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  • Connecting Users to iSeries

    I?m not too sure this is the correct area to post this type of question as it is network related, but I?m hoping you guys can help anyway.

    One of our clients wants to save on network costs and move from a fixed point to point (2Mb) link from their network to ours to a public internet routed VPN connection.

    I?m not a network guy but this seems to me to be a potential for increased latency, and reduced response times due to the additional routing that is likely to over the public internet plus the higher contention ratio that is likely to be on the line over a direct site to site.

    Having said that the likely hood is that we would allocate 5Mb for the VPN tunnel at our end.

    The question I have is two fold, one am I worrying unnecessarily, they would after all only be using standard iAccess for Windows sessions for 5250 emulation. There is spooled data produced and sent to remote writers (physical printers on their network).
    There is generally an average of 50 ? 60 concurrent users and their workload is predominantly interactive, although a few functions do submit batch jobs.

    The second question is, does IBM publish a minimum specification of line or network that should be used for iSeries access workloads? If so can anyone point me in the right direction please?

    The problem is I don?t have any information to go back to the client to advise either way as to the legitimacy of their plan.

  • #2
    Re: Connecting Users to iSeries

    If your client was on a 2MB (I'm guessing T1 connection?) from their site to yours and you are going to now be allocating 5MB for the new VPN tunnel I'm thinking that you shouldn't have any bandwidth issues. I can connect to our network via VPN from home over the internet and while there is, at times a bit of latency (hardly noticeable ever) for the most part is very stable. Now, your connection will not be quite as stable, but it should not have real latency issues. Once you start using the internet at large as part of your network you can have stability issues.

    I would say that its worth giving a shot. If it doesn't work out, you can always go back. Have them keep the 2MB connection available in case of emergency for maybe a month or so until you guys see how its going to work out. That way you can always switch back and search out other avenues if necessary.
    Your future President
    Bryce

    ---------------------------------------------
    http://www.bravobryce.com

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    • #3
      Re: Connecting Users to iSeries

      Yep, it is currently T1. My manager is currently saying that the pipe allocation will be 5MB but when he sees the revenue slow due to not being able to charging for their line provision and or management, I can see that tunnel being throttled back to 2MB max.

      It is the latency that worries me as I am assuming that the contention ratio of the connection is going to be higher than the current site to site.

      Currently the client can’t use the connection for any other purpose than the iSeries traffic, I am again assuming that they will be using the connection they have to the public internet for their email and company internet traffic as well as the private VPN to us.

      I can foresee their iSeries users blaming our application or our iSeries for poor response times or instability of their sessions.

      However I might just be paranoid.

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      • #4
        Re: Connecting Users to iSeries

        No, you aren't just paranoid. You are correct, the users will blame you most likely. That's the way it is on this platform. They can't imagine that the big cool interwebs could be the source of their issues....

        Little anecdote for you....
        We have HA setup for our production machine. Our HA box is located 200 miles away from us. We used to have a T1 line that we pretty much pegged full time. Our maximum vulnerability window was about 7 hours at one point due to the journal entries just not being able to get through the saturated pipe. Then the network guys decided that instead of spending more money on a T3 connection we would just go through a VPN internet connection. Now our maximum vulnerability window is maybe 2 or 3 hours and that is only after night processing.... however, we do drop our connection between the boxes (albeit for only a few seconds, if that) a couple times a day because sometimes traffic just doesn't work very well out in cyber space.

        I'm guessing that if your VPN connection hardware/software on the network side is robust enough to handle the number of concurrent connections you should be fine. There will be times when things won't be as snappy, but that might be acceptable when you look at the amount of money you save. I'm guessing they'll be going from about $1500/month to maybe $100/month???
        Your future President
        Bryce

        ---------------------------------------------
        http://www.bravobryce.com

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        • #5
          Re: Connecting Users to iSeries

          Being a service provider, it is actually possible we will see a revenue drop and the client will save money, well on paper. Lost productivity might be a hidden cost. However, the reason for the question isn't to justify a revenue stream, it is just to guard against a change in connection method ending in our core servic provision seen in a bad light through no fault of the service.

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          • #6
            Re: Connecting Users to iSeries

            Although a good reason to keep both connections going for a while is to ensure a smooth transition, I would also use it to show that latency issues are due to the new connection, and not the system.
            Michael Catalani
            IS Director, eCommerce & Web Development
            Acceptance Insurance Corporation
            www.AcceptanceInsurance.com
            www.ProvatoSys.com

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            • #7
              Re: Connecting Users to iSeries

              And, if you find that latency is an issue, you could set an official company policy that the recommended method is via a direct T1 connection, not VPN. So when they complain you can point to that piece of policy and say... we told you this could happen, here is how to fix it.
              Your future President
              Bryce

              ---------------------------------------------
              http://www.bravobryce.com

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              • #8
                Re: Connecting Users to iSeries

                Thanks for the replies guys.... some sensible suggestions and pointers. We will keep the direct link going for a couple of months and take on board the point about needing to get a policy in place for these connections.

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                • #9
                  Re: Connecting Users to iSeries

                  If the only thing the VPN clients will be running is 5250 emulation, it will be fine running over VPN provided there is enough bandwidth to handle the number of people that will be using it.

                  How many users we talking about at one time? 5MB is a hefty pipeline and should perform reasonably well.

                  -John Andersen
                  Introducing The IBM i and AS/400 Training That 100% Guarantees You Will Learn Key Administration Tasks...

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                  • #10
                    Re: Connecting Users to iSeries

                    i would like to personally thank you for all of the zombie threads....
                    I'm not anti-social, I just don't like people -Tommy Holden

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                    • #11
                      Re: Connecting Users to iSeries

                      Can you throw QoS on the VPN?

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