kern/78821: ALLMULTI on Vlan Interfaces

[Alain Thivillon]

>Number:         78821
>Category:       kern
>Synopsis:       ALLMULTI on Vlan Interfaces
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Mar 14 15:20:08 GMT 2005
>Closed-Date:
>Last-Modified:
>Originator:     Alain Thivillon
>Release:        FreeBSD 5.3-RELEASE-p5 i386
>Organization:
HSC
>Environment:
System: FreeBSD fw.hsc.fr 5.3-RELEASE-p5 FreeBSD 5.3-RELEASE-p5 #5: Fri Mar 11 17:26:07 CET 2005 root at fw.hsc.fr:/usr/obj/usr/src/sys/FW i386
Networks interfaces: em Intel Card with 4 vlans.


>Description:
        When using mrouted on a system with Vlan interfaces, FreeBSD
        fails to set ALLMULTI flag on vlan parent interface.

        As result, IGMP query responses are not received by mrouted
        unless router is actually client of multicast group, and 
        mrouted fails to forward multicast packets on these interfaces,
        even if there is group members.

>How-To-Repeat:

        Configure ip forwading between 2 vlans interfaces on a MROUTING
        kernel, launch mrouted and watch mrouted forwarding table
        when a client send IGMP Host Membership Report. The table
        is not updated until router himself is group member (and thus
        multicast group address is programmed on parent interface).

>Fix:

	As this is done for standard multicast code, setting ALLMULTI
        flag on vlan interface should set ALLMULTI on parent interface.

        Alternatively, a "allmulti/-allmulti" option to ifconfig should be sufficient
        to let mrouted works on vlan interfaces.

>Release-Note:
>Audit-Trail:
>Unformatted: