L3 Handoff and LAN Automation

[mjrduarte]

Hi!

In my test environment, I'm deploying a C9500 as Border Node, connected to a Fusion Router (C9300) and a C9300 as the edge device.
I did LAN Automation with the Fusion Router as the seed.
The process went as expected, the C9500 and the C9300 were discovered and configured.
When I was configuring the Border Node role on the C9500, and chose the IP transit I created previously, it asks for the interface to do the handoff. If I choose the same interface as the uplink to the Fusion Router, it gives the error that the interface has an IP address (as it should have).
My question is: do I have to have a second uplink between the C9500 and the Fusion Router? Is there any other wau to do this (100Gb ports are expensive).

Thank you for any help.

[M02@rt37]

Hello @mjrduarte 

What about using sub-interface ?

This solution involves using sub-interfaces to logically separate the traffic on the same physical interface between the C9500 border node and the fusion routeur. Instead of requiring a second expensive physical uplink, you create a sub-interface on the existing uplink port by configuring it with a unique VLAN id and IP address. For instance, on the uplink interface: TenGigabitEthernet1/1/1, you define TenGigabitEthernet1/1/1.100 with VLAN id 100 and assign the necessary IP address for the IP transit handoff. This way, the physical interface can handle multiple types of traffic, each on different sub-interfaces, thus effectively separating and managing the IP transit without additional hardware costs...

[andy!doesnt!like!uucp]

the reason is after automation of BNs from FNs interconnects between them became routed interfaces. Same time, when BN is configured for L3-handoffs it must have its interconnects to FN switched .1q trunks.
this entire work is for redoing. 

[Boort · Accepted solution]

When you do the L3 handoff on a switch the catalyst center will add the link networks for the layer 3 outs as SVIs.

Just convert the interface to L2 trunk and move the ip address on the switch to an SVI in global. Add .1q tag on a subinterface on the fusion switch. Add a manual bgp neighbor in global for routing or continue with ISIS. Up to you.

[mjrduarte]

Thank you for your suggestions.
What I ended up doing was creating an VLAN interface on both switches, and moved the physical interface configuration to that VLAN, then changed the physical interfaces to L2 trunks.