Internet DRAFT - draft-hareskini-i2rs-pbr-info-model
draft-hareskini-i2rs-pbr-info-model
I2RS working group S. Hares
Internet-Draft Huawei
Intended status: Standards Track S. Kini
Expires: April 30, 2015 Ericsson
A. Ghanwani
Dell
R. Krishnan
Brocade
Q. Wu
Huawei
D. Bogdanovic
Juniper Networks
October 27, 2014
An Information Model for Basic Network Policy
draft-hareskini-i2rs-pbr-info-model-00
Abstract
This document defines the I2RS Policy-Based Routing (PBR) policy
information model describing I2RS interactions with the PBR in a
routing system. The PBR IM uses Policy Core Information Model (PCIM)
framework (RFC3060, RFC3460, and RFC3644) to specify the ordered
route list within the PBR RIB adapted to I2RS.
Status of This Memo
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Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Definitions and Acronyms . . . . . . . . . . . . . . . . . . 3
3. The Policy Based Routing Information Model Overview . . . . . 4
3.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. PBR-RIB module . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. PBR RIB . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.2. PBR Rule Component . . . . . . . . . . . . . . . . . . . 10
4.3. I2RS PRB RIB interaction with PBR RIB . . . . . . . . . . 12
5. Relationship between PBR Rule Model and RIB Information Model 13
6. Discussion of I2RS related issues . . . . . . . . . . . . . . 14
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
8. Security Considerations . . . . . . . . . . . . . . . . . . . 15
9. Informative References . . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction
The Interface to the Routing System (I2RS)
[I-D.ietf-i2rs-architecture] architecture calls out for read and
write access to the information and state within the routing
elements. The I2RS client interacts with the I2RS agent in one or
more network routing systems.
This I2RS Policy-Based Routing (PBR) Information model defined in
this document describes the I2RS interaction with PBR within a
routing element.
The PBR requires an ordered list of policy. This PBR informational
model uses the Policy Core Information Model (PCIM) framework as
described in [RFC3060] with its extensions in [RFC3460] and QOS model
in [RFC3644]. The adaptation of the PCIM model to I2RS use is
described in [I-D.hares-i2rs-bnp-info-model].
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2. Definitions and Acronyms
CLI
Command Line Interface
IGP
IGP is an Interior Gateway Protocol
Information Model
is an abstract model of a conceptual domain, independent of a
specific implementations or data representation
MPLS
Multi-Protocol Label Switching.
NETCONF
The Network Configuration Protocol
PBR
Policy Based Routing.
PBR Default RIB
The PBR Default RIB is the default Routing Information Based use
based for forwarding traffic for routes which do not match any
PBR.
PBR-RIB
Policy Based Routing-Routing Information Base
PCIM
Policy Core Information Model directly and indirectly the work of
the PCIM Working Group.
Policy Rule
The PCIM framework defines a policy rule is often represented by
"if Condition then action". The action may have set, modify, or
notify actions. The [I-D.hares-i2rs-bnp-info-model] provides
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examines of how ACLs, Prefix lists, and more complex BGP policy
can be combined into a policy rule.
Policy Group
The PCIM Framework defines policy groups as a group of policy
rules into ordered and prioritized groups of policy.
Policy Set
The PCIM framework defines a the Policy set (specifically the
PolicySetComponent) as an aggregation class that allows
aggregation of Policy Groups and the nesting of Policy Groups
under Policy set rules. The PolicySet rules include nesting
policies and matching strategies (all-matching or first-match),
priorities between rules, and roles. One of the roles that must
be conditionally matched is the models denotation of "read-only"
or "read-write" policy rules into ordered and prioritized groups
of policy. The [I-D.hares-i2rs-bnp-info-model] suggests that non-
nested policy groups may be sufficient for initial I2RS and
configuration work.
RIB IM
RIB Informational Model (RIB IM) [I-D.ietf-i2rs-rib-info-model]
Routing instance
Routing Code often has the ability to spin up multiple copies of
itself into virtual machines. Each Routing code instance or each
protocol instance is denoted as N_INSTANCE in the text below.
SNMP
The Simple Network Management Protocol
3. The Policy Based Routing Information Model Overview
Policy Based Routing (PBR) is a widely used term in the industry to
describe a a technique used to make packet forwarding decisions
decisions based on policies set by the network administrator. PBR
enables network administrator to forward the packet based on other
criteria than the destination address in the packet, which is used to
lookup an entry in the routing table.
The PBR problem can be viewed as a resource allocation problem that
incorporates business decision with routing. PBR may be used to
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provide many benefits, including better resource allocation, load
balancing and QoS.
Routing decisions in PBR are based on several criteria beyond
destination address, such as application, IP protocol used, identity
of the end system, and even packet size. Policy actions are
typically applied before applying QoS constraints since policy
actions may overrides QoS constraint.
The I2RS use cases which benefit from PBR are: Protocol independent
Use cases and large flow use cases described in
[I-D.hares-i2rs-usecase-reqs-summary]
The PBR policies are specified in most routers/switches as an ordered
set of rules. Each policy rule has a set of match conditions, and a
set of actions which may include forwarding actions and QoS actions.
Since policy rules, groups of policy, and ordered sets of policy are
used in other protocols (BGP or MPLS), these policy rules have been
abstracted into a basic network policy instantiation of the PCIM
([RFC3060], [RFC3460], and [RFC3644]). This instantiation include in
the ordered policy rule the references to other policy match-action
conditions such as the ACLs ([I-D.bogdanovic-netmod-acl-model]), and
Prefix list ([I-D.zhdankin-netmod-bgp-cfg]).
3.1. Scope
A PBR IM can be considered in either a top-down view examining the
policy which controls the data flow or from a bottom-up view which
considers the data plane. A top-down view considers how policies
control protocols (BGP or IGPs (ISIS/OSPF)) transfer of routes to
determine how data flows. The bottoms-up view considers the
forwarding data planes that must be supported. In this view,the
match filters must consider IP [both IPv4 and IPv6], but may also
consider MPLS and encapsulated protocols such as TCP [RFC0793], UDP
[RFC0768], STCP [RFC4960], ICMP [RFC0792]. This draft takes the
bottoms-up viewpoint which looks at how the PBR RIB controls the data
plane.
This draft considers match and action filters for the data-planes
using IP (both IPv4 [RFC0791] and IPV6 [RFC2460]).
4. PBR-RIB module
A PBR-RIB is an entity that contains an ordered set of policy routes
and is analogous to a RIB defined in [I-D.ietf-i2rs-rib-info-model].
An ordered set of policy routes implies that the insertion into a
PBR-RIB must allow for inserting of a PBR route at any specific
position and deleting a route at a specific position. The ability to
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change a policy rule at a specific position combines these two
functions (deleting an existing policy rule and adding a new policy
rule).
Each PBR-RIB is contained within a routing instance, but one routing
instance (named by an INSTANCE_NAME) can contain multiple PBR RIBs.
Each routing instance is associated with a set of interfaces, a
router-id a PBR default-RIB, and list of PBR-RIBs. Only some of the
interfaces associated with a routing instance may be associated with
a PBR-RIB. Each interface can be associated with at most one PBR
RIB.
Packets arriving on an interface associated with a PBR-RIB will be
forwarded based on a PBR-RIB in the list or PBR Default RIB (if no
matches occur). The policy processing within the PBR process within
the routing system is expected to do the following:
o When a packet successfully matches a PBR Match term/entry, the
corresponding policy-actions are applied.
o If a packet does not match a PBR match term/entry, the PBR
processing, goes to the next term/entry in the order, and looks
for a match, within the current filter or goes to the next filter
in the list. This continues until either a PBR match term/entry
is successfully matched, or no more filters in the list exists.
o If no match has been found within the PBR filter list, then the
packet will be forwarded using the PBR Default-RIB if one exists.
If no PBR Default-RIB is specified, the packet will be discarded.
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+-------------------------------+
| routing instance |
+--|--------|---------------+---+
* | |
| | |
+-----------+ +-------------+ +-----------+
|interface* | |PBR_RIB *list| |PBR-Default|
| list | | | |-RIB |
+-----------+ +--|----------+ +---|-------+
| RIB (RIB-info IM)
^
/|\
+-----------^-----------+
| PBR RIB* list |
+-----------|-----------+
|
+-----------------------+
| BNP Policy Set | [Note: This layer
| | can be skipped if
|(nested ordered policy | groups are not nested.]
| from RFC3466) |
+----------|------------+
|
+-----------------------+
| BNP-Policy-Group* |
| |
|(list of ordered groups|
| RFC3466 policy group |
| augmented with I2RS |
| scope) |
+-----------|-----------+
|
+-----------------------+
| BNP-Policy-Rule* |
| |
| (ordered list of |
| RFC3466 policy rules) |
| augmented with |
| policy-order, status, |
| and refcnt) with ACL |
| and other condition- |
| action matches |
+-----------------------+
Figure 1: Routing instance with PBR RIB
The PBR entries associated with each PBR in a routing instance are:
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pbr-instance-name
Name of Routing instance
pbr-router-id
router id associated with the PBR function of the Routing instance
Interface_list
A list of interfaces that all of the PBR RIBs operate over. This
list must be a subset of the interface_list associated with the
routing instance.
PBR Default RIB
A RIB contained in the same routing instance that can be used to
forward packets when the FIB entries in the PBR-RIB list do not
match the packets. The PBR Default-RIB forwards based on
destination based routing.
PBR-RIB* list
list of PBR-RIBs
The Top-level Yang structure for the PBR RIB is:
module: PBR
+--PRB-RIB-module
+--rw pbr-instance-name
+--rw pbr-router-id uint32
+--rw pbr-interface*
| +--rw pbr-interface interface-ref-id
+--rw PBR-Default-RIB
+--rw PBR-RIB
+--rw PBR-RIB-Name
+--rw PBR-RIB-AFI
+--rw PBR-RIB-intf*
+--rw PBR-status-info
| +--rw pbr-update-ref uint64
+--rw PBR-Ordered-Route-Policy
+--rw pbr-group-policy* [group-policy-ref]
| +--rw group-policy-ref uint16
| +--rw group-policy-name string
| +--ro group-policy-status-info
| | +--ro group-policy-status
| | +--ro group-policy-inactive-reason
| +--rw policy-rule* [policy-rule-ref]
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| +--rw policy-rule-ref
| +--ro policy-rule-status-info
| | +--ro policy-rule-status enumeration
| | +--ro policy-rule-inactive-reason
| +--rw pbr-match-filter* [nr-policy-match]
| +--rw pbr-match-term
| | +--rw pbr-match-condition
| | | +--rw nr-policy-match
| | | +--rw pbr-ipv4-matches
| | | +--rw pbr-ipv6-matche
| | | +--rw pbr-transport-matches
| | | +--rw pbr-combo-operator
| | +--rw pbr-rule-action
| | +--rw pbr-QOS-acts [nbr-act]
| | +--rw npbr-act
| | +--rw set-in-ipv4-packet
| | | ...
| | +--rw set-in-ipv6-packet
| | | ...
| | +--rw set-vendor
| | | . . .
| +--rw pbr-forwarding-actions
| | +--rw pbr-std-fwd enumeration
| | +--rw pbr-vendor-fw enumeration
+--rw pbr-policy-set[policy-set-name]
+--rw policy-set-name
+ . . .
Figure 2: PBR RIB Yang Structure
4.1. PBR RIB
Each PBR RIB has the following:
o PBR-RIB-Name - Name identifier for PBR RIB
o PBR-RIB-AFI - AFI Supported by the PBR RIB
o PBR-RIB-intf* - Interface PBR operates on. Note that an interface
can be associated with at most one PBR RIB. For example
interfaces eth1 and eth2 can be associated to PBR_RIB, but these
two interfaces cannot be connected to any other PBR RIB.
o PBR-Status-info - status at PBR RIB level which includes number of
times since reconfiguration this PBR has been updated.
o PBR-Ordered-Route-Policy contains two sub-elements:
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* pbr-group-policy - group policy list indexed by group-policy-
ref number. Policy group contains a reference number (group-
policy-ref), name, status-info, and a list of policy-rules. the
group policy status can be one of the following: installed,
active, inactive, I2RS-active, and I2RS-inactive). The
inactive reason can be one of the following: null, poicy-
conflict, i2rs-supersedes, unsupported).
* pbr-policy-set - policy set identified by name
Initially, it is expected the simply group policy list will be
sufficient. (See [I-D.hares-i2rs-bnp-info-model] for an examples of
the policy rules can contain ACL policy, Prefix-list policy, and more
complex (match/set) policy.)
4.2. PBR Rule Component
A PBR policy rule used by has the following general architecture.
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+-----------------------+
| Policy Rule |
| (PBR usage) |
+--|-----------------|--+
: : .......
: : : :
+--------V-------+ +-------V-------+ :
| PBR Condition | | PBR Action |<...
+----------------+ +-+----------+--+
/|\ /|\
"extends"| | "extends"
+---+ +--------+
| |
+-------^-------+ +-----^---------+
| QoS Action | |Forward Action |
+---------------+ +---------------+
: : : : : :
....: : :..... .....: : :.....
: : : : : :
+----V---+ +---V----+ +--V---+ +-V------++--V-----++--V-----+
|Set | |QoS | |QoS | |Forward ||Next Hop||Next Hop|
|Operator| |Variable| |Value | |Operator||Variable||Value |
+--------+ +--------+ +------+ +--------++--+-----++--------+
/|\
| "extends"
+---^----+
|Next Hop|
|Type |
+--------+
Figure 3: Policy Rules for PBR routing
The policy-rule contains the following:
o PBR-match-filter - ordered PBR match field for a route entry which
contains either:
* nr-policy-match - order number in match sequence
* pbr-ipv4-matches - one or more matches of IPv4 source address,
IPv4 destination address, IPv4 Protocol, IPv4 TOS/DSCP field,
IPv4 ICMP field, and the length of the packet. These matches
can be exact matches, longest prefix matches for addresses, or
range matches for values in TOS/DSCP field, ICMP field or
length of packet.
* pbr-iv6-matches - one or more match of IPv6 source address,
IPv6 destination address, IPvs Traffic class (DSCP), IPv6 Flow
label, IPv6 payload length, IPv6 next-header, hop-limit. These
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matches can be exact matches, longest prefix matches for
addresses, or range matches.
* pbr-transport-matches - one or more matches in source port or
destination port
* pbr-combo-operator - logical OR or logical AND that combine
matches in one match filter.
o pbr-rule-action* - An ordered list of policy actions that includes
the following:
* npbr-acts - order number in action sequence
* Actions: set values in one or more of the following:
+ IPv4 packets in IPv4 source address, IPv4 destination
address, IPv4 Protocol, IPv4 TOS/DSCP field, IPv4 ICMP field
or the length of the packet. (Please note that hardware
data plane forwarders may only be able to set TOS/DSCP while
software data plane forwarders may be able set additional
fields.)
+ IPv6 packets in IPv6 source address, IPv6 destination
address, IPv6 Protocol value, IPv6 Flow, or IPv6 packet
length.
* pbr-forwarding-actions - which includes
+ pbr-std-forwarding - (enumeration) forwarding packet
- Drop_Packet - drop packet
- Drop_Packet_ICMP - dropping packet with ICMP unreachable
sent
- Forward_Packet_specific - send to specific next hop
- Forward_Packet_default - forward based on PBR Default RIB
+ pbr-vendor-fwd - Vendor specific action
4.3. I2RS PRB RIB interaction with PBR RIB
The I2RS client-agent pair PBR process within a routing process to
add ephemeral these changes to the PBR State so that
PBR-running = PBR-config + PBR-I2RS-ephemeral
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The I2RS ephemeral state will not survive a reboot of the machine.
Upon a reboot, the I2RS client must reload the I2RS Agent with the
I2RS PBR RIB state lost in the reboot.
The PBR RIB module must allow both the I2RS client-agent to to read
the PBR IM as as query or as a notification stream. The pbr-update-
ref parameter of the PBR-status-info provides an update count for the
PBR configuration to indicate if the PBR has been updated with
additions or deletions of the PBR policy rules. This provides the
I2RS interface a quick way to check for changes by other entities to
the PBR route list.
5. Relationship between PBR Rule Model and RIB Information Model
The RIB in a router with I2RS is the following:
running RIB = configured-RIB + routes-installed-from-protocols +
I2RS-ephemeral-state
As described in [I-D.ietf-i2rs-rib-info-model], the I2RS ephemeral
RIB information in routing instance contains a collection of RIBs,
interfaces, and routing parameters including the following:
o The set of interfaces indicates which interfaces are associated
with this routing instance.
o The RIBs specify how incoming traffic is to be forwarded based on
destination (E.g. RIB and PBR-RIB).
o The routing parameters control the information in the RIBs.
PBR RIB and RIB can not be used at the same time, which means:
o If a router doesn't support policy based routing, a router MUST
use RIB and MUST not use PBR RIB.
o If a router supports policy based routing:
* PBR-RIB is used
* Multiple PBR-RIBs may exist within a routing instance
* An interface can be associated with at most one PBR-RIB
* The PBR Default RIB is used if several criteria beyond
destination address is not matched.
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6. Discussion of I2RS related issues
This section record the issues with the initials of the person who
recorded it.
Forwarding per interface (JMH)
- The authors believe the forwarding per interface is covered by
the attachment of a PBR to interface-list.
Centralized or Distributed Policy Strategy (JMH)
The authors believe this structure can be used by either
centralized or distributed forwarding for configuration or the
I2RS ephemeral datastpre.
policy database-enforcement points architecture (JMH)
The authors believe this yang modules describes the PBR which
provides a specific enforcement of forwarding policy. The wider
constraints of how policy groups are stored, administered or
distributed should be engaged at a higher layer. The authors note
the Policy-Group project in OpenDaylight has an architecture for
policy enforcement that renders the results to a particular
instantiation in nodes. One such instantiation could be the I2RS
policy.
policy rule conflicts (JMH)
Detection of policy rule conflicts are done by the policy module
receiving the configuration or ephemeral I2RS stream. The policy
can be reject or installed and rejected from active use due to
conflicts at either the policy group level or the policy rule
level. At the policy group level the group-policy-status-info
contains a status of installed, active, or installed-inactive. If
the status is inactive the group-policy-inactive-reason can
indicate policy-conflicts. The policy-rule has a similar status
(policy-rule-status-info with policy-rule-status and policy-rule-
inactive-reason).
7. IANA Considerations
This draft includes no request to IANA.
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8. Security Considerations
TBD.
9. Informative References
[I-D.bogdanovic-netmod-acl-model]
Bogdanovic, D., Sreenivasa, K., Huang, L., and D. Blair,
"Network Access Control List (ACL) YANG Data Model",
draft-bogdanovic-netmod-acl-model-02 (work in progress),
October 2014.
[I-D.hares-i2rs-bnp-info-model]
Hares, S. and Q. Wu, "An Information Model for Basic
Network Policy", draft-hares-i2rs-bnp-info-model-00 (work
in progress), September 2014.
[I-D.hares-i2rs-usecase-reqs-summary]
Hares, S., "Summary of I2RS Use Case Requirements", draft-
hares-i2rs-usecase-reqs-summary-00 (work in progress),
July 2014.
[I-D.ietf-i2rs-architecture]
Atlas, A., Halpern, J., Hares, S., Ward, D., and T.
Nadeau, "An Architecture for the Interface to the Routing
System", draft-ietf-i2rs-architecture-05 (work in
progress), July 2014.
[I-D.ietf-i2rs-rib-info-model]
Bahadur, N., Folkes, R., Kini, S., and J. Medved, "Routing
Information Base Info Model", draft-ietf-i2rs-rib-info-
model-03 (work in progress), May 2014.
[I-D.zhdankin-netmod-bgp-cfg]
Alex, A., Patel, K., and A. Clemm, "Yang Data Model for
BGP Protocol", draft-zhdankin-netmod-bgp-cfg-01 (work in
progress), October 2014.
[RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
August 1980.
[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, September
1981.
[RFC0792] Postel, J., "Internet Control Message Protocol", STD 5,
RFC 792, September 1981.
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[RFC0793] Postel, J., "Transmission Control Protocol", STD 7, RFC
793, September 1981.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.
[RFC3060] Moore, B., Ellesson, E., Strassner, J., and A. Westerinen,
"Policy Core Information Model -- Version 1
Specification", RFC 3060, February 2001.
[RFC3460] Moore, B., "Policy Core Information Model (PCIM)
Extensions", RFC 3460, January 2003.
[RFC3644] Snir, Y., Ramberg, Y., Strassner, J., Cohen, R., and B.
Moore, "Policy Quality of Service (QoS) Information
Model", RFC 3644, November 2003.
[RFC4960] Stewart, R., "Stream Control Transmission Protocol", RFC
4960, September 2007.
Authors' Addresses
Susan Hares
Huawei
7453 Hickory Hill
Saline, MI 48176
USA
Email: shares@ndzh.com
Sriganesh
Ericsson
Email: sriganesh.kini@ericsson.com
Anoop Ghanwani
Dell
Email: anoop@alumni.duke.edu
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Ram Krishnan
Brocade
Email: ramk@Brocade.com
Qin Wu
Huawei
Beijing
China
Email: Bill.Wu@huawei.com
Dean Bogdanovic
Juniper Networks
Westford, MA
Email: deanb@juniper.net
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