Echelon i.LON 600 LonWorks/IP Server - Manual (Page 96)

Section 3: Appendixes
NAT gateway and enter 131.23.203.17:1628 in the Configuration Server. The
L
ON W ORKS /IP packets would flow unimpeded.
You will run into problems with your network if your ISP does not offer static addresses.
Even if static port mapping is enabled on your NAT gateway, you may not be able to
access computers within your home because the house IP address (provided by the ISP)
may change unpredictably. This is a common problem.
Use a static IP address for both your NAT gateway and the i.LON in your home.
DNS
DNS is the Internet’s Domain Name System. This system allows you to convert hard (or
numeric) IP addresses (for example 131.23.203.17) into one based on letters and words
(www.myhouse.com). To be able to use names instead of hard IP addresses to browse the
Internet, you must specify at least one DNS server when you setup your PC’s TCP/IP
networking. If you selected “Obtain an IP address automatically”, the DNS server is
obtained automatically from the DHCP server at the same time that the PC obtains its IP
address.
Note: When a browser tries to view a web site, it asks the DNS server to translate the
name of a web site into an IP address. It then uses the IP address to contact the web site.
The actual IP packets never contain the proper name of the Web site, only the hard IP
address that was resolved by the DNS server.
If you had a static IP address at your home, you could register that IP address with one of
the Internet registrars (such as register.com) and associate a name with that static IP
address. The registrar will propagate the address/name pair throughout the Internet’s
DNS servers for you, allowing you ultimately to tell people to go to www.myhouse.com
instead of 131.23.203.17.
This only works for static IP addresses because each time you change the address, you
need to contact the registrar to setup the new address/name pair across the Internet. This
may take up to two days for an address/name pair to propagate through the entire
Internet.
DNS/DHCP Relationship
DNS and DHCP are separate standards. A network may use DNS without using DHCP
and vice versa. You can, however, link DNS and DHCP servers in a single network so
that all addresses could be allocated dynamically (easy to administer) but still referenced
by name (easy for users). While this can work for private networks (usually within
corporations), it is not practical for the Internet.
DNS and the Echelon L
ON
W
ORKS
/IP Configuration Server
The Configuration Server can use DNS to resolve a name, but the i.LON 600 devices can
not. When you type myilon.echelon.com:1628 into the Configuration Server instead of
205.229.51.11:1628, the Configuration Server goes to the local DNS server (defined on
that PC) to resolve myilon.echelon.com to a hard address and then sends that hard
address to all i.LON 600s on your L
ON W ORKS /IP channel. This works until one of the IP
addresses changes.
If you want to reference your i.LONs only by DNS name, you must leave the
Configuration Server running on your network. The Configuration Server will
periodically query the DNS server to verify that all hard IP addresses are still correct. If
88 Using NAT, DNS, DHCP & DDNS with a L ON W ORKS Network