draft-ietf-mboned-ipv4-uni-based-mcast-04.txt		draft-ietf-mboned-ipv4-uni-based-mcast-05.txt
	Network Working Group D. Thaler		Network Working Group D. Thaler
	Internet-Draft Microsoft		Internet-Draft Microsoft
	Expires: January 27, 2008 July 26, 2007		Expires: August 28, 2008 February 25, 2008
	Unicast-Prefix-based IPv4 Multicast Addresses		Unicast-Prefix-based IPv4 Multicast Addresses
	draft-ietf-mboned-ipv4-uni-based-mcast-04.txt		draft-ietf-mboned-ipv4-uni-based-mcast-05.txt
	Status of this Memo		Status of this Memo
	By submitting this Internet-Draft, each author represents that any		By submitting this Internet-Draft, each author represents that any
	applicable patent or other IPR claims of which he or she is aware		applicable patent or other IPR claims of which he or she is aware
	have been or will be disclosed, and any of which he or she becomes		have been or will be disclosed, and any of which he or she becomes
	aware will be disclosed, in accordance with Section 6 of BCP 79.		aware will be disclosed, in accordance with Section 6 of BCP 79.
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF), its areas, and its working groups. Note that		Task Force (IETF), its areas, and its working groups. Note that
	skipping to change at page 1, line 33		skipping to change at page 1, line 33
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	The list of current Internet-Drafts can be accessed at		The list of current Internet-Drafts can be accessed at
	http://www.ietf.org/ietf/1id-abstracts.txt.		http://www.ietf.org/ietf/1id-abstracts.txt.
	The list of Internet-Draft Shadow Directories can be accessed at		The list of Internet-Draft Shadow Directories can be accessed at
	http://www.ietf.org/shadow.html.		http://www.ietf.org/shadow.html.
	This Internet-Draft will expire on January 27, 2008.		This Internet-Draft will expire on August 28, 2008.
	Copyright Notice		Copyright Notice
	Copyright (C) The IETF Trust (2007).		Copyright (C) The IETF Trust (2008).
	Abstract		Abstract
	This specification defines an extension to the multicast addressing		This specification defines an extension to the multicast addressing
	architecture of the IP Version 4 protocol. The extension presented		architecture of the IP Version 4 protocol. The extension presented
	in this document allows for unicast-prefix-based allocation of		in this document allows for unicast-prefix-based assignment of
	multicast addresses. By delegating multicast addresses at the same		multicast addresses. By delegating multicast addresses at the same
	time as unicast prefixes, network operators will be able to identify		time as unicast prefixes, network operators will be able to identify
	their multicast addresses without needing to run an inter-domain		their multicast addresses without needing to run an inter-domain
	allocation protocol.		allocation protocol.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
	2. Address Space . . . . . . . . . . . . . . . . . . . . . . . . . 3		2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
	3. Security Considerations . . . . . . . . . . . . . . . . . . . . 4		3. Address Space . . . . . . . . . . . . . . . . . . . . . . . . . 4
	4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4		4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
	5. Informative References . . . . . . . . . . . . . . . . . . . . 5		5. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
	Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 5		6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
	Intellectual Property and Copyright Statements . . . . . . . . . . 6		7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 5
			8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
			8.1. Normative References . . . . . . . . . . . . . . . . . . . 6
			8.2. Informative References . . . . . . . . . . . . . . . . . . 6
			Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 6
			Intellectual Property and Copyright Statements . . . . . . . . . . 7
	1. Introduction		1. Introduction
	RFC 3180 [RFC3180] defined an experimental allocation mechanism		RFC 3180 [RFC3180] defined an experimental allocation mechanism
	(called "GLOP") in 233/8 whereby an Autonomous System (AS) number is		(called "GLOP") in 233/8 whereby an Autonomous System (AS) number is
	embedded in the middle 16 bits of an IPv4 multicast address,		embedded in the middle 16 bits of an IPv4 multicast address,
	resulting in 256 multicast addresses per AS. Advantages of this		resulting in 256 multicast addresses per AS. Advantages of this
	mechanism include the ability to get multicast address space without		mechanism include the ability to get multicast address space without
	an inter-domain multicast address allocation protocol, and the ease		an inter-domain multicast address allocation protocol, and the ease
	of determining the AS of the owner of an address for debugging and		of determining the AS that was assigned the address for debugging and
	auditing purposes.		auditing purposes.
	Some disadvantages of GLOP include:		Some disadvantages of GLOP include:
	o RFC 4893 [RFC4893] expands the size of an AS number to 4 bytes,		o RFC 4893 [RFC4893] expands the size of an AS number to 4 bytes,
	and GLOP cannot work with 4-byte AS numbers.		and GLOP cannot work with 4-byte AS numbers.
	o When an AS covers multiple sites or organizations, administration		o When an AS covers multiple sites or organizations, administration
	of the multicast address space within an AS must be handled by		of the multicast address space within an AS must be handled by
	other mechanisms, such as manual administrative effort or MADCAP		other mechanisms, such as manual administrative effort or MADCAP
	[RFC2730].		[RFC2730].
	o During debugging, identifying the AS does not immediately identify		o During debugging, identifying the AS does not immediately identify
	the owning organization when an AS covers multiple organizations.		the correct organization when an AS covers multiple organizations.
	o Only 256 addresses are automatically available per AS, and		o Only 256 addresses are automatically available per AS, and
	obtaining any more requires administrative effort.		obtaining any more requires administrative effort.
	More recently, a mechanism [RFC3306] has been developed for IPv6 that		More recently, a mechanism [RFC3306] has been developed for IPv6 that
	provides a multicast range to every IPv6 subnet, which is at a much		provides a multicast range to every IPv6 subnet, which is at a much
	finer granularity than an AS. As a result, the first three		finer granularity than an AS. As a result, the first three
	disadvantages above are avoided (and the last disadvantage does not		disadvantages above are avoided (and the last disadvantage does not
	apply to IPv6 due to the extended size of the address space).		apply to IPv6 due to the extended size of the address space).
	Another advantage of providing multicast space to a subnet, rather		Another advantage of providing multicast space to a subnet, rather
	than just to an entire AS, is that multicast address allocation		than just to an entire AS, is that multicast address assignment
	within the range need only be coordinated within the subnet.		within the range need only be coordinated within the subnet.
	This draft specifies a mechanism similar to [RFC3306], whereby a		This draft specifies a mechanism similar to [RFC3306], whereby a
	range of IPv4 multicast address space is provided to each		range of global IPv4 multicast address space is provided to each
	organization that has unicast address space. A resulting advantage		organization that has unicast address space. A resulting advantage
	over GLOP is that the mechanisms in IPv4 and IPv6 become more		over GLOP is that the mechanisms in IPv4 and IPv6 become more
	similar.		similar.
	This document proposes an experimental method of statically		2. Terminology
	allocating multicast address ranges with global scope. As described
	in section Section 4, this experiment will last for a period of one
	year, but may be extended.
	2. Address Space		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 [RFC2119].
	(RFC-editor: replace TBD below with IANA-assigned value, and delete		3. Address Space
	this note.)
			(RFC-editor: replace TBD in this section and the next with IANA-
			assigned value, and delete this note.)
	A multicast address with the prefix TBD/8 indicates that the address		A multicast address with the prefix TBD/8 indicates that the address
	is a Unicast-Based Multicast (UBM) address. The remaining 24 bits		is a Unicast-Based Multicast (UBM) address. The remaining 24 bits
	are used as follows:		are used as follows:
	Bits: | 8 | Unicast Prefix Length | 24 - Unicast Prefix Length |		Bits: | 8 | Unicast Prefix Length | 24 - Unicast Prefix Length |
	+-----+-----------------------+----------------------------+		+-----+-----------------------+----------------------------+
	Value: | TBD | Unicast Prefix | Group ID |		Value: | TBD | Unicast Prefix | Group ID |
	+-----+-----------------------+----------------------------+		+-----+-----------------------+----------------------------+
	For organizations with a /24 or shorter prefix, the unicast prefix of		For organizations with a /24 or shorter prefix, the unicast prefix of
	the organization is appended to the common /8. Any remaining bits		the organization is appended to the common /8. Any remaining bits
	may be assigned by any mechanism the organization wishes. For		may be assigned by any mechanism the organization wishes.
	example, an organization that has a subnet with a /24 or shorter
	prefix assigned to a link may wish to embed the entire subnet prefix		For example, an organization that has a /16 prefix assigned might
	within the multicast address, with the remaining bits assigned by		choose to assign multicast addresses manually from the /24 multicast
	hosts within the link (e.g., using manual configuration).		prefix derived from the above method. Alternatively, the
			organization might choose to delegate the use of multicast addresses
			to individual subnets that have a /24 or shorter unicast prefix, or
			it might choose some other method.
	Organizations with a prefix length longer than 24 do not receive any		Organizations with a prefix length longer than 24 do not receive any
	multicast address space from this mechanism; in such cases, another		multicast address space from this mechanism; in such cases, another
	mechanism must be used.		mechanism must be used.
	Compared to GLOP, an AS will receive more address space via this		Compared to GLOP, an AS will receive more address space via this
	mechanism if it has more than a /16 for unicast space. An AS will		mechanism if it has more than a /16 for unicast space. An AS will
	receive less address space than it does from GLOP if it has less than		receive less address space than it does from GLOP if it has less than
	a /16.		a /16.
	The owner of a UBM address can be determined by taking the multicast		The organization that is assigned the UBM address can be determined
	address, shifting it left by 8 bits, and identifying the owner of the		by taking the multicast address, shifting it left by 8 bits, and
	address space covering the resulting unicast address.		identifying who has been assigned the address space covering the
			resulting unicast address.
	3. Security Considerations		The embedded unicast prefix MUST be a global unicast prefix (i.e., no
			loopback, multicast, link-local, or private-use IP address space).
			In addition, since global unicast addresses are not permanently
			assigned, UBM addresses MUST NOT be hard-coded in applications.
			4. Examples
			The following are a few examples of the structure of unicast-prefix
			based multicast addresses.
			o Consider an organization that has been assigned the global unicast
			address space 192.0.2.0/24. This means that organization can use
			the global multicast address TBD.192.0.2 without coordinating with
			any other entity. Someone who sees this multicast address and
			wants to find who is using it can mentally shift the address left
			by 8 bits to get 192.0.2.0, and then look up who has been assigned
			unicast address space that includes that address.
			o Consider an organization has been assigned a larger address space,
			x.y.0.0/16. This organization can use the global multicast
			address space TBD.x.y.0/24 without coordinating with any other
			entity, and can assign addresses within this space by any
			mechanism the organization wishes. Someone who sees a multicast
			address (say) TBD.x.y.10, and wants to find who is using it can
			mentally shift the address left by 8 bits to get x.y.10.0, and can
			then look up who has been assigned unicast address space that
			includes that address.
			5. Security Considerations
	The same well known intra-domain security techniques can be applied		The same well known intra-domain security techniques can be applied
	as with GLOP. Furthermore, when dynamic allocation is used within a		as with GLOP. Furthermore, when dynamic allocation is used within a
	prefix, the approach described here may have the effect of reduced		prefix, the approach described here may have the effect of reduced
	exposure to denial of space attacks, since the topological area		exposure to denial of space attacks, since the topological area
	within which nodes compete for addresses within the same prefix is		within which nodes compete for addresses within the same prefix is
	reduced from an entire AS to only within an individual organization		reduced from an entire AS to only within an individual organization
	or an even smaller area.		or an even smaller area.
	4. IANA Considerations		6. IANA Considerations
	IANA should assign a /8 in the IPv4 multicast address space for this		IANA should assign a /8 in the global IPv4 multicast address space
	purpose.		for this purpose.
	This assignment should time out one year after the assignment is		7. Acknowledgments
	made. The assignment may be renewed at that time.
	5. Informative References		This document was updated based on feedback from the MBoneD working
			group. In particular, Tim Chown, Toerless Eckert, Prashant Jhingran,
			Peter Koch, John Linn, Dave Meyer, Pekka Savola, Greg Shepherd, and
			Stig Venaas provided valuable suggestions on the text.
			8. References
			8.1. Normative References
			[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
			Requirement Levels", BCP 14, RFC 2119, March 1997.
			8.2. Informative References
	[RFC2730] Hanna, S., Patel, B., and M. Shah, "Multicast Address		[RFC2730] Hanna, S., Patel, B., and M. Shah, "Multicast Address
	Dynamic Client Allocation Protocol (MADCAP)", RFC 2730,		Dynamic Client Allocation Protocol (MADCAP)", RFC 2730,
	December 1999.		December 1999.
	[RFC3180] Meyer, D. and P. Lothberg, "GLOP Addressing in 233/8",		[RFC3180] Meyer, D. and P. Lothberg, "GLOP Addressing in 233/8",
	BCP 53, RFC 3180, September 2001.		BCP 53, RFC 3180, September 2001.
	[RFC3306] Haberman, B. and D. Thaler, "Unicast-Prefix-based IPv6		[RFC3306] Haberman, B. and D. Thaler, "Unicast-Prefix-based IPv6
	Multicast Addresses", RFC 3306, August 2002.		Multicast Addresses", RFC 3306, August 2002.
	skipping to change at page 6, line 7		skipping to change at page 7, line 7
	Microsoft Corporation		Microsoft Corporation
	One Microsoft Way		One Microsoft Way
	Redmond, WA 98052		Redmond, WA 98052
	USA		USA
	Phone: +1 425 703 8835		Phone: +1 425 703 8835
	Email: dthaler@microsoft.com		Email: dthaler@microsoft.com
	Full Copyright Statement		Full Copyright Statement
	Copyright (C) The IETF Trust (2007).		Copyright (C) The IETF Trust (2008).
	This document is subject to the rights, licenses and restrictions		This document is subject to the rights, licenses and restrictions
	contained in BCP 78, and except as set forth therein, the authors		contained in BCP 78, and except as set forth therein, the authors
	retain all their rights.		retain all their rights.
	This document and the information contained herein are provided on an		This document and the information contained herein are provided on an
	"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS		"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
	OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND		OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
	THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS		THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
	OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF		OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
End of changes. 21 change blocks.
	38 lines changed or deleted		86 lines changed or added
This html diff was produced by rfcdiff 1.34. The latest version is available from http://tools.ietf.org/tools/rfcdiff/