BugZero | Cisco BugID CSCvw09998 - flexlink+ alt port forwarding igmp queries caused ...

Loading...

Operational Defect Database

A free repository of operational (non-security) bugs centralized through custom integrations with leading IT vendors.

Product

BugZero Prevent
BugZero Plan
Operational Risk Scoring
Vendor Integrations

Company

Plans
Value Guide
About
Contact us
Legal

Resources

Blog
ServiceNow App
Trust Center
Risk Management
NIST
DORA

Operational Defect Database

A free repository of operational (non-security) bugs centralized through custom integrations with leading IT vendors.

Product

BugZero Prevent
BugZero Plan
Operational Risk Scoring
Vendor Integrations

Company

Plans
Value Guide
About
Contact us
Legal

Resources

Blog
ServiceNow App
Trust Center
Risk Management
NIST
DORA

©2025 BugZero. All Rights Reserved.

Privacy Policy Terms of Service

BugZero | Cisco BugID CSCvw09998 - flexlink+ alt port forwarding igmp queries caused ...

ODD
Cisco
CSCvw09998

Cisco - Defect ID: CSCvw09998

flexlink+ alt port forwarding igmp queries caused multicast traffic loop

ODD
Cisco
CSCvw09998

Cisco - Defect ID: CSCvw09998

flexlink+ alt port forwarding igmp queries caused multicast traffic loop

Last updated on February 22nd, 2026

BugZero Risk Score
7.8 High

Overall: 7.8

Severity: 8.2

Lifecycle: 9.1

Popularity: 5.1

What is the BugZero Risk Score?

Cisco Integration

Learn more about where this data comes from

Cisco Integration

BugZero Plan

Streamline upgrades with automated vendor bug scrubs

BugZero Plan

BugZero Prevent

Wish you caught this bug sooner? Get proactive today.

BugZero Prevent

Bug Details

Description

Symptom

As long as "show ip igmp snooping mrouter" contains flexlink+ alt port, the alt port will forward igmp queries. It caused multicast traffic loop.

Conditions

Flexlink+ in use on 16.12.03, 16.12.04

Workaround

disable IGMP Snooping on the switch hosting the Flexlink+ pair.

Further Problem Description

Longer term solution might be to have the multicast optimization disabled my default and add a new CLI to enable/disable it independently from L2 multicast snooping.

Change history

2026-01-11 Added: 16.12.3, 16.12.4, 17.3.1

Relevant Products

Click on a version to see all relevant bugs

Affected versions:16.12.3, 16.12.4, 17.3.1

Fixed versions: 16.12.10, 16.12.10a, 16.12.11, 16.12.12, 16.12.13, 16.12.14, 16.12.6, 16.12.6a, 16.12.7, 16.12.8, 16.12.9, 17.05.01c, 17.10.1, 17.10.1a, 17.10.1b, 17.11.1, 17.11.1a, 17.12.02a, 17.12.1, 17.12.1a, 17.12.1w, 17.12.1x, 17.12.1y, 17.12.1z, 17.12.1z1, 17.12.1z2, 17.12.1z3, 17.12.1z4, 17.12.1z5, 17.12.1z6, 17.12.2, 17.12.2a, 17.12.3, 17.12.3a, 17.12.4, 17.12.4a, 17.12.4b, 17.12.5, 17.12.5a, 17.12.5b, 17.12.5c, 17.12.5d, 17.12.6, 17.12.6a, 17.12.6b, 17.13.1, 17.13.1a, 17.14.1, 17.14.1a, 17.15.1, 17.15.1a, 17.15.1b, 17.15.1w, 17.15.1x, 17.15.1y, 17.15.1z, 17.15.2, 17.15.2a, 17.15.2b, 17.15.2c, 17.15.3, 17.15.3a, 17.15.3b, 17.15.4, 17.15.4a, 17.15.4b, 17.15.4c, 17.15.4d, 17.15.4s1, 17.15.5, 17.16.1, 17.16.1a, 17.17.1, 17.18.1, 17.18.1a, 17.18.1w, 17.18.1x, 17.18.2, 17.3.3, 17.3.3a, 17.3.4, 17.3.4a, 17.3.4b, 17.3.4c, 17.3.5, 17.3.5a, 17.3.5b, 17.3.6, 17.3.7, 17.3.8, 17.3.8a, 17.5.1, 17.5.1a, 17.5.1b, 17.5.1c, 17.6.1, 17.6.1a, 17.6.1w, 17.6.1x, 17.6.1y, 17.6.1z, 17.6.1z1, 17.6.2, 17.6.3, 17.6.3a, 17.6.4, 17.6.5, 17.6.5a, 17.6.6, 17.6.6a, 17.6.7, 17.6.8, 17.6.8a, 17.7.1, 17.7.1a, 17.7.1b, 17.7.2, 17.8.1, 17.8.1a, 17.9.1, 17.9.1a, 17.9.1w, 17.9.1x, 17.9.1x1, 17.9.1y, 17.9.1y1, 17.9.2, 17.9.2a, 17.9.3, 17.9.3a, 17.9.4, 17.9.4a, 17.9.5, 17.9.5a, 17.9.5b, 17.9.5c, 17.9.5d, 17.9.5e, 17.9.5f, 17.9.6, 17.9.6a, 17.9.6b, 17.9.7, 17.9.7a, 17.9.7b, 17.9.8, Bengaluru-17.5.1, Gibraltar-16.12.6

Relevant Products

Click on a version to see all relevant bugs

Affected versions:16.12.3, 16.12.4, 17.3.1

Fixed versions: 16.12.10, 16.12.10a, 16.12.11, 16.12.12, 16.12.13, 16.12.14, 16.12.6, 16.12.6a, 16.12.7, 16.12.8, 16.12.9, 17.05.01c, 17.10.1, 17.10.1a, 17.10.1b, 17.11.1, 17.11.1a, 17.12.02a, 17.12.1, 17.12.1a, 17.12.1w, 17.12.1x, 17.12.1y, 17.12.1z, 17.12.1z1, 17.12.1z2, 17.12.1z3, 17.12.1z4, 17.12.1z5, 17.12.1z6, 17.12.2, 17.12.2a, 17.12.3, 17.12.3a, 17.12.4, 17.12.4a, 17.12.4b, 17.12.5, 17.12.5a, 17.12.5b, 17.12.5c, 17.12.5d, 17.12.6, 17.12.6a, 17.12.6b, 17.13.1, 17.13.1a, 17.14.1, 17.14.1a, 17.15.1, 17.15.1a, 17.15.1b, 17.15.1w, 17.15.1x, 17.15.1y, 17.15.1z, 17.15.2, 17.15.2a, 17.15.2b, 17.15.2c, 17.15.3, 17.15.3a, 17.15.3b, 17.15.4, 17.15.4a, 17.15.4b, 17.15.4c, 17.15.4d, 17.15.4s1, 17.15.5, 17.16.1, 17.16.1a, 17.17.1, 17.18.1, 17.18.1a, 17.18.1w, 17.18.1x, 17.18.2, 17.3.3, 17.3.3a, 17.3.4, 17.3.4a, 17.3.4b, 17.3.4c, 17.3.5, 17.3.5a, 17.3.5b, 17.3.6, 17.3.7, 17.3.8, 17.3.8a, 17.5.1, 17.5.1a, 17.5.1b, 17.5.1c, 17.6.1, 17.6.1a, 17.6.1w, 17.6.1x, 17.6.1y, 17.6.1z, 17.6.1z1, 17.6.2, 17.6.3, 17.6.3a, 17.6.4, 17.6.5, 17.6.5a, 17.6.6, 17.6.6a, 17.6.7, 17.6.8, 17.6.8a, 17.7.1, 17.7.1a, 17.7.1b, 17.7.2, 17.8.1, 17.8.1a, 17.9.1, 17.9.1a, 17.9.1w, 17.9.1x, 17.9.1x1, 17.9.1y, 17.9.1y1, 17.9.2, 17.9.2a, 17.9.3, 17.9.3a, 17.9.4, 17.9.4a, 17.9.5, 17.9.5a, 17.9.5b, 17.9.5c, 17.9.5d, 17.9.5e, 17.9.5f, 17.9.6, 17.9.6a, 17.9.6b, 17.9.7, 17.9.7a, 17.9.7b, 17.9.8, Bengaluru-17.5.1, Gibraltar-16.12.6

Top Cisco Defects

9.7Defect ID: CSCwe44571
FMC: GEOLOCATION size is causing upgrade failures
9.7Defect ID: CSCvp16482
ASA reloads when establishing simultaneous ASDM sessions
9.7Defect ID: CSCun06260
XE3.13 Gatekeeper Hardening
9.7Defect ID: CSCvf84211
WLC dataplane reloads unexpectedly due to core 0 hung and RML interrupt handling
9.7Defect ID: CSCvf76274
Cisco APs can no longer join the WLC; CAPWAP-3-DTLS_DB_ERR

Ready to prevent the next vendor outage?

Links

Original Vendor Announcement

Cisco Integration

Learn more about where this data comes from

Cisco Integration

BugZero Plan

Streamline upgrades with automated vendor bug scrubs

BugZero Plan

BugZero Prevent

Wish you caught this bug sooner? Get proactive today.

BugZero Prevent