Routing between VLANS

Posted on 2004-09-18
Last Modified: 2010-04-17
Ok Here is the scenerio,
I am converting a school from a flat class c public IP range to a vlan'd private IP setup. I am using a cisco 3600 router to do my routing between vlans. To try and minimize the impact to the school I am trying to do a phased conversion. I have configured my sub interfaces on my router fastethernet port in the following manner

ip address 204.xx.xx.65
ip adress secondary

ip address


I have additional entries such as the dhcp helper address and on my dhcp server I have the default gateway for the subnets set to the ip address on the sub interface.

On the 204.xx.xx.xx network is a server that I have shares setup on for an eduactional program.

The issue is once I place the ports in the new vlans I get my ip address, gateway information and dns and wins servers information on the client ok but when I try to browse to the shares on the server in the 204 network I cannot see them. I have to manually put in the 204.xx.xx.65 gateway address on the client in the 10.xx network to see the shares,which tells me I have a routing issue. but not sure where to go from here?

Thanks for your help
Question by:Mavant
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LVL 79

Accepted Solution

lrmoore earned 500 total points
ID: 12093261
Make sure that the port connecting the switch to the 3600 is a designated trunk port.
Set the encapsulation and vlan assignment on each sub-interface:

fa 0/0
  ip address 204.xx.xx.65
  ip address secondary

fa 0/0.10
  ip address
   encapsulation dot1q 10

fa 0/0.11
  ip address
   encapsulation dot1q 11

Notice that VLAN 1 gets attached automatically to the major interface without specifying encapsulation or vlan.
LVL 79

Expert Comment

ID: 12093283
Your routing issue may be the other way 'round. What is the default gateway of the server on the 204.x.x.x subnet? Does it point to the router .65?

Do you have a WINS server set up? Are the clients pointing to it? If not WINS, how about DDNS, and are the clients set to "register this connection in dns" ?

You can alternatively enable netbios broadcasts through the router/vlans:
Global config commands:
  ip forward-protocol udp 137
  ip forward-protocol udp 138


Author Comment

ID: 12093352
Thanks I will give this a try and let you know tomorrow.
LVL 11

Expert Comment

ID: 12099035
If you can get to the shares by entering the address manually, then you do NOT have a "routing issue" -- routing is working.

What you have is a "name resolution" issue -- the processes that convert a hostname to an address are not working.  These typically include:

1.  DNS

2.  Broadcast -- default for Windows file sharing, doesn't traverse routers....

3.  WINS -- Windows solution that DOES traverse routers....


Since this problem is showing up when you insert the router between the VLANs, I would look at #2 and #3 and guess that you don't have WINS set up anywhere.


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