Inter VLAN Can't Join Domain

Unanswered Question
Aug 17th, 2009

Hi All Pros,

I am just wondering if anyone faced this issue before where a host in another VLAN is unable to join Ms Windows domain which is in another VLAN? It does not have any access list because both are connected to the same switch (C3560). InterVLAN routing already enable. We have tested telnet to most of the ports involved in Active Directory from one host VLAN to Server VLAN. Server team checked that the Domain Controller and DNS is running FINE. Now we are stucked in between, not knowing what is the problem.

Host in VLAN 211 just unable to join domain to Server in VLAN 214. But host is able to join when in same VLAN 214.

Your help is very much appreciated.

I have this problem too.
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Giuseppe Larosa Mon, 08/17/2009 - 07:35

Hello Chow,

try the following

int vlan 214

ip helper-address AD-server-ip-address

the difference when in the same ip subnet is that server can be discovered with a broadcast

Hope to help


derict Mon, 08/17/2009 - 18:10

Hi Giuseppe,

The DHCP server is actually not in the Domain Controller. There is one WLC in the network working as DHCP for the entire network.

We have tried setting all IP in VLAN 214 or 211 manually to host but still not able to join domain.

derict Tue, 08/18/2009 - 00:46

All connected through LAN... There isn't any client in VLAN 214 ...We only did it for testing purpose..

derict Tue, 08/18/2009 - 08:17

yes, PING and TELNET is working from VLAN 211 to VLAN 214..

Mohamed Sobair Tue, 08/18/2009 - 08:46


If hosts on vlan 211 able to ping hosts on vlan 214, then this is probably LDAP Protocol issue.

Could you confirm that port 389 TCP is not blocked any where?



derict Tue, 08/18/2009 - 19:36


There isn't any access-list that block inter Vlan communication. However, I will try to do a telnet from VLAN 211 to DC through TCP 389 ... but i think if the DC is listening to this port, it shouldn't be any problem.

derict Tue, 08/18/2009 - 22:41

ok, i've tested and we are able to telnet from 211 to DC through TCP 389 ...


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