13.3. Configuring agents in sFlowTrend-Pro
An sFlow agent is responsible for sending sFlow
data to sFlowTrend-Pro from a switch (or router) or a host. In the case of
a switch or router, one
agent will be associated with the device, and the IP address of the
agent will normally be the same (or one of the) IP address used for
the switch. Switches can be configured to send sFlow from sFlowTrend-Pro
using SNMP, or alternatively the switch can be manually configured.
For hosts, normally the agent runs on a physical host.
This agent can send data for both that host, and any virtual machines
that are running on that host. Hosts are configured to send sFlow
either through DNS or manually.
Select the
→
menu item to launch the
Configure agents dialog.
This dialog contains a table which lists all the
agents that sFlowTrend-Pro is receiving sFlow from. For switches, it also
allows you to change the SNMP settings for each
switch, and to tell sFlowTrend-Pro about switches that it should
configure via SNMP to send sFlow.
The table includes the following columns:
- Status
-
This column uses color coded symbols to
indicate the overall status of the agent:
The agent is enabled and sFlowTrend-Pro is
receiving sFlow (and, if the agent is a switch or
router, it can communicate with the switch using
SNMP).
The agent is disabled, but sFlowTrend-Pro is receiving
sFlow from it. Or, if the agent is a switch, then
either sFlowTrend-Pro is receiving CLI configured sFlow from
it, and sFlowTrend-Pro is unable to communicate with the
switch via SNMP to get the interface names, or
sFlowTrend-Pro is still in the process of configuring sFlow
on the switch. See
Section 14.1.7, “sFlowTrend-Pro cannot communicate with the switch using SNMP”.
The agent is enabled, but sFlowTrend-Pro is not
receiving sFlow. If the agent is a switch,
then this can also mean sFlowTrend-Pro cannot
communicate with the switch using SNMP to enable
it. See
Section 14.1.6, “sFlowTrend-Pro is not receiving sFlow from a switch or host”
and
Section 14.1.7, “sFlowTrend-Pro cannot communicate with the switch using SNMP”.
The agent is disabled and sFlowTrend-Pro is not
receiving sFlow from it.
A switch setting has been changed in the
Configure agents dialog,
but the change has not been deployed (operation
pending). sFlowTrend-Pro will deploy the change when
you click the OK button.
The tooltip for the status symbol gives more
detail on the status of the agent.
- Type
-
The type column displays the type of agent:
whether it is a switch or a host:
The agent is a switch or router.
The agent is a host.
The agent is both a switch/router and a host.
- DNS name
-
The domain name obtained from the reverse
DNS lookup of the SNMP IP address of the
agent.
- SNMP IP address
-
The IP address that sFlowTrend-Pro will use to
communicate with the agent, if it is a switch,
via SNMP to
obtain the friendly system and interface
names. This is also the IP address that
sFlowTrend-Pro will use when using SNMP to
configure the switch to send sFlow, if
Configure via SNMP
is selected.
- sFlow agent address
-
The IP address that is used by the sFlow
agent to uniquely identify itself. This address is
learnt from the
sFlow data and cannot be changed in
sFlowTrend-Pro.
For a switch, in many cases the sFlow agent
address will be the same as the SNMP IP
address. However if the switch is switching
between multiple VLANs, the sFlow agent
address may be in a VLAN that is not
routable to the host that is running sFlowTrend-Pro.
In which case you can change the SNMP IP address to
tell sFlowTrend-Pro how to communicate with the switch.
- Enable
-
Check this checkbox if you would like
sFlowTrend-Pro to receive and store data for this agent.
You can use the checkbox in the title row for the
header to enable or disable all agents.
- Configure sFlow via SNMP
-
For a switch, check this checkbox if you would like
sFlowTrend-Pro to use SNMP to configure the switch to
send sFlow.
- Use global SNMP settings
-
For a switch, check this box if you would like
sFlowTrend-Pro to use
the global SNMP settings (see
Section 13.2.3, “Configuring global SNMP settings”)
when communicating with the switch using SNMP.
If this box is not checked you can specify the
SNMP settings for this switch by clicking on the
button.
sFlowTrend-Pro uses SNMP to query the switch for the
systemGroup and ifTable, so that it can present
friendly names for the switch and its interfaces.
If sFlowTrend-Pro is to use SNMP to configure the switch
to send sFlow, these settings must allow write
access to the sFlow MIB.
-
Edit
-
Although most of the commonly changed agent
settings can be edited in the table, for a
switch you can edit all the settings and view
the detailed status of the switch by
clicking on this button. For example, if you
want to configure switch specific SNMP settings,
click this button and enter the correct settings
(see Section 13.2.3.1, “SNMP v2c settings”
and Section 13.2.3.2, “SNMP v3 settings”).
-
Delete
-
Delete the agent from the sFlowTrend-Pro and
stop further data collection. If this agent
has been configured by SNMP to send sFlow,
sFlowTrend-Pro will disable sFlow before
deleting the switch.
You can click with the left button
on a column heading to sort the table by that column.
You can also click with the
Shift+left
mouse button to add secondary sort columns.
Any changes made to agents and their settings will not be
implemented until the OK button is clicked.
13.3.1. Adding a switch configured via SNMP
Clicking on the
Add switch agent
button launches a dialog that allows you to enter the
details for a new switch. This should be used when you
wish to tell sFlowTrend-Pro about a switch that should be
configured via SNMP to send sFlow. Enter the following
information:
- SNMP IP address
-
The IP address that sFlowTrend-Pro should use when
communicating with the switch via SNMP.
- Use global SNMP settings
-
Check this box if you would like sFlowTrend-Pro to use
the global SNMP settings (see
Section 13.2.3, “Configuring global SNMP settings”).
If this box is unchecked, you can click on
Change SNMP settings to
specify the SNMP settings specific to this switch.
You can ask sFlowTrend-Pro to communicate with the switch
using SNMP v2c or v3
(see Section 13.2.3.1, “SNMP v2c settings”
and Section 13.2.3.2, “SNMP v3 settings”).
Make sure that the SNMP settings that you enter will
allow sFlowTrend-Pro write access to the sFlow MIB.
- Enable
-
Check this box if you want sFlowTrend-Pro to enable and start
collecting data from this switch. sFlowTrend allows
data to be collected from only five switches, so if
five switches are already enabled, the
Enable
checkbox will be inactive and you must disable one of
the other switches before you can enable the new switch.
- Configure sFlow via SNMP
-
Check this box if sFlowTrend-Pro is to use SNMP to configure
the switch to send sFlow.
sFlowTrend-Pro will not configure the switch until the
Configure agents
dialog has been closed by clicking the
OK
button.
13.3.2. Verifying switch configuration and status
Once you have submitted the changes that you have made
in the
Configure agents
dialog, by clicking the
OK
button, when you go to the Network,
Interfaces, Counters,
Top N, Circles, or
Root cause tabs and select a switch, the
sFlowTrend-Pro status bar (see
Section 1.1, “Introducing sFlowTrend-Pro”)
will show the status of the switch that is currently selected.
The message in the status bar
will give information on whether sFlowTrend-Pro can
communicate with the selected switch using SNMP, has
successfully used SNMP to configure the selected switch to send
sFlow (if this option has been chosen), and whether
sFlowTrend-Pro is receiving sFlow from the selected switch.
You can also view the status of a switch by selecting the
→
menu item to launch the
Configure agents
dialog and then viewing the tooltip for the color coded
switch status symbol or using the edit
button to view the detailed status of a switch
(see above).
The status message will also indicate if there is a
problem with the configuration, for example:
- No SNMP
-
sFlowTrend-Pro cannot communicate with the
switch using SNMP. Verify that the
sFlowTrend-Pro is using the correct SNMP settings
and that there are no firewalls
in the network or on the host that are
blocking SNMP. See
Section 14.1.7, “sFlowTrend-Pro cannot communicate with the switch using SNMP”
for troubleshooting tips.
-
Cannot configure sFlow with SNMP - SNMP
write access denied
-
sFlowTrend-Pro is not using the correct SNMP
settings that allow write access to the
sFlow MIB or the switch is
not configured to allow SNMP set from
the system running sFlowTrend-Pro.
-
Cannot configure sFlow with SNMP - no sFlow
MIB
-
The switch cannot be configured via SNMP
to send sFlow. Instead, you must use
the switch CLI to configure sFlow (see
Appendix A, Configuring switches to send sFlow.
- Already in use
-
Another application has already
configured this switch to send sFlow
and there are no additional resources to
send sFlow to sFlowTrend-Pro as well.
Disable the other application so that
the switch can be configured by
sFlowTrend-Pro. You can identify the other
applications which have already
configured the switch by using the edit
button. The
Additional switch details
section, under Other owners
lists the IP addresses of the other
systems which have configured the switch,
together with a description of the
application. Alternatively, you can configure
sFlowTrend-Pro so that it removes the other
application's claim on the switch and replaces
it with its own (see
Section 15.1, “Server custom configuration settings”,
sflowtrend.useForce
).