Vonage/PAP2/Switch problems

Discussion in 'VOIP' started by Dan M, Oct 25, 2005.

  1. Dan M

    Dan M Guest

    Not so much a problem as a curiosity. I'm hoping someone has seen this
    before and knows why it happens.

    At the office we've got a 7 MBit connection coming in from Nexweb. The
    incoming connection goes to a 10/100 switch (let's call it switch 1). One
    port of switch 1 goes to a WiFi router which also provides DHCP service
    for devices connecting to it wirelessly devices connecting through the
    rear-panel ethernet switch ports. One of the ethernet ports on the back of
    the WiFi router goes to another 10/100 switch (let's call this one switch

    If the PAP2 is connected to a port on switch 1 all works as expected. If I
    plug it into a port on switch 2 the ethernet light never lights and the
    power light keeps flashing in it's one-two pattern that says it's
    rebooting (or acquiring a signal or whatever the heck it's doing). If I
    plug it into one of the ethernet ports on the back of the WiFi router, it
    functions normally.

    So the summary is: plugged into a switch one hop from our net connection:
    works. Plugged into WiFi router two hops away: works. Plugged into switch
    three hops out: doesn't work.

    The solution for now is obvious: plug into switch 1. But I'd like to
    understand *shy* it doesn't work when plugged into switch 2.

    And ideas?
    Dan M, Oct 25, 2005
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  2. Dan M

    NewMan Guest

    Firstly, if you are really using a true "switch", then there is no
    "hop". Or more precisely, a "switch" will not increase the "metric".

    A "hub", on the other hand, DOES increase the "metric", and could lead
    to the problem you describe.

    The other thing to check is the specifications on your "switch #2",
    and double check the cables you are using. Some siwtches, like the
    Linksys SD2008, are very advanced and do not care what kind of cables
    are used. Switches like the SD2008 will automatically adjust
    operations to compensate for "straight through" and "cross-over"
    cables. This is very useful because you just use what you have, plug
    and play - no problem. But older switches usually require that
    straight through cables are used. Cross-over cables should only be
    used for things like uplinking to other equipment.

    So check your specs and your cables. Make sure that everything is
    connected properly. Your switch #2 should be connected to the wifi
    router through the uplink port. If not, you may have to use a
    cross-over cable and one of the regular ports. Some routers and
    switches actually had a physical switch on them to change the
    crossover function. You may have to change the position of the
    function switch (I had one of these pesky things on a hub once - pain
    in the neck). If there is an "uplink" port, then use of it usually
    precludes the use of one of the other ports (often port 1).

    Download the manuals, read'em, and check those cables. This is my bet.

    Personally, I think the PAP2 is a piece of junk. This was the first
    VOIP interface that my provider sent to me. It did not work properly
    AT ALL. It constantly screwed up, and had to be reset. To the point
    that I had to reset it before I made a call. I had two lines on it.
    You are supposed to be able to use them both simultaneously, but with
    the one I had - NO WAY. If one line was in use, the other would not
    call out or permit a call in. Even then, after calling on one line,
    you had to unplug the power to reset before you could make a call on
    the other line! That damn PAP2 almost cost my provider my business!

    And I tried EVERYTHING. I am also a network sysadmin, so I know my
    plumbing. lol. I finally got a switch, and activated a second IP form
    my ISP - just to show my provider that is was NOT my hardware.

    I insisted on getting a different box - so they gave me an RT31P2-NA.
    This box works just fine. I have noted that sometimes my service does
    not work as expected. What they told me is that they change config
    files from time to time, and that sometimes it takes a while for the
    VOIP box to reload the information. I can - and do - force the
    situation by powering down the box, letting it sit for 5 min, and then
    powering up again. I now do this every couple of days, and I have had
    NO problems with the service since.

    VOIP has a LONG way to go, but it still saves me money. :)

    NewMan, Oct 26, 2005
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  3. Dan M

    Dan M Guest

    So check your specs and your cables. Make sure that everything is
    I'm pretty sure that the cables are all appropriate. I've got a couple
    dozen PCs also plugged in to switch #2 and they all work fine.

    I realize that using switches won't actually increase the real hop count
    - that was just my clumsy attempt to quantify how many active devices we
    were connecting through :)

    So the mystery is, PCs connected to switch #2 operate great, but the PAP2
    connected to the same switch doesn't. It doesn't even activate the link
    LED on the front panel. I guess that will remain a mystery for a while.

    Thanks for the response!

    Dan M, Oct 26, 2005
  4. Dan M

    NewMan Guest

    What happens if you plug switch 2 into the internet, and plig the PAP2
    into switch 2???

    You may want to get your voip provider to configure your PAP2 with a
    static address for your LAN. Then you can enable that address for the
    DMZ. This might help.

    Let us know how it goes.
    NewMan, Oct 26, 2005
  5. Dan M

    wkearney99 Guest

    At the office we've got a 7 MBit connection coming in from Nexweb. The

    Sounds like you've got things in a bit of a rats nest. Why are you daisy
    chaining switches this way? Why aren't the Wifi router and "Switch 2" both
    connected to the incoming 10/100 switch? No sense in layering things more
    than is necessary.

    How many devices do you have on this network? Most low-end Wifi routers are
    really not up to handling more than a dozen lightly-used computers. Their
    onboard packet handling really can't keep up. No, it's not merely about
    having the ports, it's about having enough CPU in the devices to properly
    handle the load.
    So why not leave it there? It's potentially a high-bandwidth device.
    There's little sense in putting it further 'downstream' from the actual
    internet connection. You just overload the other switches passing along
    traffic that doesn't really need to go through them.
    Sounds like it's a cabling issue. Probably straight-through versus

    Flatten the network and don't chain devices any more than necessary. It's
    probably better to have more ports on the immediate connection, switch 1,
    and then into that. Instead of into switch 1, then into the wifi router and
    then to another. Ethernet does have restrictions on how many packet hops
    are tolerated within a subnet. That may be at issue here but it's more
    likely a load issue.

    -Bill Kearney
    wkearney99, Oct 27, 2005
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