Description

This article describes the issue of the message '/kernel: mld6_input: src :: is not link-local (grp=400:0:ff02::1)' randomly being displayed in the logs.

Symptoms

The following is part of the Multicast Listener Discovery protocol implementation, as per RFC 3810:

/kernel: mld6_input: src :: is not link-local (grp=400:0:ff02::1)

Every time a MLD query packet comes in with an unspecified source address, it is logged as a warning.

Solution

 

Refer to RFC 3810 , section 5.1.14. Source Addresses for Queries:

All MLDv2 Queries MUST be sent with a valid IPv6 link-local source
address. If a node (router or host) receives a Query message with
the IPv6 Source Address set to the unspecified address (::), or any
other address that is not a valid IPv6 link-local address, it MUST
silently discard the message and SHOULD log a warning.

Prior to DAD ... the unspecified address must be used.

These entries are therefore expected and the trigger is external to the router. Furthermore, they are only warnings and the logging severity level appropriately indicates this.

To stop the messages, see KB9382- How to prevent certain syslog messages from being written to the log file?
[juniper.net]

Related Information