On Wed, 15 Jun 2011 22:27:35 +0100, Toby <(E-Mail Removed)>
wrote:
>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!?
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.
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