draft-ietf-i2rs-rib-info-model-00.txt		draft-ietf-i2rs-rib-info-model-01.txt
	Network Working Group N. Bahadur, Ed.		Network Working Group N. Bahadur, Ed.
	Internet-Draft R. Folkes, Ed.		Internet-Draft
	Intended status: Informational Juniper Networks, Inc.		Intended status: Informational R. Folkes, Ed.
	Expires: March 20, 2014 S. Kini		Expires: April 21, 2014 Juniper Networks, Inc.
			S. Kini
	Ericsson		Ericsson
	J. Medved		J. Medved
	Cisco		Cisco
	September 16, 2013		October 18, 2013
	Routing Information Base Info Model		Routing Information Base Info Model
	draft-ietf-i2rs-rib-info-model-00		draft-ietf-i2rs-rib-info-model-01
	Abstract		Abstract
	Routing and routing functions in enterprise and carrier networks are		Routing and routing functions in enterprise and carrier networks are
	typically performed by network devices (routers and switches) using a		typically performed by network devices (routers and switches) using a
	routing information base (RIB). Protocols and configuration push		routing information base (RIB). Protocols and configuration push
	data into the RIB and the RIB manager install state into the		data into the RIB and the RIB manager install state into the
	hardware; for packet forwarding. This draft specifies an information		hardware; for packet forwarding. This draft specifies an information
	model for the RIB to enable defining a standardized data model. Such		model for the RIB to enable defining a standardized data model. Such
	a data model can be used to define an interface to the RIB from an		a data model can be used to define an interface to the RIB from an
	skipping to change at page 1, line 43		skipping to change at page 1, line 44
	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 March 20, 2014.		This Internet-Draft will expire on April 21, 2014.
	Copyright Notice		Copyright Notice
	Copyright (c) 2013 IETF Trust and the persons identified as the		Copyright (c) 2013 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 3, line 13		skipping to change at page 3, line 13
	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
	1.1. Conventions used in this document . . . . . . . . . . . . 6		1.1. Conventions used in this document . . . . . . . . . . . . 6
	2. RIB data . . . . . . . . . . . . . . . . . . . . . . . . . . . 6		2. RIB data . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
	2.1. RIB definition . . . . . . . . . . . . . . . . . . . . . . 6		2.1. RIB definition . . . . . . . . . . . . . . . . . . . . . . 6
	2.2. Routing instance . . . . . . . . . . . . . . . . . . . . . 7		2.2. Routing instance . . . . . . . . . . . . . . . . . . . . . 7
	2.3. Route . . . . . . . . . . . . . . . . . . . . . . . . . . 8		2.3. Route . . . . . . . . . . . . . . . . . . . . . . . . . . 8
	2.4. Nexthop . . . . . . . . . . . . . . . . . . . . . . . . . 10		2.4. Nexthop . . . . . . . . . . . . . . . . . . . . . . . . . 9
	2.4.1. Nexthop types . . . . . . . . . . . . . . . . . . . . 12		2.4.1. Nexthop types . . . . . . . . . . . . . . . . . . . . 12
	2.4.2. Nexthop list attributes . . . . . . . . . . . . . . . 13		2.4.2. Nexthop list attributes . . . . . . . . . . . . . . . 12
	2.4.3. Nexthop content . . . . . . . . . . . . . . . . . . . 14		2.4.3. Nexthop content . . . . . . . . . . . . . . . . . . . 13
	2.4.4. Nexthop attributes . . . . . . . . . . . . . . . . . . 14		2.4.4. Special nexthops . . . . . . . . . . . . . . . . . . . 14
	2.4.5. Nexthop vendor attributes . . . . . . . . . . . . . . 15		3. Reading from the RIB . . . . . . . . . . . . . . . . . . . . . 14
	2.4.6. Special nexthops . . . . . . . . . . . . . . . . . . . 15		4. Writing to the RIB . . . . . . . . . . . . . . . . . . . . . . 15
	3. Reading from the RIB . . . . . . . . . . . . . . . . . . . . . 16		5. Events and Notifications . . . . . . . . . . . . . . . . . . . 15
	4. Writing to the RIB . . . . . . . . . . . . . . . . . . . . . . 16		6. RIB grammar . . . . . . . . . . . . . . . . . . . . . . . . . 16
	5. Events and Notifications . . . . . . . . . . . . . . . . . . . 16		7. Inter-domain extensions to the RIB . . . . . . . . . . . . . . 18
	6. RIB grammar . . . . . . . . . . . . . . . . . . . . . . . . . 17		7.1. Extension to Routing Instance . . . . . . . . . . . . . . 18
	7. Using the RIB grammar . . . . . . . . . . . . . . . . . . . . 19		7.2. Extension to Route . . . . . . . . . . . . . . . . . . . . 19
	7.1. Using route preference and metric . . . . . . . . . . . . 20		7.3. Inter-domain extensions to RIB grammar . . . . . . . . . . 19
	7.2. Using different nexthops types . . . . . . . . . . . . . . 20		8. Using the RIB grammar . . . . . . . . . . . . . . . . . . . . 19
	7.2.1. Tunnel nexthops . . . . . . . . . . . . . . . . . . . 20		8.1. Using route preference . . . . . . . . . . . . . . . . . . 19
	7.2.2. Replication lists . . . . . . . . . . . . . . . . . . 20		8.2. Using different nexthops types . . . . . . . . . . . . . . 20
	7.2.3. Weighted lists . . . . . . . . . . . . . . . . . . . . 21		8.2.1. Tunnel nexthops . . . . . . . . . . . . . . . . . . . 20
	7.2.4. Protection lists . . . . . . . . . . . . . . . . . . . 21		8.2.2. Replication lists . . . . . . . . . . . . . . . . . . 20
	7.2.5. Nexthop chains . . . . . . . . . . . . . . . . . . . . 22		8.2.3. Weighted lists . . . . . . . . . . . . . . . . . . . . 20
	7.2.6. Lists of lists . . . . . . . . . . . . . . . . . . . . 22		8.2.4. Protection lists . . . . . . . . . . . . . . . . . . . 21
	7.3. Performing multicast . . . . . . . . . . . . . . . . . . . 22		8.2.5. Nexthop chains . . . . . . . . . . . . . . . . . . . . 21
	7.4. Solving optimized exit control . . . . . . . . . . . . . . 23		8.2.6. Lists of lists . . . . . . . . . . . . . . . . . . . . 22
	8. RIB operations at scale . . . . . . . . . . . . . . . . . . . 23		8.3. Performing multicast . . . . . . . . . . . . . . . . . . . 22
	8.1. RIB reads . . . . . . . . . . . . . . . . . . . . . . . . 24		8.4. Solving optimized exit control . . . . . . . . . . . . . . 22
	8.2. RIB writes . . . . . . . . . . . . . . . . . . . . . . . . 24		9. RIB operations at scale . . . . . . . . . . . . . . . . . . . 23
	8.3. RIB events and notifications . . . . . . . . . . . . . . . 24		9.1. RIB reads . . . . . . . . . . . . . . . . . . . . . . . . 23
	9. Security Considerations . . . . . . . . . . . . . . . . . . . 24		9.2. RIB writes . . . . . . . . . . . . . . . . . . . . . . . . 23
	10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24		9.3. RIB events and notifications . . . . . . . . . . . . . . . 23
	11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 24		10. Security Considerations . . . . . . . . . . . . . . . . . . . 24
	12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 25		11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24
	12.1. Normative References . . . . . . . . . . . . . . . . . . . 25		12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 24
	12.2. Informative References . . . . . . . . . . . . . . . . . . 25		13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 24
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 26		13.1. Normative References . . . . . . . . . . . . . . . . . . . 24
			13.2. Informative References . . . . . . . . . . . . . . . . . . 24
			Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 25
	1. Introduction		1. Introduction
	Routing and routing functions in enterprise and carrier networks are		Routing and routing functions in enterprise and carrier networks are
	traditionally performed in network devices. Traditionally routers		traditionally performed in network devices. Traditionally routers
	run routing protocols and the routing protocols (along with static		run routing protocols and the routing protocols (along with static
	config) populates the Routing information base (RIB) of the router.		config) populates the Routing information base (RIB) of the router.
	The RIB is managed by the RIB manager and it provides a north-bound		The RIB is managed by the RIB manager and it provides a north-bound
	interface to its clients i.e. the routing protocols to insert routes		interface to its clients i.e. the routing protocols to insert routes
	into the RIB. The RIB manager consults the RIB and decides how to		into the RIB. The RIB manager consults the RIB and decides how to
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	RIB. Using the information model, one can build a detailed data		RIB. Using the information model, one can build a detailed data
	model for the RIB. And that data model could then be used by an		model for the RIB. And that data model could then be used by an
	external entity to program a network device.		external entity to program a network device.
	The rest of this document is organized as follows. Section 2 goes		The rest of this document is organized as follows. Section 2 goes
	into the details of what constitutes and can be programmed in a RIB.		into the details of what constitutes and can be programmed in a RIB.
	Guidelines for reading and writing the RIB are provided in Section 3		Guidelines for reading and writing the RIB are provided in Section 3
	and Section 4 respectively. Section 5 provides a high-level view of		and Section 4 respectively. Section 5 provides a high-level view of
	the events and notifications going from a network device to an		the events and notifications going from a network device to an
	external entity, to update the external entity on asynchronous		external entity, to update the external entity on asynchronous
	events. The RIB grammar is specified in Section 6. Examples of		events. The RIB grammar is specified in Section 6. Section 7
	using the RIB grammar are shown in Section 7. Section 8 covers		extends the RIB for use in inter-domain cases. Examples of using the
	considerations for performing RIB operations at scale.		RIB grammar are shown in Section 8. Section 9 covers considerations
			for performing RIB operations at scale.
	1.1. Conventions used in this document		1.1. Conventions used in this document
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in [RFC2119].		document are to be interpreted as described in [RFC2119].
	2. RIB data		2. RIB data
	This section describes the details of a RIB. It makes forward		This section describes the details of a RIB. It makes forward
	skipping to change at page 6, line 35		skipping to change at page 6, line 36
	| |		| |
	interface(s) RIB(s)		interface(s) RIB(s)
	|		|
	|		|
	| 0..N		| 0..N
	route(s)		route(s)
			Figure 2: RIB model
	2.1. RIB definition		2.1. RIB definition
	A RIB is an entity that contains routes. A RIB is identified by its		A RIB is an entity that contains routes. A RIB is identified by its
	name and a RIB is contained within a routing instance (Section 2.2).		name and a RIB is contained within a routing instance (Section 2.2).
	The name MUST be unique within a routing instance. All routes in a		The name MUST be unique within a routing instance. All routes in a
	given RIB MUST be of the same type (e.g. IPv4). Each RIB MUST		given RIB MUST be of the same type (e.g. IPv4). Each RIB MUST
	belong to some routing instance.		belong to some routing instance.
	A RIB can be tagged with a MULTI_TOPOLOGY_ID. If a routing instance		A RIB can be tagged with a MULTI_TOPOLOGY_ID. If a routing instance
	is divided into multiple logical topologies, then the multi-topology		is divided into multiple logical topologies, then the multi-topology
	skipping to change at page 7, line 41		skipping to change at page 7, line 44
	The set of interfaces indicates which interfaces are associated with		The set of interfaces indicates which interfaces are associated with
	this routing instance. The RIBs specify how incoming traffic is to		this routing instance. The RIBs specify how incoming traffic is to
	be forwarded. And the routing parameters control the information in		be forwarded. And the routing parameters control the information in
	the RIBs. The intersection set of interfaces of 2 routing instances		the RIBs. The intersection set of interfaces of 2 routing instances
	SHOULD be the null set. In other words, an interface MUST NOT be		SHOULD be the null set. In other words, an interface MUST NOT be
	present in 2 routing instances. Thus a routing instance describes		present in 2 routing instances. Thus a routing instance describes
	the routing information and parameters across a set of interfaces.		the routing information and parameters across a set of interfaces.
	A routing instance MUST contain the following mandatory fields.		A routing instance MUST contain the following mandatory fields.
	o INSTANCE_NAME: A routing instance is identified by its name,		o INSTANCE_NAME: A routing instance is identified by its name,
	INSTANCE_NAME. This SHOULD be unique across all routing instances		INSTANCE_NAME. This MUST be unique across all routing instances
	in a given network device.		in a given network device.
	o INSTANCE_DISTINGUISHER: Each routing instance MUST have a
	distinguisher associated with it. It enables one to distinguish
	routes across routing instances. The route distinguisher MUST be
	unique across all routing instances in a given network device.
	How the INSTANCE_DISTINGUISHER is allocated and kept unique is
	outside the scope of this document. The instance distinguisher
	maps well to BGP route-distinguisher for virtual private networks
	(VPNs). However, the same concept can be used for other use-cases
	as well.
	o rib-list: This is the list of RIBs associated with this routing		o rib-list: This is the list of RIBs associated with this routing
	instance. Each routing instance can have multiple RIBs to		instance. Each routing instance can have multiple RIBs to
	represent routes of different types. For example, one would put		represent routes of different types. For example, one would put
	IPv4 routes in one RIB and MPLS routes in another RIB.		IPv4 routes in one RIB and MPLS routes in another RIB.
	A routing instance MAY contain the following optional fields.		A routing instance MAY contain the following optional fields.
	o interface-list: This represents the list of interfaces associated		o interface-list: This represents the list of interfaces associated
	with this routing instance. The interface list helps constrain		with this routing instance. The interface list helps constrain
	the boundaries of packet forwarding. Packets coming on these		the boundaries of packet forwarding. Packets coming on these
	interfaces are directly associated with the given routing		interfaces are directly associated with the given routing
	instance. The interface list contains a list of identifiers, with		instance. The interface list contains a list of identifiers, with
	each identifier uniquely identifying an interface.		each identifier uniquely identifying an interface.
	o ROUTER_ID: The router-id field identifies the network device in		o ROUTER_ID: The router-id field identifies the network device in
	control plane interactions with other network devices. This field		control plane interactions with other network devices. This field
	is to be used if one wants to virtualize a physical router into		is to be used if one wants to virtualize a physical router into
	multiple virtual routers. Each virtual router MUST have a unique		multiple virtual routers. Each virtual router MUST have a unique
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	the boundaries of packet forwarding. Packets coming on these		the boundaries of packet forwarding. Packets coming on these
	interfaces are directly associated with the given routing		interfaces are directly associated with the given routing
	instance. The interface list contains a list of identifiers, with		instance. The interface list contains a list of identifiers, with
	each identifier uniquely identifying an interface.		each identifier uniquely identifying an interface.
	o ROUTER_ID: The router-id field identifies the network device in		o ROUTER_ID: The router-id field identifies the network device in
	control plane interactions with other network devices. This field		control plane interactions with other network devices. This field
	is to be used if one wants to virtualize a physical router into		is to be used if one wants to virtualize a physical router into
	multiple virtual routers. Each virtual router MUST have a unique		multiple virtual routers. Each virtual router MUST have a unique
	router-id. ROUTER_ID MUST be unique across all network devices in		router-id. ROUTER_ID MUST be unique across all network devices in
	a given domain.		a given domain.
	o as-data: This is an identifier of the administrative domain to
	which the routing instance belongs. The as-data fields is used
	when the routes in this instance are to be tagged with certain
	autonomous system (AS) characteristics. The RIB manager can use
	AS length as one of the parameters for making route selection. as-
	data consists of a AS number and an optional Confederation AS
	number ([RFC5065]).
	2.3. Route		2.3. Route
	A route is essentially a match condition and an action following the		A route is essentially a match condition and an action following the
	match. The match condition specifies the kind of route (IPv4, MPLS,		match. The match condition specifies the kind of route (IPv4, MPLS,
	etc.) and the set of fields to match on. Figure 2 represents the		etc.) and the set of fields to match on. Figure 3 represents the
	overall contents of a route.		overall contents of a route.
	artwork		artwork
	route		route
	| | |		| | |
	+---------+ | +----------+		+---------+ | +----------+
	| | |		| | |
	0..N | | | 0..N		0..N | | | 1..N
	route-attributes match nexthop-list		route-attributes match nexthop-list
	|		|
	|		|
	+-------+-------+-------+--------+		+-------+-------+-------+--------+
	| | | | |		| | | | |
	| | | | |		| | | | |
	IPv4 IPv6 MPLS MAC Interface		IPv4 IPv6 MPLS MAC Interface
	Figure 2: Route model		(Unicast/Multicast)
			Figure 3: Route model
	This document specifies the following match types:		This document specifies the following match types:
	o IPv4: Match on destination IP in IPv4 header		o IPv4: Match on destination IP in IPv4 header
	o IPv6: Match on destination IP in IPv6 header		o IPv6: Match on destination IP in IPv6 header
	o MPLS: Match on a MPLS tag		o MPLS: Match on a MPLS tag
	o MAC: Match on ethernet destination addresses		o MAC: Match on ethernet destination addresses
	o Interface: Match on incoming interface of packet		o Interface: Match on incoming interface of packet
	o IP multicast: Match on (S, G) or (*, G), where S and G are IP		o IP multicast: Match on (S, G) or (*, G), where S and G are IP
	prefixes		prefixes
	skipping to change at page 9, line 45		skipping to change at page 9, line 20
	attributes.		attributes.
	o ROUTE_PREFERENCE: This is a numerical value that allows for		o ROUTE_PREFERENCE: This is a numerical value that allows for
	comparing routes from different protocols (where static		comparing routes from different protocols (where static
	configuration is also considered a protocol for the purpose of		configuration is also considered a protocol for the purpose of
	this field). It is also known as administrative-distance. The		this field). It is also known as administrative-distance. The
	lower the value, the higher the preference. For example there can		lower the value, the higher the preference. For example there can
	be an OSPF route for 192.0.2.1/32 with a preference of 5. If a		be an OSPF route for 192.0.2.1/32 with a preference of 5. If a
	controller programs a route for 192.0.2.1/32 with a preference of		controller programs a route for 192.0.2.1/32 with a preference of
	2, then the controller entered route will be preferred by the RIB		2, then the controller entered route will be preferred by the RIB
	manager. Preference should be used to dictate behavior. For more		manager. Preference should be used to dictate behavior. For more
	examples of preference, see Section 7.1.		examples of preference, see Section 8.1.
	o ROUTE_METRIC: Route preference is used for comparing routes from
	different protocols. Route metric is used for comparing routes
	learned by the same protocol. If a controller wishes to program 2
	or more routes to the same destination, then it can use the metric
	field to disambiguate the 2 routes. For more examples, see
	Section 7.1.
	o LOCAL_ONLY: This is a boolean value. If this is present, then it		o LOCAL_ONLY: This is a boolean value. If this is present, then it
	means that this route should not be exported into other RIBs or		means that this route should not be exported into other RIBs or
	other RIBs.		other RIBs.
	o rpf-check-interface: Reverse path forwarding (RPF) check is used		o rpf-check-interface: Reverse path forwarding (RPF) check is used
	to prevent spoofing and limit malicious traffic. For IP packets,		to prevent spoofing and limit malicious traffic. For IP packets,
	the IP source address is looked up and the rpf-check-interface		the IP source address is looked up and the rpf-check-interface
	associated with the route for that IP source address is found. If		associated with the route for that IP source address is found. If
	the incoming IP packet's interface matches one of the rpf-check-		the incoming IP packet's interface matches one of the rpf-check-
	interfaces, then the IP packet is forwarded based on its IP		interfaces, then the IP packet is forwarded based on its IP
	destination address; otherwise, the IP packet is discarded. For		destination address; otherwise, the IP packet is discarded. For
	MPLS routes, there is no source address to be looked up, so the		MPLS routes, there is no source address to be looked up, so the
	usage is slightly different. For an MPLS route, a packet with the		usage is slightly different. For an MPLS route, a packet with the
	specified MPLS label will only be forwarded if it is received on		specified MPLS label will only be forwarded if it is received on
	one of the interfaces specified by the rpf-check-interface. If no		one of the interfaces specified by the rpf-check-interface. If no
	rpf-check-interface is specified, then matching packets are no		rpf-check-interface is specified, then matching packets are no
	subject to this check. This field overrides the		subject to this check. This field overrides the
	ENABLE_IP_RPF_CHECK flag on the RIB and interfaces provided in		ENABLE_IP_RPF_CHECK flag on the RIB and interfaces provided in
	this list are used for doing the RPF check.		this list are used for doing the RPF check.
	o as-path: A route can have an as-path associated with it to
	indicate which set of autonomous systems has to be traversed to
	reach the final destination. The as-path attribute can be used by
	the RIB manager in multiple ways. The RIB manager can choose
	paths with lower as-path length. Or the RIB manager can choose to
	not install paths going via a particular AS. How exactly the RIB
	manager uses the as-path is outside the scope of this document.
	For details of how the as-path is formed, see Section 5.1.2 of
	[RFC4271] and Section 3 of [RFC5065].
	o route-vendor-attributes: Vendors can specify vendor-specific		o route-vendor-attributes: Vendors can specify vendor-specific
	attributes using this. The details of this field is outside the		attributes using this. The details of this field is outside the
	scope of this document.		scope of this document.
	2.4. Nexthop		2.4. Nexthop
	A nexthop represents an object or action resulting from a route		A nexthop represents an object or action resulting from a route
	lookup. For example, if a route lookup results in sending the packet		lookup. For example, if a route lookup results in sending the packet
	out a given interface, then the nexthop represents that interface.		out a given interface, then the nexthop represents that interface.
	skipping to change at page 11, line 39		skipping to change at page 11, line 30
	|		|
	nexthop-chain		nexthop-chain
	|		|
	1..N |		1..N |
	nexthop		nexthop
	|		|
	+------- nexthop-attributes
	|
	|		|
	+--------+------+------------------+------------------+		+--------+------+------------------+------------------+
	| | | |		| | | |
	| | | |		| | | |
	nexthop-id egress-interface logical-tunnel tunnel-encap		nexthop-id egress-interface logical-tunnel tunnel-encap
			Figure 4: Nexthop model
	Nexthops can be identified by an identifier to create a level of		Nexthops can be identified by an identifier to create a level of
	indirection. The identifier is set by the RIB manager and returned		indirection. The identifier is set by the RIB manager and returned
	to the external entity on request. The RIB data-model SHOULD support		to the external entity on request. The RIB data-model SHOULD support
	a way to optionally receive a nexthop identifier for a given nexthop.		a way to optionally receive a nexthop identifier for a given nexthop.
	For example, one can create a nexthop that points to a BGP peer. The		For example, one can create a nexthop that points to a BGP peer. The
	returned nexthop identifier can then be used for programming routes		returned nexthop identifier can then be used for programming routes
	to point to the same nexthop. Given that the RIB manager has created		to point to the same nexthop. Given that the RIB manager has created
	an indirection for that BGP peer using the nexthop identifier, if the		an indirection for that BGP peer using the nexthop identifier, if the
	transport path to the BGP peer changes, that change in path will be		transport path to the BGP peer changes, that change in path will be
	seamless to the external entity and all routes that point to that BGP		seamless to the external entity and all routes that point to that BGP
	peer will automatically start going over the new transport path.		peer will automatically start going over the new transport path.
	Nexthop indirection using identifier could be applied to not just		Nexthop indirection using identifier could be applied to not just
	unicast nexthops, but even to nexthops that contain chains and nested		unicast nexthops, but even to nexthops that contain chains and nested
	nexthops (Section 2.4.1).		nexthops (Section 2.4.1).
	skipping to change at page 12, line 37		skipping to change at page 12, line 26
	header		header
	o Lists of lists - recursive application of the above		o Lists of lists - recursive application of the above
	o Indirect nexthops - pointing to a nexthop identifier		o Indirect nexthops - pointing to a nexthop identifier
	o Special nexthops - for performing specific well-defined functions		o Special nexthops - for performing specific well-defined functions
	It is expected that all network devices will have a limit on how many		It is expected that all network devices will have a limit on how many
	levels of lookup can be performed and not all hardware will be able		levels of lookup can be performed and not all hardware will be able
	to support all kinds of nexthops. RIB capability negotiation becomes		to support all kinds of nexthops. RIB capability negotiation becomes
	very important for this reason and a RIB data-model MUST specify a		very important for this reason and a RIB data-model MUST specify a
	way for an external entity to learn about the network device's		way for an external entity to learn about the network device's
	capabilities. Examples of when and how to use various kinds of		capabilities. Examples of when and how to use various kinds of
	nexthops are shown in Section 7.2.		nexthops are shown in Section 8.2.
	Tunnel nexthops allow an external entity to program static tunnel		Tunnel nexthops allow an external entity to program static tunnel
	headers. There can be cases where the remote tunnel end-point does		headers. There can be cases where the remote tunnel end-point does
	not support dynamic signaling (e.g. no LDP support on a host) and in		not support dynamic signaling (e.g. no LDP support on a host) and in
	those cases the external entity might want to program the tunnel		those cases the external entity might want to program the tunnel
	header on both ends of the tunnel. The tunnel nexthop is kept		header on both ends of the tunnel. The tunnel nexthop is kept
	generic with specifications provided for some commonly used tunnels.		generic with specifications provided for some commonly used tunnels.
	It is expected that the data-model will model these tunnel types with		It is expected that the data-model will model these tunnel types with
	complete accuracy.		complete accuracy.
	skipping to change at page 14, line 12		skipping to change at page 13, line 47
	(or unavailable), then traffic MUST be load balanced over elements		(or unavailable), then traffic MUST be load balanced over elements
	with protection preference of 2.		with protection preference of 2.
	2.4.3. Nexthop content		2.4.3. Nexthop content
	At the lowest level, a nexthop can point to a:		At the lowest level, a nexthop can point to a:
	o identifier: This is an identifier returned by the network device		o identifier: This is an identifier returned by the network device
	representing another nexthop or another nexthop chain.		representing another nexthop or another nexthop chain.
	o EGRESS_INTERFACE: This represents a physical, logical or virtual		o EGRESS_INTERFACE: This represents a physical, logical or virtual
	interface on the network device.		interface on the network device.
	o address: This can be an IP address or MAC address or ISO address.		o address: This can be an IP address or MAC address.
	* An optional RIB name can also be specified to indicate the RIB		* An optional RIB name can also be specified to indicate the RIB
	in which the address is to be looked up further. One can use		in which the address is to be looked up further. One can use
	the RIB name field to direct the packet from one domain into		the RIB name field to direct the packet from one domain into
	another domain. For example, a MPLS packet coming in on an		another domain. For example, a MPLS packet coming in on an
	interface would be looked up in a MPLS RIB and the nexthop for		interface would be looked up in a MPLS RIB and the nexthop for
	that could indicate that we strip the MPLS label and do a		that could indicate that we strip the MPLS label and do a
	subsequent IPv4 lookup in an IPv4 RIB. By default the RIB will		subsequent IPv4 lookup in an IPv4 RIB. By default the RIB will
	be the same in which the route lookup was performed.		be the same in which the route lookup was performed.
	* An optional egress interface can be specified to indicate which		* An optional egress interface can be specified to indicate which
	interface to send the packet out on. The egress interface is		interface to send the packet out on. The egress interface is
	skipping to change at page 14, line 38		skipping to change at page 14, line 25
	send the packet out on. The egress interface is useful when the		send the packet out on. The egress interface is useful when the
	network device contains Ethernet interfaces and one needs to		network device contains Ethernet interfaces and one needs to
	perform an ARP lookup for the IP packet.		perform an ARP lookup for the IP packet.
	o logical tunnel: This can be a MPLS LSP or a GRE tunnel (or others		o logical tunnel: This can be a MPLS LSP or a GRE tunnel (or others
	as defined in this document), that is represented by a unique		as defined in this document), that is represented by a unique
	identifier (E.g. name).		identifier (E.g. name).
	o RIB_NAME: A nexthop pointing to a RIB indicates that the route		o RIB_NAME: A nexthop pointing to a RIB indicates that the route
	lookup needs to continue in the specified RIB. This is a way to		lookup needs to continue in the specified RIB. This is a way to
	perform chained lookups.		perform chained lookups.
	2.4.4. Nexthop attributes		2.4.4. Special nexthops
	Certain information is encoded implicitly in the nexthop and does not
	need to be specified by the controller. For example, when a IP
	packet is forwarded out, the IP TTL is decremented by default. Same
	applies for an MPLS packet. Similarly, when an IP packet is sent
	over an ethernet interface, any ARP processing is handled implicitly
	by the network device and does not need to be programmed by an
	external device.
	A nexthop can have some attributes associated with it. The purpose
	of the attributes is to either override implicit behavior (like that
	related to TTL processing) or to guide the network device to perform
	something specific. Vendor specific attributes can also be
	specified. The details of vendor specific attributes is outside the
	scope of this document.
	2.4.4.1. Nexthop flags
	Nexthop flags in a nexthop is an optional attribute that is used to
	denote specific connotation to hardware. Two common types of
	operations are specified using nexthop flags.
	o NO_DECREMENT_TTL: This indicates that the IPv4 time-to-live field
	in an IPv4 packet MUST NOT be decremented before the packet is
	forwarded. This may be applied one when an IPv4 packet is
	encapsulated in a tunnel (E.g. MPLS) and one wants to hide the
	fact that the packet is going through a tunnel.
	o NO_PROPAGATE_TTL: This indicates that the IPv4 time-to-live field
	in an IPv4 packet MUST NOT be propagated into an equivalent field,
	when the IPv4 packet is tunneled. For example, if the IPv4 packet
	is tunneled over MPLS, then the network device should use the
	default time-to-live value for the outer MPLS header. This field
	can also be used to indicate that when a tunnel terminates, one
	does not propagate the outer header's time-to-live value into the
	inner header. So, on MPLS tunnel termination, one does not
	propagate the MPLS TTL value into the IPv4 header.
	The TTL nexthop flags can be used to simulate a Pipe model for
	tunnels. See [RFC3443] for a detailed understanding of Pipe model
	and Uniform model.
	2.4.5. Nexthop vendor attributes
	This field has been defined for vendor specific extensions. The
	contents of this field are beyond the scope of this document.
	2.4.6. Special nexthops
	This document specifies certain special nexthops. The purpose of		This document specifies certain special nexthops. The purpose of
	each of them is explained below:		each of them is explained below:
	o DISCARD: This indicates that the network device should drop the		o DISCARD: This indicates that the network device should drop the
	packet and increment a drop counter.		packet and increment a drop counter.
	o DISCARD_WITH_ERROR: This indicates that the network device should		o DISCARD_WITH_ERROR: This indicates that the network device should
	drop the packet, increment a drop counter and send back an		drop the packet, increment a drop counter and send back an
	appropriate error message (like ICMP error).		appropriate error message (like ICMP error).
	o RECEIVE: This indicates that that the traffic is destined for the		o RECEIVE: This indicates that that the traffic is destined for the
	network device. For example, protocol packets or OAM packets.		network device. For example, protocol packets or OAM packets.
	skipping to change at page 17, line 16		skipping to change at page 16, line 10
	notifications. A brief list of suggested notifications is as below:		notifications. A brief list of suggested notifications is as below:
	o Route change notification, with return code as specified in		o Route change notification, with return code as specified in
	Section 4		Section 4
	o Nexthop resolution status (resolved/unresolved) notification		o Nexthop resolution status (resolved/unresolved) notification
	6. RIB grammar		6. RIB grammar
	This section specifies the RIB information model in Routing Backus-		This section specifies the RIB information model in Routing Backus-
	Naur Form [RFC5511].		Naur Form [RFC5511].
	<routing-instance> ::= <INSTANCE_NAME> <INSTANCE_DISTINGUISHER>		<routing-instance> ::= <INSTANCE_NAME>
	[<interface-list>] <rib-list>		[<interface-list>] <rib-list>
	[<ROUTER_ID>] [<as-data>]		[<ROUTER_ID>]
	<as-data> ::= <AS_NUMBER> [<CONFEDERATION_AS>]
	<interface-list> ::= (<INTERFACE_IDENTIFIER> ...)		<interface-list> ::= (<INTERFACE_IDENTIFIER> ...)
	<rib-list> ::= (<rib> ...)		<rib-list> ::= (<rib> ...)
	<rib> ::= <RIB_NAME> <rib-family>		<rib> ::= <RIB_NAME> <rib-family>
	[<route> ... ] [<MULTI_TOPOLOGY_ID>]		[<route> ... ] [<MULTI_TOPOLOGY_ID>]
	[ENABLE_IP_RPF_CHECK]		[ENABLE_IP_RPF_CHECK]
	<rib-family> ::= <IPV4_RIB_FAMILY> | <IPV6_RIB_FAMILY> |		<rib-family> ::= <IPV4_RIB_FAMILY> | <IPV6_RIB_FAMILY> |
	<MPLS_RIB_FAMILY> | <IEEE_MAC_RIB_FAMILY>		<MPLS_RIB_FAMILY> | <IEEE_MAC_RIB_FAMILY>
	<route> ::= <match> <nexthop-list>		<route> ::= <match> <nexthop-list>
	[<route-attributes>]		[<route-attributes>]
	[<route-vendor-attributes>]		[<route-vendor-attributes>]
	<match> ::= <ipv4-route> | <ipv6-route> | <mpls-route> |		<match> ::= <ipv4-route> | <ipv6-route> | <mpls-route> |
	<mac-route> | <interface-route>		<mac-route> | <interface-route>
	<ipv4-route> ::= <ipv4-prefix> [<multicast-source-ipv4-address>]		<ipv4-route> ::= <destination-ipv4-address> | <source-ipv4-address> |
			(<destination-ipv4-address> <source-ipv4-address>)
			<destination-ipv4-address> ::= <ipv4-prefix>
			<source-ipv4-address> ::= <ipv4-prefix>
	<ipv4-prefix> ::= <IPV4_ADDRESS> <IPV4_ADDRESS_LENGTH>		<ipv4-prefix> ::= <IPV4_ADDRESS> <IPV4_ADDRESS_LENGTH>
	<ipv6-route> ::= <ipv6-prefix> [<multicast-source-ipv6-address>]		<ipv6-route> ::= <destination-ipv6-address> | <source-ipv6-address> |
			(<destination-ipv6-address> <source-ipv6-address>)
			<destination-ipv6-address> ::= <ipv6-prefix>
			<source-ipv6-address> ::= <ipv6-prefix>
	<ipv6-prefix> ::= <IPV6_ADDRESS> <IPV6_PREFIX_LENGTH>		<ipv6-prefix> ::= <IPV6_ADDRESS> <IPV6_PREFIX_LENGTH>
	<mpls-route> ::= <MPLS> <MPLS_LABEL>		<mpls-route> ::= <MPLS> <MPLS_LABEL>
	<mac-route> ::= <IEEE_MAC> ( <MAC_ADDRESS> )		<mac-route> ::= <IEEE_MAC> ( <MAC_ADDRESS> )
	<interface-route> ::= <INTERFACE> <INTERFACE_IDENTIFIER>		<interface-route> ::= <INTERFACE> <INTERFACE_IDENTIFIER>
	<multicast-source-ipv4-address> ::= <IPV4_ADDRESS>		<multicast-source-ipv4-address> ::= <IPV4_ADDRESS>
	<IPV4_PREFIX_LENGTH>		<IPV4_PREFIX_LENGTH>
	<multicast-source-ipv6-address> ::= <IPV6_ADDRESS>		<multicast-source-ipv6-address> ::= <IPV6_ADDRESS>
	<IPV6_PREFIX_LENGTH>		<IPV6_PREFIX_LENGTH>
	<route-attributes> ::= [<ROUTE_PREFERENCE>] [<ROUTE_METRIC>]		<route-attributes> ::= [<ROUTE_PREFERENCE>] [<LOCAL_ONLY>]
	[<LOCAL_ONLY>]
	[<address-family-route-attributes>]		[<address-family-route-attributes>]
	<address-family-route-attributes> ::= <ip-route-attributes> |		<address-family-route-attributes> ::= <ip-route-attributes> |
	<mpls-route-attributes> |		<mpls-route-attributes> |
	<ethernet-route-attributes>		<ethernet-route-attributes>
	<ip-route-attributes> ::= [<as-path>] [<rpf-check-interface>]		<ip-route-attributes> ::= [<rpf-check-interface>]
	<as-path> ::= (<as-path-segment-type> <as-list>) [<as-path> ...]
	<as-path-segment-type> ::= <AS_SET> | <AS_SEQUENCE> |
	<AS_CONFED_SEQUENCE> | <AS_CONFED_SET>
	<as-list> ::= (<AS_NUMBER> ...) [<as-path>]
	<rpf-check-interface> ::= <interface-list>		<rpf-check-interface> ::= <interface-list>
	<mpls-route-attributes> ::= [<rpf-check-interface>]		<mpls-route-attributes> ::= [<rpf-check-interface>]
	<ethernet-route-attributes> ::= <>		<ethernet-route-attributes> ::= <>
	<route-vendor-attributes> ::= <>		<route-vendor-attributes> ::= <>
	<nexthop-list> ::= <special-nexthop> |		<nexthop-list> ::= <special-nexthop> |
	((<nexthop-list-member>) |		((<nexthop-list-member>) |
	([<nexthop-list-member> ... ] <nexthop-list> ))		([<nexthop-list-member> ... ] <nexthop-list> ))
	skipping to change at page 18, line 45		skipping to change at page 17, line 35
	[<LOAD_BALANCE_WEIGHT>]		[<LOAD_BALANCE_WEIGHT>]
	<nexthop-chain> ::= (<nexthop> ...)		<nexthop-chain> ::= (<nexthop> ...)
	<nexthop-chain-identifier> ::= <NEXTHOP_NAME> | <NEXTHOP_ID>		<nexthop-chain-identifier> ::= <NEXTHOP_NAME> | <NEXTHOP_ID>
	<nexthop> ::= (<nexthop-identifier> | <EGRESS_INTERFACE> |		<nexthop> ::= (<nexthop-identifier> | <EGRESS_INTERFACE> |
	(<nexthop-address>		(<nexthop-address>
	([<RIB_NAME>] | [<EGRESS_INTERFACE>])) |		([<RIB_NAME>] | [<EGRESS_INTERFACE>])) |
	(<tunnel-encap> [<EGRESS_INTERFACE>]) |		(<tunnel-encap> [<EGRESS_INTERFACE>]) |
	<logical-tunnel> |		<logical-tunnel> |
	<RIB_NAME>)		<RIB_NAME>)
	[<nexthop-attributes>]
	[<nexthop-vendor-attributes>]
	<nexthop-identifier> ::= <NEXTHOP_NAME> | <NEXTHOP_ID>		<nexthop-identifier> ::= <NEXTHOP_NAME> | <NEXTHOP_ID>
	<nexthop-address> ::= (<IPv4> <ipv4-address>) |		<nexthop-address> ::= (<IPv4> <ipv4-address>) |
	(<IPV6> <ipv6-address>) |		(<IPV6> <ipv6-address>) |
	(<IEEE_MAC> <IEEE_MAC_ADDRESS>) |		(<IEEE_MAC> <IEEE_MAC_ADDRESS>)
	(<ISO> <ISO_ADDRESS>)
	<special-nexthop> ::= <DISCARD> | <DISCARD_WITH_ERROR> |		<special-nexthop> ::= <DISCARD> | <DISCARD_WITH_ERROR> |
	(<RECEIVE> [<COS_VALUE>] [<rate-limiter>])		(<RECEIVE> [<COS_VALUE>] [<rate-limiter>])
	<rate-limiter> ::= <>		<rate-limiter> ::= <>
	<logical-tunnel> ::= <tunnel-type> <TUNNEL_NAME>		<logical-tunnel> ::= <tunnel-type> <TUNNEL_NAME>
	<tunnel-type> ::= <IP> | <MPLS> | <GRE> | <VxLAN> | <NVGRE>		<tunnel-type> ::= <IP> | <MPLS> | <GRE> | <VxLAN> | <NVGRE>
	<tunnel-encap> ::= (<IPV4> <ipv4-header>) |		<tunnel-encap> ::= (<IPV4> <ipv4-header>) |
	(<IPV6> <ipv6-header>) |		(<IPV6> <ipv6-header>) |
	(<MPLS> <mpls-header>) |		(<MPLS> <mpls-header>) |
	skipping to change at page 19, line 38		skipping to change at page 18, line 24
	[<TOS_VALUE>] [<TTL_VALUE>]) |		[<TOS_VALUE>] [<TTL_VALUE>]) |
	(<MPLS_POP> [<TTL_ACTION>])		(<MPLS_POP> [<TTL_ACTION>])
	<gre-header> ::= <GRE_IP_DESTINATION> <GRE_PROTOCOL_TYPE> [<GRE_KEY>]		<gre-header> ::= <GRE_IP_DESTINATION> <GRE_PROTOCOL_TYPE> [<GRE_KEY>]
	<vxlan-header> ::= (<ipv4-header> | <ipv6-header>)		<vxlan-header> ::= (<ipv4-header> | <ipv6-header>)
	[<VXLAN_IDENTIFIER>]		[<VXLAN_IDENTIFIER>]
	<nvgre-header> ::= (<ipv4-header> | <ipv6-header>)		<nvgre-header> ::= (<ipv4-header> | <ipv6-header>)
	<VIRTUAL_SUBNET_ID>		<VIRTUAL_SUBNET_ID>
	[<FLOW_ID>]		[<FLOW_ID>]
	<nexthop-attributes> ::= [<NEXTHOP_ADDRESS_FAMILY>]		Figure 5: RIB rBNF grammar
	[<nexthop-flags>]
	<NEXTHOP_ADDRESS_FAMILY> ::= <IPV4> | <IPV6> | <ISO> | <IEEE MAC>
	<nexthop-flags> ::= [<NO_DECREMENT_TTL>] [<NO_PROPAGATE_TTL>]
	<nexthop-vendor-attributes> ::= <>
	7. Using the RIB grammar		7. Inter-domain extensions to the RIB
			This section describes inter-domain extensions to the Routing
			Information Base to allow an external entity to learn about and
			program inter-domain information associated with the RIB and it's
			routes. In the absence of this extension, the network device MUST
			NOT return any routes that have inter-domain information associated
			(such as autonomous-system path information).
			7.1. Extension to Routing Instance
			A routing instance is augmented with an optional parameter called as-
			data.
			as-data is an identifier of the administrative domain to which the
			routing instance belongs. The as-data fields is used when the routes
			in this instance are to be tagged with certain autonomous system (AS)
			characteristics. The RIB manager can use AS length as one of the
			parameters for making route selection. as-data consists of a AS
			number and an optional Confederation AS number ([RFC5065]).
			7.2. Extension to Route
			Routes are augmented with an optional parameter called as-path.
			A route can have an as-path associated with it to indicate which set
			of autonomous systems has to be traversed to reach the final
			destination. The as-path attribute can be used by the RIB manager in
			multiple ways. The RIB manager can choose paths with lower as-path
			length. Or the RIB manager can choose to not install paths going via
			a particular AS. How exactly the RIB manager uses the as-path is
			outside the scope of this document. For details of how the as-path
			is formed, see Section 5.1.2 of [RFC4271] and Section 3 of [RFC5065].
			7.3. Inter-domain extensions to RIB grammar
			<routing-instance> ::= <INSTANCE_NAME>
			[<interface-list>] <rib-list>
			[<ROUTER_ID>] [<as-data>]
			<as-data> ::= <AS_NUMBER> [<CONFEDERATION_AS>]
			<ip-route-attributes> ::= [<rpf-check-interface>] [<as-path>]
			<as-path> ::= (<as-path-segment-type> <as-list>) [<as-path> ...]
			<as-path-segment-type> ::= <AS_SET> | <AS_SEQUENCE> |
			<AS_CONFED_SEQUENCE> | <AS_CONFED_SET>
			<as-list> ::= (<AS_NUMBER> ...) [<as-path>]
			Figure 6: RIB rBNF grammar - Inter-domain extensions
			8. Using the RIB grammar
	The RIB grammar is very generic and covers a variety of features.		The RIB grammar is very generic and covers a variety of features.
	This section provides examples on using objects in the RIB grammar		This section provides examples on using objects in the RIB grammar
	and examples to program certain use cases.		and examples to program certain use cases.
	7.1. Using route preference and metric		8.1. Using route preference
	Using route preference one can pre-install protection paths in the		Using route preference one can pre-install protection paths in the
	network. For example, if OSPF has a route preference of 10, then one		network. For example, if OSPF has a route preference of 10, then one
	can install a route with route preference of 20 to the same		can install a route with route preference of 20 to the same
	destination. The OSPF route will get precedence and will get		destination. The OSPF route will get precedence and will get
	installed in the FIB. When the OSPF route goes away (for any		installed in the FIB. When the OSPF route goes away (for any
	reason), the protection path will get installed in the FIB. If the		reason), the protection path will get installed in the FIB. If the
	hardware supports it, then the RIB manager can choose to pre-install		hardware supports it, then the RIB manager can choose to pre-install
	both routes, with the OSPF nexthop getting preference.		both routes, with the OSPF nexthop getting preference.
	Route preference can also be used to prevent denial of service		Route preference can also be used to prevent denial of service
	attacks by installing routes with the best preference, which either		attacks by installing routes with the best preference, which either
	drops the offending traffic or routes it to some monitoring/analysis		drops the offending traffic or routes it to some monitoring/analysis
	station. Since the routes are installed with the best preference,		station. Since the routes are installed with the best preference,
	they will supersede any route installed by any other protocol.		they will supersede any route installed by any other protocol.
	Route metric is used to disambiguate between 2 or more routes to the		8.2. Using different nexthops types
	same destination with the same preference and in the same RIB. One
	usage of this is to install 2 routes, each with a different nexthop.
	The preferred nexthop is given a better metric than the other one.
	This results in traffic being forwarded to the preferred nexthop. If
	the preferred nexthop fails, then the RIB manager will automatically
	install a route to the other nexthop.
	7.2. Using different nexthops types
	The RIB grammar allows one to create a variety of nexthops. This		The RIB grammar allows one to create a variety of nexthops. This
	section describes uses for certain types of nexthops.		section describes uses for certain types of nexthops.
	7.2.1. Tunnel nexthops		8.2.1. Tunnel nexthops
	A tunnel nexthop points to a tunnel of some kind. Traffic that goes		A tunnel nexthop points to a tunnel of some kind. Traffic that goes
	over the tunnel gets encapsulated with the tunnel encap. Tunnel		over the tunnel gets encapsulated with the tunnel encap. Tunnel
	nexthops are useful for abstracting out details of the network, by		nexthops are useful for abstracting out details of the network, by
	having the traffic seamlessly route between network edges.		having the traffic seamlessly route between network edges.
	7.2.2. Replication lists		8.2.2. Replication lists
	One can create a replication list for replication traffic to multiple		One can create a replication list for replication traffic to multiple
	destinations. The destinations, in turn, could be complex nexthops		destinations. The destinations, in turn, could be complex nexthops
	in themselves - at a level supported by the network device. Point to		in themselves - at a level supported by the network device. Point to
	multipoint and broadcast are examples that involve replication.		multipoint and broadcast are examples that involve replication.
	A replication list (at the simplest level) can be represented as:		A replication list (at the simplest level) can be represented as:
	<nexthop-list> ::= <nexthop> [ <nexthop> ... ]		<nexthop-list> ::= <nexthop> [ <nexthop> ... ]
	The above can be derived from the grammar as follows:		The above can be derived from the grammar as follows:
	<nexthop-list> ::= <nexthop-list-member> [<nexthop-list-member> ...]		<nexthop-list> ::= <nexthop-list-member> [<nexthop-list-member> ...]
	<nexthop-list> ::= <nexthop-chain> [<nexthop-chain> ...]		<nexthop-list> ::= <nexthop-chain> [<nexthop-chain> ...]
	<nexthop-list> ::= <nexthop> [ <nexthop> ... ]		<nexthop-list> ::= <nexthop> [ <nexthop> ... ]
	7.2.3. Weighted lists		8.2.3. Weighted lists
	A weighted list is used to load-balance traffic among a set of		A weighted list is used to load-balance traffic among a set of
	nexthops. From a modeling perspective, a weighted list is very		nexthops. From a modeling perspective, a weighted list is very
	similar to a replication list, with the difference that each member		similar to a replication list, with the difference that each member
	nexthop MUST have a LOAD_BALANCE_WEIGHT associated with it.		nexthop MUST have a LOAD_BALANCE_WEIGHT associated with it.
	A weighted list (at the simplest level) can be represented as:		A weighted list (at the simplest level) can be represented as:
	<nexthop-list> ::= (<nexthop> <LOAD_BALANCE_WEIGHT>)		<nexthop-list> ::= (<nexthop> <LOAD_BALANCE_WEIGHT>)
	[(<nexthop> <LOAD_BALANCE_WEIGHT>)... ]		[(<nexthop> <LOAD_BALANCE_WEIGHT>)... ]
	The above can be derived from the grammar as follows:		The above can be derived from the grammar as follows:
	<nexthop-list> ::= <nexthop-list-member> [<nexthop-list-member> ...]		<nexthop-list> ::= <nexthop-list-member> [<nexthop-list-member> ...]
	<nexthop-list> ::= (<nexthop-chain> <nexthop-list-member-attributes>)		<nexthop-list> ::= (<nexthop-chain> <nexthop-list-member-attributes>)
	[(<nexthop-chain>		[(<nexthop-chain>
	<nexthop-list-member-attributes>) ...]		<nexthop-list-member-attributes>) ...]
	<nexthop-list> ::= (<nexthop-chain> <LOAD_BALANCE_WEIGHT>)		<nexthop-list> ::= (<nexthop-chain> <LOAD_BALANCE_WEIGHT>)
	[(<nexthop-chain> <LOAD_BALANCE_WEIGHT>) ... ]		[(<nexthop-chain> <LOAD_BALANCE_WEIGHT>) ... ]
	<network-list> ::= (<nexthop> <LOAD_BALANCE_WEIGHT>)		<nexthop-list> ::= (<nexthop> <LOAD_BALANCE_WEIGHT>)
	[(<nexthop> <LOAD_BALANCE_WEIGHT>)... ]		[(<nexthop> <LOAD_BALANCE_WEIGHT>)... ]
	7.2.4. Protection lists		8.2.4. Protection lists
	Protection lists are similar to weighted lists. A protection list		Protection lists are similar to weighted lists. A protection list
	specifies a set of primary nexthops and a set of backup nexthops.		specifies a set of primary nexthops and a set of backup nexthops.
	The <PROTECTION_PREFERENCE> attribute indicates which nexthop is		The <PROTECTION_PREFERENCE> attribute indicates which nexthop is
	primary and which is backup.		primary and which is backup.
	A protection list can be represented as:		A protection list can be represented as:
	<nexthop-list> ::= (<nexthop> <PROTECTION_PREFERENCE>)		<nexthop-list> ::= (<nexthop> <PROTECTION_PREFERENCE>)
	[(<nexthop> <PROTECTION_PREFERENCE>)... ]		[(<nexthop> <PROTECTION_PREFERENCE>)... ]
	A protection list can also be a weighted list. In other words,		A protection list can also be a weighted list. In other words,
	traffic can be load-balanced among the primary nexthops of a		traffic can be load-balanced among the primary nexthops of a
	protection list. In such a case, the list will look like:		protection list. In such a case, the list will look like:
	<nexthop-list> ::= (<nexthop> <PROTECTION_PREFERENCE>		<nexthop-list> ::= (<nexthop> <PROTECTION_PREFERENCE>
	<LOAD_BALANCE_WEIGHT>)		<LOAD_BALANCE_WEIGHT>)
	[(<nexthop> <PROTECTION_PREFERENCE>		[(<nexthop> <PROTECTION_PREFERENCE>
	<LOAD_BALANCE_WEIGHT>)... ]		<LOAD_BALANCE_WEIGHT>)... ]
	7.2.5. Nexthop chains		8.2.5. Nexthop chains
	A nexthop chain is a nexthop that puts one or more headers on an		A nexthop chain is a nexthop that puts one or more headers on an
	outgoing packet. One example is a Pseudowire - which is MPLS over		outgoing packet. One example is a Pseudowire - which is MPLS over
	some transport (MPLS or GRE for instance). Another example is VxLAN		some transport (MPLS or GRE for instance). Another example is VxLAN
	over IP. A nexthop chain allows an external entity to break up the		over IP. A nexthop chain allows an external entity to break up the
	programming of the nexthop into independent pieces - one per		programming of the nexthop into independent pieces - one per
	encapsulation.		encapsulation.
	A simple example of MPLS over GRE can be represented as:		A simple example of MPLS over GRE can be represented as:
	skipping to change at page 22, line 33		skipping to change at page 22, line 16
	The above can be derived from the grammar as follows:		The above can be derived from the grammar as follows:
	<nexthop-list> ::= <nexthop-list-member> [<nexthop-list-member> ...]		<nexthop-list> ::= <nexthop-list-member> [<nexthop-list-member> ...]
	<nexthop-list> ::= <nexthop-chain>		<nexthop-list> ::= <nexthop-chain>
	<nexthop-list> ::= <nexthop> [ <nexthop> ... ]		<nexthop-list> ::= <nexthop> [ <nexthop> ... ]
	<nexthop-list> ::= <tunnel-encap> (<nexthop> [ <nexthop> ...])		<nexthop-list> ::= <tunnel-encap> (<nexthop> [ <nexthop> ...])
	<nexthop-list> ::= <tunnel-encap> (<tunnel-encap>)		<nexthop-list> ::= <tunnel-encap> (<tunnel-encap>)
	<nexthop-list> ::= (<MPLS> <mpls-header>) (<GRE> <gre-header>)		<nexthop-list> ::= (<MPLS> <mpls-header>) (<GRE> <gre-header>)
	7.2.6. Lists of lists		8.2.6. Lists of lists
	Lists of lists is a complex construct. One example of usage of such		Lists of lists is a complex construct. One example of usage of such
	a construct is to replicate traffic to multiple destinations, with		a construct is to replicate traffic to multiple destinations, with
	high availability. In other words, for each destination you have a		high availability. In other words, for each destination you have a
	primary and backup nexthop (replication list) to ensure there is no		primary and backup nexthop (replication list) to ensure there is no
	traffic drop in case of a failure. So the outer list is a protection		traffic drop in case of a failure. So the outer list is a protection
	list and the inner lists are replication lists of primary/backup		list and the inner lists are replication lists of primary/backup
	nexthops.		nexthops.
	7.3. Performing multicast		8.3. Performing multicast
	IP multicast involves matching a packet on (S, G) or (*, G), where		IP multicast involves matching a packet on (S, G) or (*, G), where
	both S (source) and G (group) are IP prefixes. Following the match,		both S (source) and G (group) are IP prefixes. Following the match,
	the packet is replicated to one or more recipients. How the		the packet is replicated to one or more recipients. How the
	recipients subscribe to the multicast group is outside the scope of		recipients subscribe to the multicast group is outside the scope of
	this document.		this document.
	In PIM-based multicast, the packets are IP forwarded on an IP		In PIM-based multicast, the packets are IP forwarded on an IP
	multicast tree. The downstream nodes on each point in the multicast		multicast tree. The downstream nodes on each point in the multicast
	tree is one or more IP addresses. These can be represented as a		tree is one or more IP addresses. These can be represented as a
	replication list ( Section 7.2.2 ).		replication list ( Section 8.2.2 ).
	In MPLS-based multicast, the packets are forwarded on a point to		In MPLS-based multicast, the packets are forwarded on a point to
	multipoint (P2MP) label-switched path (LSP). The nexthop for a P2MP		multipoint (P2MP) label-switched path (LSP). The nexthop for a P2MP
	LSP can be represented in the nexthop grammar as a <logical-tunnel>		LSP can be represented in the nexthop grammar as a <logical-tunnel>
	(P2MP LSP identifier) or a replication list ( Section 7.2.2) of		(P2MP LSP identifier) or a replication list ( Section 8.2.2) of
	<tunnel-encap>, with each tunnel encap representing a single mpls		<tunnel-encap>, with each tunnel encap representing a single mpls
	downstream nexthop.		downstream nexthop.
	7.4. Solving optimized exit control		8.4. Solving optimized exit control
	In case of optimized exit control, a controller wants to control the		In case of optimized exit control, a controller wants to control the
	edge device (and optionally control the outgoing interface on that		edge device (and optionally control the outgoing interface on that
	edge device) that is used by a server to send traffic out. This can		edge device) that is used by a server to send traffic out. This can
	be easily achieved by having the controller program the edge router		be easily achieved by having the controller program the edge router
	(Eg. 192.0.2.10) and the server along the following lines:		(Eg. 192.0.2.10) and the server along the following lines:
	Server:		Server:
	<route> ::= <rib-name> <match> (<edge-router>		<route> ::= <rib-name> <match> (<edge-router>
	<edge-router-interface>)		<edge-router-interface>)
	skipping to change at page 23, line 43		skipping to change at page 23, line 23
	(<MPLS_PUSH> <100>)		(<MPLS_PUSH> <100>)
	(<GRE> <192.0.2.10> <GRE_PROTOCOL_MPLS>)		(<GRE> <192.0.2.10> <GRE_PROTOCOL_MPLS>)
	Edge Router:		Edge Router:
	<route> ::= <mpls-rib> <mpls-route> <nexthop>		<route> ::= <mpls-rib> <mpls-route> <nexthop>
	<route> ::= <mpls-rib> (<MPLS> <100>) <interface-10>		<route> ::= <mpls-rib> (<MPLS> <100>) <interface-10>
	In the above case, the label 100 identifies the egress interface		In the above case, the label 100 identifies the egress interface
	on the edge router.		on the edge router.
	8. RIB operations at scale		9. RIB operations at scale
	This section discusses the scale requirements for a RIB data-model.		This section discusses the scale requirements for a RIB data-model.
	The RIB data-model should be able to handle large scale of		The RIB data-model should be able to handle large scale of
	operations, to enable deployment of RIB applications in large		operations, to enable deployment of RIB applications in large
	networks.		networks.
	8.1. RIB reads		9.1. RIB reads
	Bulking (grouping of multiple objects in a single message) MUST be		Bulking (grouping of multiple objects in a single message) MUST be
	supported when a network device sends RIB data to an external entity.		supported when a network device sends RIB data to an external entity.
	Similarly the data model MUST enable a RIB client to request data in		Similarly the data model MUST enable a RIB client to request data in
	bulk from a network device.		bulk from a network device.
	8.2. RIB writes		9.2. RIB writes
	Bulking (grouping of multiple write operations in a single message)		Bulking (grouping of multiple write operations in a single message)
	MUST be supported when an external entity wants to write to the RIB.		MUST be supported when an external entity wants to write to the RIB.
	The response from the network device MUST include a return-code for		The response from the network device MUST include a return-code for
	each write operation in the bulk message.		each write operation in the bulk message.
	8.3. RIB events and notifications		9.3. RIB events and notifications
	There can be cases where a single network event results in multiple		There can be cases where a single network event results in multiple
	events and/or notifications from the network device to an external		events and/or notifications from the network device to an external
	entity. On the other hand, due to timing of multiple things		entity. On the other hand, due to timing of multiple things
	happening at the same time, a network device might have to send		happening at the same time, a network device might have to send
	multiple events and/or notifications to an external entity. The		multiple events and/or notifications to an external entity. The
	network device originated event/notification message MUST support		network device originated event/notification message MUST support
	bulking of multiple events and notifications in a single message.		bulking of multiple events and notifications in a single message.
	9. Security Considerations		10. Security Considerations
	All interactions between a RIB manager and an external entity MUST be		All interactions between a RIB manager and an external entity MUST be
	authenticated and authorized. The RIB manager MUST protect itself		authenticated and authorized. The RIB manager MUST protect itself
	against a denial of service attack by a rogue external entity, by		against a denial of service attack by a rogue external entity, by
	throttling request processing. A RIB manager MUST enforce limits on		throttling request processing. A RIB manager MUST enforce limits on
	how much data can be programmed by an external entity and return		how much data can be programmed by an external entity and return
	error when such a limit is reached.		error when such a limit is reached.
	The RIB manager MUST expose a data-model that it implements. An		The RIB manager MUST expose a data-model that it implements. An
	external agent MUST send requests to the RIB manager that comply with		external agent MUST send requests to the RIB manager that comply with
	the supported data-model. The data-model MUST specify the behavior		the supported data-model. The data-model MUST specify the behavior
	of the RIB manager on handling of unsupported data requests.		of the RIB manager on handling of unsupported data requests.
	10. IANA Considerations		11. IANA Considerations
	This document does not generate any considerations for IANA.		This document does not generate any considerations for IANA.
	11. Acknowledgements		12. Acknowledgements
	The authors would like to thank the working group co-chairs and		The authors would like to thank the working group co-chairs and
	reviewers on their comments and suggestions on this draft. The		reviewers on their comments and suggestions on this draft. The
	following people contributed to the design of the RIB model as part		following people contributed to the design of the RIB model as part
	of the I2RS Interim meeting in April 2013 - Wes George, Chris		of the I2RS Interim meeting in April 2013 - Wes George, Chris
	Liljenstolpe, Jeff Tantsura, Sriganesh Kini, Susan Hares, Fabian		Liljenstolpe, Jeff Tantsura, Sriganesh Kini, Susan Hares, Fabian
	Schneider and Nitin Bahadur.		Schneider and Nitin Bahadur.
	12. References		13. References
	12.1. Normative References		13.1. Normative References
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119, March 1997.		Requirement Levels", BCP 14, RFC 2119, March 1997.
	12.2. Informative References		13.2. Informative References
	[I-D.atlas-i2rs-problem-statement]		[I-D.atlas-i2rs-problem-statement]
	Atlas, A., Nadeau, T., and D. Ward, "Interface to the		Atlas, A., Nadeau, T., and D. Ward, "Interface to the
	Routing System Problem Statement",		Routing System Problem Statement",
	draft-atlas-i2rs-problem-statement-02 (work in progress),		draft-atlas-i2rs-problem-statement-02 (work in progress),
	August 2013.		August 2013.
	[I-D.hares-i2rs-use-case-vn-vc]		[I-D.hares-i2rs-use-case-vn-vc]
	Hares, S., "Use Cases for Virtual Connections on Demand		Hares, S., "Use Cases for Virtual Connections on Demand
	(VCoD) and Virtual Network on Demand using Interface to		(VCoD) and Virtual Network on Demand using Interface to
	Routing System", draft-hares-i2rs-use-case-vn-vc-00 (work		Routing System", draft-hares-i2rs-use-case-vn-vc-00 (work
	in progress), February 2013.		in progress), February 2013.
	[I-D.white-i2rs-use-case]		[I-D.white-i2rs-use-case]
	White, R., Hares, S., and A. Retana, "Protocol Independent		White, R., Hares, S., and A. Retana, "Protocol Independent
	Use Cases for an Interface to the Routing System",		Use Cases for an Interface to the Routing System",
	draft-white-i2rs-use-case-01 (work in progress),		draft-white-i2rs-use-case-01 (work in progress),
	August 2013.		August 2013.
	[RFC3443] Agarwal, P. and B. Akyol, "Time To Live (TTL) Processing
	in Multi-Protocol Label Switching (MPLS) Networks",
	RFC 3443, January 2003.
	[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway		[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
	Protocol 4 (BGP-4)", RFC 4271, January 2006.		Protocol 4 (BGP-4)", RFC 4271, January 2006.
	[RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P.		[RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P.
	Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF",		Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF",
	RFC 4915, June 2007.		RFC 4915, June 2007.
	[RFC5065] Traina, P., McPherson, D., and J. Scudder, "Autonomous		[RFC5065] Traina, P., McPherson, D., and J. Scudder, "Autonomous
	System Confederations for BGP", RFC 5065, August 2007.		System Confederations for BGP", RFC 5065, August 2007.
	skipping to change at page 26, line 16		skipping to change at page 25, line 38
	Topology (MT) Routing in Intermediate System to		Topology (MT) Routing in Intermediate System to
	Intermediate Systems (IS-ISs)", RFC 5120, February 2008.		Intermediate Systems (IS-ISs)", RFC 5120, February 2008.
	[RFC5511] Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax		[RFC5511] Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax
	Used to Form Encoding Rules in Various Routing Protocol		Used to Form Encoding Rules in Various Routing Protocol
	Specifications", RFC 5511, April 2009.		Specifications", RFC 5511, April 2009.
	Authors' Addresses		Authors' Addresses
	Nitin Bahadur (editor)		Nitin Bahadur (editor)
	Juniper Networks, Inc.
	1194 N. Mathilda Avenue
	Sunnyvale, CA 94089
	US
	Phone: +1 408 745 2000		Email: nitin_bahadur@yahoo.com
	Email: nitinb@juniper.net
	URI: www.juniper.net
	Ron Folkes (editor)		Ron Folkes (editor)
	Juniper Networks, Inc.		Juniper Networks, Inc.
	1194 N. Mathilda Avenue		1194 N. Mathilda Avenue
	Sunnyvale, CA 94089		Sunnyvale, CA 94089
	US		US
	Phone: +1 408 745 2000		Phone: +1 408 745 2000
	Email: ronf@juniper.net		Email: ronf@juniper.net
	URI: www.juniper.net		URI: www.juniper.net
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