9
•
An HTTP operation gets a Web page.
•
A DHCP operation gets an IP address through DHCP.
•
A DNS operation translates a domain name to an IP address.
•
An ICMP echo operation sends an ICMP echo request.
•
A UDP echo operation sends a UDP packet.
•
An SNMP operation sends one SNMPv1 packet, one SNMPv2c packet, and one SNMPv3
packet.
•
A path jitter operation is accomplished in the following steps:
a.
The operation uses tracert to obtain the path from the NQA client to the destination. A
maximum of 64 hops can be detected.
b.
The NQA client sends ICMP echo requests to each hop along the path. The number of
ICMP echo requests is set by using the
probe packet-number
command.
•
A UDP tracert operation determines the routing path from the source to the destination. The
number of the probe packets sent to each hop is set by using the
probe count
command.
Collaboration
NQA can collaborate with the Track module to notify application modules of state or performance
changes so that the application modules can take predefined actions.
Figure 6 Collaboration
The following describes how a static route destined for 192.168.0.88 is monitored through
collaboration:
1.
NQA monitors the reachability to 192.168.0.88.
2.
When 192.168.0.88 becomes unreachable, NQA notifies the Track module of the change.
3.
The Track module notifies the static routing module of the state change.
4.
The static routing module sets the static route to invalid according to a predefined action.
For more information about collaboration, see
High Availability Configuration Guide
.
Threshold monitoring
Threshold monitoring enables the NQA client to take a predefined action when the NQA operation
performance metrics violate the specified thresholds.
describes the relationships between performance metrics and NQA operation types.
Application modules
Detection
modules
Sends the
detection results
Sends the track
entry status
Track
module
Associates with
a detection entry
Associates with
a track entry
VRRP
Static routing
PBR
NQA
Smart Link
