< draft-ietf-v6ops-v6nd-problems-03.txt		draft-ietf-v6ops-v6nd-problems-04.txt >
	v6ops I. Gashinsky		v6ops I. Gashinsky
	Internet-Draft Yahoo!		Internet-Draft Yahoo!
	Intended status: Informational J. Jaeggli		Intended status: Informational J. Jaeggli
	Expires: July 28, 2012 Zynga		Expires: August 5, 2012 Zynga
	W. Kumari		W. Kumari
	Google Inc		Google Inc
	January 25, 2012		February 02, 2012
	Operational Neighbor Discovery Problems		Operational Neighbor Discovery Problems
	draft-ietf-v6ops-v6nd-problems-03		draft-ietf-v6ops-v6nd-problems-04
	Abstract		Abstract
	In IPv4, subnets are generally small, made just large enough to cover		In IPv4, subnets are generally small, made just large enough to cover
	the actual number of machines on the subnet. In contrast, the		the actual number of machines on the subnet. In contrast, the
	default IPv6 subnet size is a /64, a number so large it covers		default IPv6 subnet size is a /64, a number so large it covers
	trillions of addresses, the overwhelming number of which will be		trillions of addresses, the overwhelming number of which will be
	unassigned. Consequently, simplistic implementations of Neighbor		unassigned. Consequently, simplistic implementations of Neighbor
	Discovery (ND) can be vulnerable to deliberate or accidental denial		Discovery (ND) can be vulnerable to deliberate or accidental denial
	of service, whereby they attempt to perform address resolution for		of service, whereby they attempt to perform address resolution for
	skipping to change at page 2, line 4 ¶		skipping to change at page 2, line 4 ¶
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at http://datatracker.ietf.org/drafts/current/.		Drafts is at http://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	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."
	This Internet-Draft will expire on July 28, 2012.		This Internet-Draft will expire on August 5, 2012.
	Copyright Notice		Copyright Notice
	Copyright (c) 2012 IETF Trust and the persons identified as the		Copyright (c) 2012 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	skipping to change at page 7, line 33 ¶		skipping to change at page 7, line 33 ¶
	existing entries in the neighbor cache, and unable to answer Neighbor		existing entries in the neighbor cache, and unable to answer Neighbor
	Solicitation). This condition can result in the inability to resolve		Solicitation). This condition can result in the inability to resolve
	new neighbors and loss of reachability to neighbors with existing ND-		new neighbors and loss of reachability to neighbors with existing ND-
	Cache entries. During testing it was concluded that 4 simultaneous		Cache entries. During testing it was concluded that 4 simultaneous
	nmap sessions from a low-end computer was sufficient to make a		nmap sessions from a low-end computer was sufficient to make a
	router's neighbor discovery process unusable and therefore forwarding		router's neighbor discovery process unusable and therefore forwarding
	became unavailable to the destination subnets.		became unavailable to the destination subnets.
	The failure to maintain proper NDP behavior whilst under attack has		The failure to maintain proper NDP behavior whilst under attack has
	been observed across multiple platforms and implementations,		been observed across multiple platforms and implementations,
	including the largest routers available (when this document was		including the largest modern router platforms available (at the
	started) from two of the largest vendors.		inception of work on this document).
	5. Neighbor Discovery Overview		5. Neighbor Discovery Overview
	When a packet arrives at (or is generated by) a router for a		When a packet arrives at (or is generated by) a router for a
	destination on an attached link, the router needs to determine the		destination on an attached link, the router needs to determine the
	correct link-layer address to use in the destination field of the		correct link-layer address to use in the destination field of the
	layer 2 encapsulation. The router checks the Neighbor Cache for an		layer 2 encapsulation. The router checks the Neighbor Cache for an
	existing Neighbor Cache Entry for the neighbor, and if none exists,		existing Neighbor Cache Entry for the neighbor, and if none exists,
	invokes the address resolution portions of the IPv6 Neighbor		invokes the address resolution portions of the IPv6 Neighbor
	Discovery [RFC4861] protocol to determine the link-layer address of		Discovery [RFC4861] protocol to determine the link-layer address of
	skipping to change at page 12, line 20 ¶		skipping to change at page 12, line 20 ¶
	No IANA resources or consideration are requested in this draft.		No IANA resources or consideration are requested in this draft.
	9. Security Considerations		9. Security Considerations
	This document outlines mitigation options that operators can use to		This document outlines mitigation options that operators can use to
	protect themselves from Denial of Service attacks. Implementation		protect themselves from Denial of Service attacks. Implementation
	advice to router vendors aimed at ameliorating known problems carries		advice to router vendors aimed at ameliorating known problems carries
	the risk of previously unforeseen consequences. It is not believed		the risk of previously unforeseen consequences. It is not believed
	that these mitigation techniques or the implementation of finer-		that these mitigation techniques or the implementation of finer-
	grained queuing of NDP activity create additional security risks or		grained queuing of NDP activity create additional security risks or
	DoS exposure.		DOS exposure.
	10. Acknowledgements		10. Acknowledgements
	The authors would like to thank Ron Bonica, Troy Bonin, John Jason		The authors would like to thank Ron Bonica, Troy Bonin, John Jason
	Brzozowski, Randy Bush, Vint Cerf, Tassos Chatzithomaoglou, Jason		Brzozowski, Randy Bush, Vint Cerf, Tassos Chatzithomaoglou, Jason
	Fesler, Wes George, Erik Kline, Jared Mauch, Chris Morrow and Suran		Fesler, Wes George, Erik Kline, Jared Mauch, Chris Morrow and Suran
	De Silva. Special thanks to Thomas Narten and Ray Hunter for		De Silva. Special thanks to Thomas Narten and Ray Hunter for
	detailed review and (even more so) for providing text!		detailed review and (even more so) for providing text!
	Apologies for anyone we may have missed; it was not intentional.		Apologies for anyone we may have missed; it was not intentional.
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