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ivwildbilFlag for United States of America

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Problem Connecting to some computers on a different subnet

Our VoIP and corporate networks are on seperate subnets.  We are having a problem with our VoIP server connecting to the Exchange server.  We can ping through from one subnet to the other from the routers and from the VoIP to the DC on the corporate side and vise versa but no other servers on the corporate side will talk with the VoIP server.  This was working then and there have not been any changes to routing or major changes to the serverr
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cmarandi
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How is your DNS setup?  Is there a forwarder on the DNS for each subnet?  

WINS running anywhere?  Maybe on one subnet and not the other, therefore causing DNS on one subnet to purge records because of decay.
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Name resolution is working fine.  The VoIP server is using one of the DCs for DNS resolution.
Switch configuration... Are you using a managed switch?  On my managed switch I control the traffic types going between the two subnets... for example no icmp.
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ivwildbil
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Kind of an odd question:
Did you recently introduce a 2003 R2 DC where you had to upgrade the active directory to 31?
Could this be a Netbios issue??

Netbios broadcasts are not routeable, meaning it will not propogate over different subnets, through a VPN tunnel or across NAT.

Wins is routeable and can be used to bridge the two subnets. All you need is a WINS connection between your PDCe (as the domain master browser) and a server on the other side (as a master browser for that subnet).

I have seen netbios broadcasts work for a while, then just die for no appearant reason.

Here is a good article that explains the Browser service:
http://www.microsoft.com/resources/documentation/windowsnt/4/server/reskit/en-us/net/chptr3.mspx?mfr=true

I'm still baffled as to why it would suddenly change... That's why I was asking about the R2... When you introduce an R2, you have to upgrade the AD to 31 which changes the domain name scheme to must have the .com
So I wonder if a schema changed that is causing the VOIP to not communicate with the domain properly.
R2 was not recently changed and there have been no major changes to AD architeture.
No changes on Exchange?   Can you make sure the VOIP is configured properly and is using the correct Exchange settings?