How do I configure configure the switch to allow the wifi router through the netowrk?

Posted on 2008-10-25
Last Modified: 2012-06-21
Hello Everyone,

Here's my dilemma, my company would like to give its clients access to the internet through a linksys Wifi router (WRT54G). I don't want to give them access to the corp. network for security reasons but I would like them to be able to access the internet, I'm looking for more of a pass-thru type of setup.

I'm a newbie to switch configuration, as mentioned the switch im dealing with is a Netgear GS7245T I'm not exactly sure where i need to add the IP address of the router to allow this type of access.

The router itself is setup and ready to go, I can connect to it wirelessly but can only gain access locally, as in the corp LAN.

if it helps this is my setup,

wireless connection connected to a Cisco 2600
connected to a Cisco 1700
connected to a Netgear GS724T switch
Question by:chris_irvine
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Accepted Solution

pit1140 earned 500 total points
ID: 22804706
This is a common setup.

If you have more than one static ip address you may buy a second WRT54G; you connect both to your uplink and use different subnets; ask your provider to set the ports not seeing each other too.

A better approach would be VLAN, see

You may flash your Firmware on the WRT54G to some open source software. they may have a ready-to-go-software-solution for free. for example: dd-wrt, open-wrt, tomato, see:

LVL 23

Expert Comment

ID: 22804833
Is the netgear plugged into a Cisco 1700 and the WRT54G plugged into the netgear?

I think the goal should be to configure the NETGEAR as a VLAN switch.

Make sure the netgear is equipped with recent firmware and has 802.1Q VLAN tagging capability.
Then create a new VLAN using an unused VLAN number for the WRT54G using the webui and assign the switch port to the vlan.

Next is the hard part...  you need to provide a connection between the WRT54G and the  1700 or 2600 router  that is connecting you to the internet.

It is good if you can provide this routing on a device outside any internal firewalls.

You need a connection between an interface on the routing device and a port on the netgear switch with access to the VLAN that the 54G is on.

If your router has many independently routable ethernet interfaces (i.e. Ethernet0, Ethernet1, and Ethernet2/0), then you can run another cable between your router and the netgear,   and configure the new interface on the router with a different subnet (that the 54G is to use).

A better solution (which is not available on 10 megabit  normal ethernet interface),
only on FastEthernet, if both devices support  802.1Q  VLAN Tagging on the ports being plugged on both sides,
you can avoid the need to run extra wires for each new security domain.

What this means if you are not using VLAN 802.1Q tagging already...
is you take down your internet connection
(make sure you can rollback all changes if at any step you determine you cannot proceed...   depending on your exact hardware,  there may be difficulties,
I.E.  backup all configs first):

Change the configuration on the router.   Remove IP addresses the simple "FastEthernet0" or "FastEthernet0/0"  interface
direct the router to use 802.1q  encapsulation on that interface,
and then create a  subinterface for each VLAN  
interface FastEthernet0
  ip address
interface FastEthernet0
   no ip address
interface FastEthernet0.1
    ip address
    encapsulation dot1Q native 1
    ! you essentially move the IP and much other logical config to this above interface
interface FastEthernet0.10
    ip address
    encapsulation dot1Q 10

! To use (for example) have vlan1 as one network and vlan10 as another....

Then on the switch,  change the port the router is plugged into from being a normal access port   to being a VLAN tagged port,  also sometimes called trunk port
(but netgear may use the term 'trunk' to refer to something completely unrelated).

And set the   default vlan  or native vlan for the port on the Netgear side  to
match the  VLAN you have chosen as being "NATIVE"  on the router side of the 802.1q link you created.

When you are successful,   internet connectivity for the rest of your hosts should work, you should be able to ping the internet.

A laptop plugged into the port assigned to the "linksys"  VLAN  and assigned an IP in the proper subnet should be able to ping the VLAN interface on the router.

But it should not be able to ping other devices on your network, even if you change its ip to be in your normal subnet.

Once you can verify that much,  setting up internet connectivity is a matter of getting your router to handle the situation.

Most likely you will need NAT rules and "ip nat inside" on the  tagged subinterface.

Another possibility is if your provider  gives you a public ip range to use, you can apply that instead.

Or perhaps your NAT will be handled by a different router, and in that case, it only needs to be updated to accept the additional range used by the linksys and know what to do with traffic destined for the new private IP range.


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