Cisco 520 % IP addresses may not be configured on L2 links.

[richarddowna]

Hello !

I purchased a Cisco 520 and am trying to set it up on my home network.

Its ADSL PPPoA for WAN.

I am trying to setup 2 LANS.

One General Network

One DMZ for webhosting.

Now, since this router has 4 ethernet ports, i assumed i did not need VLANS.

Except when i try configure an interface with an IP address i get this error:

% IP addresses may not be configured on L2 links.

Now. Ive looked around on the internet about this error. And it seems that since these interfaces are not Layer 3 interfaces,

they need to be associated  with VLANS.

This would be OK. Except this requires an IP address on an interface on the router! Back to square one!

This is how I would normaly do it:

conf t

vlan 10

ip address 192.168.2.0 255.255.255.0

conf t

int fa0

switchport mode access

swtchport access vlan 10

Now the problem with this is, what would be the default gateway of the connecting device?

My understanding is that the ethernet port needs an ip address for example 192.168.2.1

Any help would be greatly appreciated!

[cadet alain]

Hi,

conf t

vlan 10

ip address 192.168.2.0 255.255.255.0  <----- This is not an host ip address but a subnet address so the Cisco device won't let you enter this.

what would be the default gateway of the connecting device? 

the address of the Vlan interface you configured. By default they are all members of  Vlan1.

My understanding is that the ethernet port needs an ip address for example 192.168.2.1

this is true for a L3 port but not for a L2( switch) port. These 4 ethernet ports are switch ports.

Regards.

Alain.

[richarddowna]

So would i be correct in setting it up like this: ?

conf t

vlan 10

name general

ip address 192.168.10.1 255.255.255.0

exit

vlan 20

name DMZ

ip address 192.168.20.1 255.255.255.0

exit

int fa0

switchport mode access

switchport access vlan 10

int fa1

switchport mode access

switchport access vlan 20

And the default gateway for the PC connected to fa0 would be 192.168.10.1?

Thanks

[cadet alain · Accepted solution]

the good config would be:

conf t

vlan 10

name general

vlan 20

name DMZ

int  vlan 10

ip address 192.168.10.1 255.255.255.0

exit

int  vlan 20

ip address 192.168.20.1 255.255.255.0

exit

int fa0

switchport mode access

switchport access vlan 10

int fa1

switchport mode access

switchport access vlan 20

And the default gateway for the PC connected to fa0 would be 192.168.10.1?

Exact.

Regards.

Alain.

[richarddowna]

Interesting, i try add the vlans to the default config and it tells me :

Vlan can not be added. Maximum number of 4 vlan(s) in the database.

I then type: (to try see what vlans are configured by default)

R1#sh vlan brief

% Ambiguous command:  "sh vlan brief"

What?!

Im currently doing CCNA 3 and this is a valid command!

Is there an IOS syntax difference? /sad

Here is a sh ip int brief:

Interface                  IP-Address      OK? Method Status                Protocol

ATM0                       unassigned      YES NVRAM  initializing          down

ATM0.1                     unassigned      YES unset  initializing          down

Dialer0                    unassigned      YES NVRAM  up                    up

FastEthernet0              unassigned      YES unset  up                    down

FastEthernet1              unassigned      YES unset  up                    down

FastEthernet2              unassigned      YES unset  up                    down

FastEthernet3              unassigned      YES unset  up                    down

NVI0                       unassigned      YES unset  administratively down down

Vlan1                      unassigned      YES NVRAM  administratively down down

Vlan75                     192.168.75.1    YES NVRAM  up                    down

[cadet alain]

the syntax here is sh vlan-sw br

Regards.

[richarddowna]

Thank you. That solves this issue!

Cheers!