dot1q vlans

[ttnnee]

I have a 4006 switch and a 3640 router with one fast ethernet port. I set up two vlans on the switch (vlan 1 & vlan 2) and trunk one of the ports that the router is on. I set the trunk to dot1q encapsulation in nonegiotate mode. On the router side I set up this config.

config t
int fa 1/0
ip address 10.250.237.254 secondary
ip address 10.250.230.254
int fa 1/0.2
encapsulation dot1q 2
ip addresss 10.250.224.254
description Vlan 2

I cant get the intervlan routing to work. I think the problem is the fact that with the IOS I am using on the router I cannot use the "encapsulation dot1q 1 native" command on the sub-interface. This is why I didn't create a sub-interface for vlan 1. Does anyone have any ideas? I think the problem is that the native vlans arent matching on both sides. The native vlan on the switch side is 1.

 

[Jsteve]

That is your problem. You need to have both vlans configured on the router to perform inter Vlan communication. Why are you using dot1q? why are you using a secondary address? personaly I would config it this way.

Switch(config)#ip address 10.250.230.x 255.255.255.0
Switch(config)#ip default-gateway 10.250.230.254
Switch(config)#vtp domain myswitch
Switch(config)#vtp server
Switch(config)#vlan 1 name sales
Switch(config)#vlan 2 name Audit
Switch(config)#int e0/1
Switch(config-if)#vlan-membership static 1
Switch(config-if)#desc VLAN1
Switch(config-if)#int e0/2
Switch(config-if)#vlan-membership static 2
Switch(config-if)#desc VLAN2
Switch(config-if)#int f0/26
Switch(config-if)#duplex full
Switch(config-if)#trunk on
Switch(config-if)#desc trunk to router3640

Router on a stick config

Router(config)#int f1/0
Router(config-if)#no ip address
Router(config-if)#int f0/0.1
Router(config-if)#ip address 10.250.230.254 255.255.255.0
Router(config-if)#int f0/0.2
Router(config-if)#encap isl 1
Router(config-if)#ip address 10.250.237.254 255.255.255.0
Router(config-if)#int f0/0.3
Router(config-if)#encap isl 2
Router(config-if)#ip address 10.250.224.254 255.255.255.0

 

[ttnnee]

I actually have tried that config too. My switch doesn't support isl, that is why I am using dot1q. Also the 4000 series uses Cat OS, so the commands for the switch you used would not work. I do see your point though. I have set-up intervlan routing before with ISL but the ios on the router was a newer version that allowed the command "encapsulation dot1q 1 native" command. With the ios I am using it wont allow to use the "native" part of the command, and my router doesn't have enough flash to upgrade. I am using secondary commands because there is more than one subnet on a vlan, so they need a default gateway.

 

[Jsteve]

Here's a link that may help you.

http://www.cisco.com/warp/public/473/50.shtml

 

[thirt]

You can either use on the router side:

encapsulation dot1Q 1 native (since 12.1(3)T)

or

In the earlier Cisco IOS versions, it is important not to configure VLAN1 interface as a sub-interface. The router then expects a tag dot1q frame on VLAN1 and the switch is not expecting a tag on VLAN1. As a result, no traffic will pass between VLAN1 on the switch and the router

 

[Guest_imported]

Anyone know where I can get a lab for a CCNA class for configuring router on a stick? I have 4 Catalyst 2600 routers, a Catalyst 2601 , and a pair of Catalyst 2950 switches, and lotsa ethernet cabling.