Switched Ports

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Revision as of 23:31, 28 July 2006 by Rmc (Talk | contribs)
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With an older router, you can make for instance ports 3 and 4 to reside outside the router's NAT. Devices attached to these ports will request an own IP address from the ISP instead of getting a private IP address from your WRT. One might want to have such behaviour when having unsorted firewall issues with a SIP operator.

nvram set vlan0ports="1 2 5*" 
nvram set vlan1ports="0 3 4 5" 
nvram commit 
reboot 

According to the user reports, this is confirmed to work at least with a WRT54GSv1.1 after power cycling the router.

If you want to recover the default settings, write the following within ssh session:

nvram set vlan0ports="1 2 3 4 5*" 
nvram set vlan1ports="0 5" 
nvram commit 
reboot

The Port Numbering Explained

The numbers mean the following:

  • WRT54G v4 & WRT54GS v3
0  = port 4
1  = port 3
2  = port 2
3  = port 1
4  = WAN
5  = CPU internal
5* = CPU internal default
  • WRT54G v2/v3 & WRT54GS v1/v2
0  = WAN
1  = port 1
2  = port 2
3  = port 3
4  = port 4
5  = CPU internal
5* = CPU internal default

The variable vlan0ports equals to the natted LAN side. Correspondently vlan1ports refers to the WAN side, outside the router's internal NAT addressing scheme.

A little extra explanation regarding port 5: the switch that is built in to the router is a 6 port switch. The sixth port (numbered 5) is the only port not connected to an outside connector. Instead, it is directly connected to the et0 interface on the motherboard. Port 5 must be included on any VLAN that must be visible to the CPU. The asterisk (*) signifies that the VLAN it is attached to is the default VLAN: if the switch receives a packet on port 5 that is not tagged it is put into the VLAN where the * is configured. Always make sure this is vlan0.

The WLAN interface does not support VLANs. It is, however, usually bridged to vlan0.