Errors adding a subscriber to a CM 5.x cluster

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Hello there,

I am adding a subscriber to a CM cluser in 5.13

I get the following error/screen


COnfiguration validation with CM-PUB ( failed

Could not send/recieved UDP packets to publisher on port 8500

-Is network connection to CM-PUB up?

-Is the MTU Size correct for this network

-Doe the network allow packet fragments


I can ping the servers,

any suggestions?


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andres.pasten Thu, 01/15/2009 - 07:45
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I've the same problem. I tried rebooting publisher, and error still appears.

I've tried using a crossover cable between Pub and the new Sub, and nothing happens, so the switch is not the problem.

There is ping connectivity between servers.

Any idea?

Andres Pasten

Adexus S.A.

Jaime Valencia Thu, 01/15/2009 - 08:42
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did you created the SUB in the PUB config before installing it??



if this helps, please rate

andres.pasten Thu, 01/15/2009 - 12:56
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Yes, it was created.

The problem was the DNS config, because on Pub was enabled and not on Sub, because I received a warning that DNS doesn't have records for CCM servers.

Finally I've put on an isolated vlan pub and sub, and then the instalation worked fine because there was no DNS available.

It's a pity that the error message doesn't say anything about the DNS problem. It only indicates a problem with network, MTU and fragmentation.

See you.

Andres Pasten

Adexus S.A.

martinbuffleo Mon, 11/02/2009 - 07:07
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Help I'm getting the same issue. I've rebooted the Publisher 3 times now. Both boxes are set to use the same DNS servers which have forward and reverse lookups.

I have even dropped the MTU down to 1400 on both.

Not sure what else to do.

andres.pasten Mon, 11/02/2009 - 07:18
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The issue is related to the DNS servers, I couldn't set correctly customers's machines, so I moved Publisher and the new Subscriber to a vlan with no access to DNS server, and in the instalation procedure you skip the dns validation when it says that you cannot reach that server.

It's the only way it worked to me. The other option is to remove the DNS config in all servers before installing the new subscriber.


Andres Pasten

martinbuffleo Mon, 11/02/2009 - 07:47
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How do I remove DNS client settings from the Publisher?

I am pre building this in a lab and trying to do this accross a simulate Branch VPN.

If I set my switch to have both subnets to get the intial sync completed would I be alright to the move it back to it's planned location.

martinbuffleo Tue, 11/03/2009 - 01:26
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I have removed all referneces to DNS and still no joy. Should I have a go at joining it on one switch, with two VLANs.

I just worried if it does work it wont help me find my issue.

Ricardo Saya Fri, 11/13/2009 - 06:48
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I had this issue in the installation of a new subscriber. I resolved the issue retyping the security password when fail the first time.


Ricardo Saya Mon, 11/16/2009 - 06:23
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if you have tried several times add the subscriber to cluster without success, maybe you are in a point that is necesary reinstall the subscriber again. Also, verify that versions of CallManager are identical (Publisher and the new Subscriber), network connectivity between them, that the name of Subscriber was added in the Publisher Administration (this is the first step when you go to install the server).


martinbuffleo Mon, 11/16/2009 - 06:35
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I have added the Sub on to the Publisher, using the Web interface.

Do you have a guide for adding a Sub to a cluster?

Both my Call Managers came pre installed and were ordered at the same time. So I'd Hope they are the same version.

Ricardo Saya Mon, 11/16/2009 - 06:52
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In this page you can find the installation guides of all version of Cisco CallManager:

For version 5.1(3):

When you are installing the CallManger you can see the version on the top of screen and with the Web Administracion in the menu About.

When you buy a Cisco CallManager it comes with the DVD of installation. Also, you need licenses for the Servers and IP Phones (DLUs).

I recommend you reading the installation guide, Cisco explain everything.


cesarpuga Fri, 12/18/2009 - 13:19
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Hi Martin,

both server's are in the same network? you are using a IPSEC tunnel? if the answer is yes, maybe you need to apply the following command to the wan interface:

"crypto ipsec df-bit clear"



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