Sigma - Globals Do Not Work When Using IP Address Structure 192.168.xxx.xxx with Subnet Mask 255.255.0.0

[Product_Support]

Issue

Sigma global points are not functioning correctly when the IP address structure is 192.168.xxx.xxx with a subnet mask of 255.255.0.0 (16-bit mask).

Product Line

Satchwell BAS & Sigma

Environment

Satchwell Sigma

Cause

The issue arises due to a mismatch between the IP address class and the subnet mask used. Specifically:

• 192.168.xxx.xxx is a Class C IP address.
• Class C addresses require a minimum subnet mask of 255.255.255.0 (24-bit).
• Using a Class B subnet mask (255.255.0.0) with a Class C address is invalid and leads to improper network segmentation.
• This misconfiguration disrupts the broadcast domain, preventing Sigma globals from functioning correctly.

Resolution

An IP address is divided into two main parts:

• Network ID
• Host ID

The Subnet Mask determines how many bits are allocated to the Subnet ID and Host ID.

Examples:

1. Valid Configuration (Class C):

   • IP Address: 192.168.0.1
   • Subnet Mask: 255.255.255.0 (24-bit)
   • Subnet ID Bits: 0
   • Host ID Bits: 8
   • Broadcast Address: 192.168.0.255

2. Invalid Configuration (Class C with Class B Mask):

   • IP Address: 192.168.xxx.xxx
   • Subnet Mask: 255.255.0.0 (16-bit)
   • This is invalid because Class C addresses require a minimum of 24-bit subnet masks.

3. Valid Configuration (Class B):

   • IP Address: 190.168.xxx.xxx
   • Subnet Mask: 255.255.0.0 (16-bit)
   • This is valid because 190.x.x.x falls within the Class B range.

---

To ensure Sigma globals function correctly, choose one of the following options:

• Option 1: Use a subnet mask of 255.255.255.0 (or greater) with the 192.168.xxx.xxx IP address range.
• Option 2: Change the IP address range to a Class B address (e.g., 190.168.xxx.xxx) to match the 255.255.0.0 subnet mask.