# MLDv2: no multicast listener report received for group ff02::1:ff00:1234 on eth0

- **ID:** `networking/mldv2-query-no-report`
- **Domain:** networking
- **Category:** protocol_error
- **Verification:** ai_generated
- **Fix Rate:** 82%

## Root Cause

The multicast querier sent an MLDv2 query for a specific IPv6 group but received no listener report, indicating no active listeners on the segment.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| Linux kernel 6.5 | active | — | — |
| OpenWrt 23.05 | active | — | — |
| Cisco IOS XE 17.9 | active | — | — |

## Workarounds

1. **Verify multicast application is running and listening: netstat -an | grep -E 'ff02::1:ff00:1234' ; if missing, restart the application that joins the group** (85% success)
   ```
   Verify multicast application is running and listening: netstat -an | grep -E 'ff02::1:ff00:1234' ; if missing, restart the application that joins the group
   ```
2. **Check firewall rules on the host that may block MLD reports: sudo ip6tables -L -n | grep mld ; add allow rule if needed: ip6tables -A INPUT -p icmpv6 --icmpv6-type 143 -j ACCEPT** (80% success)
   ```
   Check firewall rules on the host that may block MLD reports: sudo ip6tables -L -n | grep mld ; add allow rule if needed: ip6tables -A INPUT -p icmpv6 --icmpv6-type 143 -j ACCEPT
   ```

## Dead Ends

- **** — If no listeners exist, increasing the interval only delays detection; it does not create listeners. (80% fail)
- **** — This may cause flooding but does not fix the missing report; the issue is at the host level. (70% fail)