vlan on Cisco 3845

Unanswered Question
Mar 29th, 2009

Is configuring vlans supported on cisco 3845 router?

I have this problem too.
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Giuseppe Larosa Mon, 03/30/2009 - 00:02

Hello Anita,

it makes sense to define Vlans only if you have some type of etherswitch module installed in the C3845.

In that case you can and actually you need to define L2 Vlans to use the ports of the module. You can also define L3 SVI vlans interfaces.

If you have only normal routed ports you can define Vlan based subinterfaces as

int f0/0

no ip address

int f0/0.100

enc dot1q 100

ip address

int fas0/0.110

enc dot1q 220

ip address

on the other side of f0/0 there is usually a L2 trunk on an external lan switch

Hope to help


anitagaur Mon, 03/30/2009 - 00:08

Hi Giuseppe,

I have a NME-X-23ES-1G network service module installed on the 3845 but I do not see interface vlan command option in the router. IOS is 12.4(18b)

Giuseppe Larosa Mon, 03/30/2009 - 01:28

Hello Anita,

your module is so smart that it has its own IOS image.

you need to telnet to the module and to configure it.


Cisco EtherSwitch service modules do not have a physical console interface, but are accessible for software configuration and other operational procedures through console sessions between the Cisco EtherSwitch service module and the host router.


So in your case the switch module is hosted by the router but has its own IOS image and configuration.

I've used only the dumb etherswitch modules that are configured from the router.

Hope to help


turnera Thu, 06/11/2009 - 08:24

Yes they are, I am using NME-X-23ES-1G modules in our network. Get rid of (upgrade) the IPBASE IOS and you can accomplish much more with these modules.


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