FAQ

Frequently Asked Questions for NAV

Is vendor X / device Y supported?

NAV supports any managed (SNMP v1 or v2c-enabled) routing and switching device that implements the relevant, standard IETF MIB support.

Unfortunately, many vendors seem to eschew some of these important IETF MIBs in favor of their own, proprietary SNMP MIB modules. NAV has adequate support for proprietary MIBs from large vendors such as Cisco and Hewlett Packard, as these have been a mainstay in the Norwegian higher education sector for years.

For any other vendors, we suggest that you just add your devices to NAV and see whether NAV reports what you want it to report. If it doesn’t, submit a question to the mailing list, nav-users@lister.sikt.no.

Why are there gaps in my graphs?

There are multiple possible sources for problems like this. Please read our guide to debugging choppy graph issues.

Why does NAV list my device’s uplink as N/A?

This means that topology discovery has failed for some reason.

Uplinks/downlinks in NAV require VLAN topology detection to be completed, as directionality of links is part of this information. NAV may have actually found the neighboring device on your port just find, but is unable to detect which VLANs are active on the link - since directionality information is missing, NAV doesn’t know whether the neighbor represents an uplink or a downlink.

Please see our guide for troubleshooting topology for more information.

Why doesn’t device X show as down in the status page when I know it’s down?

First, browse the device in ipdevinfo (search for it by name or IP in the NAVbar). Does it list as up or down here?

Has the device been placed on maintenance, or has the alert already been acknowledged by someone else? Check your status filter.

Remember, the event engine holds back boxDown alerts for up to four minutes (configurable in eventengine.conf) while waiting for the situation to resolve itself. While waiting for the recovery, the device may be marked as down in its ipdevinfo page, without an actual alert having been posted yet.

If things still seem to not work, ensure both pping and eventengine are running, using the nav status command. Then check the logs of these programs to see whether they have detected the situation. pping.log should indicate whether pping has failed to get a ping response from the device. eventengine.log should indicate whether the event engine has detected pping’s notice of this.

A device is down, I see it on the status page, my profile should cover the event, but I am not alerted. Why?

First, verify that the alert engine (nav status alertengine) is running. Use alertengine.log to verify that alert engine processed such an alert. Did it cover your user? If not, double check your active profile. You may want to make a new profile that covers every alarm, to see if you get any alerts then.

Why is my Cisco switch’ syslog full of SNMP-3-AUTHFAIL messages for requests from my NAV server?

Because of what Cisco calls community indexing. A 802.1q-enabled Cisco switch will maintain separate switching information MIB instances (BRIDGE-MIB) for each active VLAN.

Querying for switching information for VLAN 20 requires NAV to modify the SNMP community used for communicating with the switch. If the community is public, NAV must use the community public@20.

To obtain all entries from the forwarding tables of such a switch (i.e. in order to facilitate NAV’s machine tracking and topology functionality), or just to know which interfaces are switch ports, NAV must know which VLANs are actively forwarded by the switch. Sometimes, Cisco devices report active VLANs that it doesn’t have a BRIDGE-MIB instance for.

Unfortunately, if NAV tries to query a VLAN that has no BRIDGE-MIB instance, the switch will log this as an SNMP authentication failure.

I added a new IP Device using SeedDB, but nothing happens. Why?

NAV’s SNMP collector, ipdevpoll, should notice the new IP Device within 2 minutes. Be patient. If you’re impatient, restart ipdevpoll, or check its log file, ipdevpoll.log.

How do I make NAV send SMS alerts?

NAV provides an SMS daemon to dispatch SMS alerts. The daemon uses a plugin system to provide support for multiple methods of SMS message dispatch. Examples include a dispatcher for a locally-attached GSM device (using Gammu), a dispatcher for a simple email-to-SMS interface, a dispatcher for simple REST-based web SMS API’s. You could also write your own plugin.

We’ve always recommended attaching a GSM device directly to your NAV server, to ensure that you have an out-of-band way of being notified about network problems. To do so, get a GSM device that’s supported by Gammu.

We’ve found it’s best to avoid handsets, as these are built to be exactly that: Handsets. Sometimes, they require some form of user-interaction to continue operating, which isn’t always feasible in a datacenter. At Sikt, we’ve had good results with GSM terminals from Siemens/Cinterion/Gemalto.

How long are ARP and CAM records kept in the database?

NAV stores ARP an CAM records indefinitely, making them available for search in the Machine Tracker web UI.

However, in some jurisdictions, this type of data is considered personally identifiable and its retention is regulated by privacy laws. You may therefore be required by law to remove old ARP and CAM records from your database.

The navclean command line program can be used to delete old ARP and CAM records from the database. Many users run a navclean command from their crontabs to clean out old ARP and CAM records, like in this example:

# m h  dom mon dow   command
* 6 * * * navclean --force --arp --cam --interval '6 months'

See the output of navclean --help for usage details.