Hi David,

erm... sorry to sound abit DUM, but can you explain what you mean please?

Regards

Simon

On 19 Aug 2014, at 18:22, David Peall david@dnservices.co.za wrote:

On 19 Aug 2014, at 6:24 PM, Simon Smith simonsmith5521@gmail.com wrote:

...

Hi All,

this is a daft random question, can i monitor a device via multiple ip addresses?

for instance, we have a site with a mikrotik router,

they currently have 3 internet lines (DONT ASK!) 2xADSL,1xFTTC

currently we use PPPOE on the router so we can see the mikrotik directly,

ive enabled SNMP remotely and i monitor the box via 1 of the ADSL lines, however its constantly goes up and down and never makes up its mind!

Mikrotik's don’t like asymmetrical SNMP traffic sort that out and it might come right.

— David Peall _______________________________________________ observium mailing list observium@observium.org http://postman.memetic.org/cgi-bin/mailman/listinfo/observium

DNS RR does not turn it into a traffic load balancer. You’re confused if you think that DNS RR functions anything like a load balancer where traffic may come in on one interface and leave on another. I do understand your concern, though. If the router has a route to the Observium host via one interface and an SNMP query comes in on another interface then that won’t work, but that’s not a problem with DNS RR. That’s a problem with the device and network configuration itself and the problem would exist whether or not someone were to use DNS RR. If Simon can currently and reliably query the device using any of the IPs configured then creating a DNS RR entry to rotate through them won’t make any difference. The only issue is as I mentioned before, if the IP changes or one of the links goes down then a portion of the SNMP queries will fail whenever the bad IP comes up in the DNS rotation.

-Hogan

On Aug 19, 2014, at 11:43 AM, David Peall david@dnservices.co.za wrote:

The SNMP traffic must come in and go out the same interface.

— David Peall

On 19 Aug 2014, at 7:24 PM, Simon Smith simonsmith5521@gmail.com wrote:

...

Hi David,

erm... sorry to sound abit DUM, but can you explain what you mean please?

Regards

Simon

On 19 Aug 2014, at 18:22, David Peall david@dnservices.co.za wrote:

...

On 19 Aug 2014, at 6:24 PM, Simon Smith simonsmith5521@gmail.com wrote:

...

Hi All,

this is a daft random question, can i monitor a device via multiple ip addresses?

for instance, we have a site with a mikrotik router,

they currently have 3 internet lines (DONT ASK!) 2xADSL,1xFTTC

currently we use PPPOE on the router so we can see the mikrotik directly,

ive enabled SNMP remotely and i monitor the box via 1 of the ADSL lines, however its constantly goes up and down and never makes up its mind!

Mikrotik's don’t like asymmetrical SNMP traffic sort that out and it might come right.

— David Peall _______________________________________________ observium mailing list observium@observium.org http://postman.memetic.org/cgi-bin/mailman/listinfo/observium

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observium mailing list observium@observium.org http://postman.memetic.org/cgi-bin/mailman/listinfo/observium

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observium mailing list observium@observium.org http://postman.memetic.org/cgi-bin/mailman/listinfo/observium

Hi Simon,

It would say server down because it would only try the IP in the rotation handed to it by the resolver, it doesn’t have the ability to understand that there are 3 IPs to check. The “ping” utility is a good example because it works the same way, if you ping a hostname that is a DNS RR pointing to 3 IPs then ping would try the IP determined by the resolver. Run ping again and it should ping a different IP. Run ping again and you may get the 3rd IP or you may get the 1st IP…or the 2nd…but in any event the tools don’t see 3 IPs and check all 3, they see 1 IP that is provided by the resolver. DNS RR is mainly a way to do poor man’s load balancing across multiple servers, it doesn’t provide any means for failover or redundancy since there are no health checks to monitor and add/remove IPs that are down from the rotation.

Hope this makes sense. :)

-Hogan

On Aug 19, 2014, at 12:51 PM, Simon Smith simonsmith5521@gmail.com wrote:

Hi Hogan

i fully understand where you are coming from now and i thank everyone for there help and advise :)

Question, if did put multiple ip addresses in the DNS and say for instance the first IP it tried is down (no reply)

would it simple move onto the next ip as when it queried the DNS name it has multiple ips or would it just say OH NO server down...?

• Simon

On 19 Aug 2014, at 19:59, Hogan Whittall whittalh@yahoo-inc.com wrote:

...

DNS RR does not turn it into a traffic load balancer. You’re confused if you think that DNS RR functions anything like a load balancer where traffic may come in on one interface and leave on another. I do understand your concern, though. If the router has a route to the Observium host via one interface and an SNMP query comes in on another interface then that won’t work, but that’s not a problem with DNS RR. That’s a problem with the device and network configuration itself and the problem would exist whether or not someone were to use DNS RR. If Simon can currently and reliably query the device using any of the IPs configured then creating a DNS RR entry to rotate through them won’t make any difference. The only issue is as I mentioned before, if the IP changes or one of the links goes down then a portion of the SNMP queries will fail whenever the bad IP comes up in the DNS rotation.

-Hogan

On Aug 19, 2014, at 11:43 AM, David Peall david@dnservices.co.za wrote:

...

The SNMP traffic must come in and go out the same interface.

— David Peall

On 19 Aug 2014, at 7:24 PM, Simon Smith simonsmith5521@gmail.com wrote:

...

Hi David,

erm... sorry to sound abit DUM, but can you explain what you mean please?

Regards

Simon

On 19 Aug 2014, at 18:22, David Peall david@dnservices.co.za wrote:

...

On 19 Aug 2014, at 6:24 PM, Simon Smith simonsmith5521@gmail.com wrote:

...

Hi All,

this is a daft random question, can i monitor a device via multiple ip addresses?

for instance, we have a site with a mikrotik router,

they currently have 3 internet lines (DONT ASK!) 2xADSL,1xFTTC

currently we use PPPOE on the router so we can see the mikrotik directly,

ive enabled SNMP remotely and i monitor the box via 1 of the ADSL lines, however its constantly goes up and down and never makes up its mind!

Mikrotik's don’t like asymmetrical SNMP traffic sort that out and it might come right.

— David Peall _______________________________________________ observium mailing list observium@observium.org http://postman.memetic.org/cgi-bin/mailman/listinfo/observium

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observium mailing list observium@observium.org http://postman.memetic.org/cgi-bin/mailman/listinfo/observium

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observium mailing list observium@observium.org http://postman.memetic.org/cgi-bin/mailman/listinfo/observium

On 19/08/2014 23:06, Simon Smith wrote:

however the ability to monitor a device with multiple ip addresses by either entering multiple ip address or even a dns entry with multiple ips would be a good feature for Observium…

That doesn't even remotely make sense, sorry.

Tom

DNS queries convert hostname to an IP to connect to. If Simon wants to create a round-robin DNS entry with the 3 IPs then that should work just fine. Won’t work with /etc/hosts, though, and doesn’t address the changing dynamic IP so if the IP changes and DNS isn’t updated then polling will fail every time the old IP comes up in the rotation.

-Hogan

On Aug 19, 2014, at 10:33 AM, Michiel Klaver michiel@klaver.it wrote:

Observium doens't query directly to IP addresses, but uses hostnames from DNS.

This is a classic case for DynDNS.

Simon Smith wrote at 19-08-2014 18:24:

...

Hi All,

this is a daft random question, can i monitor a device via multiple ip addresses?

for instance, we have a site with a mikrotik router,

they currently have 3 internet lines (DONT ASK!) 2xADSL,1xFTTC

currently we use PPPOE on the router so we can see the mikrotik directly,

ive enabled SNMP remotely and i monitor the box via 1 of the ADSL lines, however its constantly goes up and down and never makes up its mind!

the other issue i have is the FTTC line is dynamic ip and never stays the same for more then 48hrs

so in my mind, /etc/hosts or DNS for site1.router goes to 1.2.3.4, 5.6.7.8, 9.10.11.12

then every check it always use one of three ip addresses ?

am i correct?

or is the another way of monitoring this device?

regards

Simon

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