Download Network Environments and OpenManage Remote Install

Network Environments
and OpenManage
Remote Install
Enterprise Systems Group (ESG)
Dell White Paper
By Danny Bertram, Benjamin Lai, and
Anusha Ragunathan
November 2002
Contents
Introduction ................................................................................................................................. 4
Embedded Dell DHCP Server.................................................................................................. 6
Types of Scopes .................................................................................................................... 6
Requirements of the Embedded DHCP Server .............................................................. 7
Restrictions Involving Scopes ........................................................................................... 7
Multiple Network Interface Cards (NIC)s and IP Addresses ..................................... 7
Router Support ..................................................................................................................... 7
Coexistence with other DHCP/PXE Servers .................................................................... 8
Coexistence with other DHCP Servers on the Same Local Subnet ............................ 8
Coexistence with other DHCP Servers on a Remote Subnet ....................................... 8
DHCP Client on Remote Install Agents................................................................................. 9
Vendor Class ID ................................................................................................................... 9
DHCP Clients IP Renewal ................................................................................................. 9
Can Clients Respond to a DHCP Server in the Network other than the DDHCP
Server? .................................................................................................................................... 9
How Remote Install Image Server Finds the Agents......................................................... 11
Installation of Remote Install Agents ............................................................................ 11
Discovery Process............................................................................................................... 11
Capture Process Reset IP Address ......................................................................................... 13
Processes Involving Storage Shares ...................................................................................... 14
How Storage Works ........................................................................................................... 14
Setting up Storage Shares................................................................................................. 14
Best Practices for Network Topology ................................................................................... 16
Single Connection Network Segment............................................................................ 16
Single Management, Multiple Connection Network Segment ................................ 17
Admin Console and Image Server in Separate Subnets............................................. 18
Multiple Management Subnets....................................................................................... 19
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Figures
Figure 1: Target System Across the Router from the Kickstart Engine (on the Image Server) ........12
Figure 2: Single Connection Network Segment .....................................................................................16
Figure 3: Admin Console Outside the Single Network Segment .........................................................18
Figure 4: Multiple Management Subnets ................................................................................................19
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Section
1
Introduction
Dell OpenManage™ Remote Install is a solution for provisioning and
configuring Dell™ PowerEdge™ 1655MC blade servers in remote and
automated mode over a network by using image-based technology.1
The networking environment in OpenManage Remote Install includes:

DHCP (Dynamic Host Configuration Protocol) Server
DHCP provides a method for passing configuration information to hosts on
a TCP/IP network. DHCP is based on the Bootstrap Protocol (BOOTP) for
boot network devices, but adds the capability of automated allocation of
reusable network addresses and additional configuration options. DHCP
works with BOOTP relay agents.
DHCP is a network protocol used to administer IP Addresses on a network.
Each computer configured to use DHCP requests an IP address from the
DHCP server as it starts.

Pre-OS and Post-OS Agents
Target systems have Agents that enable clients (DHCP, pump or PXE (Preboot Execution Environment)) to request IP addresses.

TFTP (Trivial File Transfer Protocol) Server
TFTP Server is used to download the boot image to the target systems.

PXE Server
PXE Server encompasses the DHCP Server, TFTP Server, and the logic
control behind the boot process. PXE is three technologies that create a
standard set of pre-boot services in the boot firmware of Intel Architecture
systems:

A protocol for requesting the allocation of a network address and
requesting the download of a boot image

A set of APIs in the system’s pre-boot firmware use by the boot image or
BIOS
1OpenManage
Remote Install: Remote Configuration and Image-Based Deployment for Dell Servers By
Richard Landau and John Zhang, Ph.D. (Power Solutions August 2002
http://www.dell.com/us/en/esg/topics/power_ps3q02-landau.htm )
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
A method of initiating the pre-boot firmware to execute the PXE protocol
on the system
Using these technologies, a system can enter a network, acquire a network
address and perform a network-based boot process.
Dell PowerEdge servers include NICs with PXE BIOS support, and can be
configured to boot first from the network through the BIOS boot order.
PXE co-exists with other boot devices such as Floppy, CDROM, and Hard files.
Boot order is defined in the system’s BIOS.

Image Storage Server
Remote Install Storage Server is used for storing:

Images that are captured from target systems

Update packages that are used to configure the settings of target
systems.
This study provides in detail the functionality and working of these components
in OpenManage Remote Install. It also provides guidance to network
administrators who are trying to setup Remote Install by providing best
practices.
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Section
2
Embedded Dell DHCP Server
Dell OpenManage Remote Install includes an integrated DHCP/PXE server. The
integrated DHCP/PXE server is a full function DHCP server configured to
support only specific clients. The PXE function is configured to only respond to
Dell PowerEdge servers. All PXE-enabled Dell servers will be booted with the
Dell OpenManage Remote Install pre-OS agent, which is a mini Linux operating
system that Remote Install TFTP server sends out. The pre-OS detects the
hardware and operating system on the target system. If the target system type is
not in the supported list of Remote Install, Dell DHCP (DDHCP) will deny this
system and block it from PXE boot again. As of version 1.0, Remote Install only
supports Dell PowerEdge 1655MC servers.
The embedded DHCP/PXE server supports multiple subnets, both local via
multiple NIC adapters, and remote subnets across DHCP Relay-enabled routers.
The embedded DHCP server can coexist with other DHCP servers on the
network, and will only respond to Dell PowerEdge servers which are PXE bootenabled or are specially configured DHCP clients. There are two different types
of Scopes supported by the embedded DHCP server. A Scope is a definition of
network configuration for a subnet. For the embedded DHCP these are: IP
address, subnet mask, and gateway.
Types of Scopes
There are two types of DHCP scopes used by Remote Install:
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1.
General Purpose
General Purpose scopes are allocated for PXE booting target systems. A
general purpose-defined IP address is reserved for each managed system.
Users must have a general purpose scope for each subnet that contains a
managed server.
2.
System Management
System Management scopes allocate an IP address, subnet mask, and
gateway for the system management card of the PowerEdge 1655MC and for
Dell solution systems with the Dell Kick-Start support. The system
management scope uses the vendor class and user class options of the DHCP
protocol to identify the clients to which it will respond.
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Requirements of the Embedded DHCP Server
As with most DHCP server products, the embedded DHCP Server requires static
IP addresses configured on the host system. Other requirements:

DHCP Server requires a scope definition for each subnet for the server to
respond.

There can be only one Dell Remote Install server on a subnet. The embedded
DHCP server on the second Dell Remote Install server to startup will be
disabled.

Remote Install does not support using an external DHCP server in place of
the embedded DHCP server.
Restrictions Involving Scopes
Each system discovered by Remote Install has a general purpose scope defined
by the IP address assigned to it. This IP address remains assigned to the system
for PXE use even after the system is configured with a static IP address during
the configuration stage. The IP address reserved for PXE boot will be displayed
on the configuration page of Remote Install for systems in the “Wait for
configuration” state and can be statically assigned to better allocate the IP
address for a given subnet.
Once an IP address is assigned for PXE boot, when a system is discovered it
cannot be changed by editing the scope definition unless the system is deleted
and re-discovered.
Multiple Network Interface Cards (NIC)s and IP Addresses
DHCP Server automatically detects the available IP addresses for the host system
and listens on each for DHCP and PXE clients. The server will only respond to
those that have a General Purpose DHCP scope defined for their subnet.
Router Support
DHCP is fundamentally a LAN-based protocol because it depends on the ability
of a client system to broadcast a request over Ethernet. A DHCP server must be
able to hear the broadcast message. While most Ethernet switches are
transparent to broadcast messages, most IP routers are not. Routers are usually
configured to block Ethernet broadcast messages. Therefore, without some
assistance, a DHCP server generally can support client systems on a single
physical LAN segment only. The "DHCP Relay" feature of most routers can
provide that assistance.
The integrated DHCP/PXE server supports clients across routers. Most routers
manufactured in the last several years include a feature called “DHCP Relay”
that enables DHCP servers to serve more than one physical LAN segment.
DHCP Relay is specified in RFC1542. A DHCP Relay function forwards DHCP
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request messages (broadcast by client systems that want address assignments) to
a specified DHCP server on some other LAN or subnet; and it forwards the
replies from the DHCP server back to the client systems. With the cooperation of
DHCP Relay enabled routers, a single DHCP server can provide service to client
systems on multiple LAN segments. A separate DHCP scope must be
configured for each subnet.
For details on using routers with Remote Install agents, see Section 4: How Remote
Install Image Server Finds the Agents on Target Systems.
Coexistence with other DHCP/PXE Servers
There can be no PXE servers on the same network as a Dell Remote Deployment
server that can respond to a managed node. Dell Remote Deployment will PXE
boot and discover all Dell PowerEdge 1655MC servers on the local subnet and
remote subnets configured to relay DHCP requests to it.
Coexistence with other DHCP Servers on the Same Local Subnet
The embedded DHCP server can co-exist with another DHCP server, however
the managed server must be configured with a static IP address or the other
DHCP server will have to be configured to not respond to the MAC address of a
managed server. The embedded DHCP server will only respond to servers that
have been PXE booted and managed by Dell Remote Install. The embedded
DHCP server can also be configured to respond to the System Management Card
of the PowerEdge 1655MC, and to servers configured with Dell solutions that
offer Kick-Start support on remote subnets.
Coexistence with other DHCP Servers on a Remote Subnet
The embedded DHCP server can co-exist with another DHCP server on a remote
subnet only if the DHCP server on the other network is specifically configured
not to respond to the server to be managed by Dell Remote Deployment. The
configuration depends on the embedded DHCP to find target systems.
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Section
3
DHCP Client on Remote Install Agents
Remote Install Agents start the DHCP client communicates with Dell DHCP
(DDHCP) Server to obtain a temporary IP Address for starting communication
with the Image Server. The temporary IP Address is obtained by running the
DHCP Client daemon on all the Network Interfaces that do not have an IP
Address. The DHCP Client runs with the Vendor Class ID called ‘DellKickstart’
to identify itself to the Dell DHCP Server that it is a valid address request from
the target system.
Vendor Class ID
DHCP clients use vendor class ID to identify their vendor type and
configuration. Vendors use vendor class ID to convey identifying information
relating to hardware, operating system, etc. In Remote Install, DHCP clients use
the vendor class ID ‘DellKickstart’ to identify the target system hardware as a
Dell system to the DDHCP Server.
DHCP Clients IP Renewal
A DHCP client renews its IP address with the DHCP server once the lease time
expires. This way the communication between the Image Server and the target
system is continual. But, on a Linux system after a static IP is assigned to the
NIC, the DHCP client will still keep renewing its lease throughout, which means
the NIC configuration set by the Image Server would possibly get overwritten by
the DHCP client. In order to avoid this conflict, the Remote Install Linux agent
kills the DHCP client after the target system is configured. This way the new IP
Address that the NIC is configured through takes effect.
Can Clients Respond to a DHCP Server in the Network other than the
DDHCP Server?
As far as the DHCP client in the OS level is concerned, the client can obtain
DHCP IP Address from a different DHCP server on the same subnet, unless the
other DHCP server blocks the client request due to restrictions in its
configurations. After the client obtains IP address, the agents start
communicating with the Image Server as expected.
The user has to be careful in this scenario. The reason is that, if the other DHCP
server hands out an address that is in a different subnet from that of the DDHCP
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server, then there would be no further communication between the client and the
DHCP server, and thus the system would get disconnected from the DDHCP
Server and consequently from the Image Server.
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Section
4
How Remote Install Image Server Finds the
Agents
Installation of Remote Install Agents
Installation of the Remote Install Agents is done using the Dell OpenManage
Systems Management CD in either of the following modes:

Configure Mode of Installation sets all NICs of the target system to obtain
DHCP IP Address from the DDHCP Server. This type of agent installation
will also disable the auto-IP function on the target system. After successful
configuration auto-IP will be enabled again.

Do not Configure Mode of Installation retains the existing Network settings of
all NICs in the target system.
Discovery Process
Remote Install includes a configuration engine called Kickstart Engine. This
engine communicates with the Remote Install agents on the target systems to
configure operating system parameters such as:

Time-zone

Hostname

Domain name

Administrator password

Adding a user

Setting the DNS information

Setting the NIC information
There are three ways in which the Kickstart Engine finds the agents installed on
the target systems:
1.
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BROADCAST
Kickstart Engine sends broadcast (BEACON) messages every 30 seconds to
all systems in the same network. The Remote Install agent replies to the
BEACON with an AVAILABLE message. This way the Kickstart Engine
discovers that a target system is available on the network.
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2.
UNICAST
The DHCP Client on the target system requests IP Address from the DDHCP
Server. The information that a target system requested an IP Address is
communicated to the Kickstart Engine. Then, Kickstart Engine sends unicast
messages to the target system.
3.
USING STATICIP.TXT
If the target system sends DHCP client requests to the DHCP server, then
that information is communicated to the Kickstart Engine and Unicast
messages is sent over to the target systems. If there is a target system that has
a static IP address and the user installs the agents in the Don’t configure
mode, then the target system will not run the DHCP client for its NICs. Also,
if the target system is across the router, then the Kickstart Engine will not be
able to communicate with this system since the broadcast messages will not
reach the other side of the router, see Figure 1. But since the target system
has a static IP Address, the DHCP client never gets to run on the target
system. As a result, the Kickstart Engine needs to communicate directly to
the target system This is made possible by defining a file called StaticIP.txt in
installDrive:\dell\openmanage\netstart. This file contains the IP Address of
the target system so that Kickstart Engine can communicate with the target
system.
Image
Server
Router
Target System with
static IPwith Agent
installed in nocfg
mode
Figure 1: Target System Across the Router from the Kickstart Engine (on the
Image Server)
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Section
6
Capture Process Reset IP Address
A target system can be captured for two purposes:
1.
Deployment to other servers
2.
Backup
When a system is captured for deployment to other servers, the network
personalization of the source system should be cleaned up so that deployment to
other servers does not result in IP Address conflicts.
Before the target system is captured for deployment to other servers, Pre-capture
scripts are run in order to remove the network personalization of the Captured
Image. The Pre-capture scripts do the following:

Clear out the IP Address of the NICs of the target source system and set
them to DHCP

Clear out the hostname of the target source system

Clear out the domain name of the target source system
This process is handled using Microsoft sysprep utility in Windows.
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Section
7
Processes Involving Storage Shares
How Storage Works
Remote Install storage is used to store images of the target systems and the
update packages needed to configure the settings of the target systems. Remote
Install can access the storage locally on the image server, or the storage on a
remote system on the network (storage server) if a shared folder is available.
When stored images are deployed to a target system, the target system opens a
SMB (server message block) connection to the storage share using the IP and
share name. So no matter what kind of network environment is involved, the
only requirement for using storage is that the target system can route to the
storage location.
Target systems will only access the storage location when they are in Active OS
mode.
Setting up Storage Shares
Procedures for setting up a storage share are quiet simple. Users need to enter
the storage location (\\IPAddress\share format) with a user name and
password. Remote Install does not allow an empty user name, but does allow an
empty password to add storage.
To make sure the storage settings are valid, users need to globally consider their
network settings:
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
In most cases, users should set up a storage location for each of their subnets.
A target system in one subnet can talk to the storage location in the same
subnet.

If users do not want to manage too many storage directories, they can choose
to have one storage system connect to all subnets, and define the same
storage locations multiple times with different IP addresses.

Even if different storage locations point to the same physical directory
location, the images under one storage location cannot be accessed by target
systems in another subnet unless routing functionality is applied. Remember
that the target system always needs to mount the storage location by the IP
defined.

Users can turn on the routing functionality in the network environment. In
the active operating system, the target system uses the dynamic IP address
assigned by DDHCP. Users need to define the default gateway when they
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define the DHCP scope. The gateway information will be used for routing
purposes.
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Section
8
Best Practices for Network Topology
Remote Install can be setup in a variety of network topologies. This section
defines the best practices for Remote Install Network topology.
Single Connection Network Segment
This configuration is a simple network configuration in which the image server,
target systems, and admin console are all in one subnet, see Figure 2. The image
server and target systems either have a single NIC, or they have multiple NICs
but only one is connected and all others are disabled or unplugged.
Figure 2: Single Connection Network Segment
A single connection network segment requires:
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
All target systems must have PXE boot enabled in the BIOS settings. PXE
boot must be set before booting from local disks. Without PXE booting,
target systems are not manageable by Remote Install.

Remote Install Image server normally lists all NICs of a target system that it
recognizes. If a NIC is not recognized by the OS (due to lack of driver), or a
NIC is disabled, then the image server will not recognize it. But if a NIC is
unplugged but enabled, then it is configurable by the image server.

Remote Install lists all NICs of a target system in the order that the OS lists
them, which might not be the order a user prefers. Users need to make clear
that this preferential order maps to the NIC physical location so that he/she
configures the right NIC with the right IP address. If users mistakenly
configure the NIC connected to image server, then communication between
image server and target system will be lost and the target system is no longer
managed.

When users enter the file path string from admin console, all drive letters C:
D: and so on are interpreted as image server local drives. It does not refer to
the local drive of the system where admin console resides.
The above network setting requirements not only apply to a single connection
network segment, but also apply to all other settings.
Single Management, Multiple Connection Network Segment
In this configuration, multiple NICs exist for the target systems. Each target
system has one NIC connected to the management network. Target systems have
other NICs connected to other subnets.
This setting can be chosen when users do not want DHCP/PXE in the data center.
They can build a LAN of management segments and have one NIC (NIC1 in the
figure below) of the target system connected to this LAN without interference
with the data center networking (NIC 2).
Setting this type of network requires:
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
Since all target systems have another NIC connection to the data center or
Internet, the IP configuration is very sensitive. User should choose No
configure mode when installing Remote Install agent on the image server
when they introduce a legacy system to Remote Install. If they have to
configure the NIC, clarify the order of all NICs and configure the right one.

When capture such a target system, users should be aware that “Capture for
deployment” has some influences on the target system. A mini-setup
Sysprep process runs after capture. This capture will also erase all static IP
addresses on the target system and replace with DHCP settings. To avoid
DHCP problems, users can either take the system offline and configure it
before replacing it in the data center, or if offline is not an option (e.g., the
target system is a web server and need to be on duty all the time), users can
choose the “Capture for backup” option so that the target system is
untouched. However, with this option the image being saved has the same
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IP address as the original system. If users deploy that image to another target
system, they should not introduce the system to the data center until they reconfigures the IP. Otherwise, IP address conflicts will occur.

Remote Install configuration does not support multi-host servers (multiple IP
on single NIC). Users cannot add an IP address to a NIC, as it will erase the
old IP address and assign a new one.
Admin Console and Image Server in Separate Subnets
In this configuration, the admin console is not in the management subnet
(management network), see Figure 3. Users should prepare the web hosting of
the image server so it can hear the request from the admin console. Also, since
the image server has multiple live connections, the embedded DDHCP will listen
on all of these connections.
Figure 3: Admin Console Outside the Single Network Segment
Setting up this type of network requires:

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The image server has more than one NIC connection. The embedded
DDHCP server is designed to listen to all subnets, so the DDHCP server will
not only receive requests from the management segment, but also from other
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subnets including the one with the admin console. However, Remote Install
DDHCP will never assign an IP address to a wrong system.

Even though DDHCP server listens on all subnets that connect to the image
server, it will only hand out DHCP addresses in the Remote Install DHCP
scopes. If users do not want DDHCP to interference with a certain subnet,
they can delete any scopes defined in that range.

If a scope has been defined for a subnet, DDHCP will assign an IP address to
a target system only if the target system had been PXE booted from the
Image server. In order for PXE boot to take place, users need to adjust the
boot sequence.
Multiple Management Subnets
In this configuration, the image server is used to manage multiple subnets, see
Figure 4.
Figure 4: Multiple Management Subnets
Setting this type of network requires:

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The image server must somehow discover the target systems in the other
side of router. Please refer to Section 4: How Remote Install Image Server finds
the Agents for the discovery process.
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
Setting up the storage for Remote Install has more options since different
subnets are involved. Please refer to Section 7: Setting up Storage Shares for
details.

If the image server has more than one connection with the target system,
then Remote Install might not work as expected since image server could
pick up either NIC to send out packets to the target system. Remote Install
encourages users to have only connection between the image server and a
target system.
THIS WHITE PAPER IS FOR INFORMATIONAL PURPOSES ONLY, AND MAY CONTAIN TYPOGRAPHICAL
ERRORS AND TECHNICAL INACCURACIES. THE CONTENT IS PROVIDED AS IS, WITHOUT EXPRESS OR
IMPLIED WARRANTIES OF ANY KIND.
Dell, OpenManage, and PowerEdge are trademarks of Dell Computer Corporation. Other trademarks and trade names
may be used in this document to refer to either the entities claiming the marks and names or their products. Dell
disclaims proprietary interest in the marks and names of others.
©Copyright 2002 Dell Computer Corporation. All rights reserved. Reproduction in any manner whatsoever without the
express written permission of Dell Computer Corporation is strictly forbidden. For more information, contact Dell.
Information in this document is subject to change without notice.
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