Basics Networking
NETWORKING
A JNIOR must be properly configured to participate reliably on the local
network. Network configuration can be quite complex and a great deal
of planning often goes into the structuring of commercial networks. While
the IT Department or appropriate networking professionals should be
consulted when adding devices like the JNIOR to a network, some relatively
simple concepts are all that are needed to get the JNIOR up and running.
The JNIOR is a wired network device. While WiFi and Cellular adapters are
available to provide the JNIOR with such connectivity, the device is typically
connected to a
Network Switch via a CAT5 cable. Any number of computers,
printers and devices connected to a network switch or multiple switches
constitutes a
Local Area Network or LAN. The connected devices can all
message one another.
A
Wireless Access Point provides wireless connectivity and is at some
overly simplified level just a big multi-port network switch in the sky.
WiFi extends the wired network and all devices both wired and wireless are
able to communicate with one another.
A
Wireless Router often serves on the local network side as a network switch
with wireless access. The router has another connection allowing it to be
connected to another network which is often referred to as the
Wide Area
Network or WAN.
ETHERNET MAC ADDRESS
Just as when someone wishes to send you a letter they need your postal
address or when they send you an email they need your email address, a
machine on the LAN can send another a message if it knows its
Media Access
Control or MAC address. This is an address like9c:8d:1a:00:07:f9 and is
something that thankfully you never really need to know.
On the wire that MAC address is absolutely necessary to get packets of
information from one place to another. Of importance is that every device
manufactured should have a unique MAC address permanently programmed. Each
JNIOR has a unique address and the prefix 9c:8d:1a is assigned to INTEG.
This can be used to identify all of the Series 4 JNIOR products on a network.
IP ADDRESSING
As opposed to the MAC address the address that you do need know to communicate
with devices locally and outside is the
Internet Protocol address or
IP Address. This is an address that looks something like 192.168.2.37 which
is not all that easy to remember either. Typically the first three numbers
(or octets) displayed here are consistent for every device on the LAN. Only
the last octet varies.
On the network, and very much in the background, there is a procedure for
finding the MAC address for any destination with an IP address. You need
not know much more about it.
While a JNIOR may be assigned any IP address it has but one MAC address. Units
are labeled with the programmed MAC address and this can also be obtained
by using the IPCONFIG command in the Command Line Console.
CLIENT vs. SERVER
When you open your Browser and enter a URL it is typically some text like
https://jnior.com
In this case you are a
Client and are attempting to connect to a
Server
located at INTEG. Fortunately you do not need to know the IP Address
209.195.188.92 in order to make the connection.
You will want to use the browser to access the JNIOR. In this case you
need to know its IP address because it is a
Server . The URL would
look like:
http://192.168.2.37
On some networks you may be able to reach the JNIOR using its hostname. The
JNIOR also registers its 'Birth Name' which is comprised of its numeric
serial number with a 'jr' 2-character prefix. For example these two URLs
can both reach the same JNIOR.
http://bruce_dev
http://jr615010258
By default the hostname is initially the birth name. This can be altered using
the
HOSTNAME command. The ability to reach a JNIOR using these names is
dependent upon the network configuration for name resolution. This may or
may not work depending on your network's capabilities.
The serial number for the JNIOR can be located on the rear label.
IP SETTINGS
To properly configure the JNIOR for the network there are 2 critical IP
settings and 3 fairly important settings. These are as follows:
1. IP Address 192.168.2.37
2. Subnet Mask 255.255.255.0
3. Gateway Address 192.168.2.1
4. Primary DNS 8.8.8.8
5. Secondary DNS 8.8.4.4
If you are uncertain as to the proper settings for your network you may
try the Dynamic Host Conbfiguration Protocol (DHCP). Most routers enable
this protocol. This helps computers join the network and properly configure.
The JNIOR now ships with DHCP enabled.
DHCP can be enabled from the command line with the following command:
ipconfig -d
In the Support Tool it is a selection. Right-click on the JNIOR in the
Beacon tab and select
Configure and then
IP Configuration . There is a
selection to enable DHCP. After a minute if DHCP is available the JNIOR
will acquired a valid network setup.
You can then check the IP configuration through the Support Tool or by
using
IPCONFIG. This will give you items 2 thru 5 in the above list. DHCP
IP addresses themselves are
leased . While it is likely that the JNIOR will
retain the assigned IP address for some time, that address is assigned from
a pool (range of addresses) and can change. Since you need the IP address to
communicate with the JNIOR you don't need it to be a moving target.
The solution is then to disable DHCP and assign a
fixed IP address which
should be outside of the DHCP range. You will need to get that address from
your network administrator. In a pinch you can use the
ARP -U command to
locate a low-numbered unused address. This ARP command scans the network and
reports any addresses that do not actively respond.
You can then disable DHCP again using the Support Tool or with the following
command:
ipconfig -r
The JNIOR may retain the DHCP configuration. It is important to reassign the
IPv4 address outside of the DHCP range either using the Support Tool or
command. For example:
ipconfig -a 192.168.2.37
SUBNET MASK
It was mentioned that the first 3 numbers or octets of IP addresses on the
local network typically all match. The local network must use only a small
range of all possible IP addresses as those outside of the range are then
used to access hosts and devices all over the world. The local address scheme
uses an address range typically reserved for individual local networks.
The
Subnet Mask defines the portion of the IP address that must match that
assigned to the JNIOR for any local network participant. This is a bit mask
specifying bit by bit from the left (most-significant bit) the bits that
must match between source IP address (the JNIOR) and destination. So with a
typical local network a subnet mask of 255.255.255.0 indicates that all of
the bits in the first 3 octets must match for local communications. With 8
bits per octet (byte) there are 24 bits from the left that must match.
You may also see the IP address specified as for example 192.168.2.37/24 .
When the destination address DOES NOT match in every indicated bit position
the destination is assumed to be outside of the local network. The source
then attempts to contact the destination using the
Gateway device. The
gateway then potentially providing access to the Wide Area Network and
hopefully the host destination.
The Subnet Mask can be set using the Support Tool or using
IPCONFG. In
these command examples the latter sets both the IP Address and Subnet Mask
in one step.
ipconfig -s 255.255.255.0
ipconfig -a 192.168.2.37/24
If you erroneously set the Subnet Mask, communications may fail to reach some
members of the local network or some external hosts. This may depend on the
operation of the gateway which might optionally assist in properly locating
the destination as still being on the local network. Basically, the subnet
mask typically is set identically for all members of the local network. More
complex network topologies are possible. It is best to consult your network
administrator.
GATEWAY
The
Gateway is a device on the local network that also is a member of
another network. The latter being presumably connected to the Wide Area
Network and ultimately possibly the Internet. The Gateway then is likely the
router for the local network. It serves as a bridge to the outside world.
If a Gateway address is not properly defined the JNIOR will not be able to
contact hosts outside of the local network. In a typical automation scenario
it may not seem that the JNIOR would have any reason to communication outside
of the local network. The JNIOR periodically reaches out to a NTP server in
order to synchronize its clock. This occurs about every 4 hours and relies on
proper Gateway settings and DNS.
The JNIOR can also be configured to send email notifications. For this to be
possible the unit also needs to access the outside world. It is important to
properly define the Gateway IP address.
DNS SETTINGS
The Domain Name System is a huge distributed database spread across the
Internet. Its basic function is to translate a domain name like those you use
in URLs to IP addresses. You use a DNS server to convert the website
jnior.com to the INTEG IP address 209.195.188.92 so that behind the scenes
your computer can communicate with the company's server and the browser can
render the website.
While the JNIOR does not have its own browser it is configured with domain
names that it will need to convert to IP addresses from time to time. In
particular the JNIOR synchronizes its clock with an external NTP Server. The
NTP server is located by first requesting an IP address from a DNS server for
the domain:
pool.ntp.org
There are other NTP services that you can use. This one selects from a large
pool of available NTP servers and offers an IP address for one that can best
service your location. With a DNS server properly specified the
DATE command
can reach out and synchronize. For example:
bruce_dev /> date -n
Requesting time sync from pool.ntp.org (195.33.242.132)
Clock synchronized by NTP
Wed Jul 28 11:28:51 EDT 2021
bruce_dev />
Note here that pool.ntp.org has been resolved to the address 195.33.242.132
and that the JNIOR successfully synchronized its clock.
There are two DNS addresses, a
Primary and a
Secondary . A DNS server may
get too busy to respond or may be down for service. It is critical to have a
backup. We specify a primary and a secondary DNS server address in hopes that
at least one of the two is available to help us. The JNIOR may try the primary
first and if there is no timely response attempt to use the secondary. It may
also just ask both and take the first response and run with it.
The
NSLOOKUP command can be used to resolve domains. For example:
bruce_dev /> nslookup jnior.com
Issuing DNS request (<0.1s)
Inet Addr Domain
209.195.188.92 jnior.com
bruce_dev />
If DNS addresses are not defined or if the DNS Servers cannot be reached
the JNIOR clock will likely drift away from the correct time. This may only
affect the timestamps that appear in logs. If the application is performing
tasks on a schedule those events may not occur on time. Email notifications
if configured will not be deliverable. You might use the Google public DNS
addresses 8.8.8.8 and 8.8.4.4 although there are many other servers
available.
NTP TIME SYNC
The JNIOR clock is set at the factory and is likely to drift many seconds or
even minutes by the time the unit is in your hands. While you can set the time
and date using the
DATE command it is preferred that a NTP server be used
for automatic time synchronization.
With proper IP configuration and access to the Internet the JNIOR will obtain
the current time immediately after boot and then by default every 4 hours. If
the JNIOR is operating in a sandboxed network or otherwise restricted by
firewall it is recommended that the
#IpConfig/NTPServer registry key be
defined with a local NTP time source.
Additionally the JNIOR uses the NTP synchronization to calibrate both the
hardware and software clocks (JANOS v2.4 and later). This calibration occurs
during the first few days of operation assuming access to the NTP server.
SUMMARY
For proper network use the JNIOR needs 1) a unique IP Address valid for the
local network; 2) A proper Subnet Mask for the local network; 3) A Gateway
IP Address for access to the outside world; And, 4) at least one valid DNS
server address. DHCP can be a valuable tool for discovering settings for all
but the IP address itself. Finally, the IP Address must be uniquely defined
for each device on the network. The JNIOR will query for conflicts during
boot. If the IP address assigned to the JNIOR is claimed by another device on
the network the JNIOR will not be available. In this case it will report an
IP Address of 0.0.0.0 and will remain accessible through the Support Tool
for reconfiguration.
SEE ALSO
HELP Topics:
IPCONFIG,
ARP,
NSLOOKUP,
DATE
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