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New Member

SMTP Service is flickered when Mail Server point to VIP!

Hi all,

On module CSM, real mail server is repeated either probe fail or operate about 5 minutes when I set Mail Server point to VIP. On the contrary if I set to Real server. But it's normaly before. And when I use my DNS server to ping, the Real server response, but with external dns- the VIP is response.

Please show me how to fix this issue, my customers can't use mail. Thanks.


Cisco Employee

Re: SMTP Service is flickered when Mail Server point to VIP!

I'm sorry but I absolutely do not understand your problem description.

Could you please use ip address in your explanation.

Like from client x.x.x.x going to vip x.x.x.x it fails but to server x.x.x.x it works.

Also, you have extracted the vlan part of the config. It is quite important to know if you are in one-armed mode, bridge mode, or ...

Please include this information.

Next, what about the other vips ?

Does it work for HTTP ?

Finally, you will have to capture a sniffer trace of the front and back end csm vlan simulatnously so we can see what is happening.


New Member

Re: SMTP Service is flickered when Mail Server point to VIP!

Hi Gilles,

My problems are below:

DNS querry: Client use nslookup tool to querry the dns servers but Timeout for sometime.

SMTP Probe: CSM probes smtp service of Mail server farm in OUTOFSERVICE state, during this time CSM drops all smtp connections to Mail server.

I detected an error in DNS1 server and fixed it, then the DNS querry is now OK.

On the CSM, I tried to increase the probe waiting time to 45s instead of 10s by default, so far it is OPERATIONAL.

I think this issue is that mail server response too late for CSM probe smtp.

Thnks for your support.


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