DNS SRV Redundancy

[Leo Salcie Tejeda]

Hi everyone,

I'm working with two CME(CME 1 and CME 2) supporting all our phone in a active/stadby redundacy scheme. We need to have a redundacy for our thirdparty phone (X-lite, YeaLink...) to register with CME 2 when CME 1 be down. For this scheme we're trynig to use DNS SRV to setup at all thirdparty phone the SIP server name as cme.lab.local, if CME 1 is down, phone should be able to know it and be able to register with CME2.

Right know, I'm able to resolve cme1.lab.local and cme2.lab.local but isn't working when I try to resolve cme.lab.local as my SIP server name. Here my configuration:

ip domain name lab.local

ip name-server 127.0.0.1

ip dns server

ip domain-lookup

ip host cme2.lab.local 192.168.6.14

ip host cme1.lab.local 192.168.6.10

ip host cme.lab.local srv 1 25 5060 cme1.lab.local

ip host cme.lab.local srv 2 25 5060 cme2.lab.local

Result:

ADSL-CubeCUCM#ping cucm1.lab.local

Translating "cucm1.lab.local"...domain server (196.3.81.5)

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 192.168.6.10, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms

ADSL-CubeCUCM#

ADSL-CubeCUCM#

ADSL-CubeCUCM#ping cucm2.lab.local

Translating "cucm2.lab.local"...domain server (196.3.81.5)

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 192.168.6.14, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms

ADSL-CubeCUCM#

ADSL-CubeCUCM#ping cucm.lab.local

Translating "cucm.lab.local"...domain server (196.3.81.5)

Translating "cucm.lab.local"...domain server (196.3.81.5)

% Unrecognized host or address, or protocol not running.

As a reference it's use this guide: http://ben.thepolzins.us/2010/02/06/using-dns-srv-records-with-ios-dial-peers/

Any help would be appreciated

Regards

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[Ayodeji Okanlawon]

Your post does not show that you have defined the SRV records....Have you done this?

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"opportunity is a haughty goddess who waste no time with those who are unprepared"

[Leo Salcie Tejeda]

@aokanlawon, thanks for the response. I thought these lines command should be the SRv record:

ip host cme.lab.local srv 1 25 5060 cme1.lab.local

ip host cme.lab.local srv 2 25 5060 cme2.lab.local

Am I missing something?

Regards

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[Ayodeji Okanlawon · Accepted solution]

Your srv config is not correct. You define SRV records with the protocol its going to use either tcp or udp as shown below

ip host _sip._udp.cmgroup1.lab.local srv 1 50 5060 cucm1.lab.local

ip host _sip._udp.cmgroup1.lab.local srv 1 50 5060 cucm2.lab.local

ip host _sip._udp.cmgroup1.lab.local srv 1 50 5060 cucm3.lab.local

or for tcp

ip host _sip._tcp.cvp.cisco.com srv 1 50 5060 cvp4cc3.cisco.com

ip host _sip._tcp.cvp.cisco.com srv 1 50 5060 cvp4cc2.cisco.com

ip name-server 127.0.0.1

ip domain name lab.local

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"opportunity is a haughty goddess who waste no time with those who are unprepared"

[Leo Salcie Tejeda]

It work like a charm!

Just need a little help from this two command:

Windows: ipconfig /flushdns

Router:clear host all *

A important note: Some softphone/ IP phone doesn't support DNS SRV Failover (but DNS SRV is supported) so for test porpuse you will need to reset the phone.

Regards

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[Ayodeji Okanlawon · Accepted solution]

Leo,

Glad I could help. Out of curiosity why the 4 stars for a correct answer?

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"opportunity is a haughty goddess who waste no time with those who are unprepared"

[Leo Salcie Tejeda]

Chrome didn't let me choose Correct Answer or select the star, that's weird...I'm back to Firefox...

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[Ayodeji Okanlawon]

Thanks Leo! Hahaha the highly advertised and rated Chrome is the culprit.

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"opportunity is a haughty goddess who waste no time with those who are unprepared"

[iptuser55]

Hi

I'm trying to do the same but can not enter in the commend you highlighted

ip host_sip._udp      

Is it IOS SW level related as it will not let me do so

thanks

[Ayodeji Okanlawon]

If you cant see the commands, then its most likely your IOS doesnt support it