Border/Fusion "ip route-cache same-interface"

[Benjamin-A]

Hello

could someone please explain to me, why we we will use "ip route-cache same-interface" instead of CEF on on the IP Transit Handoff SVIs and Edge Node SVIs? Shouldn't cef be more effective? Why would we choose fast-switching over cef here?

interface <int>
description vrf interface to External router
vrf forwarding <VRF>
ip address <address>
no ip redirects
ip route-cache same-interface
bfd interval 100 min_rx 100 multiplier 3

I was also wondering why is it set at the Border Device but not on the Fusion Device in the following Guide (as both use SVIs)? 

https://www.cisco.com/c/en/us/support/docs/cloud-systems-management/dna-center/213525-sda-steps-to-configure-fusion-router.html#anc13

When do I need/want to set it?

From the configuration Guides the description is that it is suggested on partially meshed media such as Frame Relay or WCCP, but thats not the case here, isn't it? 

Many thanks in advance!

[Andrii Oliinyk]

i'm also pretty curious about it. only advantage of the fast-switching i can see is ability to see ip cach w/o extra efforts :0D

[jedolphi]

Coincidentally someone else raised this same ask 2 weeks ago. It's possibly no longer required in the SD-Access Fabric. As best I can tell it does no harm. Give us a week or two to do all the appropriate testing and then if it's not needed I'll put in a change to remove it. No need to add it to the Fusion Device CLI.

[ja-robertson]

I have this same question.  currenlty running SDA with DNAC version Version 2.3.5.6-70143 and it is still disabling CEF on BDR and Edge Node.  Should I disable on Fusion Interface? 

[Andrii Oliinyk]

i keep staying with thought that "ip route-cache same-interface" was used by developers in earlier versions to support IP-cache (for LISP maybe :0?) needs. I'm pretty sure its placing on the FN-side especially in IP-transit generally makes 0 sense.  

[jedolphi · Accepted solution]

Agreed, no need to add to fusion interfaces.