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  • Isolating bad T1...how?

    I am an admin for a company with around 60 users, shoretel 6, around 4 ShoreGear24 voice switches and a pair of T1s in a single trunk group. Recently one of our T1s developed this really nasty signalling error where the D-channel will just drop out and then come back...which means that whichever call is on that trunk will just drop. Needless to say, having multiple users (some of which are sales folk) come up to you complaining about disconnected calls is...disconcerting.

    Now, since we have a pair of T1s I would like to send all voice traffic from the faulty T1 to the good T1, or until the bad T1 is fixed. The problem is that when I send the bad T1 PRI a command to put it out of service, I get no incoming calls at all. Doesn't the system load-balance so when one T1 is out of service, the other will take over? Or is this to be handled on the TelCo side?

    I am not a Telco engineer...I am the server support guy being shoehorned into this role due to staff attrition. What steps should I look into for troubleshooting this?
    Last edited by WANg; 08-29-2008, 08:35 AM.

  • #2
    Inbound routing is done on the telco side of the house. If telco is only routing calls on the first t-1 then when you put it out of service you have effectively stopped al inbound traffic. You need to get in touch with your carrier and find out how they are routing calls. If they are routing you inbound on both spans get them to put the first span out of service until the signalling issue can be resolved.

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    • #3
      Pri

      Are the PRI's at different locations?

      Teleman is on it. Inbound routing is done by the telco. I have never seen any sort of load balancing/fail over with PRI's like you are wanting for small business.

      The real question is why are the PRI's going down in the first place. They should be damn near rock solid.

      Outbound traffic should auto-redirect by the shoretel system. inbound you are hosed.

      When I have problems like you describe I....
      1. Call the telco and have them replace the smartjack - even if I have to pay for it.
      2. Have the telco do an end to end test (from your equipment, even using your patch cable) using a T-bird or test box
      3. Check the configs on the T1 shoretel switch - misconfigured settings can cause exactly what you describe..... intermittent slip/timing/signaling errors.

      can you post your t1 config?

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      • #4
        Originally posted by eazeaz View Post
        Are the PRI's at different locations?

        Teleman is on it. Inbound routing is done by the telco. I have never seen any sort of load balancing/fail over with PRI's like you are wanting for small business.

        The real question is why are the PRI's going down in the first place. They should be damn near rock solid.

        Outbound traffic should auto-redirect by the shoretel system. inbound you are hosed.

        When I have problems like you describe I....
        1. Call the telco and have them replace the smartjack - even if I have to pay for it.
        2. Have the telco do an end to end test (from your equipment, even using your patch cable) using a T-bird or test box
        3. Check the configs on the T1 shoretel switch - misconfigured settings can cause exactly what you describe..... intermittent slip/timing/signaling errors.

        can you post your t1 config?


        (Sorry, had to take the circuit ID and MAC addresses out. Security policy).

        Both T1 switches have the exact same configuration.

        In regards to the other questions - no, the 2 T1s go to the same physical plant, and the engineer that I took over from had no idea why there are 2 T1s going to the office...I guess that in case of one T1 falling over the other can be taken over with a single call to the Telco.

        Okay, now in terms of calling the Telco, will they be able to tell me how the calls are routed?

        If, say, I have PRI1 (which has a bad circuit) and PRI2 (which has an okay circuit), and PRI1 is the only trunk used for incoming calls, I can have the Telco route all calls to the other circuit so PRI2 is handling all calls, and then bring down PRI1, and all incoming/outgoing calls will work just fine -
        Is that correct?
        Last edited by WANg; 08-29-2008, 10:20 AM.

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        • #5
          I just had this same discussion with our AT&T rep today. It is called "overflow" in the AT&T world, and it costs an extra $5 a month. They are also looking into putting our two PRI lines into a trunk group to basically do the same thing.

          So to answer your question, yes, call the telco and tell them that you want all DID numbers associated with the bad PRI1 moved OR overflowed to the good PRI2. If you simply do an overflow, the calls will not overflow UNLESS the PRI1's channels are all full OR you physically take down the T1 (i.e. I'm not sure that simply putting your T1 switch out of service will be enough to tell the telco to overflow the calls to PRI2.)

          When you call, tell them this is an urgent issue and not to delay. They will drag their feet like they always do, so keep the pressure on.

          As for getting the issue resolved. I also had the same issue you described with one of my PRI's. I ended up swapping my two T1 voice switches with each other to prove that my equipment was not the bad equipment. You might want to try the same thing if it is easy (mine were in different buildings so it was a little time consuming, about 30 minute outage for our users.) After I did this, I began to hound the telco tech support because I all but proved that it was THEIR issue. Then I learned something special from the on-site telco guy. When you call the tech support, and they are dragging their feet, say "I want to speak with the escellation manager on duty" and then tell the manager you want the issue escellated immediately. Call them every hour on the hour and indicate you want the issue escellated again. Each time you call, ask them "what escellation level is this at right now?" to confirm that they did document the previous escellation. By bumping up your escellation level, it will make sure the telco company doesn't put your issue on the back burner.

          One other word of warning when dealing with the telco. You may get bumped between their T1 group and their PRI switching group. This is normal. The PRI switching guys will ask the T1 group to confirm their T1 build out is solid before they stop dragging their feet and make sure it is not their switching gear that is going bad! Took me a week to get them to finally realize they had gear going bad in the CO! Stupid AT&T...:alucard:

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          • #6
            Technically it is not a good idea to add multiple T1's to the same group for this very reason, it is very difficult to find as well as for troubleshooting.

            My suggestion is if it is a t1 and needs replace to recreate your Trunk Grps to be Two and make it cleaner

            You can run a qsig monitor from the command prompt and watch the qsig info.

            If the Carrier has done there job, theoretically you should be able to take all the channels out of service on the known bad T1 and all calls should fail over or follow the busy tot he next Circuit (If your carrier has done there job)

            If they are not then you will need them to remote forward or as bob said overflow that last Channel to the Next circut


            Also did you intentionally leave the MAC address off the T1 Swicth?

            if that is the way it is then your config is messed up, choose find Switch and match that MAC with what is on the back of the T1, this may be the source of your issue
            Attached Files
            Last edited by Jlorenz; 08-29-2008, 05:00 PM.

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            • #7
              Jon you mentioned "You can run a qsig monitor from the command prompt and watch the qsig info."

              Where is this qsig monitor? Is it on the Shoretel or is it software you have to purchase?

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              • #8
                Originally posted by Kennytlaloc View Post
                Jon you mentioned "You can run a qsig monitor from the command prompt and watch the qsig info."

                Where is this qsig monitor? Is it on the Shoretel or is it software you have to purchase?
                Command line form
                Shoreline Communications\Shoreline Server

                it runs under ipbxctl -sigmon <IP ADDRESS OF T1>

                You can run ipbxctl -sigmon for the command line options

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                • #9
                  Thanks very much.

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