVS package,
ESnet data sharing applet, etc.) so there are
no additional costs there.
• Audio kit is a weak spot with us. We use
the inexpensive SoundPoint/PC, which is
OK though its connectors are unreliable.
Better audio kit would be nice – but rapidly
gets very expensive. I don't personally have
any recommendations, sorry.
Conclusions
• Desktop videoconferencing is working for the community
and some (e.g in CDF) say we couldn't have survived
without it.
• There are some glitches, unwanted complexity and
duplication of service offerings, but these are not of our
making.
• For studio work we still look to our central campus
service. Some other groups have own investment in kit.
• I still feel that data-sharing is under-used, maybe because
of the different service offerings and user perception of
complexity, but I'd recommend taking another look.
The End