Networking Basics; Ip Addressing; About The Subnetwork Mask; Cidr Addressing - Distech Controls ECLYPSE ECY-STAT User Manual

IPv4 Communication Fundamentals

Networking Basics

When manually configuring the TCP/IP interface on an ECY-STAT (the DHCP option is not used), an
IP address, subnetwork mask, and a default gateway are required in the Network Settings.

IP Addressing

The most widely used internet addressing scheme is IPv4. It codes an IP address in 32 bits.
An IPv4 address is made up of two parts defined by a subnetwork mask; the network portion (which
identifies a specific network or subnetwork) and the host portion (which identifies a specific device).

About the Subnetwork Mask

Devices on the same sub-network can address IP packets to each other directly without routing. The
range of IP addresses available in a sub-network is defined by the subnetwork mask. This is also
called the subnetwork mask's 'address space'. The subnetwork mask is coded in 32 bits as follows.
An IP packet addressed to a device on another network portion will have to be routed through the
router's WAN port as such an address is not local. BACnet/IP broadcast discovery messages such as
"Who-Is" do not pass through network routers that separate subnetworks. This means that BACnet/IP
controllers on different subnetworks will not normally communicate with each other.
BBMD allows broadcast message to pass through a router: on each subnet, a single device has
BBMD enabled. Each BBMD device ensures BACnet/IP connectivity between subnets by forwarding
broadcast messages found on its subnetwork to each other, and then onto the local subnetwork as a
broadcast message. See
The table below contains the recommended network classes for the ECY-STAT. Refer to the Distech Controls
IP Networking Guide for more information.
Network Class CIDR Subnetwork
/8
/9
/16
/17
/24
/25

CIDR Addressing

Another way to express the subnetwork mask is through CIDR addressing (Classless Inter-Domain
Routing) which is written as a slash and a number which represents the number of true bits set in the
subnetwork mask. For example, the subnetwork mask 255.128.0.0 is 11111111 10000000 00000000
00000000 in binary or /9.
An IP address can be expressed with its CIDR subnetwork mask in the form of 192.168.0.0/24 for ex-
ample.
14
BBMD Settings.
Block Number of Subnetworks
Mask Size according to the Network Type
Class A
255.0.0.0 256 1
255.128.0.0 128 2
255.255.0.0 256 256
255.255.128.0 128 512
255.255.255.0 256 65536
255.255.255.128 128 131072
Number of Hosts
according to the Network Type
Class B Class C Class A
16777214
8388606
1 65534
2 32766
256 1 254
512 2 126
ECLYPSE Connected Thermostat (ECY-STAT)
Class B Class C
65534
32766
254 254
126 126