User scenarios for Networking Policy Control.
Authors: C. de Laat, L. Gommans
contact: C.T.A.M.deLaat@phys.uu.nl
The purpose of this document is to collect user requirements for Quality
of Service enabled networks for different (parts of) applications. This
should help discussions in other areas such as the Bandwidth Broker requirements
to make sure that the invented solutions will work for certain application
and user needs. Please note that the requirements are written on the application
layer. They might translate differently to (connection-less) network layers.
Computer based education
In this case the tutor places education material on a server, to which
students connect. The students can do this at any time. Depending if video
or audio or dynamic applets for a virtual laboratory are embedded in the
material, bandwidth requirement are only of the type "throughput". Authentication
and authorisation are essential on network and application layer.
Collaboratory
A collaboratory is a setup, which allows experimentators to inspect and
control (parts of) an experimental setup from another location using networking
facillities. A collaboratory consists of mainly three functional parts:
data connections, control connections and groupware. The latter includes
A/V systems for videoconferencing and inspection. The three parts generally
have different network requirements:
-
data connections
Data connections usually require a certain minimum bandwidth. Since
the required bandwidth is usually relatively high and limited bufferspace
in the network, round trip time is not specially required. In our case
this is implemented via the use of object data bases (Objectivity).
-
control connections
Controlling equipment via the network requires low but guaranteed bandwith
and a guaranteed upper limit of the rtt. In our case these services will
be implemented on top of CORBA.
-
groupware
Groupware A/V will be discussed below at the telephony and video items.
E-commerce
Secure fully authenticated channels. Most probably the speeds and round
trip times do not matter, as long as transaction take less than a (few)
second and can be overlapped.
Distributed Computing
Connections between a set of (super)computers working together on a computational
intensive task. Computers exchange small messages to inform the others
of results of computations needed as imput for the next calculations. The
computers are effectively waiting at synchronize points for those messages.
Therefore, round trip time should be as low as possible. Those meesages
are usually not very large, so, bandwidth should not be a big issue.
IP-telephony
Voice over IP. Needs low jitter and low round trip time. Also needs a low
but fixed bandwidth. The low bandwidth might be a problem, since nowadays
it is a very small fraction of the gigabit linespeeds. Computations of
allocation schemes might not have such resolutions.
Video
Video conferencing as a replacement for getting together. Mad, isn't it?
-
P-P
Point to Point video conferencing (person to person). Needs kind of
VBR bandwidth (every 20 or 40 ms a frame).
-
Group
Extra multicast requirement. One person talks to a group without feedback
-
Group-P-P
Everybody talks to everybody at the same time. Is the same as N * Group.
However, round trip time might now be important.
Definitions
PRTT =
Policy Round Trip Time
BBRTT =
Bandwidth Broker Round Trip Time
Initiator = user side, initiator
of the request
Peer(s) = site(s)
to which user is connecting
Requirements
|
|
Initiator
Authent
|
Peer(s)
Authent
|
Client
pays
|
Server
pays
|
BW
|
RTT
|
Jitter
|
Multicast
|
Packet
loss
allowed
|
Max
PRTT
|
dynamical
contract
|
|
Computer based education
|
X
|
|
X
|
|
X
|
|
|
X
|
|
minuts
|
|
|
Collaboratory Data
|
X
|
X
|
X
|
|
X
|
X
|
|
X
|
|
days
|
X
|
|
Collaboratory Control
|
X
|
X
|
X
|
|
|
X
|
|
|
|
days
|
|
|
E-commerce
|
X
|
X
|
X
|
X
|
|
|
|
|
|
seconds
|
|
|
Distributed Computing
|
X
|
|
|
|
|
|
|
|
|
days
|
X
|
|
IP-telephony
|
X
|
|
X
|
|
|
X
|
X
|
|
X
|
seconds
|
|
|
Video P-P
|
X
|
|
|
|
VBR
|
X
|
X
|
|
X
|
seconds
|
X
|
|
Video Group
|
X
|
|
|
|
VBR
|
|
|
|
|
|
|
|
Video G-P-P
|
|
|
|
|
VBR
|
|
X
|
X
|
X
|
minuts
|
X
|