Network Address Translation / Firewall; Ip Network Segmentation - Distech Controls ECLYPSE ECY-STAT User Manual

Network Address Translation / Firewall

A router's uplink port provides Network Address Translation (NAT) and firewall functions.
NAT is a method to hide the private IP addresses of a range of devices (connected to LAN ports) be-
hind a single IP address presented at the WAN uplink port. NAT uses a mechanism to track requests
to WAN IP addresses and readdresses the outgoing IP packets on exit, so they appear to originate
from the router itself. In the reverse communications path, NAT again readdresses the IP packet's
destination address back to the original source private IP address.
Due to this tracking mechanism, only requests originating from the LAN side can initiate communica-
tions. A request from the WAN to the router cannot be mapped into a private address as there is no
outbound mapping for the router to use to properly readdress it to a private IP address. This is why a
NAT acts as a firewall that blocks unsolicited access to the router's LAN side.
Most routers allow you to open a port in the firewall so that WAN traffic received at a specific port num-
ber is always forwarded to a specific LAN IP address. The standard port numbers used by ECY-STAT
controllers is explained in chapter IP Network Protocols and Port Numbers.

IP Network Segmentation

For efficient network planning, normally the ECY-STAT controllers will be assigned to their own net-
work segment of an IP network or subnetwork. This is done as shown in the figure below.
Figure 3: Network Segment for HVAC IP Controllers
For certain wireless topologies, a wireless router can be used to connect to the ECY-STAT. In this
scenario, a wireless operator interface (laptop or tablet) can be used for commissioning as shown in
the figure below.
Figure 4: Network Segment for HVAC IP Controllers with a Wireless Access Point
ECLYPSE Connected Thermostat (ECY-STAT)
ISP Modem (Fiber, Cable, DSL)
Gateway Router
1 2 3
Company
Computer
Network
To To To
Device Device Device
1 2 3
Router for
HVAC IP
Controllers
To IP To IP To IP
Controller Controller Controller Controller
IPv4 Communication Fundamentals
To ISP Network
LAN
Network
4
UPLINK
4
UPLINK
To IP
17