Replacing BVI Int Cisco 1941 (IOS) with BDI Int Cisco ISR4321 (IOS-XE)

[CompCJtoo]

Hi all. For a couple of years I've had two Cisco 1941 routers running IOS and BVI interfaces to support some end user devices. I have two Cisco ISR4321 running IOS-XE which from what I've read you must do BDI interfaces. I attached a diagram and applicable config of how the 1941s are configured/connected currently and the ISR4321 routers will be connected the same way.

I've attempted a few times what I thought would work on the ISR4321 routers, but I'm not successful communicating from RTR1 (when its a ISR4321) to the MLS switch. I'm confused on the difference in implementation of bvi to bdi even after reading how the technology works. How would the current 1941 configs translate to the ISRs running IOS-XE? Thanks.

[paul driver]

Hello

Attached is a example of  asr4321 bridged interfaces in relation to your cisco 1941 rtrs bridged  interfaces
Is this similar to what you have already tested?

[CompCJtoo]

Hello.  Thanks for the feedback.  I tried your recommendation, but no joy.  I ran into some syntax errors.  Nonetheless, I attached what the end config was.  I also attached what I had previously attempted (Attempt 1) prior this forum post.  Should I not have int vlan(s) on the 4321?

Its in the show output of my initial post, but I've noticed that the trunk to the L2 switch and VLANs show UP/UP for "show int bri", but the 4321 never can communicate with the MLS. 

[CompCJtoo]

Hello.  So I've made some headway on achieving end to end communication from RTR2 to the MLS.  However, my issue now is that I cannot receive an IP address via DHCP hanging off RTR2 or RTR1.  I'm testing with a laptop on VLAN 700.  DHCP is working throughout the network and for this particular VLAN as other end user devices are on it and operating properly.  From RTR1 and RTR2 I can ping the DHCP server 10.10.10.254 as well as other devices on other VLANs.  

I tried configuring an interface vlan 700 with the ip helper-address command on both RTR1 and RTR2 with no joy.  Then I tried putting the command rewrite ingress tag pop 1 symmetric on each service instance, but still no joy.  I don't completely understand the rewrite ingress tag... commands function or how it works. I attached the applicable config from each router.  Thanks in advance for any help on what I'm missing for dhcp to work or explaining how the rewrite ingress tag command works.

[CompCJtoo · Accepted solution]

I figured out how to get the ISRs with IOS-XE working using BDI instead of BVI.  Aside from the config, on RTR2-4321 I had to connect  Gi0/1/0 of the switch module to the built-in Gi0/0/0 for the end user device to be able to access LAN resources and Internet.   Attached are the final configs if it helps anyone.