Network Working Group C. Partridge Request for Comments: 2711 BBN Category: Standards Track A. Jackson BBN October 1999 IPv6 Router Alert Option Status of this Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (1999). All Rights Reserved.
AbstractThis memo describes a new IPv6 Hop-by-Hop Option type that alerts transit routers to more closely examine the contents of an IP datagram. This option is useful for situations where a datagram addressed to a particular destination contains information that may require special processing by routers along the path.
routed without further datagram parsing. Hosts originating IPv6 datagrams are required to include this option in certain circumstances. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC-2119]. RFC-2460] specifies the meaning of the first three bits. By zeroing all three, this specification requires that nodes not recognizing this option type should skip over this option and continue processing the header and that the option must not change en route. There MUST only be one option of this type, regardless of value, per Hop-by-Hop header.
Value: A 2 octet code in network byte order with the following values: 0 Datagram contains a Multicast Listener Discovery message [RFC-2710]. 1 Datagram contains RSVP message. 2 Datagram contains an Active Networks message. 3-65535 Reserved to IANA for future use. Alignment requirement: 2n+0 Values are registered and maintained by the IANA. See section 5.0 for more details.
Section 2.1 is registered and maintained by IANA. New values are to be assigned via IETF Consensus as defined in RFC 2434 [RFC-2434].
[RFC-2119] Bradner, S., "Key words for use in RFC's to Indicate Requirement Levels", BCP 14, RFC 2119, March 1977. [RFC-2205] Braden, B. (ed.), Zhang, L., Berson, S., Herzog, S. and S. Jamin, "Resource ReSerVation Protocol (RSVP)", RFC 2205, September 1997. [RFC-2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. [RFC-2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", RFC 2460, December 1998. [RFC-2710] Deering, S., Fenner, W. and B. Haberman, "Multicast Listener Discovery (MLD) for IPv6", RFC 2710, October 1999.
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