46
645M 4G/LTE CELLULAR ROUTER
MN032003EN March 2017 www.eaton.com
Figure 48 . : Admin — system reset
3.8.5 System reset
4 IP addressing
4.1 Overview
When 645M cellular router is connected to a cellular carrier,
it will always have at least two IP addresses. The first is the
local area network (LAN) address. The 645M can be accessed
through either the LAN 1 or LAN 2 Ethernet connectors on
the front panel using this IP address. This IP address is user
configurable and is saved locally in the 645M. The factory
default IP address is 192.168.1.50 with a subnet mask of
255.255.255.0.
The second 645M IP address is assigned by the cellular carrier
each time the 645M connects to the cellular network. Often,
this IP address is publicly accessible from the Internet, however
in some instances the cellular carrier may assign an IP address
that is protected by firewalls. When a publicly accessible IP
address is assigned, data flows can be initiated from either the
645M or from the Internet. When an IP address is protected
by cellular firewalls, data flows can only be initiated from the
645M. In either case, after a data flow has been established,
data is free to move in both directions.
For mobile models equipped with Wi-Fi, the 645M will be
assigned a third IP address on the Wi-Fi wireless network.
4.2 IP addressing tutorial
The default LAN subnet of the 645M consists of addresses
from 192.168.1.0 to 192.168.1.255. The first and last IP
addresses of a subnet are always reserved, no matter what the
subnet size is. The first IP address in the subnet is the Network
ID. The last IP address in the subnet is the Broadcast Address.
The example below illustrates a sample 645M network. The
subnet consists of IP addresses ranging from 192.168.1.0
to 192.168.1.255. The subnet mask is 255.255.255.0. This is
sometimes written in shorthand notation as: 192.168.1.50/24
since the subnet mask 255.255.255.0 contains 24 ones then 8
zeros when it is converted to binary.
The first address 192.168.1.0 is reserved for the Network ID.
The last address 192.168.1.255 is reserved for the broadcast
address. There are 254 valid IP addresses that may be assigned
to hosts on the LAN network.
Ethernet Subnet Mask
255.255.255.0
Network ID
192.168.1.0 (reserved – first IP
address in subnet)
Broadcast Address
192.168.1.255 (reserved – last IP
address in subnet)
ELPRO 645M
192.168.1.50/24
PLC/RTU #1
192.168.1.10/24
Computer #1
192.168.1.125/24
By changing the subnet mask, the network can be made to
include as many or as few IP addresses as desired. Ethernet
devices can only talk directly to other devices that have IP
addresses within the same IP subnet. For example, Computer
#1 from the example above can only talk with locally connected
devices that have IP addresses between 192.168.1.1 and
192.168.1.254. When Computer #1 wants to talk to another
server on the Internet, it will send its data packet to the local
gateway. In this case the local gateway is the 645M router.
Since the 645M has two IP addresses (each IP address is on
a separate subnet), it can forward the packet from the LAN
network (192.168.1.0/24) to the cellular network. The packet will
continue to be forwarded in a similar fashion, from subnet to
subnet, until it reaches its final destination.
4.3 Private versus public IP addresses
Certain address ranges in the in IPv4 address space have been
reserved as private IP address. Private IP addresses can be
used by anyone, without the need to register for an IP address
assignment from the IANA (Internet Assigned Numbers
Authority). However, private IP addresses are not routable
on the Internet. Routers on the Internet will typically drop
any packets that are destined for a private IP address. These
addresses are reserved for local use only.
Common Private IP Address Ranges
10.0.0.0
to
10.255.255.255
172.16.0.0 to 172.31.255.255
192.168.0.0 to 192.168.255.255
Devices using Private IP addresses must have a router with
NAT (network address translation) capability to access the
Internet. By default, the 645M will perform the NAT function
on all outgoing traffic. The 645M router will change the source
IP address from the private IP of the local host to the 645M’s
public IP address which was assigned by the cellular carrier.
Since the outgoing packet has been modified, a remote server
or website on the Internet will think the packet came directly
from the 645M radio. It will reply back to the cellular IP address
of the 645M. The 645M radio remembers which traffic flows
have been established and routes the incoming return traffic
back to the desired host device on the local area network.
Click the
Reboot
… button to reset the system. It takes
approximately 30 seconds for the system to come back online.
4 Ip addressing