N-Tron 7506GX2 User Manual

708, 709FX, 710FX2, 711FX3, 712FX4, 714FX6,

716, 7010TX, 7012FX2, 7018, & 7506GX2 Series

Managed Industrial

Ethernet Switch

DHCP Technical Instructions

Revision 2010-11-15 Page 1 of 33

Contents

Contents .................................................................................................................................................................. 2

Overview ................................................................................................................................................................. 3

Configuring DHCP Server and Relay Agent .......................................................................................................... 4

Examples ................................................................................................................................................................. 4

N-Tron DHCP Setup Process – Basic Setup Flow ................................................................................................. 5

Getting connected with N-Tron DHCP Server ....................................................................................................... 6

DHCP Menu............................................................................................................................................................ 6

Figure: Menu_1 ................................................................................................................................................... 6

Enabling the DHCP Server ................................................................................................................................. 7

Setting up the DHCP Server Profiles .................................................................................................................. 7

Figure: Profile_1 .............................................................................................................................................. 7

Setting up the DHCP Server Mappings .............................................................................................................. 8

Figure: Mapping_1 .......................................................................................................................................... 8

Setting up a Dynamic Range ............................................................................................................................... 8

Topology:......................................................................................................................................................... 8

Setting up a Static Range .................................................................................................................................. 10

Basic configuration using Option 82 Relay Agent ........................................................................................ 10

Topology:....................................................................................................................................................... 10

N-Tron Relay Agent Setup Process – Basic Setup Flow .................................................................................. 12

Setup Option 82: Relay Agent Switch ........................................................................................................... 13

N-Tron DHCP Server Static Range Setup Process – Basic Setup Flow ........................................................... 14

Setup Option 82: DHCP Server Switch ......................................................................................................... 15

Setting up a Single IP ........................................................................................................................................ 17

Basic configuration using Option 61 or MAC Address ................................................................................ 17

Topology:....................................................................................................................................................... 17

Setting up an N-Tron Switch as a Client Device .................................................................................................. 19

Topology ........................................................................................................................................................... 19

Example ............................................................................................................................................................. 19

Relay Agent - Stand Alone ................................................................................................................................... 21

Setting up the Relay Agent to obtain a Local IP Address ................................................................................. 21

Topology:....................................................................................................................................................... 21

Advanced DHCP Server Topologies .................................................................................................................... 22

Setting up a redundant DHCP Server using 2 N-Rings across N-Link ............................................................. 22

Topology 1:.................................................................................................................................................... 22

Firmware/Config – TFTP ..................................................................................................................................... 29

SUPPORT ............................................................................................................................................................. 31

N-TRON Limited Warranty .................................................................................................................................. 32

Revision 2010-11-15 Page 2 of 33

Overview

The Dynamic Host Configuration Protocol (DHCP) provides configuration parameters to Internet hosts.
DHCP consists of two components: a protocol for delivering host-specific configuration parameters from a
DHCP server to a host and a mechanism for allocation of network addresses to hosts. DHCP is built on a
client-server model, where designated DHCP server hosts allocate network addresses and deliver
configuration parameters to dynamically configured hosts. (DHCP is explained in RFC 2131).

The N-Tron DHCP Switch can be configured to be a DHCP Server, a DHCP Relay Agent, or both.

DHCP Server - manages and allocates IP address from a pool of address, defined by Profiles, to

requesting Clients.

Relay Agent – receives DHCP requests messages and directs them to a specific DHCP server.

Before sending the DHCP request, the Relay Agent appends identifying information into the
message (Circuit ID + Remote ID).

o Circuit ID – contains information that identifies the port location that the DHCP request

comes from. For example (TX1-0001) defines request came from Port 1 – VLAN 1.

o Remote ID – contains information that identifies the Relay Agent device. (For example: the

IP address or MAC address of the Relay Agent.)

It can also Assign a Local IP address when a client is connected to a specific port. Relay Agent is
explained in RFC 3046.

The N-Tron DHCP Server supports several methods of allocating IP address in a managed manner.

Dynamic Range – IP address allocation is Dynamic and is based on the first free IP address in the

defined range. The IP address could be different each time the Client makes a request.

Static Range: Option 82 Relay Agent- IP address allocation is Static and is based on matching

Option 82 information received from a Relay Agent. The same IP address will be given each time to
a specific Client.

Single IP: Option 61 or MAC - IP address allocation is Static and is based on matching Option 61

information received from a Client. The same IP address will be given each time to a specific
Client.

Revision 2010-11-15 Page 3 of 33

Configuring DHCP Server and Relay Agent

The following information will be helpful as you configure the N-Tron DHCP Server. A high level flow of
the basic configuration is provided by Figure: Flow_DHCP_1.

In order to use the DHCP server in offering IP addresses, several configuration steps are essential. N-Tron
uses Profiles and Mappings to organize how the IP’s will be offered to Clients. You must have at least one
Profile defined in order to add mappings.

The menu Setup Profiles shows DEFAULT as a Profile. The DEFAULT Profile allows you to define some
changeable parameters that are automatically included within the Profile you define. The changeable
Profile entries can be seen by pressing the, Advanced, button when adding a Profile. You do not have to
make use of this DEFAULT Profile. The DEFAULT Profile information is used by the DHCP Server when
communicating with the DHCP Client. The use of the DEFAULT Profile simplifies the changing of
information of already defined Profiles by automatically inserting data found in the DEFAULT profile into
the Profile used when allocating an IP addresses to a Client.

The Profile Setup has entries to define an Address Pool range. It is important to decide what this range
should be, since your IP address mappings will be a subset of this range. Profiles cannot overlap their
Address Pool ranges with other Profiles.

The Profile Setup Lease Time: designates the amount of time an IP will be honored by a Server that has
made an offer to a Client. The Lease Time insures that the IP address offered by the Server will not be
offered to any other Client device until the Lease expires. The Client will use a renewal process to maintain
the IP for longer periods of time by requesting an extension for the address from the server.

Saving DHCP Settings and Data: The DHCP Profiles, Mappings and Bindings are stored in the N-Tron
switch file system when you click on the screen Update button. These changes are automatically saved for
you. Parameters such as Enabling and Disabling the DHCP Server are part of the switch Settings
configuration and you will be prompted by a message to save your changes.

Examples

Examples are provided for the following settings:

Setting up a Dynamic Range
Setting up a Static Range
Setting up a Single IP
Setting up an N-Tron Switch as a Client Device
Setting up the Relay Agent to obtain a Local IP Address
Setting up a redundant DHCP Server using 2 N-Rings across N-Link

Revision 2010-11-15 Page 4 of 33

DHCP Server

Enable DHCP

Server

DHCP Server

Setup Profiles

DHCP Server

Setup IP Maps

Relay Agent

Relay & Local IP

Setup

N-Tron Client

Switch

Setup DHCP Client

DHCP Server

Create

Dynamic Range

DHCP Server

Create

Static Range

DHCP Server

Create

Single IP

N-Tron

DHCP Setup

Process

N-Tron DHCP Setup Process – Basic Setup Flow

Figure: Flow_DHCP_1

Revision 2010-11-15 Page 5 of 33

Getting connected with N-Tron DHCP Server

N-Tron Switches provide a Web Interface for all your DHCP configurations.
The two main menus for DHCP configuration are:

DHCP – contains the configuration for both the DHCP Server and Relay Agent.
Administration – clicking on Administration / System / IP Configuration menu, allows you to

configure the DHCP Client to be either Static or DHCP. In order to receive an IP address
from a DHCP Server the switch must be configured for DHCP.

DHCP Menu

Figure: Menu_1

Revision 2010-11-15 Page 6 of 33

Enabling the DHCP Server

Click on: DHCP / Server / Setup Profiles. See Figure: Menu_1
Click on: Modify Button. See Figure: Setup_1
Click on Server Enabled Box and select Enabled.
Click on Update Button.
Click on Saved.

Figure: Setup_1

Setting up the DHCP Server Profiles

Click on: DHCP / Server / Setup Profiles. See Figure: Menu_1
Click on: Add Profile button. See Figure: Setup_1
Enter a Network Profile Name: Ex. One
Enter an Address Pool Start: Ex. 192.168.2.1
Enter an Address Pool End: Ex. 192.168.2.254
Click on Update when finished.

Figure: Profile_1

Revision 2010-11-15 Page 7 of 33

Setting up the DHCP Server Mappings

DHCP

Client

Mappings are used to define rules that are used in determining what IP address will be

offered to the client.

N-Tron provides the following Mapping Types:

Figure: Mapping_1

Setting up a Dynamic Range

IP address allocation is Dynamic and is based on the first free IP address in the defined

range. The IP address could be different each time the Client makes a request.

Topology:

Example:

In this example connections can be made to any port on the server or on a switch connected to the
server. The IP address given will be the next available address in the range defined.

Setup:

Click on: DHCP / Server / Setup IP Maps. See Figure: Menu_1
Click on: Dynamic Range. See Figure: Mapping_1
Reference Figure: Dynamic_1 below.
Select the Profile you wish to add this mapping too.
Enter Low IP: Ex. 192.168.2.25
Enter High IP: Ex. 192.168.2.35
Click Update when finished.

Figure: Dynamic_1

Revision 2010-11-15 Page 8 of 33

Mapping:

The resulting mapping from the setup can be viewed by clicking on DHCP / Server / Setup

IP Maps. See Figure: Dynamic_2 below.

Figure: Dynamic_2

Connection:

Connect the Ethernet cable to the device and to a port on the Server.

Powering On and Status Display:

Power on the client device. The device will request an IP address from the Server. The

Server will offer the client an IP address from the dynamic range. Allow 20 - 30seconds for
the DHCP transactions to finalize.

To view status: Click on DHCP / Server / View Bindings

Figure: Dynamic_3

The Web browser can now be used to view and configure the client device.

Revision 2010-11-15 Page 9 of 33

Setting up a Static Range

TX1

192.168.2.100

Using a static IP address enables the DHCP Server to assign a DHCP Client the same IP

address each time the device is connected to a designated port on a Relay Agent.

Basic configuration using Option 82 Relay Agent

The setup for this method is a 2 step process and will be described below.

 The first step is to setup the Relay Agent. See Setup Option 82: DHCP Server Switch.
 The second step is to setup the DHCP Server. See Setup Option 82: DHCP Server Switch.

Topology:

Example : A connection is made from the Client to a designated port (TX1) on the Relay

Agent.

In this example:

Make configuration on the Relay Agent. See Figure: Option82_1

The Relay Agent has been enabled.
The address of the DHCP server has been specified in the DHCP Server 1 IP as

192.168.2.213.

The Remote ID selected is the IP address of the Relay Agent.
The Relay Status has been enabled. This specifies that the relay agent should send a

request for an IP on behalf of the Client when the Client is connected to port TX1 and
that the VLAN the request will be using is 1.

The default string information provided in the field Other Data will be used (TX1-0001).

Configuration on the Server side should match the configuration on the Relay Agent: See
Figure: Option82_2

The Remote ID’s and Circuit ID’s are the same for the Port selected.
When a request for an IP arrives to the DHCP Server from the Relay Agent, the DHCP

Server will compare the Remote and Circuit ID’s and if they match, an IP will be offered.

In this case the Client will receive the IP address 192.168.2.100.

Revision 2010-11-15 Page 10 of 33