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j0den_57525's avatar
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Feb 07, 2011

SMTP reply

Hi All,



I am a Newbie to the F5 products but am impressed so far..



I currently am wrapping my head around an Issue on our LTM with regard to our Virtual server setup for SMTP (for exchange).



We have set a very basic config with virtual server using TCP profile to a a pool with two nodes.


When we send a telnet request on port 25 to the VIP the response look to be a open session with no input (i.e. black screen that flickers for repsonse).



When we look at our exchange logs to it sends the "helo" and responds to "helo".


From that point the response is quit from LTM?



Looking through the TCP profile i cannot see a reason that LTM would send a quit message?


Is it dependant on domain names?



Any help is appreciated.



2 Replies

  • Hi J0den,



    LTM shouldn't be sending any SMTP responses unless you're using an iRule to explicitly do so. Can you capture a tcpdump on the client and server side VLAN(s) and compare the two to see what LTM might be doing when the issue occurs? See SOL411 for details on using tcpdump:



    sol411: Overview of packet tracing with the tcpdump utility




    If you need help capturing or analyzing tcpdumps, you can open a case with F5 Support.



  • Cheers,



    Thats the exact steps i am taking.


    interesting to note that logs from the server side show the response back through to the ltm , and on the ltm i can telnet and get responses form the ehlo command to the pool members.



    there are currently no persistance or irules in place for this traffic , it only uses the TCP profile.