
ENI Configuration (Node 248 to 254)
Subnet Mask
A subnet mask is used to interpret IP addresses when the network is divided into subnets. If your network is not divided into subnets, then leave the subnet mask at the default or allow the ENI Configuration Utility to assign a default.
The subnet mask defaults to
Table 4.4 Subnet Mask Auto-Detect Operation
When the IP Address is set to: | And the Subnet Mask is in |
| The Subnet Mask is set to: |
|
|
Out of Box: 0.0.0.0 | |
|
|
Class A address | 255.0.0.0 |
|
|
Class B address | 255.255.0.0 |
|
|
Class C address | 255.255.255.0 |
|
|
Subnet Mask
•Reading the subnet mask when the IP address is 0.0.0.0 returns a value of 0.0.0.0.
•When you manually configure the subnet mask,
•The ENI validates the configured subnet mask and if:
–The first octet is not equal to 255, the ENI returns status 0x10 and reverts to the previous mask, or
–The first octet is 255, but the remaining mask is not proper, the ENI returns status 0x10 and reverts to the previous mask.
•The definition of “proper” is that the mask must be a contiguous series of 1’s with no zeroes in between (i.e. 255.0.0.0 or 255.224.0.0 or 255.192.0.0 are valid, but 255.160.0.0 is not).
Security Mask
The Security Mask, when configured, allows you to restrict controller access to sources with IP addresses that are within some prescribed range. For example, if you wanted to restrict all message sources to be from within a company’s allocated IP address range, a Security Mask could be configured that would block any IP address outside that range. This only applies to messages to the controller. Web page access, for example, is not restricted.
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