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
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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
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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
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| | | |
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
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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
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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.
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| |
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).
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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.
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(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
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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>)
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(<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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