Integrator's Manual

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Appendix A
COM24 IP Configuration Considerations
The COM24 cards have a lot of flexibility when it comes to selecting an IP addressing scheme to
use on your COM1000 system. This flexibility can be very helpful in making sure you get the
optimal IP configuration for your installation, but it also has the potential to make the system
non-operational if care is not exercised when changing these parameters. If the front Ethernet
port is connected, the back Ethernet port will be disabled.
This section is intended to give you a more comprehensive understanding of the IP assignment
modes in order to minimize the risk of this happening. Following a basic description of the IP
assignment operation is a walkthrough for each mode setting, as well as general guidelines for
when to select a certain mode over another, in addition to examples of what IP address may be
assigned to a card in each case.
A.1 INTRODUCTION
Before getting into the details of configuring your COM24 IP addressing scheme, it is essential
that you understand the basic functionality of the COM24 IP assignment algorithm. This
information is provided to explain some oddities you may encounter when observing the COM24
card‟s behavior at boot-up.
The following steps describe generally what happens to a card during a normal boot cycle:
1. Early on in the boot cycle, the COM24 card will perform a DHCP request and store an
initial IP address.
2. If you have selected a mode that is not dependent upon a DHCP server, the card will
overwrite this address once it comes fully online.
As a result of this series of operations, you may notice that the cards‟ IP addresses will appear to
change as they progress through the boot cycle. Consequently, you should disregard any IP
address reported until the card is fully booted.
The following sections will describe each of the fields available in the “User Config” section of
the Advanced Tune page. It is important to note that the COM24 cards‟ IP addresses are only
assigned at boot-up and that you must reset the cards in order for any changes to take effect.