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Hi, I manage (for heritage purposes, not because I want to) a CentOS-based billing router for a resort; the router manages a network of 40 guest rooms and conference rooms, ...
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  1. #1
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    DHCP Issues?


    Hi,

    I manage (for heritage purposes, not because I want to) a CentOS-based billing router for a resort; the router manages a network of 40 guest rooms and conference rooms, managing client connections and monitoring usage and billing for it. The customer has recently complained about excessive slowness in response when managing the accounts on the system via a web interface (apache/php/pgsql). I don't see much unusual activity via top.

    The router was originally designed in the days before ubiquitous smart-phones and tablets, and it made me wonder about DHCP activity: what I found is lots of current DHCP leases (see the attached file)dhcpd.leases.txt.tar.gz; I also checked /var/log/messages, which was overflowing with DHCP traffic (see the attached file)dhcp_traffic.txt.tar.gz.

    I'm wondering whether this sort of DHCP traffic is normal in a such an environment, if it could be the cause of the perceived slowness, and - most important, what to do about it?

    --

    Regards,
    Edwin Humphries

  2. #2
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    Sounds like a problem with the database.

    Set up a test webpage that doesn't access the db and see how fast the server responds. If the page responds fast, then it's most likely not network/apache related. Databases grow in size over time, so my first guess is you've got some slow lookup in you're database/web software.

  3. #3
    Linux Engineer docbop's Avatar
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    Quote Originally Posted by mizzle View Post
    Sounds like a problem with the database.

    Set up a test webpage that doesn't access the db and see how fast the server responds. If the page responds fast, then it's most likely not network/apache related. Databases grow in size over time, so my first guess is you've got some slow lookup in you're database/web software.
    I agree and mysql isn't great how it manages storage space and sometimes it's worth getting a good database dump, then deleting and reloading the database. It will get you drive space back and tighten up the database itself. Our developer databases were always in better shape because they were daily dumps and reloads of the production DB so we saw the advantage daily.

  4. #4
    Linux Guru Rubberman's Avatar
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    1. The router is configured to lease addresses for a week (7 days). Reduce this to one day. That will keep the addresses from overflowing the 254 current lease limit for your subnet.
    2. See #1.

    This has nothing to do with the database that I can see, but your subnet has, as mentioned in #1 above, a 254 device/lease limit. If you have a lot of traffic (even with 40 rooms, you can easily get 254 dhcp connection requests per week), then limiting the lease time is critical. If this is still a problem, then you might want to check into routers that allow more address space for the local network. IE, some will allow up to 64K addresses. These are higher-end routers/dhcp servers, but may be needed given your conference center activities. Your clients will have phones, laptops, tablets that all will want to connect to the local network. The one day lease limit may help with this.
    Sometimes, real fast is almost as good as real time.
    Just remember, Semper Gumbi - always be flexible!

  5. #5
    Linux User Steven_G's Avatar
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    Quote Originally Posted by Rubberman View Post
    1. The router is configured to lease addresses for a week (7 days). Reduce this to one day. That will keep the addresses from overflowing the 254 current lease limit for your subnet.
    2. See #1.

    This has nothing to do with the database that I can see, but your subnet has, as mentioned in #1 above, a 254 device/lease limit. If you have a lot of traffic (even with 40 rooms, you can easily get 254 dhcp connection requests per week), then limiting the lease time is critical. If this is still a problem, then you might want to check into routers that allow more address space for the local network. IE, some will allow up to 64K addresses. These are higher-end routers/dhcp servers, but may be needed given your conference center activities. Your clients will have phones, laptops, tablets that all will want to connect to the local network. The one day lease limit may help with this.
    Agreed.

    My wife is the manager of a small hotel. She gets the IT work dumped on her. She had a similar problem with an old monster system; the above solution (limiting lease time) sped her customers throughput up significantly.

  6. #6
    Linux Guru Rubberman's Avatar
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    Glad to be of help.
    Sometimes, real fast is almost as good as real time.
    Just remember, Semper Gumbi - always be flexible!

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