EXOS with an AutoSense enabled uplink for ZTP+

[Configterminal]

Hello all!  I've been busy testing and labbing an EXOS switch getting deployed via ZTP+ when connected to an upstream auto-sensed enabled fabric engine port.  I'm wondering if anyone has got this 100% figured out and in production because there are some questions I have about how to get this working exactly the way I'd like.

As I understand it, when you factory reset and boot an EXOS switch connected upstream to a fabric engine "auto-sense" port, the port automagically goes into fa/flex-uni mode via the auto-sense code.  The issue is, the EXOS will basically get an IP using it's Default/Untagged VLAN b/c it tries every VLAN it can to get an IP on.  This all goes well until you decide, as part of ZTP+ you want XMC to create a management VLAN and use that IP range for it's management interface.  The problem is, even with using port-templates on the EXOS side to add vlans to the upstream trunk, since from the VOSS side it's FA, those same VLANs don't get added to the FA autosense port.

Essentially, I want to set an fa-management vlan from the VOSS side facing the EXOS switch, but I can't since this conflicts with auto-sense, as you can't configure both on a port simultaneously.  Inherently, auto-sense works when onboarding another VOSS switch but it's a bit funky with EXOS from my testing.  Has anyone got this figured out and can point me to some guides or something on how to do this?

[Ludovico_Steven]

You can set this auto-sense command on the VSP/FabEng side:

auto-sense fa proxy-no-auth i-sid <i-sid>

It will result in the VOSS side plumbing that I-SID as untagged for the EXOS switch (instead of Onboarding I-SID); but on the EXOS side, it will still have to use default VLAN 1.

There is no way to set an FA Mgmt VLAN on an auto-sense port where an EXOS switch is discovered (which is what is done for older ERS switches)

This design choice was forced on VOSS because EXOS does not bind dynamically created (e.g by FA) VLANs to Spanning Tree. So if an EXOS had 2 uplinks connected into two different fabric switches on auto-sense ports, if the VOSS switches tried to advertise an FA Mgmt VLAN, EXOS would loop it, in spite of the BPDUs that VOSS auto-sense ports emit. Whereas default VLAN 1 on EXOS is bound to Spanning Tree.

Anyway, auto-sense for EXOS switches is a mute point. EXOS is typically deployed with redundant uplinks into a distribution pair (of VOSS switches). Auto-sense is not currently supported on MLT/SMLT ports.

So you will never use auto-sense to deploy EXOS/SwitchEngine access typically. Instead you would pre-configure the VOSS/FabEng SMLT ports for static aggregation with FA, without FA message authentication, and with the desired FA mgmt VLAN. Now the EXOS/SwitchEng switch will automatically create the LAG, create the FA Mgmt VLAN, obtain a DHCP on it and do ZTP+ on it. From XIQ-SE you can then simply assign a different static IP in the same subnet & FA Mgmt VLAN, but outside the DHCP scope.

Using auto-sense with EXOS/SwitchEngine might make sense for smaller desktop switches, which have a single uplink.