Network Traffic

Enabling Ethernet on an MPE/iX system increases the number of broadcast packets the system receives. If your installation has had network traffic problems in the past, or you expect this increase in traffic to affect your network performance, there are two things you can do:

First, if the node is not a gateway, verify that the store and forward feature has been disabled.
Second, as part of an overall network plan, examine the MPE/iX subnet feature as a means for managing network traffic.

Store and Forward

Traffic problems may occur if you use the default configuration for store and forward buffers. If the node you are updating is not a gateway node, you can decrease network traffic by disabling store and forward.

Creating Subnets

Subnetting is used to divide one large network into smaller subnetworks (subnets). Subnets are configured using the IP subnet mask as described under "Update the IP Protocol Configuration."

Update the IP Protocol Configuration

To enter an IP subnet mask for each node in the subnetwork and/or to disable store and forward, do the following:

Run NMMGR.PUB.SYS.
At the Open Configuration/Directory File screen, ensure that the configuration file NMCONFIG.PUB.SYS appears as the configuration file name. You want to open the file by pressing the [Open Config] key.
The Main screen is displayed. At the Command prompt, enter the direct path name as follows and then press the [Enter] key:
@NETXPORT.NI.niname.PROTOCOL.IP
where niname is the configured LAN NI that supports Ethernet.
From the IP Protocol Configuration screen, enter the IP subnet mask you have selected for this subnetwork in the IP Mask field. The subnet mask is specified in the same format as the IP address without the preceding letter (A, B, or C). The 32-bit mask is grouped in octets expressed as decimal integers and is delimited by a period (.) or a space. (See the paragraph "Example: Subnet Mask" later in this chapter.)
For a non-gateway node, you should disable store and forward buffers.
Enter zero (0) in the Store & Forward Buffers field.
After you have finished updating the IP Protocol Configuration, press the [Save Data] key. Next,
1. Hold down the [Shift] key and press the [Tab] key which returns you to the command prompt.
2. At the command prompt, enter: validate, then press the [Enter] key.
3. The Validate screen is displayed. Press the [Validate Netxport] key to validate the updated configuration.
To exit the NMMGR program, hold down the [Shift] key which returns you to the command prompt. At the command prompt, enter: EXIT, then press the [Enter] key.
If you changed any of the parameters, you need to restart the network in order to activate the changed configuration file as described later in this chapter under the heading, "Restarting the Network."

Example: Subnet Mask

This example shows a network using class C IP addresses which has been subnetted with the first three bits of the node address (in bold) identifying the subnetwork. The IP address for two of the nodes in the subnetwork are (in decimal and in binary):

192.006.012 041 1100 0000 0000 0110 0000 1100 0010 1001

192.006.012 055 1100 0000 0000 0110 0000 1100 0010 0111

a subnet mask for these two nodes is:

255.255.255 224 1111 1111 1111 1111 1111 1111 1110 0000




	NOTE: The network address and the three bits identifying the subnet bits are set to ones.

For this example, the decimal equivalent (255.255.255 224) is entered in the IP Subnet Mask field.

Network Traffic

Technical documentation

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Store and Forward

Creating Subnets

Update the IP Protocol Configuration

Example: Subnet Mask