Smokeping::probes::CiscoRTTMonDNS.pm - Probe for SmokePing

 *** Probes ***

 +CiscoRTTMonDNS

 forks = 5
 offset = 50%
 step = 300
 timeout = 15

 # The following variables can be overridden in each target section
 ioshost = RTTcommunity@Myrouter.foobar.com.au # mandatory
 iosint = 10.33.22.11
 name = www.foobar.com.au # mandatory
 pings = 5

 # [...]

 *** Targets ***

 probe = CiscoRTTMonDNS # if this should be the default probe

 # [...]

 + mytarget
 # probe = CiscoRTTMonDNS # if the default probe is something else
 host = my.host
 ioshost = RTTcommunity@Myrouter.foobar.com.au # mandatory
 iosint = 10.33.22.11
 name = www.foobar.com.au # mandatory
 pings = 5

A probe for smokeping, which uses the ciscoRttMon MIB functionality (Service Assurance Agent, SAA) of Cisco IOS to time ( recursive, type A) DNS queries to a DNS server.

Supported probe-specific variables:

forks

Run this many concurrent processes at maximum Example value: 5 Default value: 5

offset

If you run many probes concurrently you may want to prevent them from hitting your network all at the same time. Using the probe-specific offset parameter you can change the point in time when each probe will be run. Offset is specified in % of total interval, or alternatively as 'random', and the offset from the 'General' section is used if nothing is specified here. Note that this does NOT influence the rrds itself, it is just a matter of when data acqusition is initiated. (This variable is only applicable if the variable 'concurrentprobes' is set in the 'General' section.) Example value: 50%

step

Duration of the base interval that this probe should use, if different from the one specified in the 'Database' section. Note that the step in the RRD files is fixed when they are originally generated, and if you change the step parameter afterwards, you'll have to delete the old RRD files or somehow convert them. (This variable is only applicable if the variable 'concurrentprobes' is set in the 'General' section.) Example value: 300

timeout

How long a single 'ping' takes at maximum Example value: 15 Default value: 5

Supported target-specific variables:

ioshost

The (mandatory) ioshost parameter specifies the Cisco router, which will send the DNS requests, as well as the SNMP community string on the router. Example value: RTTcommunity@Myrouter.foobar.com.au This setting is mandatory.

iosint

The (optional) iosint parameter is the source address for the DNS packets. This should be one of the active (!) IP addresses of the router to get results. IOS looks up the target host address in the forwarding table and then uses the interface(s) listed there to send the DNS packets. By default IOS uses the (primary) IP address on the sending interface as source address for packets originated by the router. Example value: 10.33.22.11

name

The (mandatory) name parameter is the DNS name to resolve. Example value: www.foobar.com.au This setting is mandatory.

pings

How many pings should be sent to each target, if different from the global value specified in the Database section. Note that the number of pings in the RRD files is fixed when they are originally generated, and if you change this parameter afterwards, you'll have to delete the old RRD files or somehow convert them. Example value: 5

Joerg.Kummer at Roche.com

The host parameter specifies the DNS server, which the router will use.

This probe only works with IOS 12.0(3)T or higher. It is recommended to test it on less critical routers first.

To install this probe copy ciscoRttMonMIB.pm to ($SMOKEPINGINSTALLDIR)/lib/Smokeping and CiscoRTTMonDNS.pm to ($SMOKEPINGINSTALLDIR)/lib/Smokeping/probes.

The router(s) must be configured to allow read/write SNMP access. Sufficient is:

        snmp-server community RTTCommunity RW

If you want to be a bit more restrictive with SNMP write access to the router, then consider configuring something like this

        access-list 2 permit 10.37.3.5
        snmp-server view RttMon ciscoRttMonMIB included
        snmp-server community RTTCommunity view RttMon RW 2

The above configuration grants SNMP read-write only to 10.37.3.5 (the smokeping host) and only to the ciscoRttMon MIB tree. The probe does not need access to SNMP variables outside the RttMon tree.

The probe does unnecessary DNS queries, i.e. more than configured in the pings variable, because the RTTMon MIB only allows to set a total time for all queries in one measurement run (one life). Currently the probe sets the life duration to pings*2+3 seconds (2 secs is the timeout value hardcoded into this probe).

<http://people.ee.ethz.ch/~oetiker/webtools/smokeping/>

<http://www.switch.ch/misc/leinen/snmp/perl/>

The best source for background info on SAA is Cisco's documentation on <http://www.cisco.com> and the CISCO-RTTMON-MIB documentation, which is available at:

<ftp://ftp.cisco.com/pub/mibs/v2/CISCO-RTTMON-MIB.my>