kyodai
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AD Replication - SOmetimes getting "RPC server is unavailable" error
Hi there,
I have 2 Windows 2008 DCs in 2 different locations and I am often getting Replication errors from the AD replication, usually the typical "RPC server is unavailable".
I know this is easy to troubleshoot when it NEVER works, but here like 90% of the time it works and then again i sometimes have a situation where it can't replicate for a few minutes up to an hour. The weird thing is that even though I am getting the AD replication errors (RPC unavailable) i can PING, access shares, open RPD sessions and such between the 2 servers, so it's not like connectivity on that route is down or so. I'd also rule out the typical suggestions (Firewall blocks something, DNS problem, time synchronization) as it works like 90% of the time just fine. Any ideas what else i could try?
Neither DCDIAG nor REPADMIN have given any useful information. When the error occurs i can see the "RPC server not available" messages in REPADMIN but what puzzles me is that if the RPC service is really "dead" then i also shouldn't be able to get onto that machine via RPD or CIFS, but that always works fine, it's really just the AD replication that is having issues. DFS replication is also working fine, files in the DC SYSVOL get replicated instantly.
Any ideas or comments welcome!
I have 2 Windows 2008 DCs in 2 different locations and I am often getting Replication errors from the AD replication, usually the typical "RPC server is unavailable".
I know this is easy to troubleshoot when it NEVER works, but here like 90% of the time it works and then again i sometimes have a situation where it can't replicate for a few minutes up to an hour. The weird thing is that even though I am getting the AD replication errors (RPC unavailable) i can PING, access shares, open RPD sessions and such between the 2 servers, so it's not like connectivity on that route is down or so. I'd also rule out the typical suggestions (Firewall blocks something, DNS problem, time synchronization) as it works like 90% of the time just fine. Any ideas what else i could try?
Neither DCDIAG nor REPADMIN have given any useful information. When the error occurs i can see the "RPC server not available" messages in REPADMIN but what puzzles me is that if the RPC service is really "dead" then i also shouldn't be able to get onto that machine via RPD or CIFS, but that always works fine, it's really just the AD replication that is having issues. DFS replication is also working fine, files in the DC SYSVOL get replicated instantly.
Any ideas or comments welcome!
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ASKER
OK, what i found out so far is i can only replicate in one direction, from Server Berlin to Server Cologne. If i try to replicate the same context from Cologne to Berlin i get the "RPC not reachable" error. So far i have refrained from posting any error logs as we unfortunately have German versions of windows installed, so all errors are in german.
But on an attempt to replicate from Cologne to Berlin i get the notorious 1722 - The RPC Server is unavailable.
I have gone through that microsoft article and no relevant errors so far.
I tested the ports with PortqueryUI and the strange thing is that in both directions PortQueryUI gets the AD info fine via TCP 389 and 3268 and shows the information correctly.
What is a notable failure though is that UDP on port 389 fails from cologne to Berlin - the direction in which replication is not working. So this might be the cause of the error i think, at least thats the only thing i observed. Our network admin says all ports are open and i already rebooted the machine. Is AD replication "sometimes" using UDP and "Mostly" TCP? That would explain why it "sometimes" doesn't work...
But on an attempt to replicate from Cologne to Berlin i get the notorious 1722 - The RPC Server is unavailable.
I have gone through that microsoft article and no relevant errors so far.
I tested the ports with PortqueryUI and the strange thing is that in both directions PortQueryUI gets the AD info fine via TCP 389 and 3268 and shows the information correctly.
What is a notable failure though is that UDP on port 389 fails from cologne to Berlin - the direction in which replication is not working. So this might be the cause of the error i think, at least thats the only thing i observed. Our network admin says all ports are open and i already rebooted the machine. Is AD replication "sometimes" using UDP and "Mostly" TCP? That would explain why it "sometimes" doesn't work...
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ASKER
It looks like this is not really a windows issue but rather a network issue. I will still give points to all of you for your most helpful suggestions.
ASKER