Ping Monitor - NetComm NTC-220 User Manual

O P T I O N
Priority
Monitoring method
Verbose logging

Ping monitor

When Monitoring method is set to Ping, controlled ping packets can be used to determine the status of the link.
These are small packets of data that the router sends to a remote address and if the connection is up, a reply is
received. They are sent indefinitely at regular intervals that you specify. At each interval, 3 pings are sent to the first
destination address and 3 pings are sent to the second destination address configured for each WAN interface to
test the availability of the interface. The pings sent at each interval are from here on referred to as an "instance" of
pings.
Ping timers
The Periodic ping timer setting sets a regular interval at which an instance of pings is sent to test the availability of
an interface.
The Retry timer setting is activated only when all pings in an instance sent at the Periodic ping timer interval fail
and is used to set a different, usually shorter, interval to speed up the router's response to an interface failure.
Methods of evaluating ping responses
For simplicity, we recommend using only one of the two methods of evaluating the ping responses. The available
methods are:
Consecutive errors - using this method, the router will determine the availability of an interface based on a
set number of consecutive ping instance responses.
Periodic ratio monitor - using this method, the router will determine the availability of an interface based on
a set ratio of ping instance successes or failures to the number of attempts.
It should be noted that the Periodic ratio monitor evaluates an interface over a series of ping instances (defined by
the Total monitor count) and when the series has completed, the success and fail counts are reset. For example,
with the default Total monitor count value set to 10 and Failover fail count set to 5, the router sends 10 ping
instances and if 4 of those instances fail and the first instance of the next series of 10 fails, the router will not fail
over because the 5 failed instances occurred across a different series.
Failing over to a lower priority interface
Each WAN interface is independently monitored according to its own distinct settings, following the processes
outlined below.
a At a regular interval stipulated by the Periodic ping timer setting, the router sends 3 ping requests via
the interface to both the first and second destination addresses simultaneously. If it receives a reply to
any of those pings on the interface, it is considered to be up and the router continues pinging on the
interface at the Periodic ping timer interval.
b If the router does not receive a response to all six pings on the interface by the start of the next
Periodic ping timer interval, it registers this failure as a Fail count and continues to send pings to both
destination addresses at the Retry timer interval (typically set at a shorter interval than the Periodic
ping timer since there may be a problem). If a response is received to any of those pings, the router
returns to sending pings according to the Periodic ping timer setting.
NTC-220 – User Guide
UG01028 v1.2 March 2019
The priority (metric) is a numeric value which determines which
interface has priority. Lower priority values mean higher priority.
Specifies the means used to determine whether the link is up or
down.
When enabled, this logs verbose comments in the system log
related to the failover monitoring.
Table 16 – Failover configuration – Hardware link monitoring
D E S C R I P T I O N
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