Unicast Transmission of IPv 6 Multicast Messages on

Unicast Transmission of IPv 6 Multicast Messages on link-layer Sri Gundavelli Mark Townsley Ole Troan Wojciech Dec draft-gundavelli-v 6 ops-l 2 -unicast IETF 78: v 6 ops: Unicast Transmission of Multicast Messages on Link-layer 1 1

Motivation This document is about a clarification to the construction and processing rules of IPv 6 ND Messages. This clarification makes it valid for an IPv 6 receiver node to consider a received IPv 6 multicast message with a multicast destination address in the IPv 6 header, but containing an unicast destination address in the link-layer header, to be valid, withstanding all other validity considerations. The function of the link-layer is purely for transmitting the frame to a peer or to a set of peers on a given media. It is inconsequential for the network layer protocols to go across the layers and check the semantics of message delivery in the link-layer header. Any such check is a violation of the principles of protocol layering and does not serve any purpose. IETF 78: v 6 ops: Unicast Transmission of Multicast Messages on Link-layer 2

Applicability An 802. 11 wireless access point may be hosting multiple IPv 6 subnets and it would need the ability to selectively advertise hosted IPv 6 prefixes on a per-node basis. Such segregation can only be possible by sending RA’s in unicast mode. Ex: Cisco WLAN Controller Solutions. VLAN-1 AP VLAN-2 Such a message construct is used in various protocols, such as in ISATAP [RFC 5214] for sending a unicast Router Advertisement message on ISATAP interfaces. There are many other deployment scenarios, where this semantic is needed. IETF 78: v 6 ops: Unicast Transmission of Multicast Messages on Link-layer 3

Proposal This document proposes to add the following considerations that all IPv 6 sender and receiver nodes must follow: “An IPv 6 receiver node MUST NOT drop a received IPv 6 multicast message containing a multicast destination address in the IPv 6 header, but with a unicast destination address in the link-layer header, withstanding all other validity considerations as specified in the relevant IPv 6 standards specifications. ” “An IPv 6 sender node MAY choose to transmit an IPv 6 multicast message as a linklayer unicast message. In this case, the destination address in the IPv 6 header will be a multicast group address, but the destination address in the link-layer header will be an unicast address. It is up to to the system architecture as when to transmit an IPv 6 multicast message as an link-layer unicast message. ” IETF 78: v 6 ops: Unicast Transmission of Multicast Messages on Link-layer 4

Thank You IETF 78: v 6 ops: Unicast Transmission of Multicast Messages on Link-layer 5