National Ethernet from Virgin Media

Discussion in 'Network Routers' started by Toby, Jun 15, 2011.

  1. Toby

    Toby Guest

    I wonder if anyone can possibly help me here - Virgin Media are looking
    into it, but have not solved it yet..

    Sorry it's long...

    We have just had two LAN extension circuits installed between three of
    our offices, A, B and C (We are waiting for two more to complete installing)

    A is the head office, and two lines come out of this office, one to
    office B and one to office C.

    They are presented as Ethernet ports to us, and when we ordered them,
    were told they act like a really long Ethernet cable between to sites.

    These circuits are simple point to point private circuits, nothing fancy.

    Office A and B are talking to each other fine, there is an Ethernet
    cable between one of the switches in Office A, connecting to the RJ45
    port of the Virgin Media NTU in port 1 (Labelled as the name of office B)

    At the other end, in office B, another Ethernet cable connects from that
    NTU into the local network switch, so office B appears as if it is part
    of office A's network, and all the machines at office B get their IP via
    the office A's DCHP server (There inst a server there, just PC's,
    printers and a NAS drive for backups from office A)

    So far, so good.

    If we do the exact same set-up with office C, it works in the same way.
    (An Ethernet cable patched between the switch in Office A and port 2 of
    the Virgin media supplied NTU)...

    .....but it will only work when we disconnect the cable to port 1 in
    office A, that feeds office B.

    If we plug in office B (port 1 of the NTU in office A) we lose
    connectivity to office C (I connected up the Ethernet cable between the
    switch in office A and port 2, then drove over to office B, plugged in a
    laptop to the other end, and could not get an IP address, and after
    setting one manually, could not ping a server in the other office.

    I then asked someone in Office A to unplug the cable in ports 1 (going
    to office B) - still nothing, then I asked them to unplug port 2 and
    plug it back in again - I could then ping a server in office A, and get
    an IP address via DHCP).

    As soon as the cable was plugged back into port 1 in office A
    (reconnecting office B), the pings stopped from office C.

    If Office A and B are talking to each other, the NTU in office C is
    connected to the local switch and I connect a laptop to port 2 in office
    A, that works fine, I can see the local network in office C, and get an
    IP address from the DHCP server there (Which will be disabled when the
    new circuit is working!).

    It is only when port 1 and 2 of the NTU in office A are both connected
    to the local network at the same time, it doesn't work (Even if I
    connect them to different switches (on the same network)).

    The Virgin Media supplied NTU in office A is large 24 port World Wide
    Packets Lightning Edge unit, I am not sure of the model at the moment,
    but can find out tomorrow, it think it may be an LE-311.

    The NTUs in office B and C are World Wide Packets Lightning Edge 46's

    I can't see that I am doing anything wrong here - the guy at faults
    couldn't explain it, but they are looking into it (I won't hold my breath!)

    We are keen to get this working, as office C is on an old, crappy 2mb
    copper circuit that is part Virgin and part BT, which hasn't proved to
    be the most reliable of circuits...

    Any ideas!?
    Toby, Jun 15, 2011
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  2. Toby

    Char Jackson Guest

    I don't know but I assume someone will be along who does. It looks to
    me like the NTU's in B and C are configured identically to each other,
    when they should be configured slightly differently from one another
    so that A can talk to both of them without getting confused.

    Alternatively, the NTU at A is configured to only talk to a single NTU
    (which can be at either B or C, but not both).

    Either way, you can't do anything about it on your own. Virgin will
    need to clean up the provisioning of one of the NTU's at either B or
    C, or at A, depending on the specific problem.

    I could well be wrong, so please post back when you find the solution.
    Char Jackson, Jun 16, 2011
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  3. Toby

    Toby Guest

    After getting second, then third line support on the case, it was
    because spanning tree was enabled on their NTU...

    The disabled it, and all is now well!

    I assume the NTU saw it was connected to the same network twice, and
    decided to disable the second port automatically.
    Toby, Jun 17, 2011
  4. Toby

    Char Jackson Guest

    That would certainly explain it. Thanks for following up.
    Char Jackson, Jun 20, 2011
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