VLAN & Subinterface Config??

Each trunk created for a switch you need a seperate subinterface on your router... Its also good practice to have a different subnet for each Vlan. I know each switch receives a management IP and default gateway in the Native Vlan - Vlan 1 (802.1q). Those credentials are for management purposes only.

Where do you set the IP/Mask for each Trunk/VLAN?? Is this also configured on each subinterface of your router in addition to your encapsulation? (802.1q)

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Comments

Danman32

Actually you want a separate subinterface on the router for each VLAN coming in from the trunk that you want the router to route.

So, if your switch has 4 VLANs in it, and you have a VLAN trunk going to your router, you would need 4 subinterfaces on the router to address each VLAN. You specify on the subinterface the encapsulation type and VLAN identifier that the subinterface will use. The subinterface identifier doesn't have to match the VLAN identifier, but it's a good idea to corrolate them.

mp3spy

Danman32 wrote:

Actually you want a separate subinterface on the router for each VLAN coming in from the trunk that you want the router to route.

So, if your switch has 4 VLANs in it, and you have a VLAN trunk going to your router, you would need 4 subinterfaces on the router to address each VLAN. You specify on the subinterface the encapsulation type and VLAN identifier that the subinterface will use. The subinterface identifier doesn't have to match the VLAN identifier, but it's a good idea to corrolate them.

Ok so a seperate subint on your router for EACH VLAN flowing through the trunk coming off that switch. So where do you set the mask/gateway for each Vlan?

agustinchernitsky

if you are using fa0/0 for trunking on your router, you should do something like this:

(config)#int fa0/0
(config-if)#no ip address
(config-if)#int fa0/0.1 
(config-if)#ip address 192.168.0.1 255.255.255.224
(config-if)#int fa0/0.2
(config-if)#ip address 192.168.0.33 255.255.255.224

Also you should configure which type of encapsulation you are using... dot1q or isl

mp3spy

agustinchernitsky wrote:
if you are using fa0/0 for trunking on your router, you should do something like this:
(config)#int fa0/0
(config-if)#no ip address
(config-if)#int fa0/0.1 
(config-if)#ip address 192.168.0.1 255.255.255.224
(config-if)#int fa0/0.2
(config-if)#ip address 192.168.0.33 255.255.255.224
Also you should configure which type of encapsulation you are using... dot1q or isl

Ah ok, thats what I figured! Thanks for clarifying.

Danman32

To clarify, each subinterface is treated as if it were a separate physical interface, except you also add the VLAN encapsulation information to define what VLAN that subinterface belongs to off of the trunk interface.

So, whatever you would do on a dedicated physical interface, you would do on a VLAN subinterface, including assigning an IP.