Querying DHCP scope for number of available IP's

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Yoorix
Posts: 177
Joined: Wed Dec 14, 2005 8:28 am

Querying DHCP scope for number of available IP's

Post by Yoorix »

I figured out how to monitor the number of available IP's on my DHCP server using HostMonitor and want to share my experience with community.

I use "SNMP Get" test method.
There are two useful counters, specified in DHCP-MIB:
noAddInUse - 1.3.6.1.4.1.311.1.3.2.1.1.2 - number of IP's in use
noAddFree - 1.3.6.1.4.1.311.1.3.2.1.1.3 - number of available IP's

These OIDS are scope-level counters, so I have to add "scope" to the end of the OID. For example, if my DHCP server manages scope "192.168.1", I should use following OID to get the number of available IP's in this particular scope: 1.3.6.1.4.1.311.1.3.2.1.1.3.192.168.1.0

Regards,
Yoorix
JuergenF
Posts: 331
Joined: Sun Jan 26, 2003 6:00 pm
Location: Germany, North Rhine-Westphalia

Post by JuergenF »

Hi Yoorix,

that is very interesting to know !

My alternative for monitoring DHCP is this

Code: Select all

; ------- Test #01 -------


Method      = NTLog
;--- Common properties ---
DestFolder  = DCC\DE VZs\BLN - Berlin\
Title       = DHCPServer ScopeFull Berlin
Comment     = DHCPServer ScopeFull Berlin
RelatedURL  = 
ScheduleMode= Regular
Schedule    = 7 Days, 24 Hours
Interval    = 1800
Alerts      = Gen.HTML report-Retest-Alarm after 3
ReverseAlert= No
UnknownIsBad= No
WarningIsBad= Yes
UseWarning  = Yes
WarningExpr = %udv_status_bad%
UseCommonLog= Yes
PrivLogMode = Default
CommLogMode = Default
SyncCounters= No
SyncAlerts  = No
DependsOn   = list
MasterTest-Alive = Ping to blndc001 - Server Berlin
;--- Test specific properties ---
Computer    = \\blndc001
Log         = System
Source      = DHCPServer
CheckComp   = Any
CheckType   = AnyFromList
CheckID     = AnyFromList
CheckDescr  = AnyFromList
CompList    = 
TypeList    = Warning
IDList      = ^M1020^M
DescrList   = ^M95 percent utilized^M95 Prozent ausgelastet^M96 percent utilized^M96 Prozent ausgelastet^M97 percent utilized^M97 Prozent ausgelastet^M98 percent utilized^M98 Prozent ausgelastet^M99 percent utilized^M99 Prozent ausgelastet^M100 percent utilized^M100 Prozent ausgelastet^M
ReportMode  = LastEvent
udv_status_bad = ("%SuggestedSimpleStatus%"=="DOWN")

It's an EventLog test. So you don't have to care, when adding new Scopes
It's working for Geman and English Systems and gives an Alert when more than 95 Percent of the IP-Adresses of a Scope are in use
(If I remember correctly 95 % is the threshold for Event-Log entries. So you can't test for 90 %)

And a problem is not to miss the Alert.
Because the test will go to BAD only for 1 testcycle. (Just when the new Event-Log entry appears)
EDIT: So sending an eMail might be a good idea
The next test will not find a new "Bad" entry in the Event-Log. Therefore the test will change back to OK.
It's described here http://www.ks-soft.net/cgi-bin/phpBB/vi ... php?t=4238

Best regards

Juergen
Last edited by JuergenF on Fri Mar 07, 2008 5:28 am, edited 1 time in total.
Yoorix
Posts: 177
Joined: Wed Dec 14, 2005 8:28 am

Post by Yoorix »

Hi Juergen!

Your solution looks brilliant! :-)
I'll give it a try.

Thank you.

------------
Yoorix
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