Networks

Network Load (Release 4.0)
Created on: April 1998
R/3 Release: 4.0
Table of Contents
Introduction
Estimating Network Traffic
Network Traffic in Different Releases
Comparing Benchmark Results of Releases 3.0 and 4.0
Calculating the Line Capacity for the Network Traffic
Preconditions
Example
Illustration of the Network Load for 4.0
Introduction
SAP provides this documentation for its customers, partners and all parties inte
rested in initial network sizing. As the sizing of networks depends on the overa
ll system sizing, the SAP hardware partners and their respective competence cent
ers bear the responsibility.
Estimating Network Traffic
This paper contains research results on data traffic in the R/3 System. First, w
e briefly describe the communication between the presentation server and the app
lication server in a three-tier model. Then we will introduce a formula to calcu
late the line capacity that is needed for the network traffic. This formula reli
es on the results of standard benchmarks such as Sales and Distribution (SD), Fi
nancials (FI) and Materials Management (MM). Note that the benchmarks only measu
re GUI traffic and exclude local printing, graphics or the up-/download of offic
e applications.
In general, R/3 is implemented through a three-tier client-server model. Three-t
ier R/3 installations use various network components for the communication betwe
en presentation and application server on one hand and application and database
server on the other. Two-tier R/3 systems require network communication between
the presentation frontend and the central instance.
In the three-tier model, data is transferred from the presentation server to the
application server via dialog steps (screen changes). During this process, betw
een 1,5 and 2,0 KBytes are transferred on average. The line capacity between the
different layers depends on numerous factors and should be at least 10 Mbit/sec
. For configurations of medium or large-scale scale, SAP highly recommends a hig
h speed network (e.g. FDDI - 100 Mbit/s).
Network Traffic in Different Releases
Comparing various releases of the SAP GUI (2.0, 2.1, 2.2, 3.0, and 4.0), we find
two factors that influence network traffic:
1. The amount of data transferred between the application and presentation
server increases.
2. The compression logic for the GUI has improved.
Therefore the network requirements for Release 3.0 are basically the same as for
2.1 and 2.2. Customers do not need to change or upgrade their existing LAN or W
AN networks to use R/3 Release 3.0.
For Release 4.0, the number of transferred bytes per dialog step is increased sl
ighty. We obtained this data mainly by measuring the frame size in the LAN. Duri
ng every dialog step, the system sends four packages of an average of approximat
ely 1,700 Byte.
In the following figure you can see the changes in network traffic over the last
releases.

Comparing Benchmark Results of Releases 3.0 and 4.0
In SD, the screens have been completely redesigned. For measurements, we increas
ed the screen size by 10% in order to avoid further dialog steps. Also, new pull
-down menus added between 300 and 400 Bytes to the results.
FI has increased its data throughput by 13% mainly due to the extended protocol
for new functions in 4.0.
In MM, the data throughput per screen has not increased significantly, even thou
gh the variable Step-Loop dynpros were replaced with the Table Control technique
.
The increased network traffic you can see in the diagram is mainly due to growin
g cross-application functions and frontend level integration. Most of the integr
ation options lie on the server side affecting the central server LAN. No additi
onal traffic is generated for the company LAN. Upgrading to Release 4.0 will pre
sumably not require an upgrade of the network.
Calculating the Line Capacity for the Network Traffic
The following formula can be used to calculate the required line capacity for th
e network traffic between the presentation and the application server.
Preconditions
The number of users, the line utilization, the thinktime and the response time a
re input parameters for the formula. In order to ensure acceptable network respo
nse times, line utilization should not be higher than 50% also assuming that onl
y SAP dialogs are running on the network.
Definitions:
C = Required line capacity measured in bit/sec
L = Line utilization (0 < L < 1)
TThink = Thinktime between two dialog steps
TRes = Response Time
N = Total number of users with thinktime TThink and response time TR
es

C = 16.000 * N / [L * (TThink + TRes)] bit/sec
The formula is based on measurements of the R/3 FI, MM and SD Standard Applicati
on Benchmark for Release 4.0.
The connection of the presentation frontend to the application server can be est
ablished using a Local Area Network (LAN) or a Wide Area Network (WAN). All the
different network types such as Ethernet, Token Ring, FDDI, and ATM can be used.
We recommend do not to use lines with capacity less than 9,600 bit/sec. Experien
ce shows that working with the theoretical maximum leads to very spiky network tra
ffic and therefore to long response times, because the calculation averages cove
r only a few users and does not reflect real user behavior.
Example
1. 15 users, 10 sec thinktime, 2 sec response time
N = 15, L = 0.5
C = 16,000 * 15 /[ 0.5 (10 sec + 2 sec)] bit/sec = 40,000 bit/sec => 64,000 bit/
sec line
2. 30 users, 30 sec thinktime, 1 sec response time
N = 30, L = 0.5
C = 16,000 * 30 /[ 0.5 (30 sec + 1 sec)] bit/sec = 31,000 bit/sec => 64,000 bit/
sec line
Illustration of the Network Load for 4.0
The following figure illustrates the average network load between presentation l
ayer and application layer and between application layer and database layer.

SAP TechNet Knowledge Base Article
Topic: System Monitoring
Subtopic: Workload Balance
Keywords:
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