General Networking, clients seeing two seperated VLAN'ed network

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Guest

Hi,

I probably shouldn't have posted this question here, but it seems to me that
the people who take the time here to help others would be by far the best
place to start with my question.

I am currently looking after a school's network which contains two seperate
VLAN'ed networks, one for admin staff and one for curriculum users. For
reasons unbeknown to himself, the previous administrator set the network up
to utilise one 2003 server which both networks share as a DC, query for DNS
and WINS. The school also only has one domain name between both networks
which may not be a really bad thing, but its a single label domain name.

A few months ago the network went down completely, the problem being traced
to a loop in one of the switches, ever since that problem I occasionally log
onto the curriculum network, do a net view and find that I can only see the
other VLAN. I cannot actually access any of the computers on that network
(apart from the DC and file server) but I can still ping hosts on the same
network and my IP settings are correct. I have also gone around and checked
the VLAN memberships on all ports and everything is as it should be (working
from the previous administrators documentation).

The finger seems to be pointing at a looped network cable going from one
switch to another (VLAN to VLAN), but Im not totally sure...does anyone have
any suggestions as to how I should proceed wiht this before I go around and
check every cable runa nd patch lead? I have tried using GFI LAnguard to see
if that would shed any light and I have also tried using a Fluke network
analyser but that didnt show anything up either.

I would be very grateful if someone could help a Brit in need, even if he is
posting in the wrong group!!

TIA,

Kermitdafwog
 
P.S. I forgot to mention that this happens sporadically, once minute Im
seeing one network, the next minute its back to normal. This also happens on
the DC (which has 2 NICs for either network), occassionally I can only see
one side of the network (always the Admin side) and then suddenly 5 minutes
later evrythings back to normal!! This especailly is causing hassle when
manually updating Antivirus software through a central console.....I cant see
half of the hosts to patch them up!! :-)

Cheers,

Kerms
 
Thanks for your response.

That is no doubt how the network should be setup, but unfortunately for me
it isn't and I have no budget to go buying new hardware or to make large
configuration changes. We know that the network isnt very secure the way its
set up, but up until a few months ago the network was running fine. Even
this problem doesn't cause a huge inconvenience, I would just like to know
what caused it to occur.

Do you think that it would be possible to setup a win2k server as a router
to achieve what you suggest? (If so, how could I go about this with the
minimum of fuss and disruption?

I hope you can help.

Many thanks,

Kermy

Phillip Windell said:
Run one Nic in the server. The server should exist on only one network
segment. Routers are used to move traffic between network segments.

272294 - Active Directory Communication Fails on Multihomed Domain
Controllers
http://support.microsoft.com/default.aspx?scid=kb;en-us;272294

191611 - Symptoms of Multihomed Browsers
http://support.microsoft.com/default.aspx?scid=kb;EN-US;191611

--

Phillip Windell [MCP, MVP, CCNA]
www.wandtv.com


Kermitdafwog said:
P.S. I forgot to mention that this happens sporadically, once minute Im
seeing one network, the next minute its back to normal. This also happens on
the DC (which has 2 NICs for either network), occassionally I can only see
one side of the network (always the Admin side) and then suddenly 5 minutes
later evrythings back to normal!! This especailly is causing hassle when
manually updating Antivirus software through a central console.....I cant see
half of the hosts to patch them up!! :-)

Cheers,

Kerms
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