Grayhill EZCOMWL24IP User Manual

IP Users Manual

Revision A6

Friday, January 26, 2001

Grayhill EZCom IP Users Manual Rev A6 1/26/2001

Table Of Contents

Getting Started.....................................................................................................................4

Initialization ..................................................................................................................... 4

EZCom-IP Explorer Introduction ................................................................................. 4

Point-to-Point Link Example........................................................................................ 6

Windows TCP/IP Set Up ...................................................................................................13

Multipoint Store-&-Forward Example........................................................................14

Technical Reference..........................................................................................................18

Introduction ................................................................................................................... 18

Protocols And Protocol Architecture............................................................................. 19

A Simple Model.........................................................................................................20

The TCP/IP Protocol Architecture............................................................................. 21

TCP/IP Communications............................................................................................... 23

The TCP/IP Protocol Stack ....................................................................................... 23

Application Layer....................................................................................................... 23

Transport Layer......................................................................................................... 23

User Datagram Protocol............................................................................................ 25

Network Layer ........................................................................................................... 26

Overview of TCP/IP Addresses.................................................................................26

Internet Protocol Routing........................................................................................... 28

The ROUTE Utility Program...................................................................................... 31

Finding Another Machine’s Address ......................................................................... 32

Ethernet Physical Layer................................................................................................ 34

MAC Frame............................................................................................................... 34

Routing, Putting All of the Pieces Together .............................................................. 34

Subnetting..................................................................................................................... 35

How Do You Subnet?................................................................................................ 35

Determining Your Addressing Needs .................................................................... 35

Remembering Binary................................................................................................. 35

Defining Your Subnet Mask................................................................................... 36

Finding Out How Many Networks, How Many Hosts............................................. 37

Subnet IDS............................................................................................................. 37

EZCom IP Routing........................................................................................................ 40

Introduction................................................................................................................40

Indicators and Connectors ........................................................................................ 43

Grayhill EZCom-IP Explorer Program ...............................................................................44

Introduction................................................................................................................44

Views......................................................................................................................... 44

Menus & Tool Bar...................................................................................................... 45

Control Tabs.............................................................................................................. 46

Troubleshooting Guide ......................................................................................................50

LED Activity B ............................................................................................................... 50

No Ethernet Link indicator............................................................................................. 50

Link Test Failed......................................................................................................... 50

Ping Failed to Respond............................................................................................. 51

Ethernet (CSMA/CD).........................................................................................................52

Precursors................................................................................................................. 52

Description of CSMA/CD........................................................................................... 53

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List Of Tables & Figures

Table 1, Factory Default Settings.......................................................................................4

Table 2, Point-To-Point Setup Parameters ........................................................................ 6

Table 3, Example II, EZCom-IP Radio Settings...............................................................14

Table 4, Example II Device IP Addresses........................................................................ 15

Table 5, Routing Table for 192.168.1.2 (EZCom-IP radio)............................................... 16

Table 6, Routing Table for 192.168.1.1 (PC) ................................................................... 16

Table 7 Store & Forward Example Routing Summary.....................................................16

Table 8, Bit Position Values.............................................................................................. 27

Table 9, TCP/IP Address Classes—First Octet................................................................ 27

Table 10, Address Class Summary..................................................................................28

Table 11, Active Routes: .................................................................................................. 30

Table 12, Extracting a Network ID Using a Standard Subnet Mask................................. 36

Table 13, Extracting a Network ID Using a Custom Subnet Mask................................... 36

Table 14, Extracting the Target Network ID Using Standard and Custom Masks........... 36

Table 15, Creating a Custom Subnet Mask by Adding Subnetting Bits........................... 37

Table 16, Valid Subnet Numbers...................................................................................... 37

Table 17 Calculating the Subnet IDs Using Binary..........................................................38

Table 18, Subnet IDs for a Three-Bit Subnet Mask.......................................................... 38

Table 19, Table for Calculating Subnet Mask, IDs, and Number of Subnets................... 38

Table 20 Finding the Last Host ID by Subtraction............................................................ 39

Table 21 Host IDs for a Subnetted (lP) Address..............................................................39

Table 22, Finding the Last Host ID by Subtraction........................................................... 39

Table 23, Host IDs for a Subnetted Class C Address...................................................... 39

Table 24, Typical EZCom-IP Radio Routing Table .......................................................... 41

Figure 1, Local Connection................................................................................................. 4

Figure 2, EZCom Explorer Window.................................................................................... 5

Figure 3, Point-to-Point Link............................................................................................... 6

Figure 4, EZCom-IP Explorer After Finding a Radio.......................................................... 8

Figure 5, IP Address Tab.................................................................................................... 8

Figure 6, Radio Settings Tab.............................................................................................. 9

Figure 7, EZCom-IP Routing Table.................................................................................... 9

Figure 8, Diagnostics Tab................................................................................................. 10

Figure 9, Link Test Dialog................................................................................................. 11

Figure 10, Ping Utility Program......................................................................................... 11

Figure 11, Example II Network layout............................................................................... 14

Figure 12, TCP/IP Protocol Stack..................................................................................... 22

Figure 13, IP Address Formats......................................................................................... 28

Figure 14, IP Routing Logic.............................................................................................. 29

Figure 15, ARP Packet..................................................................................................... 32

Figure 16, IEEE 802.3 frame format................................................................................. 34

Figure 17, More Networks Mean Fewer Hosts Per Network & Vice Versa...................... 36

Figure 18, EZCom-IP Routing Mechanism....................................................................... 40

Figure 19, EZCom processing done at IP layer ............................................................... 40

Figure 20, EZCom-IP Indicators....................................................................................... 43

Figure 21, EZCom Explorer Window................................................................................ 44

Figure 22, Control Tabs.................................................................................................... 46

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Section

1.

Getting Started

Initialization

When you first remove an EZCom IP radio from it’s carton and apply power to it, the radio
will boot-up and go through a series of self-tests. After completing the boot process the
radio will be ready to receive configuration information. Before the radio can be used to
transmit or receive application specific information (network traffic) it must first be
configured for the network that it will be used on. All necessary configurations can be
done using the Grayhill EZCom-IP Explorer program.

A listing of all the EZCom-IP parameters along with the factory default settings for each
parameter is given in Table 1, below. In this first section “Getting Started” we will practice
configuring some EZCom-IP radios for specific examples. First we will setup a point-to­point link typical of what you may want to institute for a bench test and then we will move
on to a more involved example that will demonstrate some of the more advanced
features of you EZCom-IP radio. For readers that are looking for a more detailed
explanation of specific settings please refer to the Technical Reference section of this
manual.

Table 1, Factory Default Settings

Parameter Factory Default Comments
Radio IP Address 192.168.1.1
Network Subnet mask 255.255.255.0
Radio Mac Address ******-****** Factory set unique value
Routing Table None
Center Frequency 2.442 GHz Approximately Center of Band

Configuration can be accomplished through a local connection or remotely over the air. A
local or direct connection is when an EZCom-IP radio is connected to the local area
network where you have the Grayhill EZCom-IP Explorer program running as illustrated
in Figure 1. Remote configuration can be accomplished over the air provided that the
remote EZCom-IP radio is already set to operate at the same center frequency as the
local radio. Remote configuration is discussed in detail in the Technical Reference
section of this manual.

Figure 1, Local Connection

EZCom

EZCom-IP Explorer Introduction

Before we start on the examples in this section let’s take a few minutes to familiarize
ourselves with the EZCom-IP Explorer program. If you have not loaded the GH EZCom­IP Explorer program please do so now. The Explorer is a client side program that can be
run on any 32 bit Windows based PC. It is designed to communicate configuration and
diagnostic information with the EZCom-IP radios either directly attached or via the local
area network. The program offers the user a verity of configuration and diagnostic tools.
Figure 2, below illustrates the initial screen of the Explorer program. The screen is
divided into three main parts;

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Network

View

Control

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1. The Network View, which graphically displays the EZCom-IP, radios in the
network.

2. The Control Tabs that can be used to change configuration settings and initiate
diagnostic functions.

3. The Monitor, which can be used to observe specific communication events.

When you first start the Grayhill EZCom-IP Explorer your will see a single icon in the
Network View. This icon represents the computer that is running the GH Explorer
program. No other icons appear at this time because the Explorer program must be
prompted to go out and find any radios in the network first. If you click on the Tools menu
and then pick Find Links the Explorer will go out and find any EZCom-IP radios on the
local network.

Figure 2, EZCom Explorer Window

Tabs

GH Explorer will then add a radio icon to the Network View for each radio it finds on the
local network (see Figure 4).

The information in the Control Tab window is associated with the icon selected in the

Network View. As you click on different icons in the Network View the information in the
Control Tab View is updated with the setup values from the object represented by the

icon selected. If you select the GH Explorer icon at the top of the window (which is
selected by default when you start the program) only the IP address tab is accessible.
This is because the GH Explorer icon points to the PC that the program is running on and
not to a radio. When you select a radio icon in the Network View the information in the
Control Tab will be downloaded from the radio and displayed in the appropriate tab. If you
changing any of the information in the Control Tab and click the update button the setup
information in the radio pointed to by the icon in the Network View will be changed
accordingly.

As you can see changing the setup information in a radio is as simple as selecting which
radio you want to modify from the Network View and then entering the appropriate
information in the Control Tab view.

Monitor

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Point-to-Point Link Example

In this first example we will set up a point-to-point link between two Ethernet networks.
For simplicity we have represented both networks as consisting of one PC and one
EZCom-IP radio (router). In reality a point-to-point configuration could be used to connect
anything from a single PC and router to a fully developed enterprise network. After we
have set up the example we will uses some of the built-in EZCom diagnostic tools to test
our setup. After we complete our testing we will try a few simple client server applications
that are part of the windows operating system to demonstrate the functionality of the
network.

You will need 2 PCs and 2 EZCom-IP radios to fully implement this first example. You
may also need to have your operating system CD handy in the event that Windows wants
to copy additional files. If you don’t have 2 PCs you can still set up the example with only
one PC but you will only be able to run the built in diagnostic functions of the EZCom-IP
radio you will not be able to run the applications.

Figure 3, Point-to-Point Link

192.168.1.2

192.168.1.0

Ethernet

192.168.1.1

192.168.2.1

192.168.2.2

Ethernet

192.168.2.0

There are 3 basic steps involved in setting up this example: setting the IP addresses on
the two PCs, configuring the radios, and setting file share permissions on one of the PCs
to allow file access across the network. Table 2 shows each step along with the
parameters that need to be setup and the appropriate values.

Table 2, Point-To-Point Setup Parameters

Step Parameter Value For PC (A) &

1. Set PC IP
Addresses

Radio (A)

IP Address 192.168.1.2 192.168.2.2
Subnet Mask 255.255.255.0 255.255.255.0

Value For PC (B) &
Radio (B)

Default Gateway 192.168.1.1 192.168.2.1

2. Set Radio
Parameters

IP Address 192.168.1.1 192.168.2.1
Subnet Mask 255.255.255.0 255.255.255.0
Default Gateway 192.168.2.1 192.168.1.1
Routing Table Default Default

3. Set File Share
Permissions

File and Print sharing
for Microsoft
Networks installed

Both PCs must have an Ethernet network interface card or equivalent PCMCIA card
installed and both PCs must also have the TCP/IP protocol installed. For information on
installing your network interface card see the card manufactures installation instructions.
For help installing the TCP/IP protocol, please see the sidebar Windows TCP/IP Set Up
on page 13 of this manual.

To get started with this example take a RJ45 Category 5 patch cable and connect one
end of it to the Ethernet port on your EZCom-IP radio and connect the other end to an
open port on your network hub. If you do not have an existing network you can connect
directly to the PC’s NIC card or PCMCIA card. Now apply power to the EZCom-IP radio

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and the PC. After the PC and radio have gone through their normal boot process you
should see a green link indicator (see Figure 20, on page 43). If you do not see the green
link indicator please follow the steps in the troubleshooting guide for “No Ethernet Link”.

Now that we have a physical connection between the client PC that will be running the
EZCom-IP Explorer and an EZCom-IP radio we can begin to setup our first example.

Setting-up The PC’s IP Address

1. Click the Start button. Choose Settings, Then
Control Panel.

2. Double-click the Network icon. Your Network
window should pop up as shown on the right.

3. Select the Configuration tab.

4. Highlight TCP/IP (for your network adaptor)
under the list of components installed.

5. Click the Properties Button. You should now
see the TCP/IP properties window below.

6. Select the IP Address tab.

7. Make sure the Specify IP Address option is
selected.

8. Enter the appropriate IP Address and Subnet Mask (from the setup table on page 6)
in the spaces provided.

9. Now select the Gateway tab

10. Enter the Default Gateway (again from the setup
table) and make sure you click the ADD button.

11. Click the OK button on the TCP/IP Properties
Window.

12. Click the OK button
on the Network
Window.

After clicking the OK
button on the TCP/IP
properties tab you will
be prompted to reboot
your computer before

theses changes will take effect. Click OK.
The IP Address, Subnet Mask and Default Gateway are

now set up on your PC. Repeat these steps using the
appropriate setup values for the second PC in the
network. You may wish to reopen either one of the
properties windows to verify the values match those listed in the example’s setup table.

In the next step we will setup the radio parameters for the EZCom-IP radios that will be
used in this example.

Setting-up The Radio Parameters

Start the Grayhill EZCom-IP Explorer by selecting “EZCom-IP Explorer” from your PC’s
Start/Programs menu. After the program loads select Find Links from the Tools menu at
the top of the explorer main screen. The Searching for Radios dialog box will appear.

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Explorer

Icon

EZCom-IP

Radio

Grayhill EZCom IP Users Manual Rev A6 1/26/2001

Once the searching process is complete press OK to return to the EZCom-IP Explorer
main window.

Figure 4, EZCom-IP Explorer After Finding a Radio

The Explorer should now look like the one shown in Figure 4, above. Don’t worry if the IP
addresses and other data on your screen are not exactly as shown. What is important is
that there is an EZCom-IP radio icon below the GH Explorer icon in the Network View.
Click on the radio icon. The data in the Control Tab window will update to reflect the
current settings for the radio you just selected. If the radio you are using is new the
settings should look like those listed in Table 1, Factory Default Settings on page 4.

The first Control Tab is the IP Address Tab, which is shown in Figure 5. On this tab we
will set the radio’s IP Address, Subnet Mask and Default Gateway. In each of the
respective text boxes please enter the appropriate setting from Table 2, Point-To-Point
Setup Parameters on page 6. When you are done your IP Address tab should look like
the one shown in Figure 5 below.

Figure 5, IP Address Tab

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Don’t worry if you do not fully understand each of the settings that you are about to enter,
we will cover each of the settings in more detail in the technical reference section latter in
this manual.

Now click the Radio Tab. You should not have to change any settings on this tab. All of
the factory defaults settings should be fine. You may just want to look over the values
and verify that they match those shown if Figure 6. If any of your values are different
please change them to match.

Figure 6, Radio Settings Tab

Now click the Routing Tab. The routing table should contain two entries, which were
created automatically by the Explorer program. For our example all routing is actually
handled by the Default Gateway setting that we established on the IP Address Tab. If
there is any other entries in your routing table select them by clicking any where on the
row and then click the Delete button. Repeat this step for all extra entries. Your routing
table should look like the one shown in Figure 7 below.

Figure 7, EZCom-IP Routing Table

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Setting Up The Second PC & Radio

Now that we have completed setting up our first PC and an EZCom-IP radio we will need
to repeat the steps we followed with the second PC and radio. For the second PC and
radio use the setup information listed in the last column of Table 2 on page 6.

Testing The Radio Link

With both PCs and both radios setup we can now run a few diagnostic test to verify that
we first have a link between the radios and then a network connection from one PC to the
other. First connect the radios and PCs as shown in Figure 3. Make sure that you
connect the radios to the PC with the same subnet ID.

The first test that we will conduct will be a link test. This is to verify that the radios can
communicate. This is strictly a radio communications test and none of the network
settings are used. Select the Diagnostics Tab then click on the Link Test button. The link
test dialog box will appear. Enter the Mac Address of the radio you want to link to and
click on the Run Test button.

Figure 8, Diagnostics Tab

In the Test Results window you will see an announcement that the test is in progress.
During a link test packets are transmitted every 50 milliseconds. If you multiply the
Number of packets by this interval you can get an idea of how long the test will take.
Using the default number of packets the test should take 100*0.05 or just over a half
second.

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Figure 9, Link Test Dialog

When the Link test is complete you should see the test results in the Link Test dialog
similar to the results shown in Figure 9. If your Link Test fails, that is you don’t get a large
number of Successful packets (typically 90% to 100%), please follow the steps listed in
the Troubleshooting guide on page 50.

After successfully running a link test we will now verify that we have a logical network
connection from one PC to the other. To accomplish this we will use one of the Windows
built in network utilities known as “Ping”. Actually ping is a member of the TCP/IP protocol
suite.

Ping is a simple but very useful utility program, ping sends a special (ICMP) test packet
to a designated IP address and then listens for the packet to be echoed back.

Figure 10 shows the output of a ping request. To run the Ping utility program click Start
then select Programs and click on the MS-DOS Prompt. When the DOS Window opens
type the word ping along with the IP address of the host that you want to ping and press
enter. Ping will then transmit 4 test packets and output the round trip time it takes for
each packet to traverse the network. If you are unable to successfully ping the remote PC
in this example please follow the trouble shooting procedures on page 51 for “Ping Failed
to Respond”.

Figure 10, Ping Utility Program

If you have successfully run the link test and ping test you are ready to setup your
application to run across the wireless network.

Running our example application

Before we can run an application across the wireless link we must first install the File and
Pint sharing for Microsoft Networks service. This service is built in to the Microsoft

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Windows operating system and in essence enables the PC it’s running on to act as a file
and/or print server.

To enable file and printer sharing on your computer

1. Click on the Start Button and select Settings and Control Panel.

2. After the Control Panel dialog box opens double-click the Network icon.

3. Click File and Print Sharing.

4. Select the check box for the “I want to give others access to my files”, sharing

option. A check mark indicates the feature is activated.

5. Click OK.

6. Windows will now install the File & Print Sharing service on your PC. You will be

prompted that you must restart your computer before these changes will take
effect. Click OK,

After your computer reboots you will need to tell windows which files or folders you want
to share on the network. For this example we are going to simply share the entire C drive.

To share The C Drive

1. In Windows Explorer or My Computer, click the C drive root folder.

2. On the File menu, click Properties.

3. Click the Sharing tab, and then click Shared As. Enter the share name “Server

Drive”. Note: The Sharing tab is not visible if you don’t have file and print sharing
services enabled.

4. Click the Access Type you want, and, if necessary, enter a password.

Running Our Example Application

Now that we have File and Print sharing setup on our 192.168.2.2 PC we will access the
files on this machine from our 192.168.1.2 PC, which is at the other end of our wireless
link. The first thing we need to do is to make the Windows operating system on

192.168.1.2 aware of the network connection to 192.168.2.2. Start by:

1. Double clicking the My Computer icon on your windows desktop.

2. After the My Computer dialog opens, in the Address Bar type \\192.168.2.2\.

3. Just below the address bar you will see a dropdown list with the share name
“Server Drive”. This is the share name we gave to the c drive on 192.168.1.2.
Select the Server Drive share name by clicking on it.

4. The My Computer window should now be a listing of the files and folders on the

192.168.2.2 c drive. Now click on the Favorites menu and select Add to
Favorites.

You can now use the Server Drive just as though it was a hard drive in your 192.168.1.2
PC. Try by copying or accessing any of your data files just as you would if there were on
you c drive.

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Windows TCP/IP Set Up

Follow these instructions to install the TCP/IP protocol on your PC only after a network
card has been successfully installed. These instructions are for Windows 95 and
Windows 98. For TCP/IP setup under Windows NT or Windows 2000, please refer to
your operating system manual.

1. Click the Start button. Choose Settings, then Control Panel.

2. Double-click the Network icon. Your Network window should pop up. Select the
Configuration tab.

3. Click the Add button.

4. Double-click Protocol.

5. Highlight Microsoft under the list of manufactures.

6. Find and double-click TCP/IP in the list to the right.

7. After a few seconds you should be brought back to the main Network window. The
TCP/IP Protocol should now be listed.

8. Click OK. Windows may ask for the original Windows installation files. Supply them
as needed (i.e.: D:\win98, D:\win95, C:\windows\options\abs.)

9. Windows will ask you to restart the PC. Click Yes.

The TCP/IP Installation is complete.

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Multipoint Store-&-Forward Example

This second example is designed to demonstrate in detail how to setup and utilize the
routing functions available within a TCP/IP network using the EZCom-IP radio. It may not
be practical to setup this example because it requires at least 4 EZCom-IP radios, 4 PCs,
and a WAND router. Even if you do not setup the example it is beneficial to follow along
to develop an understanding of how to setup the different routing aspects of the network.

In our first example we relied on the default Gateway settings for both the PCs and the
EZCom-IP radio to handle all of the routing decisions. No routing table entries were
made. In this example we will endeavor to more fully illustrate the routing capabilities of
the EZCom-IP radio.

Figure 11, Example II Network layout

Ethernet

192.168. 2. 0

Ethernet

192.168. 1. 0

Ethernet

192.168. 4. 0

Router

Internet

Ethernet

192.168. 3. 0

The first step in setting up this example is to program the IP address and other settings in
the EZCom-IP radios. Probably the easiest way to handle this task is to take one PC,
which has the EZCom-IP Explorer program installed on it and directly connecting it to
each of the radios one after the other. For information and instructions on how to perform
the setup tasks from a single point in the network please refer to EZCom-IP Explore
documentation on page 44. Table 3, below is a listing of all the settings for both the IP
Address Tab and the Radio Tab that need to be set up. Most of these settings are the
factory default settings and should already be set.

Table 3, Example II, EZCom-IP Radio Settings

Tab Setting Radio A Radio B Radio C Radio D
IP Address

Radio

* Indicates Factory Default Settings

IP Address 192.168.1.2 192.168.2.2 192.168.3.2 192.168.4.2
Default Gateway 192.168.1.3 192.168.1.2 192.168.1.2 192.168.3.2
Subnet Mask 255.255.255.0 25.255.255.0 255.255.255.0 255.255.255.0
* TX & RX Center
Frequency
* PN Code (Hex) 05B8 05B8 05B8 05B8
* Modulation BPSK BPSK BPSK BPSK
* Transmit Att. level 0 dB 0 dB 0 dB 0 dB

2.441-GHz 2.441-GHz 2.441-GHz 2.441-GHz

Once we have the radio settings complete we will need to setup the TCP/IP proprieties
for the remaining devices on the four separate subnets. For this example all four subnets

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are part of the same network. The IP style network ID is 192.168.0.0 with a subnet mask
of 255.255.255.0. Therefore the third byte of the IP address is the subnet ID. The
individual subnets are simply identified as (.1), (.2), (.3) & (.4). All of the devices on all
four subnets have the same subnet mask 255.255.255.0.

The IP addresses for each of the devices in the network are listed in Table 4 below. If you
need help setting the IP addresses on the PCs please refer to Setting-up The PC’s IP
Address in the first example on page 4. If you need help setting up the IP address of your
router please refer to the manufactures instructions.

Table 4, Example II Device IP Addresses

Subnet PC EZCom-IP

Router

Radio

(.1) 192.168.1.1 192.168.1.2 192.168.1.3
(.2) 192.168.2.1 192.168.2.2 NA
(.3) 192.168.3.1 192.168.3.2 NA
(.4) 192.168.4.1 192.168.4.2 NA

Next we need to establish the routing tables for each of the devices in the network.
Before we jump into entering routing table information lets take a moment or two and
discuss the routing requirements. If you are uncertain as to what we mean when we are
talking about routing tables and default gateways you can refer to EZCom IP Routing on
page 40 of this manual.

Subnet (.1) consists of three devices: a PC, a router and an EZCom-IP radio. One port on
the router is connected to our subnet and another is connected to the Internet. The
primary purpose of the router is to allow Internet access to all of the PCs in our network.
Therefore all of the other subnets need to be able to communicate with subnet (.1).

Subnet (.4) as shown in Figure 11, is only able to communicate with subnet (.3) therefore
we will need to route subnet (.4) traffic through subnet (.3).

Subnet (.2) can only communicate with subnet (.1) therefore we will have to route any
traffic from subnet (.2) to either subnet (.3) or subnet (.4) through subnet (.1).

Since subnet (.2) can only communicate with subnet (.1) we can set the default gateway
on subnet (.2)’s EZCom-IP radio to 192.168.1.2. This will cause the radio to forward all
packets that are not specifically targeted for devices on subnet (.2) to subnet (.1). In
addition to setting the radio’s default gateway we also need to set subnet (2)’s PC default
gateway to 192.168.2.2. This will direct all datagrams that are not destine for a subnet
(.2) device to the radio.

The setup for devices on subnet (.4) are similar to what we just described for subnet (.2).
First we need to set the default gateway on the PC to 192.168.4.2 this will direct all data
traffic not intended for a device on subnet (.4) to the radio for transmission. Next we need
to set the default gateway of the radio to 192.168.3.2. This indicates to the radio that all
datagrams arriving from the network should be transmitted to the radio on subnet (.3).

The settings for subnet (.3) are slightly different than subnets (.2) & (.4) because the
radio on subnet (.3) can communicate with both subnet (.1) and (.4). First we will set the
default gateway on the PC to 192.168.3.2 thus all datagrams not intended for subnet (.3)
will be forwarded to the radio for transmission. Next we will have to set the default
gateway on the radio to 192.168.1.2 this will handle the bulk of the traffic assuming there
is a lot of Internet activity. In addition to the default gateway setting we will also need to
add a route to the routing table in the radio to forward subnet (.4) packets to the radio on
(.4). Add the following route: (Destination 192.168.4.0, Subnet Mask 255.255.255.0, Next
Hop 192.168.4.2). Please refer to the Routing Tab section on page 47 of this manual for
specific instructions on how to enter a route in the radios routing table.

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Now for subnet (.1), first we will need to set both the PC’s and radio’s default gateways to

192.168.1.3. This will insure that all packets not specifically addressed to one of our

subnets be forwarded to the Internet router. Next we need to add routes to the radio’s
routing table for all packets destined for one of our subnets. This will entail entering three
separate routes as shown in Table 5 below.

Table 5, Routing Table for 192.168.1.2 (EZCom-IP radio)

Destination Subnet Mask Next Hope Interface Origin

192.168.2.0 255.255.255.0 192.168.2.2 Radio EZCom

192.168.3.0 255.255.255.0 192.168.3.2 Radio EZCom

192.168.4.0 255.255.255.0 192.168.3.2 Radio EZCom

We will also need to add the following routes to the subnet (.1) PC’s routing table and to
the Internet routers routing table as well. If you are not familiar with the adding a route to
your PC’s routing table please refer to the sidebar “

The ROUTE Utility Program” on page 31 of this manual. For adding routes to your router
please refer to the manufactures instructions.

Table 6, Routing Table for 192.168.1.1 (PC)

Destination Subnet Mask Next Hope Interface

192.168.2.0 255.255.255.0 192.168.1.2

192.168.3.0 255.255.255.0 192.168.1.2

192.168.4.0 255.255.255.0 192.168.1.2

These PC routes were added to direct any datagrams generated by the PC destine for
one of our subnets to the radio for transmission. This is necessary because we have
already set the default gateway at the PC to 192.168.1.3, which is the Internet router. On
all of our other subnets we did not need to make individual route entries because any
datagrams that needed to be routed outside the local subnet where handled by the
default gateway entry. Subnet (.1) on the other hand has two routers, the Internet router
and the EZCom-IP radio.

In summary to setup the network illustrated in Figure 11 on page 14 you would first need
to set each device IP address as listed in Table 4 and then you would have to establish
the routing tables which are summarized in Table 7.

Table 7 Store & Forward Example Routing Summary

Subnet Device Device IP

(.1)

(.3)

PC 192.168.1.1

Radio 192.168.1.2

Router 192.168.1.3

PC 192.168.2.1 Default Gateway 0.0.0.0 192.168.2.2(.2)
Radio 192.168.2.2 Default Gateway 0.0.0.0 192.168.1.2
PC 192.168.3.1 Default Gateway 0.0.0.0 192.168.1.2
Radio 192.168.3.2

PC 192.168.4.1 Default Gateway 0.0.0.0 192.168.4.2(.4)
Radio 192.168.4.2 Default Gateway 0.0.0.0 192.168.3.2

Address

Route Type Target Next Hop

Default Gateway 0.0.0.0 192.168.1.3
Add Route 192.168.2.0 192.168.1.2
Add Route 192.168.3.0 192.168.1.2
Add Route 192.168.4.0 192.168.1.2
Default Gateway 0.0.0.0 192.168.1.3
Add Route 192.168.2.0 192.168.2.2
Add Route 192.168.3.0 192.168.3.2
Add Route 192.168.4.0 193.168.3.2
Add Route 192.168.2.0 192.168.1.2
Add Route 192.168.3.0 192.168.1.2
Add Route 192.168.4.0 192.168.1.2

Default Gateway 0.0.0.0 192.168.1.2
Add Route 192.168.4.0 192.168.4.2

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Grayhill EZCom IP Users Manual Rev A6 1/26/2001

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