Technical Advisory - Cisco Catalyst 3650 Memory Leak

Technical Advisory - Cisco Catalyst 3650 Memory Leak

There have been multiple documented memory leaks in the Cisco Catalyst 3650 series Ethernet switches. Implementing a schedule for reboots can help prevent potential problems that could result from a memory leak.

The issues outlined below primarily affect specific releases of Cisco IOS XE (Polaris and later) and can cause gradually increasing memory usage, high-memory warnings, device crashes/reloads, or network outages. The Catalyst 3650 is now an end-of-sale/end-of-support platform, so many deployments have been upgraded or replaced. Most leaks are resolved by upgrading to newer, non-vulnerable IOS XE releases.

Key Reported Issues

The following are the most notable memory-leak bugs specifically affecting the 3650 (often shared with the 3850 series):

  • Field Notice FN-70110 (Bug CSCvd45973)
    Memory leak in the platform_mgr process on 3650/3850 switches running IOS XE 16.3.3 or earlier.
    Symptoms: Syslog messages %PLATFORM-4-ELEMENT_WARNING (used memory >90%) or %PLATFORM-3-ELEMENT_CRITICAL (>95%).
    Workaround: Reload the switch.
    Fix: Upgrade to 16.3.5b or later (broader fixes in 16.5.x/16.6.x+).
  • Field Notice FN-70359 (Bug CSCvh89372)
    Memory leak in linux_iosd-imag and/or platform_mgr processes on C3650/C3850 (and some C9300/C9500) running IOS XE 16.3.x (e.g., 16.3.1–16.3.5b) or 16.6.x (e.g., 16.6.1–16.6.3).
    Monitoring command: show platform software process memory switch 1 r0 all sorted (watch RSS size).
    Workaround: Reload.
    Fix: Upgrade to 16.3.6, 16.6.4, 16.9.1, or later.
  • Additional documented bugs
    • CSCvo28206 – Memory leak in the WCM process (show process memory platform sorted).
    • CSCvn46171 – Rapid memory leak in the “FED Main Event” process (IOS XE 16.6.4a+), leading to reloads.
    • CSCvh28573 – Memory leak reported even without cabling connected.
    • CSCvn30230 – Slow memory leak (~1 MB/day) in linux_iosd-imag on Catalyst 3k platforms including the 3650.

Community reports on Cisco forums and Reddit describe similar symptoms in IOS XE 15.x and 16.x releases, often resulting in unexpected reloads.

Recommended Actions

  1. Check your current IOS XE version:
    show version
  2. Monitor memory usage:
    show platform resources
    show processes memory platform sorted
    show platform software process list switch active R0 sort memory
  3. Temporary workaround: Reload the switch when memory thresholds are reached.
  4. Permanent fix: Upgrade to the latest recommended “starred” release in your supported train (check Cisco’s download portal).
  5. If issues persist, open a Cisco TAC case with your exact version and logs.

Note: Because the 3650 is end-of-support, Cisco strongly recommends migrating to a current platform (e.g., Catalyst 9300) for long-term stability and security.