< draft-ietf-isis-igp-p2p-over-lan-01.txt		draft-ietf-isis-igp-p2p-over-lan-02.txt >
	Network Working Group Naiming Shen		Network Working Group Naiming Shen
	Internet Draft Acee Lindem		Internet Draft Acee Lindem
	Expiration Date: March 2003 Jenny Yuan		Expiration Date: September 2003 Jenny Yuan
	File name: draft-ietf-isis-igp-p2p-over-lan-01.txt Redback Networks		File name: draft-ietf-isis-igp-p2p-over-lan-02.txt Redback Networks
	Alex Zinin		Alex Zinin
	Alcatel		Alcatel
	Russ White		Russ White
	Stefano Previdi		Stefano Previdi
	Cisco Systems		Cisco Systems
	September 2002		March 2003
	Point-to-point operation over LAN		Point-to-point operation over LAN
	in link-state routing protocols		in link-state routing protocols
	draft-ietf-isis-igp-p2p-over-lan-01.txt		draft-ietf-isis-igp-p2p-over-lan-02.txt
	Status of this Memo		Status of this Memo
	This document is an Internet-Draft and is in full conformance with		This document is an Internet-Draft and is in full conformance with
	all provisions of Section 10 of RFC2026.		all provisions of Section 10 of RFC2026.
	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
	other groups may also distribute working documents as		other groups may also distribute working documents as
	Internet-Drafts.		Internet-Drafts.
	skipping to change at page 2, line 8 ¶		skipping to change at page 2, line 8 ¶
	protocols are point-to-point and broadcast. It is important to		protocols are point-to-point and broadcast. It is important to
	identify the correct circuit type when forming adjacencies,		identify the correct circuit type when forming adjacencies,
	flooding link state database packets, and representing the circuit		flooding link state database packets, and representing the circuit
	topologically. This document describes a simple mechanism to treat		topologically. This document describes a simple mechanism to treat
	the broadcast network as a point-to-point connection from the		the broadcast network as a point-to-point connection from the
	standpoint of IP routing.		standpoint of IP routing.
	1. Introduction		1. Introduction
	Point-to-point and broadcast are the two predominant circuit		Point-to-point and broadcast are the two predominant circuit
	types used by link state routing protocols such as IS-IS [ref1]		types used by link state routing protocols such as ISIS [ref1]
	[ref2] and OSPF [ref3]. They are treated differently with respect		[ref2] and OSPF [ref3]. They are treated differently with respect
	to establishing neighbor adjacencies, flooding of link-state		to establishing neighbor adjacencies, flooding link-state
	information, representation of the topology, SPF calculation and		information, representation of the topology, SPF calculation and
	protocol packets. The most important differences are that broadcast		protocol packets. The most important differences are that broadcast
	circuits utilize the concept of a designated router and are		circuits utilize the concept of a designated router and are
	represented topologically as virtual nodes in the network topology		represented topologically as virtual nodes in the network topology
	graph.		graph.
	Compared with broadcast circuits, point-to-point circuits		Compared with broadcast circuits, point-to-point circuits
	afford more straightforward IGP operation. There is no designated		afford more straightforward IGP operation. There is no designated
	router involved and there is no representation of the pseudo-node		router involved and there is no representation of the pseudo-node
	or network LSA in the link state database. For ISIS, there also is		or network LSA in the link state database. For ISIS, there also is
	skipping to change at page 4, line 27 ¶		skipping to change at page 4, line 27 ¶
	point-to-point information and expects to receive protocol packets		point-to-point information and expects to receive protocol packets
	as they would be received on a point-to-point circuit. Over LAN		as they would be received on a point-to-point circuit. Over LAN
	media, the MAC header must contain the correct multicast MAC address		media, the MAC header must contain the correct multicast MAC address
	to be received by the other side of the connection. For vLAN		to be received by the other side of the connection. For vLAN
	environments, the MAC header must also contain the proper vLAN ID.		environments, the MAC header must also contain the proper vLAN ID.
	In order to allow LAN links used to connect only two routers to be		In order to allow LAN links used to connect only two routers to be
	treated as unnumbered point-to-point interfaces, the MAC address		treated as unnumbered point-to-point interfaces, the MAC address
	resolution and nexthop IP address issues need to be addressed.		resolution and nexthop IP address issues need to be addressed.
	4.1 Operation of IS-IS		4.1 Operation of ISIS
	This p2p-over-lan circuit extension for IS-IS is only concerned		This p2p-over-lan circuit extension for ISIS is only concerned
	in pure IP routing and forwarding operation.		in pure IP routing and forwarding operation.
	Since the physically circuit is a broadcast one, the IS-IS protocol		Since the physically circuit is a broadcast one, the ISIS protocol
	packets need to have MAC addresses for this p2p-over-lan circuit.		packets need to have MAC addresses for this p2p-over-lan circuit.
	From link layer point of view, those packets are IS-IS LAN packets.		From link layer point of view, those packets are ISIS LAN packets.
	The Multi-destination address including AllISs, AllL1ISs and AllL2ISs		The Multi-destination address including AllISs, AllL1ISs and AllL2ISs
	defined in [ref1] can be used for link layer encapsulation, the		defined in [ref1] can be used for link layer encapsulation, the
	use of AllISs is recommended.		use of AllISs is recommended.
	The circuit needs to have IP address(es) and the p2p IIH over this		The circuit needs to have IP address(es) and the p2p IIH over this
	circuit MUST include the IP interface address(es) as defined in		circuit MUST include the IP interface address(es) as defined in
	[ref2]. The IP address(es) can be numbered or unnumbered.		[ref2]. The IP address(es) can be numbered or unnumbered.
	4.2 Operation of OSPF		4.2 Operation of OSPF
	skipping to change at page 6, line 37 ¶		skipping to change at page 6, line 37 ¶
	circuit for successful operation. Both routers MAY also support		circuit for successful operation. Both routers MAY also support
	one of the above listed methods for mapping ip addresses on the		one of the above listed methods for mapping ip addresses on the
	link to MAC address, and MUST support proxy ARP on the link. If		link to MAC address, and MUST support proxy ARP on the link. If
	a proprietary method of IP address to MAC address resolution is		a proprietary method of IP address to MAC address resolution is
	used by one router, both routers must be capable of using the		used by one router, both routers must be capable of using the
	same method. Otherwise, the link should be configured as a		same method. Otherwise, the link should be configured as a
	standard LAN link, with traditional IGP LAN models used.		standard LAN link, with traditional IGP LAN models used.
	6. Scalability and deployment considerations		6. Scalability and deployment considerations
	There is obvious advantage to use this extension on the LANs		While there is advantage to use this extension on the LANs
	that are connected back-to-back or only contain two routers.		that are connected back-to-back or only contain two routers,
	However, there are tradeoffs when modeling a LAN as multiple vLANs		however there are tradeoffs when modeling a LAN as multiple vLANs
	and using this extension since one does sacrifice the inherent		and using this extension since one does sacrifice the inherent
	scalability benefits of multi-access networks. In general,		scalability benefits of multi-access networks. In general,
	it will increase the link-state database size, the amount of		it will increase the link-state database size, the amount of
	packets flooded and the route calculation overhead. Network design		packets flooded and the route calculation overhead. Network design
	engineers should carefully balance between the associated		engineers should carefully balance between the associated
	overhead. The scalability impact is less of a concern if all the		overhead. The negative scalability impact is less of a concern if
	vLANs are within a single OSPF area or ISIS level.		the IGP over vLANs are within a single OSPF area or ISIS level.
	Deployment of the described technique brings noticeable benefits from		Deployment of the described technique brings noticeable benefits from
	the perspective of IP address usage, the network management and the		the perspective of IP address usage, the network management and the
	router configuration. Note, however, that use of the IP unnumbered		router configuration. Note, however, that use of the IP unnumbered
	option for point-to-point LAN links inherits the same problems as		option for point-to-point LAN links inherits the same problems as
	those present for serial links, i.e., not being able to ping or		those present for serial links, i.e., not being able to ping or
	monitor a specific interface between routers.		monitor a specific interface between routers.
	7. Security Issues		7. Security Issues
	skipping to change at page 7, line 18 ¶		skipping to change at page 7, line 18 ¶
	OSPF. For ARP to support unnumbered IP interface addresses, it needs		OSPF. For ARP to support unnumbered IP interface addresses, it needs
	to verify the p2p-over-lan circuit type described in this document		to verify the p2p-over-lan circuit type described in this document
	and to verify the ARP packet source interface address to match the		and to verify the ARP packet source interface address to match the
	IGP adjacency interface IP address. This is due to normal ARP sanity		IGP adjacency interface IP address. This is due to normal ARP sanity
	check for common subnet can not be applied in this case.		check for common subnet can not be applied in this case.
	8. Acknowledgments		8. Acknowledgments
	The authors would like to acknowledge the following individuals:		The authors would like to acknowledge the following individuals:
	(in last name alphabetical order) Pedro Marques, Christian Martin,		(in last name alphabetical order) Pedro Marques, Christian Martin,
	Danny McPherson, Ajay Patel, Tony Przygienda and Alvaro Retana.		Danny McPherson, Ajay Patel, Jeff Parker, Tony Przygienda and
			Alvaro Retana.
	9. References		9. References
	[ref1] ISO. Information Technology - Telecommunications and		[ref1] ISO. Information Technology - Telecommunications and
	Information Exchange between Systems - Intermediate System		Information Exchange between Systems - Intermediate System
	to Intermediate System Routing Exchange Protocol for		to Intermediate System Routing Exchange Protocol for
	Use in Conjunction with the Protocol for Providing the		Use in Conjunction with the Protocol for Providing the
	Connectionless-Mode Network Service. ISO, 1990.		Connectionless-Mode Network Service. ISO, 1990.
	[ref2] R. Callon. Use of OSI ISIS for Routing in TCP/IP and Dual		[ref2] R. Callon. Use of OSI ISIS for Routing in TCP/IP and Dual
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