Chapter 4:
Firewall, Failover & OOB Access
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Cellular router mode. In this case the dial-out connection to the carrier cellular network is always
on, and IP traffic is routed between the cellular connected network and the console server’s local
network ports.
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OOB mode. As above in this mode the dial-out connection to the carrier cellular network is always
on - awaiting any incoming access (from a remote site wanting to access to the console server or
attached serial consoles/network hosts)
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Failover mode. In this case a dial-out cellular connection is only established in event of a ping
failure
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Circuit Switched Data (CSD) mode. In this dial-in mode the cellular modem can receive incoming
calls from remote modems who dial a special Data Terminating number. This is a 3G mode only.
4.7.1 OOB access set up
In this mode the dial-out connection to the carrier cellular network is always on, awaiting any incoming
traffic. By default, the only traffic enabled are incoming SSH access to the console server and its serial
ports and incoming HTTPS access to the console server. There is a low level of keep alive and
management traffic going over the cellular network. Generally, the status reports and alerts from the site
can be carried over the main network.
This mode is used for out of band access to remote sites. This OOB mode is the default for
IM7200
appliances with internal cellular modems.
Out-of-Band access is enabled by default and the cellular
modem connection is always on.
To be accessed, the console server needs to have a Public IP address and it must not have SSH access
firewalled.
Almost all carriers offer corporate mobile data service/plans with a Public IP address. These plans often
have a service fee attached.
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If you have a static Public IP address plan you can also try accessing the console server using the
Public IP Address provided by the carrier. By default, only HTTPS and SSH access is enabled on
the OOB connection. You can browse to the console server, but you cannot ping it
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If you have a dynamic Public IP address plan, a DDNS service needs to be configured to enable
the remote administrator to initiate incoming access. Once this is done you can try accessing the
console server using the allocated domain name
Most providers offer a consumer grade service which provides dynamic Private IP address assignments
to 3G devices. This IP address is not visible across the Internet, but it is adequate for home and general
business use.
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With this service, the
Failover & Out-of-Band
tab on the
Status > Statistics
shows that your carrier
has allocated you a Private IP Address (i.e. in the range 10.0.0.0 – 10.255.255.255, 172.16.0.0 –
172.31.255.255 or 192.168.0.0 – 192.168.255.255)
