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A question on failover after DNS fails

vonion
Occasional Visitor

A question on failover after DNS fails

Hi,

 

I was testing the failover function on the Polycom 331 in the case DNS provider fails(actually we got a major issue two weeks ago when GoDaddy failed...).

 

The Polycom 330 was upgrade to lastest 4.0.2B. Configured with two server address and SRV discovery enabled.

 

reg.1.server.1.address="AAA.com"

.......

reg.1.server.2.address="BBB.com"

.......

reg.1.outboundProxy.port="0"
reg.1.outboundProxy.transport="DNSnaptr"

 

AAA.com is a FAKE domain name which does not actually exist.  BBB.com was configured with SRV records to point to our softswitches.

 

On my router, BIND is used to cache DNS records and DNSmasq was configured to server as local DNS server for the phones.

BIND only listens on lo interface. /etc/resolve.conf pointed to 127.0.0.1

 

------------------------------------------

# Test 1, Regular condition.

The Polycom 331 boots up and tried NAPTR, SRV, A records in sequence for AAA.com, found no answer, then it move to BBB.com and found answer for SRV records. Successfully booted up.

------------------------------------------

# Test 2, DNS provider fails

On the router, /etc/resolve.conf pointed to 155.155.155.155 which is a valid IP address but not response to DNS request. DNSmasq was configured with static SRV entries for BBB.com

 

The Polycom 331 boots up and tried NAPTR, failed.........wait 1s & retry.........wait 2s & retry..........wait 10s & retry..........wait 1s & retry.........wait 2s & retry..........wait 10s & retry..........wait 1s & retry.........wait 2s & retry..........wait 10s & retry..........

------------------------------------------

 

So it never failover to SRV, A records of AAA.com and neither did it fails to BBB.com

 

Is it a bug? I suppose a failover should allow a certain timeout(even there's no respose) and then move to the next domain on the server list.

 

Also, I found some other related parameters in polycomConfig.xsd as following, but none of them was mentioned in any of Polycom documents.

 
<xsd:attribute name="reg.1.server.1.failOver.failBack.mode" type="String_0_128">
<xsd:attribute name="reg.1.server.1.failOver.failBack.timeout" type="SInt_0_65535">
<xsd:attribute name="reg.1.server.1.failOver.failRegistrationOn" type="xsd:boolean">
<xsd:attribute name="reg.1.server.1.failOver.onlySignalWithRegistered" type="xsd:boolean">

 

Please help!

Thanks in advance!

Xi

 

Message 1 of 4
3 REPLIES 3
SteffenBaierUK
Polycom Employee & Community Manager

Re: A question on failover after DNS fails

Hello xi,

welcome to the Polycom Community.

I am not sure but did you follow the document => here <= covering failover scenarios?

 

There is also a document covering DNS cache => here <=

 

Part of the Parameters mentioned below had been introduced in SIP 3.2.3 and I can always recommend to check the Release Notes between major software releases that cover Admin Guide in order to compare newly added or removed parameters.

 

In addition the following Parameters:

 

voIpProt.server.X.failOver.onlySignalWithRegistered
voIpProt.SIP.outboundProxy.failOver.onlySignalWithRegistered
reg.X.server.Y.failOver.onlySignalWithRegistered
reg.X.outboundProxy.failOver.onlySignalWithRegistered

 There standard Value in the Admin Guide is shown as 0 but the real standard value is 1. We have an internal documentation bug open for this regarding the Admin Guides. The Eng Advisory 66546 should have the correct Information within it.

 

Please ensure to provide some feedback if this reply has helped you so other users can profit from your experience.

Best Regards

Steffen Baier

Polycom Global Services

----------------
The title Poly Employee & Community Manager is a community setting and does not reflect my role. I am just a simple volunteer in the community like everybody else. All posts and words are my own & do not represent the views of Employer.

----------------

Notice: This community forum is not an official Poly support resource, thus responses from Poly employees, partners, and customers alike are best-effort in attempts to share learned knowledge. If you need immediate and/or official assistance please open a service ticket through your proper support channels.
Please also ensure you always check the VoIP , Video Endpoint , Skype for Business , PSTN or RPM FAQ's
Message 2 of 4
vonion
Occasional Visitor

Re: A question on failover after DNS fails

Hi Steffen,

 

Thanks for the quick reply. I took a quick look of your documents.

 

I think so far the problem is not even about the 2nd server(BBB.com), but it never try to resolve SRV records of AAA.com if the phone doesn't get a response from DNS server of the NAPTR query.

 

Please see my Test 1, it  DOES fail over to BBB.com after the phone  tried NAPTR, SRV, A records in sequence for AAA.com (And for each inquiry DNS server replied "No such Name")

 

But in Test 2, the DNS Server does not reply any thing to the inqury of NAPRT for AAA.com, becuase the Upper DNS provider(155.155.155.155) for the router in Unreachable. 

 

That's why I'm thinking there's BUG. Since Upper DNS can fail occationally and this senario do exist in real.

 

Thanks,

Xi

Message 3 of 4
SteffenBaierUK
Polycom Employee & Community Manager

Re: A question on failover after DNS fails

Hello xi,

 

in order to verify if this is a bug or a simple configuration issue I or some other member of the community would need to reproduce this and test this against your scenario.

 

Myself, as a member of the support organization, am unable to do so within the community.

 

You can either wait for another member of the Polycom community to reply to yourself or raise a service ticket via your Polycom reseller.

 

Best Regards

 

Steffen Baier

----------------
The title Poly Employee & Community Manager is a community setting and does not reflect my role. I am just a simple volunteer in the community like everybody else. All posts and words are my own & do not represent the views of Employer.

----------------

Notice: This community forum is not an official Poly support resource, thus responses from Poly employees, partners, and customers alike are best-effort in attempts to share learned knowledge. If you need immediate and/or official assistance please open a service ticket through your proper support channels.
Please also ensure you always check the VoIP , Video Endpoint , Skype for Business , PSTN or RPM FAQ's
Message 4 of 4