load balance of DP to CUCM

Hello,

When configuring H323 dial-peer towards CUCM Cluster (Pub and Sub), and using the same preference for both dial-peer, but the Hunt Option is set to 1, so that the gateway will load balance calls to CUCM Servers.

I think that in that case, when one CUCM will go down, the gateway will not re-route the calls to another CUCM, if the call is destined for dead CUCM server.

For backup functionality to work, the Preference command is necessary on dial-peers.

Can you please confirm this, as I cannot get to my lab now.

Comments

  • Hi,

    Preference is configured just as a tie-breaker, and the option 1 mean it will try first the "last recent used" but will go to the next when no answer.

     

  • well, take a look at the following CUCME DN configuration, I am justing getting this as an example:

    ephone-dn 1
    number 3012
    no huntstop

    ephone-dn 2
    number 3012
    no huntstop

    ephone 1
    mac-address xxxx.xxxx.xxxx
    button 1:1
    type 7961

    ephone 2
    mac-address xxxx.xxxx.xxxx
    button 1:2
    type 7961

     

    Based on that configuration, the calls to number 3012 will go to ephone1 or ephone2 in random manner, until we configure the Preference command for Ephone-DNs.

    This is almost the same as the DP Load Balancing, except that Ephone Dial-peers will be selected in Random order.

    So when the called IP Phone is busy in CUCME (one of the 3012), the CUCME will not route the call to another 3012 and will give the Busy signal to Caller.

    And based on that I still think that the DP load balancing will not work correctly if one of the UCM server will go down, and gateway will produce Busy (or error) and will not re-route the call to another UCM, until the preference is configured for thos DPs. The CUCME Ephone-DNs are also almost the same dial-peers with their logic.

     

     

  • Yes, Ephone-Dn's are dial peers, no doubt on that. And 'huntstop' is the default behavior among all ephone-dn/dial-peers.

    For load balancing you can have two options:

    1. using the preference command which is always recommended for dial-peers where the lowest preference dial-peer will get all the calls, so you have better control here.

    2. using the 'no huntstop' command which will allow to jump to next dial-peer if primary is dead/busy/unreachable etc, the primary dial-peer would be chosed on random, so you are losing control here.

    So what does 'huntstop' means? Read the line here on CME Command Reference:

    "A huntstop prevents hunt-on-busy from redirecting a call from a busy phone into a dial-peer with a catch-all default destination."

     

    Hope it's clear now.

  • "the primary dial-peer would be chosed on random"

    Even with option 1 on the hunt option ?

     

    Best regards

  • Never, if there is lower preference set calls will direct to that dial-peer first and then seek for the next preferences upon failure. That is the reason we don't need 'no huntstop' on dial-peers as the functionality is already embedded with 'preference' command.

  • Hi Dotac,

     

    The GW will jump to the next dial-peer even if preference is same. With dial-peer hunt 1 (same match & same preference), GW will select the least matched dial-peer and will try to establish an H323 call to the configured session target. In case the CUCM configured in session target is down, H323 TCP connection establishment will fail,  accordingly GW will jump to the next dial-peer. The time it takes to jump depends on "h225 timout tcp establish <timer>".

     

    This is the same case of ePhones (assuming hunt-stop is disabled as per your configuration posted).

     

    Regards,

    Mohd Baqari

  • There is a little difference between Ephone-DN Dial-peer and normal Dial-peers:

     

    Ephone-DN Dial-peers are configured with "huntstop" by default.

    Whereas the normal DIal-peers are configured with "no hunstrop" by default  - and the Preference does not effect the Huntstop option anyhow (functionality is already embedded with 'preference' command)



    On Thu, Dec 22, 2011 at 11:44 PM, MijanurRahman <[email protected]> wrote:

    Never, if there is lower preference set calls will direct to that dial-peer first and then seek for the next preferences upon failure. That is the reason we don't need 'no huntstop' on dial-peers as the functionality is already embedded with 'preference' command.




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  • I have tested, and int case of CUCME, the same preference DNs are not hunted, unles the preference is configured. Meaning, that when the Busy or Dead phone is called, the caller hears a Busy tone, unless the Preference is configured and next DN is choosed.




     

    On Fri, Dec 23, 2011 at 1:50 AM, baqari <[email protected]> wrote:

    Hi Dotac,

     

    The GW will jump to the next dial-peer even if preference is same. With dial-peer hunt 1 (same match & same preference), GW will select the least matched dial-peer and will try to establish an H323 call to the configured session target. In case the CUCM configured in session target is down, H323 TCP connection establishment will fail,  accordingly GW will jump to the next dial-peer. The time it takes to jump depends on "h225 timout tcp establish <timer>".

     

    This is the same case of ePhones (assuming hunt-stop is disabled as per your configuration posted).

     

    Regards,

    Mohd Baqari





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  • I am so sorry, please excuse me, I forgot to type "no huntstop" command in Ephone-DNs,

    After that command the Ephone-DN began to hunt from busy DN to another available DN, even if the Preference has not been configured.

    Sorry, that's my mistake and I am very sorry for that.

  • Don't be sorry, this can happen with anyone. :)



    On Fri, Dec 23, 2011 at 2:05 PM, datoc <[email protected]> wrote:

    I am so sorry, please excuse me, I forgot to type "no huntstop" command in Ephone-DNs,

    After that command the Ephone-DN began to hunt from busy DN to another available DN, even if the Preference has not been configured.

    Sorry, that's my mistake and I am very sorry for that.




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