How to fix Cisco C9200L-24P Uplink Issue on 17.3.4b

This post is about fixing Cisco C9200L-24P uplink Issue on IOS version 17.3.4b.

Issue and Environment

1x Cisco 9200L-24P with 4x 10G SFP module

Cisco 10G SFP uplink to another Cisco Core Switch

IOS version is 17.3.4b on Cisco 9200L-24, it was the “recommended” version on Cisco website before

Physical link between Cisco 9200L-24P and Core Switch shows nice and green, no issue with fibre patching leads and panels.

Cisco 9200L-24P cannot see Cisco core switch, but core switch can see 9200L – from “show cdp neighbor”

Cisco 9200L-24P cannot communicate with core switch on layer 3, ping between SVIs does not work

Another C9200L-48PXG-4X stack with 17.03.04b IOS works completely fine


The below troubleshooting steps were carried out but none of them helped.

Change 10G SFP module

Change fibre SFP patch leads

Change fibre cores on the patch panel

Connect directly from core switch to 9200L-24 to Core SW via one patch leads

How to Fix

The issue is the “recommended” Cisco IOS 17.3.4b version. It has the bug stopping communication when you are using 10G SFP ports.

Upgrade the firmware to the newer version, tried the 17.3.5 and 17.6.3 and they resolved the uplink 10G port issue.

ICTFellaSW04>sh ver
Cisco IOS XE Software, Version 17.06.03
Cisco IOS Software [Bengaluru], Catalyst L3 Switch Software (CAT9K_LITE_IOSXE), Version 17.6.3, RELEASE SOFTWARE (fc4)
Technical Support:
Copyright (c) 1986-2022 by Cisco Systems, Inc.
Compiled Wed 30-Mar-22 21:23 by mcpre

Cisco IOS-XE software, Copyright (c) 2005-2022 by cisco Systems, Inc.
All rights reserved.  Certain components of Cisco IOS-XE software are
licensed under the GNU General Public License ("GPL") Version 2.0.  The
software code licensed under GPL Version 2.0 is free software that comes
with ABSOLUTELY NO WARRANTY.  You can redistribute and/or modify such
GPL code under the terms of GPL Version 2.0.  For more details, see the
documentation or "License Notice" file accompanying the IOS-XE software,
or the applicable URL provided on the flyer accompanying the IOS-XE

For the details steps to upgrade the IOS version, please refer back to this post.

Useful link

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