topic Re: Any implication of having slpp-guard on NNI port (from auto-sense) in ExtremeSwitching (VSP/Fabric Engine)

Any implication of having slpp-guard on NNI port (from auto-sense)

MaxHibbin — Tue, 09 Dec 2025 01:31:34 GMT

Currently our ZTP+ just applies auto-sense to all ports, however we want to deploy slpp-guard to all ports during ZTP+ onboarding as well. Thinking about NNI links, we have up to now enjoyed the flexibility that an auto-sense port can be used as an NNI link without any further configuration, but I did see in best practice guide not to put slpp-guard on NNI links, so in our case would we have to manually config NNI links? What are the implications of having slpp-guard on an NNI links, I presume the link disable itself if slpp packet is received, how likely is that if every access port also has slpp-guard on it? Seeing in another post the slpp packets "sent in the C-VLAN and encapsulated in the B-VLAN", so does this insulate the NNI from actually "receiving" slpp packet?

Re: Any implication of having slpp-guard on NNI port (from auto-sense)

gfriedl — Tue, 09 Dec 2025 14:11:05 GMT

As you already mentioned: SLPP frames across NNI links are encapsulated and could not reach the CPU to react on them; at least unless you are not going to add other than the BVLANs to NNI ports (which is impossible per default boot flag setting).

Re: Any implication of having slpp-guard on NNI port (from auto-sense)

RobertD1 — Tue, 09 Dec 2025 14:13:58 GMT

The best practices do say not to use slpp-guard on NNI links. It is not possible to enable it on a port with slpp packet-rx on it also. I believe the slpp packets get generated from the cores and slpp-guard is used at the edge to detect the loop and disable as close to the loop as possible and not to take down any important inter-switch links that would impact a lot more. That can still happen of course and sometimes both sides can go down at once as well. Not seen it used on NNI links myself.

https://extreme-networks.my.site.com/ExtrArticleDetail?an=000083496

Re: Any implication of having slpp-guard on NNI port (from auto-sense)

flan — Wed, 17 Dec 2025 14:35:25 GMT

You are correct.

According to the Best practices. (The course of which I teach) "shameless plug." SLPP is never used on NNI ports. SLPP should be used on a vIST cluster on all vlans except the vist vlan(4050) and the BVIDs (4051,4052).

with SLPP Guard -- it should be run on all layer 2 distribution switches as well as Layer 2 switches at the edge / access layer on every port except NNI. It is also recommended to enable slpp guard on auto-sense ports.

"no auto-sense enable convert-to-config" After auto-sensing an NNI port, you can apply this command to your uplinks. This might help you in your journey.

--See you in class!!!

Flan