v2r1architecture

v2r1architecture
Architectural Overview
IBM Network Computer Division
September 1999
v2r1architecture.prz
Copyright IBM Corp. 1998 -©
Course
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1
Objective/Contents
Network Station Hardware Components
Network Station Software Components
LAN Boot Logical Architecture
LAN Boot Architecture - Workgroup < 50 users
LAN Boot Architecture - Workgroup > 50 users
LAN/WAN Boot Architecture - Enterprise > 500 users
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Network Computer Division 2
Notes
The objective of this presentation is to introduce the IBM Network Station by taking a high
level architectural perspective of it's operating environment.
We first take a brief look at the hardware components and software components of the
Network Station.
We then review the generic process of booting a station on a LAN to identify the different
logical servers that are used and the type of information obtained from these servers.
Next, we repeat this boot process for three typical scenarios, that is for an environment
with less than 50 users, with more than 50 users and for an enterprise with more than 500
users and a mix of LAN/WAN access.
We try to remain at a high level to concentrate on understanding the overall generic or
architectural aspect of the boot process.
If you are hungry for additional details, the next presentation on Planning and Design takes
these same steps a bit further by looking at much more of the underlying technical details
and the choices that are available at each major step.
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Network Computer Division 3
Network Station Hardware
C
P
U
RAM
NVRAM
Boot
Firmware
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Network Computer Division 4
Notes
The first piece of the puzzle is the IBM Network Station so we first need to understand the
components that make up an IBM Network Station or pretty well any network computer for
that matter.
The core components are:
A Central Processing Unit - With the currently available models of the Network Station, the
processors range from a Power PC 403 33 MHz engine to an Intel MMX 266 MHz. This
range allows a selection based on the type and number of applications that need to be
executed on a particular station.
Random Access Memory - Part of this memory is nonvolatile (NVRAM) to allow certain
pieces of data to remain permanently between power off and power on of the station, and
the rest is traditional RAM holding the operating system, applications and data, which must
be reloaded after a power off. Note that this is a real memory system and that there is no
paging into virtual memory on disk.
Boot Firmware - This firmware is code that is given control after a power on and is
responsible for performing power on self tests as well as initiating the sequence of events
that are required for the station to contact a server on the network and download its
operating system.
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Network Computer Division 5
Network Interfaces
C
P
U
RAM
NVRAM
Boot
Firmware
LAN Adapter Manager
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Network Computer Division 6
Notes
The next component required is a network interface card that allows the station to
communicate with other hosts on the network, in particular with a server, in order to
download its operational code.
This adapter can be either an Ethernet adapter or a Token Ring adapter.
During the power on sequence, as soon as the self diagnostics tests are completed, the
adapter is opened in order for the station to be able to communicate on the network and
contact one or more servers.
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Network Computer Division 7
Monitor and Video Support
Window Manager
C
P
U
RAM
NVRAM
Boot
Firmware
LAN Adapter Manager
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Network Computer Division 8
Notes
The next component is the display monitor.
A variety of monitors are supported in different video modes and resolutions and a window
manager software component manages the windows displayed by the different
applications operating on the Network Station.
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Network Computer Division 9
Keyboard and Mouse
Window Manager
C
P
U
RAM
Keyboard
NVRAM
Boot
Firmware
Mouse
LAN Adapter Manager
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Network Computer Division10
Notes
Next is the support for keyboard and mouse input.
The keyboard is a standard 102-key PC keyboard, available in different language
configuration, and a 2-button mouse.
A 3-button mouse is supported, but not shipped with the Network Station.
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Network Computer Division11
Miscellaneous I/O Ports and Devices
IP Connected I/O
Window Manager
Parallel
Serial
USB
PCI
PCMCIA
or
Compact
Flash
C
P
U
RAM
Keyboard
NVRAM
Boot
Firmware
Mouse
LAN Adapter Manager
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Network Computer Division12
Notes
Finally, there are a variety of I/O ports and devices available, dependent on the different
models. For example:
All models have some form of audio support, ranging from 8-bit mono integrated speaker to
16-bit stereo jack on the latest models
All models have at a minimum one serial and one parallel port (except for the Series 2200).
The serial port can be used to attach a serial printer, or communication device and the
parallel port typically is used to attach a parallel printer.
The earlier models a PCMCIA Type II adapter while the latest model (the 2800) supports
PCI adapters.
Some of the latest models also provide a USB port capability allowing for easy expansion
of I/O devices connectivity.
And all models also allow the use of Flash Memory Cards in order to provide a limited local
storage capability, mostly for implementing local boot capabilities.
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Network Computer Division13
Network Station Software Components
Network Station Base Components
Base Code Firmware
POST Diagnostics, Base Network Support, Hardware Interfaces, Boot Strap, Setup
Parms
Hardware
CPU, RAM, Boot Prom, NVRAM, Network Adapter, Monitor, Mouse, Keyboard, I/O
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Network Computer Division14
Notes
The base software components illustrated in this chart form the first layer above the
hardware components.
These base components include the diagnostics routines, such as those performed during
the Power On Self Tests when the user powers on the station. Most importantly, the base
components include the firmware, which is code permanently resident on the station on a
Programmable Read Only Memory (PROM) chip, that is given control after the POST
completes and that then performs the steps necessary to boot the Network Station. This
code is called the Boot Monitor.
The boot monitor is the component responsible for booting the Network Station; it
determines how it is going to behave and how it is going to initiate the boot process by
reading some of the configuration data that is permanently recorded in the Network
Station’s NVRAM.
With this information, the boot monitor is able to contact a boot server on the network and
to download the operating system required by the particular model of the Network Station
on which the boot monitor resides.
The boot monitor can be easily replaced, when new features or functions become
available, by downloading a new version from a remote server and replacing the current
one recorded in the PROM; this process is called reflashing the PROM.
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Network Computer Division15
Network Station Software Components
Operating System Kernel
Networking, Window / Task Mgmt. Hardware Interfaces
Network Station Base Components
Base Code Firmware
POST Diagnostics, Base Network Support, Hardware Interfaces, Boot Strap, Setup
Parms
Hardware
CPU, RAM, Boot Prom, NVRAM, Network Adapter, Monitor, Mouse, Keyboard, I/O
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Network Computer Division16
Notes
The operating system is a NetBSD Unix software and it comes in two major flavors:
Prior to V2R1, the kernel was supplied by NCDinc. and was designed to run on Power PC
engines.
With V2R1, the kernel is supplied by NCinc and is designed to operate on both a Power PC
engine (except the Series 100) or on an Intel engine as available in the new Series 2800
and Series 2200.
It is important to remember that the kernel uses a linear memory model, which means that
all applications use real memory and that there is no virtual memory or memory swapping.
This is mainly because there is no local storage facility in the Netrwork Station that can be
used to swap memory to.
Adding more memory to a Network Station increases the total number of local applications
that can be run simultaneously, but not the performance. In low memory conditions,
applications may not be loaded by the kernel and in critical low memory conditions, the
kernel may close applications to free memory as a last resort.
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Network Computer Division17
Network Station Software Components
Applications loaded with desktop or on demand
3270
5250
X-11
VTxxx
ICA
WEB
Browser
Java Applications
Java Virtual Machine
Operating System Kernel
Networking, Window / Task Mgmt. Hardware Interfaces
Network Station Base Components
Base Code Firmware
POST Diagnostics, Base Network Support, Hardware Interfaces, Boot Strap, Setup
Parms
Hardware
CPU, RAM, Boot Prom, NVRAM, Network Adapter, Monitor, Mouse, Keyboard, I/O
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Network Computer Division18
Notes
Once the operating system is loaded and the user has logged in, applications can be
started automatically or they can be loaded/started on request by the user.
The native applications available to the user are:
A 3270 Emulator
A 5250 Emulator
An X windows terminal capability to access a AIX or Unix system as well as a multi-user
Windows NT system using the X11 protocol
A VTxxx emulator
An ICA client to access a WinFrame or MetaFrame server (multi-user WIndows NT) using
the ICA protocol.
A Web browser based on Netscape’s Navigator 4.5.
Finally, any Java application or applet, either home grown or available on the market, can
be executed on the Network Station’s JVM.
In summary, note that once the Network Station is powered off, all software loaded in
memory disappears, and must be reloaded after the next power on. Only the firmware
necessary to reboot the Network Station remains.
One must remember that one of the main advantages of a thin client is that since the
software resides only on the server, individual copies of the software do not need to be
maintained and updated on every station. Every time a station loads either the kernel or an
application, it is an opportunity to get a fresh updated copy of the software since it only
needs to be updated on the server in order to be propagated to all stations.
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Network Computer Division19
IPL Considerations Summary
No local file storage
all software (including kernel) must be downloaded from a
server !
Network Station only supports TCP/IP
no NetBIOS, IPX, etc.
Boot Monitor stored in flash memory
easy to update for new features/fixes
Nonvolatile RAM (NVRAM)
contains information about the Network Station hardware
and boot environment
keyboard Language
screen resolution
selectable boot processes
Media Access Control (MAC) LAN address
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Network Computer Division20
Notes
Here are a few reminders of some of the important boot considerations:
There is no local file storage on the station; therefore all software (including kernel) must be
downloaded from a server !
The Network Station only supports the TCP/IP protocol and must therefore be attached to
an IP network. NetBIOS, IPX/SPX, etc.. are not supported.
The Boot Monitor is stored in flash memory and is easy to update for new features/fixes
The Nonvolatile RAM (NVRAM) contains information about the Network Station hardware
and boot environment such as keyboard Language, screen resolution and the selectable
boot processes
The MAC address is burned in to the adapter but can also be changed to an LAA type
address.
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Network Computer Division21
Boot Monitor
POST (power on self test)
Boot Monitor Version (boot code)
Video Memory Test
RAM Memory Test
Keyboard Controller
BOS
Keyboard, Mouse, Display
Network Access
Ethernet, Token Ring
Setup Utility
Set Network Parameters
Set Boot Parameters
Set Monitor Resolutions
Set Keyboard Language
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Network Computer Division22
Notes
The boot monitor that resides in the PROM is responsible for:
Executing the POST (power on self test) that verifies the boot Monitor Version (boot code),
Video Memory, the RAM and Keyboard Controller
BOS verifies the Keyboard, Mouse, and Display and the Network Access (Ethernet or
Token Ring)
The boot monitor also offers a Setup Utility to allow the administrator to perform the
following configuration tasks:
Set Network Parameters, to specify the address of the station, the subnet mask, the
gateway address and all such parameters that allows this station to function as an IP host
Set Boot Parameters, that identifies the address of a boot server and the location of the
operating system file that needs to be downloaded. There are other servers such as
configuration servers and authentication servers that may need to be specified
Set specific station characteristics such as Monitor Resolution and Keyboard Language
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Network Computer Division23
LAN Boot Logical Architecture
IP LAN
Network
Station
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Network Computer Division24
Notes
Lets us now get on to the next major and interesting topic, that of the boot process.
We define the boot process as all the activities that must take place between the time that
the user powers on the Network Station and the time where the user is able to load an
application to do some useful work.
When broken down into the individual events, there are quite a significant number of
activities that must take place as part of the boot process, so we will use a step by step
approach to identify each of the important steps, gradually building a diagram that
summarizes all the major steps.
In this chart we first attach a Network Station to an IP LAN network. The important point to
remember is that the Network Station only supports TCP/IP so it must be attached to an IP
network.
After the station is powered on and has executed the POST tests, the boot monitor, stored
in the station’s PROM chip opens the network interface adapter to insert itself into the
network.
It uses the Media Access Control (MAC) LAN address that was stored in the nonvolatile
memory (NVRAM) along with data such as keyboard layout and screen resolution. From
this point on, this station can uniquely identify itself on the network by using its MAC
address.
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Network Computer Division25
LAN Boot Logical Architecture
DHCP
IP LAN
1
Network
Station
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Network Computer Division26
Notes
The Network Station is an IP host, and therefore, in order to communicate with other IP
hosts, it needs to have an IP address of its own. This IP address can be obtained either
from NVRAM or from a BOOTP or DHCP server on the network.
Here we use the DHCP server method, which is the recommended method. We discuss
the advantages and disadvantages of each of these methods in the Planning and Design
topic.
To obtain an IP address from a DHCP server, the station issues a broadcast (that’s the
only thing it can really do at this point since it does not yet have or own an IP address) on
the network asking any DHCP server that is listening to respond by sending an IP address
that it can use. Contained in this broadcast frame is the station’s MAC address, which
allows the station to uniquely identify itself to DHCP servers.
On receipt of this broadcast, one (or possibly more than one) DHCP server on the network
responds by allocating an IP address that the station is allowed to use for a specified
period of time. Note that the server can specifically recognize the station by its MAC
address (if this MAC address has been specifically defined in the server) or it can choose
to respond to requests originating from any MAC address.
Along with an IP address, the DHCP server can also send other vital pieces of information
such as the address of a boot server that the station should contact to obtain its operating
system, and the path to the directory where the operating system file can be found, and a
few other pieces of configuration data which we will examine in more details later.
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Network Computer Division27
LAN Boot Logical Architecture
DHCP
IP LAN
1
2
Boot
Network
Station
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Network Computer Division28
Notes
Now that the station has its own IP address, it is a recognized citizen on the network and
has the ability to communicate directly with any other IP host on the network.
Its next important task is to obtain a copy of the operating system that it requires to
operate.
There are two ways of obtaining its operating system:
The station contacts a designated boot server on the network from which it downloads a
copy of the operating system. This is the example we use here as this is the most common
case.
Or, if the station is equipped with a flash memory card, it can be configured to load its
operating system directly from this local storage device. This is a special case that will be
examined later.
Using the address of a boot server that was obtained from the DHCP server, the station
contacts the designated boot server and downloads a copy of its operating system.
Typically, in the later releases, the operating system (which we will call the kernel from
now on) is downloaded in compressed format in order to make the transfer faster and is
uncompressed by the station after receipt.
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Network Computer Division29
LAN Boot Logical Architecture
DHCP
IP LAN
1
2
3
Boot
Configs
Network
Station
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Network Computer Division30
Notes
The next task in the boot process is to set up the operational environment for this particular
station by obtaining some system configuration data from a configuration server.
System configuration data at this point are parameters such as:
Does this specific station have a printer attached?
What language is to be used during the boot sequence?
and system defaults such as :
Is the mouse defined as right-handed or left-handed for all users?
What is the background color of the screen?
What is the screen saver background bitmap?
In this description, we are showing this configuration server to be a separate physical
server, but it does not necessarily have to be. It could be on the same server as the boot
server for example. However, because we are focusing more on the concepts here than on
the actual implementation, we are using separate servers.
How does the kernel know the address of the configuration server where the configuration
files are stored? This address is supplied to the Network Station either as one of the pieces
of information returned by the DHCP server, or as a manually configured parameter in
NVRAM.
The kernel contacts the designated configuration server and downloads the system
configuration files. Some of the parameters considered as system defaults may be
overridden later on by additional configuration files that are applicable to a group or a
specific user.
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Network Computer Division31
LAN Boot Logical Architecture
DHCP
IP LAN
1
2
3
4
Boot
Configs
Login(auth)
Network
Station
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Network Computer Division32
Notes
The next major step in the boot process is to identify the user that will be using the
Network Station. The kernel gives control to a login client routine that displays a panel to
the user asking for a user name and password.
The login client then contacts an authentication server to validate the identity of the user
and that the correct password is used.
How does the login client know the address of the authentication server? There are three
possibilities:
Unless it is specifically identified, the default authentication server is the same server as the
boot server
The address of the authentication server has been specified in the DHCP data (or manually
configured in NVRAM)
The user has used the ROAM button on the login panel to manually enter the address of a
specific authentication server. This is used in case where a user has traveled to a different
location and needs to be authenticated by a server back home.
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Network Computer Division33
LAN Boot Logical Architecture
DHCP
Boot
IP LAN
1
2
3
4
5
Configs
Login(auth)
Preferences
Network
Station
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Network Computer Division34
Notes
Once the user has been authenticated, the kernel now knows the user and the group it
belongs to and is therefore in a position to download additional configuration files that are
specific to this group and this user.
These configuration files are called the user preferences (configuration data) because they
represent the specific user preferences, such as a left handed mouse when the system
default is right handed, or a particular set of colors for the desktop, etc..
In the current versions of the product (V1R3 and V2R1), the preferences server is always
the same as the authentication server, although there is a possibility to change this by a
manual alteration of one of the configuration files.
The kernel fetches the preferences configuration files based on the user name and group
name, and overrides the system defaults parameters for those parameters contained in
the preferences files.
The preferences files also contain the information necessary to identify the applications
that are to be autostarted based on the user profile, and also the setup of the desktop and
the applications to be made available to the user.
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Network Computer Division35
LAN Boot Logical Architecture
DHCP
Boot
IP LAN
1
2
3
4
5
6
Configs
Login(auth)
Preferences
Native Apps
Network
Station
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Network Computer Division36
Notes
The next step is to load the applications that are specified as autostarted, or to load
applications on request when the user click on a specific icon on the desktop to start an
application.
The native applications, such as the emulators, or any Java application or applets, are
modules that need to be downloaded from a server.
The native applications server is by default the same as the boot server and cannot be
specified otherwise at this point in time.
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Network Computer Division37
LAN Boot Logical Architecture
DHCP
Boot
IP LAN
1
2
3
4
5
6
7
Configs
Login(auth)
Preferences
Native Apps
Home
Network
Station
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Network Computer Division38
Notes
Some of the native applications allow the user to set applications preferences, such as
emulator colors for example, or, in the case of a browser, to save some bookmarks.
Because there is no local storage on the Network Station where these application
preferences can be stored, each user is given a home directory on a server where these
can be stored. This server is called the home server and, at this point, is the same sever
as the authentication server.
The home directory on the home server is automatically allocated to each user that logs on
without the user having to take any specific steps for that to happen. If the user has some
home grown local Java applications that he needs to use, and these applications require
some local storage, the home server can serve as the target server for these files.
However, this is not mandatory because in fact any remote server can be designated as a
file server and be accessed by local applications.
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Network Computer Division39
LAN Boot Logical Architecture
DHCP
Boot
IP LAN
1
2
3
4
5
6
7
Application
Server(S)
8
Configs
Web
Login(auth)
Preferences
Native Apps
Home
Network
Station
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Network Computer Division40
Notes
At this point, the boot process is essentially completed and the user has full control of his
desktop.
As the user starts different applications, it is likely that he will access one or more
application servers. For example, using a 3270 emulator will cause the user to contact a
S/390 server, using a 5250 application means accessing an AS/400 server, using an ICA
client means accessing a MetaFrame server, and using a Web Browser will give him
access to the Web.
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Network Computer Division41
LAN Boot Architecture - Workgroup < 50 users
DHCP
Boot
Configs
Login(auth)
Preferences
Native Apps
Home
IP LAN
1
2
3
4
5
6
7
AS/400
RS/6000
Windows NT 4.0
Network
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Network Computer Division42
Notes
All the servers we looked at so far have been logically and physically separated in the
diagram that we built. In practice however, some of these logical servers are actually
combined and reside on one physical machine.
For example, here is an environment that would be typical for a small workgroup, say
between 10 and 50 users. This case might be representative of a small AS/400
installation, or a small Microsoft Windows NT Terminal Server Edition installation, for
example.
All the components are on a local LAN segment and the total number of users that can be
handled is really dependent on the overall network traffic that they generate.
The servers used could be AS/400, or RS/600 or PC servers and it is possible to have a
mix of servers although that would probably be unusual in such a small environment
because of the skills required to maintain multiple platforms.
In this case, all logical servers are actually combined into one physical machine.
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Network Computer Division43
LAN Boot Architecture - Workgroup < 50 users
Application
Server(S)
DHCP
Boot
Configs
Login(auth)
Preferences
Native Apps
Home
IP LAN
1
2
3
4
5
6
7
8
Web
AS/400
RS/6000
Windows NT 4.0
Network
IBM Network Station Technical Education
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Copyright IBM Corp. 1998
CourseCorporation
materials may not be Station
reproduced in whole
or in part without the prior written permission of IBM.
Network Computer Division44
Notes
Once a station has completed its boot process by accessing this one server for all the
logical server functions it requires, it can then access any application server it needs for
the user applications.
In this case, we have shown a DHCP server but if there were a small enough number of
stations, NVRAM might be considered.
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Network Computer Division45
LAN Boot Architecture - Workgroup > 50 users
IP LAN
Network
Station
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Network Computer Division46
Notes
As we stay within a local LAN environment but move to a larger workgroup where the
number of users is above 50, there are a few more considerations that come into play,
such as the need to use multiple boot servers to maintain a reasonable performance, the
need to monitor the capacity of the LAN, and a greater need to plan for a worst case
scenario and for backup mechanisms.
In this case, it starts to make sense to separate the server functions.
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Network Computer Division47
LAN Boot Architecture - Workgroup > 50 users
DHCP
IP LAN
1
Network
Station
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Network Computer Division48
Notes
Because of the larger number of users, a DHCP server should now be used to facilitate
the management of IP addresses and to have the flexibility to easily reassign where the
stations boot from, as an example, in cases where we want to start use load balancing on
in emergency situations.
Whether to use multiple DHCP servers and where to locate these servers becomes a
question of overall network planning and design, as well as network policies within the
organization. See the next Planning and design topic for a few additional details on this
issue.
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Network Computer Division49
LAN Boot Architecture - Workgroup > 50 users
DHCP
IP LAN
1
2
Boot
AS/400
RS/6000
Windows NT 4.0
Flash Card
Network
Station
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Network Computer Division50
Notes
In this case, we need more than one boot server to satisfy the needs of all the stations and
we might install a boot server on each LAN segment, if there are multiple segments, or
allocate a boot server to IP subnets and manage this through the DHCP server.
All of this is highly dependent on the actual topology of the network and traffic volumes and
patterns.
Another possibility for a booting Network Stations is to use a flash card boot. A flash card
is like a local storage device on which can be recorded the files that are needed for
booting a station, such as the kernel, the fonts and the application modules.
The card is inserted into the Network Station and the boot monitor is directed to read these
files from the local card instead of from a server on the network.
This can be advantageous where there are a small number of users in a remote office
connected through a low bandwidth link and where a boot server in such as small location
becomes hard to justify. Other Network Stations (from 10 to 15 stations) can also boot
from another Network Station which has a boot flash card in a process called peer booting.
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Network Computer Division51
LAN Boot Architecture - Workgroup > 50 users
DHCP
Home
Preferences
Login(auth)
Configs
IP LAN
1
2
3
4
5
6
7
AS/400
RS/6000
Windows NT 4.0
Native Apps
Boot
AS/400
RS/6000
Windows NT 4.0
Flash Card
Network
Station
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Network Computer Division52
Notes
All the other servers, such as the Configuration, Authentication, Preferences and Home
servers are combined on the same physical machine, where we also have the Network
Station Manager application that can be used to manage the configuration files for system
and user definitions.
Typically, these configuration files are small, compared to the kernel and application
modules, and therefore the load on such a server is much less than on a boot server.
From an administrative point of view, it is much easier to combine all of the configuration
data and user accounts on one server rather than have to manage multiple sets of
configuration files on multiple servers.
In a Windows NT environment, even though this server could potentially reside on the
same machine than a backup domain controller, an analysis would be required first to
determine whether this can negatively impact the performance of the BDC. Typically, PDC
and BDC are machines that should be dedicated to these functions.
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Network Computer Division53
LAN Boot Architecture - Workgroup > 50 users
DHCP
Home
Preferences
Login(auth)
Configs
IP LAN
Application
Server(S)
1
2
3
4
5
6
7
8
AS/400
RS/6000
Windows NT 4.0
Web
Native Apps
Boot
AS/400
RS/6000
Windows NT 4.0
Flash Card
Network
Station
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Network Computer Division54
Notes
Once again, our Network Stations are up and operational from using these three separate
servers and they can then access their multiple applications servers just like any other
hosts.
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Network Computer Division55
LAN/WAN Boot Architecture - Enterprise > 500 users
Remote IP LAN
IP WAN
Local
IP LAN
Network
Station
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Network Computer Division56
Notes
Here is a large enterprise environment example, based on a real customer with upwards of
5000 users in 65 remote branches.
This customers uses a centralized management approach at the headquarters location
and uses network management tools such as Tivoli’s IT Director and others to manage the
remote servers and the Network Stations.
The Network Stations have SNMP MIB capabilities (read only) and can be rebooted
remotely from a central location.
The branch offices have no local Information Technology staff because the actual Network
Stations are very easy to install and maintain; they can be installed and plugged in right
out of the box without any other intervention.
The local branch offices all have local LANs which are connected to the corporate central
LAN through a variety of Wide Area Network links.
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Network Computer Division57
LAN/WAN Boot Architecture - Enterprise > 500 users
Remote IP LAN
DHCP
IP WAN
Local
IP LAN
1
Network
Station
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Network Computer Division58
Notes
The management of IP addresses is centralized and controlled through the corporate
DHCP server.
This allows the corporate network administrators to easily change the configuration data
for each an every Network Station in the network and direct them to boot from selected
boot servers, all without any intervention at the local branch office.
Access to the corporate DHCP server is through the WAN links, but the amount of
information that needs to be transmitted is minimal at this point.
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materials may not be reproduced in whole
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Network Computer Division59
LAN/WAN Boot Architecture - Enterprise > 500 users
Remote IP LAN
DHCP
IP WAN
Configs
Boot
AS/400
RS/6000
Windows NT 4.0
Flash Card
Local
IP LAN
1
2
3
Network
Station
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Network Computer Division60
Notes
Because of the amount of data that needs to be downloaded from the boot servers, these
are located on the local LAN and can be a mix a different servers.
Note that in this case, we have also located the terminal configuration files on the boot
server. These files typically do not change very often and can therefore be managed at a
central location and copied to the boot servers for operational purposes.
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Network Computer Division61
LAN/WAN Boot Architecture - Enterprise > 500 users
Remote IP LAN
DHCP
Login(auth)
AS/400
RS/6000
Windows NT 4.0
Preferences
Home
IP WAN
Native Apps
Configs
Boot
AS/400
RS/6000
Windows NT 4.0
Flash Card
Local
IP LAN
1
4
5
7
2
3
6
Network
Station
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materials may not be reproduced in whole
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Network Computer Division62
Notes
The Authentication and Preferences servers are also centralized, located on the corporate
LAN, and allows management and control of all user configuration data in a single
location.
A user from any branch can therefore easily roam from branch to branch and still always
have his user preferences stay the same.
The native applications are obtained form the local boot server but the home directories
are located on the home server at the central site, thereby facilitating the management and
backup of these files.
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materials may not be reproduced in whole
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Network Computer Division63
LAN/WAN Boot Architecture - Enterprise > 500 users
Application
Server(S)
Remote IP LAN
DHCP
Login(auth)
AS/400
RS/6000
Windows NT 4.0
Preferences
Home
Web
IP WAN
Native Apps
Configs
Boot
AS/400
RS/6000
Windows NT 4.0
Flash Card
8
1
4
5
7
Local
IP LAN
2
3
6
Network
Station
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materials may not be reproduced in whole
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Network Computer Division64
Notes
Finally, all application servers are accessed on the corporate LAN.
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Network Computer Division65
Recap - Boot Process
Power On Self Test (POST)
Displays logo, counts memory, checks keyboard and mouse
connections, LAN connections
Network Station broadcasts its MAC address and boot version to
the network (or data taken from NVRAM)
BootP or DHCP server returns the TCP/IP address of the host and
the Network Station (or data taken from NVRAM)
Also fully qualified path to the operating system kernel
TFTP or NFS is used to download the kernel
NFS or RFS (AS/400) loads the configuration files
The User Logs on and is Authenticated
NFS or RFS (AS/400) loads the user preference files
NFS or RFS (AS/400) loads the local applications
NFS or RFS (AS/400) mounts the server's file system
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Network Computer Division66
Notes
As a review, here are the key phases of the boot process.
The Power On Self Test (POST) displays the logo, counts the memory, checks the
presence of the keyboard and mouse.
The LAN adapter is opened and the station inserts itself into the network.
The station retrieves from NVRAM the information is needs to contact a boot server:
If using a Network boot (recommended method):
A DHCPDISCOVER frame is broadcasted on the network. The frame contains the MAC
address of the station.
A DHCP server returns the IP address that the station should use, the boot server
address and the path to the kernel file.
If using an NVRAM boot (For small networks or test cases):
The station loads the station IP address, the boot server address and the path to the
kernel file from the local NVRAM.
TFTP or NFS is used to download the operating system
NFS (or RFS for AS/400) is used to download the configuration files
The user logs on and gets authenticated
NFS (or RFS for AS/400) loads the user preferences files
NFS loads the application modules
NFS mounts the server’s file system
The station is ready for the user to start applications
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Network Computer Division67
Summary
Installing Network Stations is easy
Installation planning is the hard part
Understand the LAN environment of the
installation
LAN/WAN capacity needs to be well understood
Customer existing administration procedures and
desires
Security and policies
Distribution of IT skills
What service requirements are expected
This can be the main driver to the boot server
plan
Network Stations depend on the network for
a successful installation/operation
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materials may not be reproduced in whole
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Network Computer Division68
Notes
In summary, the actual installation of IBM Network Stations is easy, and installing the
actual server or servers can also be an easy task once all the planning decisions regarding
the type of server(s) to use, their location and their role have been done. However, it is the
overall installation and network planning that is the hard part.
Essentially, because the Network Stations are highly dependent on the network for their
operation, the network design and planning is the most essential and the most critical
factor in the successful implementation of Network Stations.
The key is to:
Well understand the LAN environment of the installation. That is, the LAN/WAN capacity
needs to be well understood, the existing customer administration procedures and desires
must be known, the security issues and policies of the organizations must be taken into
account as well as the distribution of IT skills.
Understand the service level that are expected or that are part of the organization policies.
The next topic focuses on the planning and design by attempting to identify all the
important planning elements that must be considered and by providing as many details as
possible on each of these elements. The objective is not necessarily to provide the
answers but to provide all the questions that should be asked and provide some insight
into the impact of some of the key decisions that are to be made.
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materials may not be reproduced in whole
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Network Computer Division69
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