All things related to multicast

[Multicast maillist <>]

As per RFC 4541 (Considerations for Internet Group Management Protocol (IGMP)and Multicast Listener Discovery (MLD) Snooping Switches), it is inferred that forwarding criteria for all multicast IPv6 address (except ff02::1) is always based on group database as MLD is mandated for all the multicast v6 address.

 

As per this, there is no special consideration for solicited multicast addresses or multicast addresses used for protocol control traffic.

 

I feel this could cause issues in protocol adjacency maintenance or DAD process.

 

Below is the link discussing about CISCO mld snooping breaking DAD functionality.

 

http://networking.itags.org/networking-tech/148011/

 

OSPFv3 adjacency could break if MLD snooping is enabled on a L2 switch between two OSPFv3 neighbors. (If the enable configuration happens just after a MLD query in the network, It would take another 120+ seconds to get the MLD report for FF02::5. OSPFv3 hello packets will not be forwarded by the MLD snooping enabled switch till report for FF02::5 is received and adjacency will break).

 

There was a draft draft-pashby-magma-simplify-mld-snooping-01.txt stating that multicast traffic for solicited addresses and control packet reserved addresses should be forwarded to all ports. But that draft was not taken forward and has expired.

 

What is the stand taken by vendors implementing MLD snooping to address the above issues?

 

Shouldn’t the MLD snooping enabled switch forward the traffic for solicited multicast address and protocol control packets to all the ports of VLAN?

 

 

Regards,

 

Magna.