Using Layer 3 Multicast Suppression Protocols Above Layer 3
draft-perkins-manet-using-rfc6621-00.txt

Abstract

This document specifies how protocols operating at layers above layer 3 can use the multicast suppression algorithms, for instance the algorithms specified in RFC 6621.

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at http://datatracker.ietf.org/drafts/current/.

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."

This Internet-Draft will expire on September 4, 2016.

Copyright Notice

Copyright (c) 2016 IETF Trust and the persons identified as the document authors. All rights reserved.

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.

Table of Contents

• 1. Introduction
• 2. Terminology
• 3. Use of multicast suppression algorithms above Layer 3
• 4. Security Considerations
• 5. IANA Considerations
• 6. Informative References
• Author's Address

1. Introduction

Limiting the number of multicast forwarders provides performance benefits when used with a protocol that relies on flooding messages throughout a network. Some good multicast suppression methods for limiting the number of multicast forwarders while maintaining complete network coverage are specified in RFC 6621 [RFC6621]. Routing protocols that use multicast can offer much greater performance using multicast suppression algorithms. Such algorithms do not affect the origination of multicast messages, but only determine whether a node needs to forward incoming multicast messages that are intended to flood the network. Enabling performance benefits for reactive manet routing protocols was a strong motivating factor in the development and publication of RFC 6621.

RFC 6621 multicast suppression algorithms are specified to operate at layer 3. Manet routing protocols use RFC 5444 [RFC5444] as a message bundling layer; they operate above layer 3. Such protocols specify that incoming multicast control messages have to be processed before regeneration; in other words, the incoming multicast message is not forwarded at all. Manet control messages are sent with the IP destination address set to the link-local multicast address LL-MANET-Routers [RFC5498] unless otherwise specified. This document specifies a way to use layer 3 multicast suppression algorithms at a layer above layer 3 so that algorithms that require network-wide flooding can reap the benefits of layer-3 multicast suppression algorithms.

2. Terminology

This document defines the following terminology:

Forwarding Node

A node that currently forwards incoming multicast messages to its neighbors, based on the results of running a multicast suppression algorithm.

Multicast Suppression Algorithm

An algorithm that determines which multicast routers are required for complete coverage of a multicast group; retransmission by other multicast routers for the multicast group is unnecessary.

Regeneration

Transmission of a message formed by processing and modification of an incoming message for an operation requiring the attention of members of a multicast group.

3. Use of multicast suppression algorithms above Layer 3

If the node is not currently a multicast forwarding node, then the node does not regenerate multicast messages even if the conditions for regeneration are satisfied.

For example, if an AODVv2 [I-D.ietf-manet-aodvv2] router is not currently a multicast forwarding node, then it does not regenerate multicast messages (e.g., RREQ or RERR) even if the conditions for regeneration are satisfied. This restriction only applies for regeneration, and does not apply for multicast RREQ or RERR messages originated by the node.

4. Security Considerations

This document does not introduce any security mechanisms, and does not have any impact on existing security mechanisms.

5. IANA Considerations

This document does not specify any IANA actions.

6. Informative References

Author's Address