AN2700 Freescale Semiconductor / Motorola, AN2700 Datasheet - Page 20

• Manufacturer Part Number: AN2700
• Description: Basic Web Server Development with MC9S12NE64 and CMX-MicroNet TCP/IP Stack
• Manufacturer: Freescale Semiconductor / Motorola

Debugging Networks
Network Connection Cannot be Established
After the device establishes an Ethernet connection, the network settings may still require adjustments.
The most common problems are:
In these two cases, the network IP address, network port information, network components, network
protocols, and server type must be reviewed.
This section deals with the issue of the network higher level protocols not establishing a connection, such
as an Internet protocol (TCP/IP) connection. One way this can be checked is with Ping. Ping is actually
an IPv4 ICMP (Internet control management protocol) echo request that is defined by the TCP/IP stack
protocol. Because Ping functionality is included in CMX-MicroNet and Windows, it can be used to debug
the network connection. If the command confirms a valid connection to a remote device by replying to the
ICMP echo request, the network is configured correctly. If, however, the Windows command does not
confirm a network connection to the remote device, the network is not configured correctly.
The key step to resolve this type of network bug is to determine how the network is designed and how the
remote device must be configured to accept a connection. Remote devices must be compliant with the
network’s design structure and protocols. When the network is set up and configured correctly, the
devices will connect. This problem is usually associated with incorrect and incompatible IP address
settings (see Configuring the IP Addresses ).
Network Connection is Established at the IP Layer with Ping, but the Devices are Not Talking
This problem is usually difficult to debug. There may be a conflict with other protocols settings. Other
possible causes can be a firewall, proxy server settings, duplex mismatch, or invalid server settings. With
an understanding of the network design and its connection capabilities, network restrictions, and
underlying communication protocols (for example, TCP/IP and NETBEUI), a user can configure the
network and the remote devices to ensure connectivity. This issue may require assistance from a system
administrator to resolve.
Network Protocol Analyzer Tools
A network protocol analyzer is a powerful and useful tool for network debugging. The network protocol
analyzer enables more visibility of packet traffic on the network connection. A network protocol analyzer
is used to monitor the connectivity of the Internet or a local area network (LAN).
The tool is capable of non-intrusively attaching itself and monitoring a dial-up or Ethernet connection. The
network protocol analyzer can be an in-house, commercial, or downloadable freeware software package.
A network protocol analyzer can be implemented in hardware also.
The overriding feature of the network protocol analyzer is its ability to capture, analyze, and decode
network packets. The network protocol analyzer must be capable of determining the communication
protocol of the network data packets. In addition, the program must be able to display a list of network
connections, the IP addresses of the connections, the data direction, and the network data port
information. The network protocol analyzer provides the detailed network information required to debug
a network.
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Devices are unreachable
Network connection is misdirected
Basic Web Server with MC9S12NE64 and CMX-MicroNet TCP/IP Stack, Rev. 0.3
Freescale Semiconductor