v2r1design
Planning and Design Considerations
IBM Network Computer Division
July 1999
v2r1design
Copyright IBM Corp. 1998 -©
Course
may not be reproduced in whole
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1
Objectives/Contents
Hardware decisions
Network decisions
Boot related decisions
Boot server decisions
Terminal configuration decisions
Authentication server decisions
Application server decisions
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Network Computer Division 2
Notes
The objective of this presentation is to provide an overview of some of the important
decisions facing an administrator while planning to implement a network of Network
Stations.
The intent is not so much to provide specific answers as to draw attention to the right
questions that should be asked when designing such an environment.
We shall first take a look at hardware related decisions, which are fairly simple, and then
move on to the network and boot related questions, followed by a look at decisions related
to each of the logical servers we discussed in the architecture topic.
Some of these decisions can be fairly involved and we do not have the time to cover all the
details in this particular presentation. We will therefore summarize a lot and direct you to
the Planning and Design chapter in the draft redbook on V2R1 on this CD for a lot more
details.
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Network Computer Division 3
Hardware Decisions Summary
Choices
Factors to consider
Model
Application types and mix
Memory Size
Number of simultaneous applications
(real memory) and print buffer
requirements.
Adapter Type
Choice of technology (TRN or Ethernet)
Monitor Type
Applications used and user
requirements
Resolution needed by user or
application
Normally 2-button (shipped); Can use
3-button for AIX.
Video Support
Mouse
I/O Ports and Devices
Audio, serial and parallel are standard;
PCI, PCMCIA, Flash card, Touch
screens, Mutiple Serial adapter card,
and others based on special needs
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Network Computer Division 4
Notes
Here is the first set of decisions faced by the administrator.
For each section, we use the same format, which is to summarize the choices that are to
be made and look at the factors to be taken into account for each of these choices.
For example, the model of the Network Station needs to be chosen in light of the
application mix to be processed on a particular station.
The memory size of a station depends on the number and type of applications to be run
simultaneously as well as on the print buffer requirements if the station has one or more
printers attached.
And so on for the different the other hardware characteristics.
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Network Computer Division 5
Network Station Models/CPU/RAM
C
P
U
RAM
NVRAM
Boot
Firmware
IBM Network Station
Model
Series 100
Series 300
Series 1000
Series 2200
Series 2800
Technology
Power PC 403
Power PC 403
Power PC 603
Intel Pentium MMX
Intel Pentium MMX
Model
Description
8361-100
8361-200
8361-110
8361-210
8361-341
8362-A22
8362-A23
8362-A52
8362-A53
8363-Txx
8363-Exx
8364-Txx
8364-Exx
Series 100 Ethernet
Series 100 Token-Ring
Series 300 Ethernet
Series 300 Token-Ring
Series 300 Twinax
Series 1000 Token-Ring (32M)
Series 1000 Token-Ring (64M)
Series 1000 Ethernet (32M)
Series 1000 Ethernet (64M)
Series 2200 Token-Ring
Series 2200 Ethernet
Series 2800 Token-Ring
Series 2800 Ethernet
Speed
33 MHz
66 MHz
200 MHz
233 MHz
266 MHz
Model
Series 100
Series 300
Series 1000
Series 2200
Series 2800
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Min.
8M
16 M
32 M
32 M
64 M
Max.
64 M
64 M
64 M
288 M
256 M
Network Computer Division 6
Notes
This chart summarizes the Network Station models available, the speed of the processor
and the amount of RAM memory available on each of the model families.
For these characteristics, the driving factor is the set of applications to be run on the
station.
Each family of Network Station is designed for a particular set of applications. For
example, the Series 300 is most appropriate for host access but not really Web access or
Java. The Series 1000 and 2200 are most appropriate to Web browser and light Java
while the Series 2800 is more suited to heavier Java work.
The memory size is then selected based mainly on the number of simultaneous
applications to be executed as the Network Station is a real memory system. More
memory does not increase performance but does allow more applications to be run
simultaneously.
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Network Computer Division 7
Network Station - LAN adapter and Video Support
Monitor Support All models Video Graphics Array (VGA)
Super Video Graphics Array (SVGA)
Super Extended Graphics Array (SXGA)
Video Support
All models Minimum: 640x480 VGA
Maximum: 1600X1200 SXGA
Video
memory
Window Manager
C
P
U
RAM
Boot
Firmware
LAN Adapter Manager
Series 100
Series 300
1 MB Base
2 MB Maximum
Series 1000
2 MB base and maximum
Series 2200
3 MB base and maximum
Series 2800
4 MB base and maximum
Model
Series 100
Series 300
Series 1000
Series 2200
Series 2800
Ethernet
10 base T
10 base T
10/100 Mb
10/100 Mb
10/100 Mb
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Token-ring
Auto 4/16 Mb
Auto 4/16 Mb
Auto 4/16 Mb
Auto 4/16 Mb
Auto 4/16 Mb
Network Computer Division 8
Notes
This chart summarizes the LAN and video support.
The LAN support is nearly the same for all models, that is a choice of either TRN or
Ethernet adapters and the decision of which adapter to use is most likely determined by
the existing network topology in existence.
The video support is similar for all models except for the amount of video memory
available, but in most cases, there is no choice to be made as the base and maximum
video memory is the same.
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Network Computer Division 9
I/O Ports and Devices
I/O
Ports
C
P
U
RAM
Boot
Firmware
102-key PC keyboard
Keyboard
Mouse
2-button mouse
LAN Adapter Manager
I/O Ports
Audio
Serial Port
Parallel Port
PCI Adapter
Slots
(half-length)
PCMCIA Type
II
USB Ports
Flash Memory
Cards
Series 100
Series 300
8-bit
Speaker
Series
1000
16-bit
Jack
Series
2200
16-bit
Stereo Output Jack
Mono Input Jack
Series
2800
16-bit
Stereo Output Jack
Mono Input Jack
8-bit
Speaker
1
1
None
1
1
None
1
1
None
No
No
No
2
1
2
Yes
Yes
Optional
No
No
No
PCMCIA
(linear C/D)
(8 to 40 MB)
No
PCMCIA
(linear C/D)
(8 to 40
MB)
No
PCMCIA
(linear C/D)
(8 to 40 MB)
2
Compact Flash
(8 MB to 96+ MB)
2
Compact Flash
(8 MB to 96+ MB)
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Network Computer Division10
Notes
Finally, the last hardware related decisions concern the choice of the I/O devices required.
Here the administrator faces a lot more diversity between the different models of the
Network Station.
In general, all models have at least one native serial and parallel port, except for the
Series 2200 which only has two USB ports.
Adapter card support consisted of PCMCIA adapters on the previous Power PC models,
replaced with PCI adapters in the newer model (Series 2800).
Finally, the flash card support consisted of linear flash cards with a maximum capacity of
40 MB whereas the newer models (2200 and 2800) support the compact flash cards which
can hold upwards of 96 MB at this time.
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Network Computer Division11
Network Planning Decisions
Assess the impact of the additional traffic generated by the boot
and application activities of the new devices
Determine whether the current capacity of the network can
handle the additional traffic and if not, what changes are required
in the current topology.
Analyse where the different logical server functions should be
located in order to meet the service level criteria of the enterprise.
Analyse the location of the servers in light of the administrative
and network management policies of the organization.
Assess whether the planned implementation meets the security
guidelines of the network.
Determine the level of fail-safe operation and backup that needs
to be implemented.
Take into account the level of IT skills required at each level in
the network.
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Network Computer Division12
Notes
There are three primary areas of planning to consider for network stations:
The installation and configuration of the Network Station units themselves. This is the easy
part.
The installation and configuration of the servers required to support these Network Stations
which represents medium difficulty.
The network design and analysis activities required to ensure that the underlying network
infrastructure can support the traffic volumes and patterns generated by the Network
Stations.
Planning the proper network infrastructure is by far the most involved and difficult aspect of
the planning cycle and this chart identifies some of the activities that must take place to
ensure a proper infrastructure.
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Network Computer Division13
Network Topology Example
Corporate HQ LAN
router
High Speed
WAN Link
Network
Station
Slow Speed
WAN Link
router
Small Division LAN
Big Division LAN
router
High Speed
WAN Link
router
Network
Station
Branch Office A1 LAN
bridge
Sales Dept.
Network
Station
bridge
Eng. Dept.
Network
Station
router
Slow Speed
WAN Link
Web
Network
Station
router
High Speed
WAN Link
router
Branch Office B1 LAN
bridge
bridge
Sales Dept.
Eng. Dept.
Network
Station
Network
Station
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Network Computer Division14
Notes
This chart represents what we might call a typical network topology into which we might
want to insert Network Stations.
This sample corporation has multiple remote branch offices, and each branch office has a
branch office LAN segment as well as a LAN segment for each department in the branch
office. Since all departments are within the same physical facility, all LAN segments in the
branch are bridged together, effectively providing a single logical LAN segment.
Each branch office’s LAN is connected to it’s divisional headquarters by a WAN link.
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Network Computer Division15
Boot Related Decisions
Choices
Boot using NVRAM or Network
Factors to consider
Number of Network Stations in the network.
NVRAM only for small number or special cases,
otherwise use DHCP.
BootP or DHCP Server
DHCP Server recommended; more flexibility than
BootP
DHCP Server Platform
Depends mainly on existing network and/or
equipment. Platform itself is not relevant.
DHCP Server Product
Depends on the features and functions desired,
such as unlisted client support, or class support,
or others.
DHCP Server Location
Depends on policies of decentralization as well as
expected topology of the network in terms of the
presence of bridges and routers
Number of DHCP Servers
This depends on the centralization policies of the
organization, the performance required and the
amount of desired redundancy
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Network Computer Division16
Notes
This chart summarizes the main decisions related to the booting process.
The primary decision is whether to use the NVRAM method of booting or BOOTP/DHCP.
If the decision is to use DHCP, which is the recommended choice in most cases, all other
decisions are DHCP-related and many are general in nature and not necessarily specific to
Network Stations.
The main aspect of DHCP design with Network Station clients is that they require more
options than PCs. Not only do they need to be served an IP address but they also need to
be served with the address of a boot server, the path to the kernel file, possibly the address
of a terminal configuration server, possibly failover addresses for these servers, and so
on.
In addition, because the clients (that is the Network Stations) come in different hardware
models and different vintages (like the previous Power PC models and the new X86
models), some information for a DHCP client needs might be different from another client.
Finally, there is also the question of the mix of different devices and possibly different
versions of the NSM software to coexist in the same environment, which introduces some
additional complexity in the design of a DHCP solution.
Let us take a look at a few of the choices.
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Network Computer Division17
DHCP and BOOTP Differences
DHCP Frame
BOOTP Frame
Code-Hw type-Length-Hops
Transaction ID
Flags
Client IP Address
Your IP Adrress
Server IP Address
Router IP Address
Client hardware address
Server Hostname
Boot file name
Vendor specific area (64 bytes)
Code-Hw type-Length-Hops
Transaction ID
Flags
Client IP Address
Your IP Adrress
Server IP Address
Router IP Address
Client hardware address
Server Hostname
Boot file name
Options (312 bytes)
Option 1 - Subnet Mask
Option 3 - Default Router
Option 4 - Time Server
Option 6 - Domain Name Server
Option 12 - Host Name
Option 15 - Domain Name
Option 28 - Broadcast Address
Option 50 - Requested IP Address
Option 51 - IP Address Lease Time
Option 66 - Boot server Address
Option 67 - Boot File name
cbechard-06/97
For example:
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Network Computer Division18
Notes
This chart illustrates the main difference between BootP and DHCP.
It is clear that DHCP has a lot more flexibility and capabilities than Bootp mainly because it
has the capability to server a lot more specific pieces of information to its clients, which is
what we need in a Network Station environment.
We therefore do not dwell very much on this and assume that DHCP is the default choice
that all will make.
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Network Computer Division19
Unlisted Client Support
Pool of IP addresses
DHCP Server
10.0.0.25
10.0.0.26
10.0.0.27
10.0.0.28
My MAC =
400000007777
Use IP address
10.0.0.1
DHCP
Client 1
MAC
400000007777
400000008888
Any MAC address
Client Definitions
IP Address
10.0.0.1
any from the pool
any from the pool
My MAC =
400000008888.
My MAC =
400000009999
Use IP address
10.0.0.26
Use IP address
10.0.0.25
DHCP
Client 2
DHCP
Client 3
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Network Computer Division20
Notes
One of the choices to be made is what actual DHCP product is used, and that is driven
mainly by the features that are available on that product to satisfy the needs of the clients.
One of those features is the "unlisted client support" which is the ability to have a DHCP
server respond to any client, even if that client’s MAC address has not been defined in the
DHCP server’s configuration file.
This is useful in cases where you do not want to keep track of MAC addresses and yet be
able to respond to any client, which we believe is the most common situation.
In this diagram, DHCP Client1 asks the DHCP server for an IP address. The server
already has the MAC address (7777) of the client identified in its configuration table and
has a fixed IP address already reserved for that specific client.
DHCP Client2 asks for an address; its MAC address is also present in the DHCP server
configuration table, but this time the configuration simply states that any address can be
used. That causes the server to allocate the next available address for a pool of
addresses, in this case 10.0.0.25.
DHCP Client3 on the other hand does not have its MAC address specifically defined in the
configuration table, but the server does have a configuration parameter that directs it to
allocate the next available address from the pool, in this case 10.0.0.26, and this is what
unlisted client support is. In other words, even though DHCP Client 3 is unknown, it still
gets served an IP address.
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Network Computer Division21
Network Station DHCP Classes
IBM Network
Station Model
Description
DHCP Class
8361-100
Series 100 - Ethernet - 8 MB
IBMNSM 2.0.0
8361-200
Series 100 - Token-Ring - 8 MB
IBMNSM 2.1.0
8361-110
Series 300 - Ethernet - 16 MB
IBMNSM 1.0.0
8361-210
Series 300 - Token-Ring - 16 MB
IBMNSM 1.1.0
8361-341
Series 300 - Twinax - 1 MB
IBMNSM 3.4.1
8361-A22
Series 1000/32 MB-TRN
IBMNSM A.2.0
8361-A23
Series 1000/64 MB -TRN
IBMNSM A.2.0
8361-A52
Series 1000/32 MB - ETH
IBMNSM A.5.0
8361-A53
Series 1000/64 MB - ETH
IBMNSM A.5.0
8363-Exx
Series 2200 - Ethernet
8363-EXX
8363-Txx
Series 2200 - Token-ring
8363-TXX
8364-Exx
Series 2800 - Ethernet
8364-EXX
8364-Txx
Series 2800 - Token-Ring
8364-TXX
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Network Computer Division22
Notes
The next very important feature is the ability of a DHCP server to support DHCP classes.
A DHCP server already identifies a DHCP client specifically by its MAC address. But there
is a need also to identify a client not necessarily as a specific unit but as a unit type.
To give you a better idea of what a DHCP class is, we list in this chart all the classes for all
the models of the IBM Network Stations.
Notice that each specific model has an associated class. A DHCP server can therefore
identify a station as a particular model without necessarily knowing which specific unit it is.
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Network Computer Division23
DHCP Class Support
Network Station
DHCPDISCOVER frame
77 More specifically, I am an IBMNSM2.1.0
1
2
3
4
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Network Computer Division24
Notes
Here is a simple example of using a DHCP class.
In this chart, the Network Station on the left sends a DHCPDISCOVER frame looking for a
DHCP server to respond.
That frame contains the MAC address of the station, as well as possibly other options, one
of which is option 77 that contains the class of this unit.
In this example, the client identifies itself as belonging to the IBMNSM2.1.0 class. From
this, we know that this is a Series 100 Token-ring machine with 8 MB.
The DHCP server configuration file does not have a specific IBMNSM2.1.0 class defined
(although it could) but it has a class configured as IBMNSM*. This actually means that all
the classes beginning with IBMNSM are acceptable.
As a result, this client is offered all the options that are defined under that class, as shown
in the bottom of the diagram (options 1 to 213).
If the client had been a regular PC instead of a Network Station, it would identify itself as a
member of an IBMNSM* class and would therefore not be offered these options.
What this means in terms of a Network Station client is that we can tailor the options to be
served based on the model of the Network Station.
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Network Computer Division25
Using Classes for Co-existence
V1R3
Boot
Server
DHCP
Server
V2R1
Boot
Server
Network
Station
Network
Station
S300
Network
Station
S1000
Network
Station
S2200
Network
Station
S1000
S2800
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Network Computer Division26
Notes
DHCP classes can be extremely useful in a coexistence environment where there is a mix
of PPC based station and X86 based stations, some still being served by V1R3 boot
servers and some being served by V2R1 servers.
When a particular station is served by the DHCP server, the fact that the DHCP server
knows what type of hardware it is allows a much easier way to ensure that the proper
configuration information is sent to the station.
For example, all X86 based stations can be directed at a V2R1 server since they are not
supported by a V1R3 server.
This is rather simplistic, and there can be much more complicated scenarios where PPC
stations are using both V1R3 and V2R1 servers, and are located in different subnets, etc.
and those need to be analyzed individually to determine the best solution. Nevertheless,
the use of classes can simplify the solution in many cases.
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Network Computer Division27
Creating a User Defined DHCP Option
Cfg Server Protocol
214
Option 98 - Authentication Server
Option 211 - Base Code Server Protocol
Option 212 - Configuration Server Address
Option 213 - Configuration Files Directory
Option 214 - Configuration Server Protocol
Option 219 - Failover Boot Server
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Network Computer Division28
Notes
Most DHCP server today have the ability to let the administrator create user-defined
options, that is, DHCP options 129 to 254.
This panel is from the IBM DHCP server for Microsoft Windows NT where option 214 is
being created, which is the option that represents the protocol to be used by the terminal
configuration server.
Remember a DHCP server can serve many options to a client but the client must have the
ability to recognize these options in order for these options to have any effect.
With NSM V2R1, the options shown in the bottom left hand corner are used and
recognized by the Network Station DHCP client code.
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Network Computer Division29
DHCP Server Updating DDNS
Pool of IP
addresses
10.0.0.25
10.0.0.26
10.0.0.27
10.0.0.28
DHCP Server
MAC
400000007777
400000008888
Any MAC
My MAC =
1 400000008888
and Update DDNS
for me!
DNS Server
IP Address
10.0.0.1
Any from the pool
Any from the pool
Name
itsonct1
Mary
Domain
itso.ral.ibm.com
itso.ral.ibm.com
3
I am updating on behalf
of the client!
mary.itso.ral.ibm.com
now uses 10.0.0.25
4
What is the address of
mary.itso.ral.ibm.com?
The address is
10.0.0.25
Use IP address
10.0.0.25
2
5
DHCP Client
Host name =
mary.itso.ral.ibm.com
Address
10.0.0.54
10.0.0.44 10.0.0.25
DNS
Client
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Network Computer Division30
Notes
This chart illustrates the process of a DHCP server updating a DDNS server after having
served a DHCP client with a new address.
Because the IP address of the client has changed, there is a need to automatically update
the DNS server so that the host name that this client was using correctly reflects the new
IP address.
To know more on this subject, please refer to the specific DHCP/DDNS presentation.
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Network Computer Division31
DHCP Broadcast
Corporate HQ LAN
DHCP
Server
router
router
Big Division LAN
DHCP
Server
DHCP
Server
router
Router with
DHCP Relay
Agent
DHCP Discover Broadcast is
received by all stations on the
bridged LAN segments
The DHCP Relay Agent in the
router, if enabled, relays the
broadcast to a specified DHCP
server
Branch Office LAN
bridge
Sales Dept.
bridge
Eng. Dept.
DHCP
Broadcast
Network
Station
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Network
Station
Network Computer Division32
Notes
An important notion to understand with DHCP is that a DHCP client uses a broadcast when it sends a
DHCPDISCOVER frame, looking for a DHCP server.
In a routed (instead of a bridged) network however, routers typically do not forward broadcasts, which
means that if the DHCP server is located on a LAN segment other than the one where the client is, the
client's broadcast cannot reach the DHCP server.
To solve this problem, routers can be configured with a DHCP Relay agent that intercepts DHCP
broadcasts and forwards them to a specific DHCP server.
For example, in this chart, the dotted line shows the travel of a DHCPDISCOVER broadcast issued by a
Network Station in the Sales Department’s LAN segment.
The broadcast travels on all three LAN segments and is received by the DHCP server on the branch office
LAN, which presumably might respond, dependent on how it is configured.
The broadcast is also received by the Router on the Branch Office LAN, and because the router has a
DHCP relay agent running, the agent looks up its configuration file to determine the address of the DHCP
server that should be the target for this broadcast, and forwards the broadcast directly to that designated
server (after placing its own IP address in the frame so that the reply willl be sent to him).
That server would also presumably respond, dependent on its configuration, but it responds to the DHCP
relay agent which turns around and forwards the server’s reply to the station.
The overall effect is the same as if the remote DHCP server had been located in the same LAN segment
as the DHCP client.
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Network Computer Division33
Divisional DHCP Servers
DHCP
Server
s
lay
Re
Division A LAN
CP
DH
Division A
Sphere of
Control
DHCP
Server
router
router
Branch Office A1 LAN
Network
Station
Division B LAN
CP
H
sD
y
la
e
router R
router
Division B
Sphere of
Control
Branch Office B1 LAN
Network
Station
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Notes
This chart shows a topology where we use one DHCP server per division in a corporate
network.
The sphere of control of a DHCP server is only over the resources in the division and all
branch office routers must have the ability to relay DHCP broadcasts to the division’s
DHCP server.
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Network Computer Division35
Corporate DHCP Server
DHCP
Server
Corporate
Sphere of
Control
Corporate HQ LAN
router
router
router
Division A LAN
router
router
Division B LAN
Corporate
IP
Network
Branch Office A1 LAN
Network
Station
Web
router
router
Branch Office B1 LAN
Network
Station
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Network Computer Division36
Notes
On the other hand, if a there is to be a corporate DHCP server, then all routers from all
LAN segments must be able to relay DHCP broadcasts to the corporate DHCP server and
its sphere of control is over the entire corporate network.
Whether divisional DHCP servers or corporate DHCP servers are used is most of the time
more a policy decision than a technical decision, based on who has control over network
facilities.
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Network Computer Division37
Obtaining an Operating System Decisions
Choices
Factors to consider
Boot server platform
Choices are AS/400, RS/6000, Windows NT
Server, Flash Card, a peer Network Station, a thin
server or actually any system that provides TFTP
or NFS services.
Where to locate the server(s)
Proximity (how close it is ) to the client, LAN media
speed, network topology
Kernel download protocol
TFTP or NFS/RFS, download speed and server
loading
Number of servers for boot
performance
Desired boot time in normal and emergency
situations
Number of servers for
redundancy
Desired boot time with some components having
failed
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Notes
Now that our Network Station has obtained an IP address from a DHCP server, the next
task is to obtain its operating system from a boot server.
The types of decisions that must be taken concerning the boot server are summarized in
this chart.
In this case, the first important decision is the platform to use for the boot server. The
choices are:
AS/400, AIX or Windows NT (and if one of these, do I use a dedicated server or not)
A flash card in the station itself
A flash card in a peer station
A thin server
Or in fact any system with a TFTP or NFS server
And the second decision is where to locate this server (except in the case of a flash card of
course).
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Network Computer Division39
Local Boot Servers
Corporate HQ LAN
router
DHCP
Server
router
Division A LAN
router
router
Division B LAN
Corporate
IP
Network
Branch Office A1 LAN
router
router
Branch Office B1 LAN
Boot Server
Boot Server
Network
Station
DHCP
Server
router
Network
Station
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Notes
This chart represents the ideal situation where there is a boot server located on each
segment where there are Network Stations.
In fact, we might even be talking about more than one server, dependent on the number of
stations there are on the LAN segment, on the performance that we expect, and on the
redundancy that we need to build into the system, which are all questions that are part of
the same decision about where to locate boot servers and how many to use.
Some of the questions to ask and to investigate are:
How fast do I need the boot process to be?
In the event of a power failure, how fast do I need to reboot all stations?
In the event of the failure of one or more servers, what alternatives do I want to build into
the system?
What service level is expected by the users?
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Network Computer Division41
Remote Boot Servers
Corporate HQ LAN
router
DHCP
Server
Boot
Server
router
router
Division A LAN
router
router
Network
Station
Division B LAN
Corporate
IP
Network
Branch Office A1 LAN
DHCP
Server
router
Boot
Server
router
Branch Office B1 LAN
Network
Station
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Notes
In this chart, we show boot servers located at the division level, across a WAN link from
the LAN segments where the stations are located.
This is definitely not an option to consider, although it is possible, because unless there is
a very small number of stations and a very high speed WAN link, it is likely that the boot
performance will not be adequate.
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Network Computer Division43
Using Thin Servers
Boot Files are
downloaded to
thin server once
(or when an
update
required)
Boot
Server
router
DHCP
Server
Division LAN
router
Boot
Files
Files are
downloaded
locally at boot
time
Router and
Thin Server
IBM 2212
Access
Utility
Branch Office LAN
Network
Station
Network
Station
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Notes
If boot servers cannot be located on the same LAN segment as the stations, one
alternative is the use of thin servers.
Thin Servers are network components such as the IBM 2212 Access Utility that have the
ability to act as a boot server by caching some of the files that are normally downloaded
from a boot server.
In other words, the client makes its request from the thin server instead of the boot server,
and the thin server is responsible for getting the proper level of the files from the boot
server in cases where it does not have the files or if the files are outdated.
The advantage is that thin servers, which normally perform other functions such as routing,
are typically located deeper into the network, and therefore much closer to clients. Load
time and bandwidth utilization can therefore be optimized while loosing none of the
advantages inherent to a central boot server.
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Network Computer Division45
Using Flash Cards
Division LAN
router
Boot
Files
DHCP
Server
Recorded on
the flash card
router
Local
Boot
Network
Station
Branch Office LAN
Peer
Boot
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Notes
Flash cards are devices on which a copy of the operating system and other files such as
font files and native applications modules can be stored. These devices can be used as a
local storage device by inserting them into a Network Station.
This allows a Network Station to rapidly load its operating system locally without having to
use any network bandwidth. The main advantage is the speed of booting and the minimal
impact this has on the network.
In this chart, the Network Station on the left, after having a flash card inserted into it, can
boot from that card as a local device. That Network Station can also be configured to
provide the same service to a certain number of peer stations, usually no more than 10.
But there are also disadvantages to flash cards that must be understood. Not only do the
cards themselves represent an additional cost but they also represent an additional cost in
terms of having to manage the distribution of the cards and having to manage the level of
the software that is recorded on the cards.
For V1R3, there were no tools that existed to manage flash cards and their contents but
with V2R1, the situation is much better because NSM now includes a configuration task
that allows the administrator to specify which components are to be recorded on a flash
card and when flash cards should be updated.
So one must be careful not to negate the benefits inherent to thin clients where the
software is managed and maintained in a central location (the boot server) and caution
must therefore be exercised in choosing this option.
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Network Computer Division47
Obtaining Terminal Configuration Files
Choices
Factors to consider
Terminal configuration server
platform
Choices are AS/400, RS/6000, Windows NT
Server, Flash Card, a peer Network Station, or a
thin server.
Platform of the server
Any platform that can run the Network Station
Manager application. Choice may depend on
existing and available equipment.
Location of the server
Easily located across a WAN link. Most likely
determined by which group has the management
responsibility or by other policies or topology
considerations.
Terminal identifier
Choices are MAC address, IP address in decimal
notation, IP address in hex notation. MAC address
is the only permanent identifier.
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Notes
The next logical step is to consider the terminal configuration server that is to server the
terminal configuration profiles.
These are the profiles that contain the configuration parameters that determine the base
operational characteristics of a particular station (before we even know about who the user
is and his preferences).
These profiles are downloaded by the station prior to the user logging in. Notice that the
decisions to be considered are similar to those we considered for the boot server, that is,
which platform to use for the server and where to locate the server or servers.
However, even though the decisions are similar, the main influencing parameter is the
amount of information to be downloaded. In this case, the amount of data is much less
than for the boot files and it is therefore a viable option to locate this server across a WAN
link.
Note the last entry in the table where a terminal identifier may need to be chosen. If the
administrator needs to configure settings particular to specific units, then each unit must
be able to be identified specifically and one must choose either MAC address, IP address
or host name as an identifier.
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Network Computer Division49
Configuration Server
Configuration
Server
NSM
DHCP
Server
Corporate HQ LAN
IP
Network
router
router
Branch Office LAN
Boot
Server
Network
Station
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Notes
This chart represents probably the most typical situation where the terminal configuration
server is located at the corporate levels where these configuration files can be centrally
managed.
However, we are faced again with the fact that the corporate network administration
policies might dictate that each division for example is responsible for managing its user,
in which case there might be a political need to use multiple terminal configuration servers
located at different levels in the organization.
In any case, the placement of these servers is less sensitive technically because the
amount of data downloaded from these is much less than from boot servers.
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Network Computer Division51
Distributing Configuration Files
NSM
Terminal CFG files
Configuration Server
Files distributed
to servers
Corporate HQ LAN
router
DHCP
Server
router
Division A LAN
router
router
Station
Division B LAN
Corporate
IP
Network
Branch Office A1 LAN
Boot Server
Configuration Server Network
DHCP
Server
router
router
router
Branch Office B1 LAN
Network
Station
Boot Server
Configuration Server
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Notes
However, one characteristic of the terminal configuration files is that they are set initially
and changes to these profiles can be infrequent. In fact, one of these files which contains
the shipped defaults which should not be changed ever.
But even though they represent much less data to be downloaded than from a boot server,
still they need to be downloaded everytime a station boots.
One way to avoid having to download these profiles over a WAN link is to locate them also
on the boot server so that they are loaded locally from the LAN while still keeping the
management of the files in a central location.
This diagram shows that the files reside at the corporate level on a server that runs NSM
in order to manipulate the files. However, these profiles are copied to the boot servers
(where they cannot be changed if NSM is not installed on the boot servers) and are loaded
from the boot server by configuring the boot server also as the terminal configuration
server.
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Network Computer Division53
Contacting an Authentication Server
Choices
Factors to consider
Platform for the server
Same as those for the terminal configuration
server.
Location of the server
Same as those for the terminal configuration
server.
Location of user accounts
Policies, existing account information, additional
network traffic if located on another server.
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Network Computer Division54
Notes
At this point in the boot process, we are ready to ask the user to identify himself and we
have to validate the user with an authentication server.
This chart now starts to be familiar because we still have some of the same decisions to
be made as with all the previous servers, mainly the choice of a platform and the location
of the server or servers.
Most decisions here have the same characteristics as for the terminal configuration server.
In this case, whatever platform is chosen must be one where NSM can be installed
because we need an important component called the Network Station Login Server which
is required to communicate with the Network Station Login client on each station.
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Network Computer Division55
Authentication Server
Configuration
Server
Authentication Server
Preferences Server
Home Server
NSM
NSM
DHCP
Server
Corporate HQ LAN
IP
Network
router
router
Branch Office LAN
Boot
Server
Network
Station
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Network Computer Division56
Notes
The authentication server, in this release as well as in the previous release, is also the
user preferences server and the home server by default.
This means that all the user specific configuration profiles and the user's home directory
are located on the same server that authenticates the users.
Actually, this is not entirely true because there is a way of manually altering the
configuration files such that the user configuration profiles can be located on a server
other than the authentication server; we direct you to the advanced configuration product
information or the redbook to find out how to change this default setting.
The user home directory however must be located on the authentication server.
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Network Computer Division57
Authentication Server and User Accounts
Configuration
Server
Authentication Server
Preferences Server
Home Server
NSM
NSM
DHCP
Server
Verify
Account
Corporate HQ LAN
IP
Network
router
router
User
Accounts
Branch Office LAN
Boot
Server
Windows NT
Primary Domain
Controller
Network
Station
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Notes
Typically, this is again a case of determining the level in the network at which the users are
managed.
If this is a highly decentralized organization, it is likely that the authentication server for a
population of Network Station users will be located at the same level in the network where
these user accounts are normally managed.
In a Microsoft Windows NT environment for example, if user accounts are located on a
Primary Domain controller at the corporate level, it is likely that the authentication server
will be located at the corporate level as well, although this is not a necessity technically
speaking.
Note that the authentication server does not have to be on the same machine as the
Primary Domain Controller. Users can be made part of a global group in the PDC and that
global group can be specified as a member of the local NSMUser group on the
authentication server. See the redbook for additional details on this and for additional
insights as to how to accomplish this.
Note that the network traffic caused by access to the PDC from the authentication server is
another consideration to be taken into account in the network design analysis.
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Network Computer Division59
Divisional Authentication Server Example
DHCP
Server
Application
Server(S)
Corporate HQ LAN
router
Configuration
Authentication
Preferences
Home
router
router
Division A LAN
router
router
Web
Division B LAN
Corporate
IP
Network
Branch Office A1 LAN
router
Configuration
Authentication
Preferences
Home
router
Branch Office B1 LAN
Boot Server
Boot Server
Native Applications
Native Applications
Network
Station
Network
Station
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Notes
In the case where we want to delegate the user administration responsibility to the
division’s network administrators, it makes more sense then to have an authentication
server in each division.
In that case, it might make sense to include the configuration server function as well on the
same server, as illustrated in this chart.
In fact, until such time that we get the possibility of separating the home server from the
authentication server, the dilemma we have is that if a lot of data is being stored in the
user's directory, then we need to locate the authentication as close to the client as possible
but, on the other hand, it is likely that from an administrative point of view, the
authentication server is probably best located at the corporate level.
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Network Computer Division61
Native Applications Server
Configuration
Server
Authentication Server
Preferences Server
Home Server
NSM
DHCP
Server
Corporate HQ LAN
IP
Network
Boot
Server
router
router
Branch Office LAN
Native Applications Server
Network
Station
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Notes
The native applications server is really a non-issue as it cannot be separated from the boot
server at this time.
In any case, it is best located on the boot server as some of the applications that need to
be loaded can be quite sizable.
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Network Computer Division63
Application Servers Decisions
Choices
Use native applications or
applications on a MetaFrame
type server
Factors to consider
The features and functions required and the
impact on the network of using one versus the
other.
Autostart applications or not
Autostart only applications that are always in use
by the user
Close applications or not
Close applications that will not be used for a
significant period of time
Use pre-configured sessions
Use Kiosk mode
Strictly a user defined choice
If using a lobby environment or single application.
Choose true kiosk mode (V2R1) or suppressed
login (V1R3)
Domain Name Server
Access to a DNS server is required to be able to
resolve IP host names, if IP hostnames are used.
Proxies
If accessing host in an external network, across a
firewall, proxy servers are required
Printers
Where are printers located, local, remote, and
which print data stream to use
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Network Computer Division64
Notes
Finally, we get to connect to application servers, which is the whole objective of preparing
the Network Station to do some useful work for the user.
As shown in this table, we do face a few other decisions here, but these may not be as
difficult as some of the network topology decisions we saw previously.
Some of the easy ones are whether to autostart applications for the user or not, and
whether to use kiosk mode, either true kiosk mode or suppressed login mode, for some
users, and whether proxies are required for a browser to access the Internet, and where to
locate printers, print servers and other file servers.
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Network Computer Division65
Application Servers
Configuration
Server
Authentication Server
Preferences Server
Home Server
NSM
DHCP
Server
Corporate HQ LAN
IP
Network
Boot
Server
router
router
Branch Office LAN
Web
Native Applications Server
Application
Server(S)
Network
Station
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Network Computer Division66
Notes
Where are application servers located? They might be just about anywhere. The
applications we are talking about can be:
A 3270 Emulator which typically has a S/390 host as the target, although it may often use
an intermediate gateway to reach the actual target host.
A 5250 Emulator session has an AS/400 as the target host.
A Web browser typically goes out to either the Intranet or the Internet to access a variety of
target IP hosts, either directly or through proxies.
A VTxxx emulator session might go to any IP host, either as a telnet session or any other
VTxxx session.
An ICA session goes out to a WinFrame or MetaFrame server (multi-user Windows NT
Server) to use Windows applications.
An X terminal session typically goes out to a Unix host or a WinCenter server (another way
of reaching Windows applications on a multi-user Windows NT server instead of using
ICA).
A local application can print to a local or remote printer.
You might also have home grown Java applications that need access to file servers and
print servers, etc.
These considerations are therefore general network considerations and not necessarily
Network Station specific.
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Network Computer Division67
Use Native Apps if possible
S/390
Host
3270 text
session
Corporate LAN
3270
Emulator
WTSE
Server
router
3270 text
session
WAN
Link
ICA session
traffic (=10 x
3270 text session)
router
Branch Office LAN
ICA
Session
Native 3270
Emulator
Network
Station
Network
Station
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Network Computer Division68
Notes
When there is a choice of using a local native application and its equivalent on a Windows
Server, careful consideration should be given to using the native application instead.
Indeed, if you look at this diagram, on the left is a Network Station running a native 3270
application with the S/390 host. The network traffic generated by this session is the
traditional text based SNA LU2 data stream, which is fairly compact.
On the right is a similar Network Station but instead of using a native 3270 emulator, it
uses an ICA session to a MetaFrame server and uses the 3270 emulator, for example
Personal Communications 3270, on the MetaFrame server.
The real SNA LU2 data stream session is therefore taking place between the MetaFrame
server and the S/390 host. The graphics information is then transmitted over the ICA
session to the user's display on the Network Station but the amount of data crossing the
WAN link is now probably 10 times greater than a native 3270 session would be, to
accomplish the same objective.
Clearly, use of native applications, in this case, is more efficient unless of course the
native applications do not support the features that the user needs to do his job.
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Network Computer Division69
Target
Server
HTTPD
FTPD
TELNETD
firewall
Proxies and Socks
HTTP
Client
TCP/IP HTTP
Client
HTTP
Protocol
HTTPD
HTTP Proxy Server
(Application gateway)
Socks-ified
HTTP Client
TCP/IP
SOCKS Server
(Secure socket server)OCKS col
firewall
S
Simulated
Client
Nonsecure network
SOCKD
Socks-ified
FTP Client
o
ot
r
P
SOC
KS
Pro
toco
l
HTTP
Socks-ified
FTP
TCP/IP
TELNET
stack
Clients
Secure network
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Network Computer Division70
Notes
If the stations are on an Intranet and they need access to external networks by going through a firewall,
there is a need to configure either proxy servers or a SOCKS server. For those who may not be familiar
with this topic, here is a brief explanation.
In the top portion of the diagram, we see on the right hand side an HTTP client, such as a web browser,
located in the secure network part, that needs to communicate with the HTTPD service on the target
server located in the nonsecure (public) network.
The client specifies the address of an HTTP proxy server, and that server actually functions as an
application gateway. An HTTPD daemon receives HTTP requests from clients on the secure side of
the network , and also functions as an HTTP client on the nonsecure side of the network, effectively
becoming the actual client of the target HTTP server (and acting on behalf of the real client which is on
the secure side of the network).
Therefore, as far as the target HTTP server is concerned, it is only aware of the HTTP proxy server
client and it has no knowledge of the real client where the original HTTP request actually originated.
In the bottom portion of the diagram, a SOCKS server is used instead of a proxy server. In this case,
the HTTP client contains a SOCKS client, that communicates with a SOCKS server to transmit the
actual HTTP request. On receipt of the request, the SOCKS server transmits the request across the
firewall, in a secure manner such that the target is also unaware of the actual real client.
In a proxy server, the HTTP application actually executes on the proxy server whereas in the case of a
SOCKS server, the HTTP application remains on the actual client and the SOCKS server provides a
secure passthru pipe.
In the case of a SOCKS client, the client application itself can be "socksified" and communicate with the
socks server or the entire TCP/IP stack can also be socksified, which then permits all applications to
communicate with a SOCKS server.
IBM Network Station Technical Education
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Copyright IBM Corp. 1998
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materials may not be reproduced in whole
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Network Computer Division71
Printing - Local and Remote Printers
Configuration
Server
Authentication Server
Preferences Server
Home Server
NSM
DHCP
Server
Corporate HQ LAN
IP
Network
router
router
Boot
Server
Application
Server(S)
3
Printer
Branch Office LAN
Native Applications Server
4
2
Printer
1
Printer
Network Station
Network Station
IBM Network Station Technical Education
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materials may not be reproduced in whole
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Network Computer Division72
Notes
Applications running on the Network Station can send print output either to a Network
Station attached printer (local printer) or to any other IP host that supports LPD (TCP/IP
printing), including another Network Station.
A local printer can be attached to the parallel port or to the serial port of the Network
Station.
The Network Station can also receive print requests from any other IP hosts that support
LPR and print locally. It cannot however reroute this output received from a remote host to
another remote printer because it actually does not have any local spooling capability due
to the lack of local disk storage.
In this example, we see that an application on the Network Station can print to a local
printer (1). Also, if a Network Station does not have its own printer attached, it can send
printed output to a printer attached to a peer station (2).
Equally, it can send printed output to any remote printer such as a printer on the branch
office LAN (3), or a to printer attached to a remote host(4).
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materials may not be reproduced in whole
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Network Computer Division73
Printing Overview
Any
TCP/IP
LPD
System
Windows NT
WinCenter
OS/400
OS/390
VM/ESA
AIX
OS/2
Another
Network
Station
IBM Network Station
Printer
Selector
Local
Applications
ncprd
(LPRD)
ncprd
(LPD)
Print API
Local Print Driver
Any
TCP/IP
LPR
System
Windows NT
WinCenter
OS/400
OS/390
VM/ESA
AIX
OS/2
Another
Network
Station
Local Printer
IBM Network Station Technical Education
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materials may not be reproduced in whole
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Network Computer Division74
Notes
How does that work? This diagram summarizes the major printing components on the
Network Station.
When an application makes a print request, it is presented with a printer selection panel on
which appear all the printers that have been defined as accessible to this station (as
configured in Network Station Manager).
If a local printer is chosen, the output is sent to the local Print API.
If a remote printer is chosen, the request is sent to the LPR daemon (LPRD) which routes
the request to the selected remote printer or print server.
Finally, a print request coming from another IP host, such as another Network Station for
example, is received by the LPD daemon which routes the request to the local printer.
IBM Network Station Technical Education
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materials may not be reproduced in whole
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Network Computer Division75
Print Transform
AS/400
LPD
Transform
PS
LPR
PCL
PCL
Datastream
PostScript
Datastream
Network Station
LPR
LPD
PS
application
SERIALD
PCL
IBM Network Station Technical Education
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materials may not be reproduced in whole
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IBM 4029
PCL
Printer
Network Computer Division76
Notes
Most local applications on the Network Stations support Postscript output but only the
3270 and 5250 emulators support PCL or ASCII as well.
If you have mainly PCL capable printers and you still want to be able to use these with the
browser for example, you can use a Print Transform utility on a host such as an AS/400.
This is illustrated in this chart where an application generates Postscrip output, sends it to
a specific print queue on the AS/400 host, where it is directed to be transformed to PCL
output, which is then rerouted to an output queue that redirects the PCL output to the
Network Station, effectively allowing a PostScript generated output to be sent to a PCL
printer.
IBM Network Station Technical Education
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Copyright IBM Corp. 1998
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materials may not be reproduced in whole
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Network Computer Division77
Where to go for more information?
Main Web Site
www.ibm.com/nc
Current Network Station Redbook
SG24-5844 Network Station Manager V2R1 Guide
Previous Network Station Redbooks
SG24-5187 AS/400 - Techniques for Deployment in a WAN
SG24-5221 Windows NT - NSM Release 3
SG24-5212 Printing
SG24-2127 Windows NT/WinCenter
SG24-4954 S/390, SG24-2016 RS/6000, SG24-2153 AS/400
Product Publications
SC41-0684 Installing NSM for AS/400
SC41-0685 Installing NSM for RS/6000
SC41-0688 Installing NSM for Windows NT
SC41-0690 Using NSM
IBM Network Station Advanced Information (On the Web Site)
IBM Network Station Technical Education
©- IBM
v2r1design
Copyright IBM Corp. 1998
CourseCorporation
materials may not be reproduced in whole
or in part without the prior written permission of IBM.
Network Computer Division78
Notes
These are the web site, redbooks and product publications where you can find additional
information on all the subjects that we have discussed in this topic.
IBM Network Station Technical Education
©- IBM
v2r1design
Copyright IBM Corp. 1998
CourseCorporation
materials may not be reproduced in whole
or in part without the prior written permission of IBM.
Network Computer Division79
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