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What if SBA fails? RRS feed

  • Question

  • Hi,

    We are planning to implement Lync with SBA's at branch offices. I have seen a lot of redundancy with regards to WAN link failures and how the SBA can re-route calls through PSTN etc... 

    I am just wondering what are the consequences are if the actual appliance fails (say hardware failure), and there is only one SBA at a site? Will anything work?

    Thanks,

    David

    Friday, October 5, 2012 5:51 PM

Answers

  • Hi Draylan,

    A couple to things to consider:

    1. When the SBA goes down, clients will be temporarily logged out until the re-registration process happens to the Lync client.  This would be down less a minute or so.  The Lync client would also display a red banner letting the users know there was a problem.  Remember, for each SBA and users homed on the SBA, the users primary registrar is the SBA, while the backup registrar is the SE server or EE pool.

    2. Since we are experiencing a hardware failure, the voice gateway (PSTN portion) will no longer respond to the SIP Options request.  It will be marked as down.  You will need to have backup routes or manually change your gateway within your Voice Policies to allow calling through the central site.  You could potentially incur more long distance charges if the central site is not close to your branch location. 

    3. If you were routing emergency services calls out the local voice gateway for that site, those calls would continue to be down.  You would need to look about offloading those from the local PSTN and move to an E911 solution.



    Adam Curry, UC Consultant, Unify Square Inc. (Blog, Twitter)

    Looking for Lync Users Groups in your area? Check out Lync Users Group

    • Proposed as answer by Tom ArbuthnotMVP Sunday, October 7, 2012 6:42 PM
    • Marked as answer by Lisa.zheng Friday, October 19, 2012 2:32 AM
    Friday, October 5, 2012 6:41 PM
  • In addition to what Adam said, if the WAN link is up, there is sufficient bandwidth to send calls over the WAN, and the user has an alternate gateway they can reach via the WAN, they should be able to carry on working as normal.

    If the WAN is restricted you may want to look at CAC to limit the concurrency of calls in the DR situation.

    If required, you can sit to SBA's on a single branch, but it adds management overhead, since a user can only be assigned to one SBA at a time.

    The thing to watch for is inbound calls, if these are on local branch ISDN and the gateway is down you will need to look to your carrier to redirect the calls.

    hope that helps

    Tom


    Tom Arbuthnot, Consultant Modality Systems
    Blog: Lync'd Up Blog Join over 300 UC Pros who subscribe for blog updates: Email or RSS
    Twitter @tomarbuthnot

    • Proposed as answer by Lisa.zheng Tuesday, October 9, 2012 1:52 AM
    • Marked as answer by Lisa.zheng Friday, October 19, 2012 2:32 AM
    Sunday, October 7, 2012 6:46 PM

All replies

  • Hi Draylan,

    A couple to things to consider:

    1. When the SBA goes down, clients will be temporarily logged out until the re-registration process happens to the Lync client.  This would be down less a minute or so.  The Lync client would also display a red banner letting the users know there was a problem.  Remember, for each SBA and users homed on the SBA, the users primary registrar is the SBA, while the backup registrar is the SE server or EE pool.

    2. Since we are experiencing a hardware failure, the voice gateway (PSTN portion) will no longer respond to the SIP Options request.  It will be marked as down.  You will need to have backup routes or manually change your gateway within your Voice Policies to allow calling through the central site.  You could potentially incur more long distance charges if the central site is not close to your branch location. 

    3. If you were routing emergency services calls out the local voice gateway for that site, those calls would continue to be down.  You would need to look about offloading those from the local PSTN and move to an E911 solution.



    Adam Curry, UC Consultant, Unify Square Inc. (Blog, Twitter)

    Looking for Lync Users Groups in your area? Check out Lync Users Group

    • Proposed as answer by Tom ArbuthnotMVP Sunday, October 7, 2012 6:42 PM
    • Marked as answer by Lisa.zheng Friday, October 19, 2012 2:32 AM
    Friday, October 5, 2012 6:41 PM
  • In addition to what Adam said, if the WAN link is up, there is sufficient bandwidth to send calls over the WAN, and the user has an alternate gateway they can reach via the WAN, they should be able to carry on working as normal.

    If the WAN is restricted you may want to look at CAC to limit the concurrency of calls in the DR situation.

    If required, you can sit to SBA's on a single branch, but it adds management overhead, since a user can only be assigned to one SBA at a time.

    The thing to watch for is inbound calls, if these are on local branch ISDN and the gateway is down you will need to look to your carrier to redirect the calls.

    hope that helps

    Tom


    Tom Arbuthnot, Consultant Modality Systems
    Blog: Lync'd Up Blog Join over 300 UC Pros who subscribe for blog updates: Email or RSS
    Twitter @tomarbuthnot

    • Proposed as answer by Lisa.zheng Tuesday, October 9, 2012 1:52 AM
    • Marked as answer by Lisa.zheng Friday, October 19, 2012 2:32 AM
    Sunday, October 7, 2012 6:46 PM