ISR4451-X interface question, L3 to L2

[Lazerunner22]

Dear all

I have a Cisco ISR 4451 (4GE,3NIM,2SM,8G FLASH,4G DRAM) with 4GE interfaces. It is possible to change those interfaces from the layer 3 interface to the layer 2 interface?  If can do that, where I can find the support documents?

Many thanks

Robbie

[mohammedshahidali88]

Hi,

You can refer below document to configure the switch ports.

https://www.cisco.com/c/en/us/td/docs/routers/access/interfaces/eesm/software/configuration/guide/4451_config.html

Rate my post if it is useful for you.

[Giuseppe Larosa]

Hello @Lazerunner22 ,

the built in GE interfaces should be layer3 only routed ports.

The router can host a module with L2 GE ports in a NIM slot.

see

https://www.cisco.com/c/en/us/products/collateral/routers/4000-series-integrated-services-routers-isr/data_sheet-c78-732542.html#ISR4000InterfacesandModulesSupport

Hope to help

Giuseppe

[Richard Burts]

Perhaps we need some clarification from Robbie about what he is attempting to achieve. Certainly there is some validity in the observation from @Giuseppe Larosa that normally interfaces on this router are layer 3 and not layer 2. But there are perhaps some other ways of looking at this question:

- it is possible to configure these interfaces to support dot1Q trunking. So would a trunk interface on the router qualify as a layer 2 configuration?

- using Integrated Routing and Bridging we can configure the GE interfaces to do bridging. Does bridging on the interfaces qualify as a layer 2 configuration?

The suggestion from @mohammedshahidali88 is for a switch module for the Service Module to have layer 2 capability. It seems to me that Robbie was asking about the installed GE interfaces rather than the Service Module. Perhaps Robbie can confirm that?

[magurwara]

Hi Richard,

I have similar situation where I need port-channel for redundancy but need VLANs to cater for different network segments.  So, my scenario is pretty much what you described as 

"- it is possible to configure these interfaces to support dot1Q trunking. So would a trunk interface on the router qualify as a layer 2 configuration?"

According to this very old link, there are several port-channel and dot1q limitations on ISR platform (but I would assume that is no longer true).

Running IOS XE 16.09.05 on a Cisco 4451-x with only the built-in Gig ports and ipbase image

Can't seem to find right documentation or pointers.

[magurwara]

Update - I have configured Port-channel and dot1q trunk on built-in Gi0/0/1-3 ports on the ISR 4451 using IOS XE 16.09.5(r) and ipbaseK9.

[Richard Burts]

Thanks for the update. Glad to know that you were successful in getting port channel and trunking to work.