Hello,

I did create the sub-interface.  I wasn't able to assign an IP address to it.

2821-1#config t
Enter configuration commands, one per line.  End with CNTL/Z.
2821-1(config)#int gi0/1.1
2821-1(config-subif)#ip address 10.x.x.6 255.255.255.0

% Configuring IP routing on a LAN subinterface is only allowed if that
subinterface is already configured as part of an IEEE 802.10, IEEE 802.1Q,
or ISL vLAN.

Hi,

You need to add 802.1q trunk before you can assign your IP

HTH

Reza

Thanks everyone for your assistance

Still no joy.  Not able to add an IP address on to the interface.  I want the VLAN1 traffic to pass back and forth through this interface and to the connected switch.

2821-1#sho run int gi0/1.1
Building configuration...

Current configuration : 109 bytes
!
interface GigabitEthernet0/1.1
encapsulation dot1Q 1 native
no snmp trap link-status
no cdp enable
end

2821-1#config t
Enter configuration commands, one per line.  End with CNTL/Z.
DET-MDF-2821-1(config)#int gi0/1.1
DET-MDF-2821-1(config-subif)#ip address 10.x.x.6 255.255.255.0
% 10.7.0.0 overlaps with Vlan1

Hello,

No I did not get that error when I applied the switchport mode trunk.

Hi,

As per your configuration which you have pasted here, already you have configured vlan 1 as L3 vlan with ip segment 10.x.x.0/24 and the same segment of ip range you trying to assign into fast ethernet sub-interface.

So, As you know,It is not possible to assign same segment of IP range into two different L3 interfaces.

your configuration in the router should be like this

no int vlan 1

int gi0/0

no ip address

int gi0/0.1

encapsulation dot1q 1 native

ip address 10.x.x.1 255.255.255.0 // As per your network range //

Finally you need to remove the ip address in vlan 1. You cannot make the router as switch 100 %. But we can configure router-on-stick method to simulate switch functinality to router.

For more information have a look into this URL, which will clarify more.

http://www.cisco.com/en/US/tech/tk389/tk815/technologies_configuration_example09186a00800949fd.shtml

regards

Karuppu

Hello,

We were using the 2821 with the 9 port ethernet switch card as the branch office router and switch.  We had a need for more ports and aquired a 3750.  On the 2821 we have multiple VLANS set up.  Throughout our domain, the switches all have the same VLANS configured.  When I get this first one configured I will be creating more interfaces and putting VLANS on those interfaces. 

To clarify I need to remove the VLAN1 from the L3.  Do I assign the current IP address of the router to the Gi0/1.1 interface or a different one? Because the  rest of the network is looking for that router (and LAN segment) at the 10.x.x.1 address. 

A question I have here would be would the Gi0/1.1 have the full gigabit bandwidth or will it be reduced by the number of subinterfaces I configure?

Thanks.

Hi,

Do I assign the current IP address of the router to the Gi0/1.1 interface or a different one? -- Yes. you can assign the vlan 1 ip address into gi0/1.1

And if you want to permit more vlan over this physical interface, create the required number of interfaces and assign those sub-interfaces into the respective vlan.

A question I have here would be would the Gi0/1.1 have the full gigabit bandwidth or will it be reduced by the number of subinterfaces I configure?

Even if you are creating the 10 sub-interfaces in a single gi0/1, the maximum throughput will be 1Gbps. it will be shared into the multiple sub-interfaces.

Hope this clarified to your question. If you need more info, raise your questions.

regards

karuppu