Internet DRAFT - draft-kini-i2rs-pbr-info-model
draft-kini-i2rs-pbr-info-model
Network Working Group S. Kini, Ed.
Internet-Draft Ericsson
Intended status: Informational R. Folkes
Expires: August 18, 2014 Juniper
J. Medved
Cisco
R. Krishnan
Brocade
A. Ghanwani
Dell
February 14, 2014
Information model for Policy Based Routing
draft-kini-i2rs-pbr-info-model-00
Abstract
Policy Based Routing (PBR) is a generic term that describes
functionality that currently exists in several routing systems where
packets are routed, not just based on the destination address but
rather based on a policy that is configured/programmed in the router.
This document describes the information model for PBR as it exists in
many current implementations.
Status of This Memo
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This Internet-Draft will expire on August 18, 2014.
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
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Abbreviations and Terminology . . . . . . . . . . . . . . . . 3
3. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. PBR-RIB definition . . . . . . . . . . . . . . . . . . . . . 4
5. Routing Instance . . . . . . . . . . . . . . . . . . . . . . 4
6. Policy Route . . . . . . . . . . . . . . . . . . . . . . . . 4
7. Policy Action . . . . . . . . . . . . . . . . . . . . . . . . 5
8. Reading, writing and notifications . . . . . . . . . . . . . 6
9. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 6
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
12. Security Considerations . . . . . . . . . . . . . . . . . . . 6
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
13.1. Normative References . . . . . . . . . . . . . . . . . . 6
13.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
Policy Based Routing (PBR) is a commonly used term that describes a
capability that has existed on many routing systems for several
years. However, PBR has not been described through an information
model published as a standard. Most network operators and
applications that want to configure/program PBR on a network element
have used vendor specific mechanisms. Defining a standardized PBR
information model can help to simplify the implementations of
existing use-cases and to define new ones. Use cases that can
benefit from PBR are described in
[I-D.krishnan-i2rs-large-flow-use-case] and
[I-D.white-i2rs-use-case].
The need to provide a standardized interface to the routing system's
functionality is described in [I-D.ietf-i2rs-problem-statement]. The
architecture for a standardized interface is described in
[I-D.ietf-i2rs-architecture] and requires standardized data models.
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This document defines a PBR information model that is fundamental to
developing a standardized data model for PBR.
At a high level PBR is a specific forwarding behavior that is applied
to traffic matched by a filter. Unlike destination address based
forwarding, the match filter in PBR can use multiple fields of the
traffic's protocol data units (PDUs).
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
2. Abbreviations and Terminology
PBR - Policy Based Routing
PBF - Policy Based Forwarding (This abbreviation has been used in the
industry synonymously with PBR. We do not use this abbreviation in
this document)
FBF - Filter Based Forwarding (This abbreviation has been used in the
industry synonymously with PBR. We do not use this abbreviation in
this document)
I2RS - Interface to Routing System
RIB - Routing Information Base
PDU - Protocol Data Unit
MPLS - Multi Protocol Label Switching
PBR-RIB - Policy Based Routing - Routing Information Base
3. Scope
The match filter is mainly restricted to IP (both IPv4 [RFC0791] and
IPv6 [RFC2460]). MPLS may be included in a future revision of this
document. Support for protocols encapsulated within IP is restricted
to TCP [RFC0793], UDP [RFC0768], SCTP [RFC4960] and ICMP [RFC0792].
This will be extended to include more protocols in future revisions.
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4. PBR-RIB definition
A PBR-RIB is an entity that contains an ordered list of policy routes
and is analogous to the RIB defined in
[I-D.ietf-i2rs-rib-info-model]. The data model MUST allow inserting
into the ordered list at any position and deleting a previously added
entry. Each PBR-RIB is contained within a routing instance. It is
identified by a name that is unique within the routing instance and
is in the same namespace as RIB names. A PBR-RIB has one of the
following types - IPv4 or IPv6. Each PBR-RIB has the following
optional fields:
o interface-list: A list of interfaces of the same type as this PBR-
RIB. It must be a subset of the interface-list of the routing
instance in which this PBR-RIB is contained.
o default-routing-RIB: A RIB of the same type contained in the same
routing instance as this PBR-RIB. When a packet does not match
any FIB entries installed using this PBR-RIB, then destination
based forwarding using FIB entries installed using the default-
routing-RIB is performed.
5. Routing Instance
This document extends the routing-instance from
[I-D.ietf-i2rs-rib-info-model] to contain PBR-RIBs. A routing
instance can optionally contain multiple PBR-RIBs. Each interface of
the routing instance can be associated with at most one PBR-RIB.
Packets arriving on an interface associated with a PBR-RIB are
forwarded using the FIB generated using the policy-routes of that
PBR-RIB.
6. Policy Route
A policy-route is a generalization of the route described in sec 2.3
of [I-D.ietf-i2rs-rib-info-model] and consists of a match-filter and
an associated policy-action (see Section 7). When a packet
successfully matches a match-filter, the corresponding policy-action
is applied and the processing for that packet terminates. The match-
filter is optional and when it is not specified, then the policy-
action is applied as if the match was successful. If a match fails,
then a match is attempted on the next policy-route in the order
specified in that PBR-RIB. Failure to match the filter of any of the
policy-routes in a PBR-RIB results in destination based forwarding
using the FIB generated by the default-routing-RIB. If a default-
routing-RIB is not specified, the packet is discarded. It should be
noted that different implementations will vary in their capabilities
for the type and number of matches and actions that they can perform.
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A mechanism to dynamically learn such capabilities is under
discussion.
The following types of operations are defined to build a match-filter
expression to be used in a policy-route.
1. Match sub-expression on one of the IP PDU fields
* Longest prefix match for IP source address or destination
address.
* An exact match or a range match for IP protocol type or IP-TOS
/DSCP.
* If the IP protocol type is one of TCP/UDP/SCTP then an exact
or range match of the source port or the destination port.
* If the IP protocol type is ICMP then an exact or range match
of the ICMP code and/or the ICMP type.
* PDU length range match.
2. A logical OR of the above sub-expressions for a given PDU field.
3. A logical negation of the above sub-expressions. This may
contain zero or more logical OR sub-expressions of a given PDU
field.
4. A logical AND of the above sub-expressions for the PDU fields.
7. Policy Action
A policy-action is an ordered sequence of zero or more PDU
manipulation/behavior actions followed by one PDU forwarding action.
It is a named entity and has its own namespace. The following PDU
manipulation/behavior actions are defined:
o Set IP-TOS/DSCP.
o A vendor-specific action. E.g. Apply a rate-limiter. This is
outside the scope of this document.
The following PDU forwarding actions are defined:
o Drop packet and optionally generate ICMP
o Forward to a specified nexthop. The nexthop is the same as
defined in sec 2.4 of [I-D.ietf-i2rs-rib-info-model]
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o Forward by destination addressed based lookup of FIB entries
installed using the default-routing-RIB
8. Reading, writing and notifications
The PBR-RIB data model has reading, writing and notification
requirements that are similar to those listed in
[I-D.ietf-i2rs-rib-info-model].
9. Open Issues
Performing actions associated with multiple policy-routes when the
packet successfully matches the match-filter of multiple policy
routes.
10. Acknowledgements
The authors would like to thank Alok Gulati and TBD for their review.
11. IANA Considerations
This memo includes no request to IANA.
12. Security Considerations
13. References
13.1. Normative References
[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-02 (work in
progress), February 2014.
[I-D.ietf-i2rs-problem-statement]
Atlas, A., Nadeau, T., and D. Ward, "Interface to the
Routing System Problem Statement", draft-ietf-i2rs-
problem-statement-00 (work in progress), August 2013.
[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-02 (work in progress), February 2014.
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[I-D.krishnan-i2rs-large-flow-use-case]
ramki, r., Ghanwani, A., Kini, S., McDysan, D., and D.
Lopez, "Large Flow Use Cases for I2RS PBR and QoS", draft-
krishnan-i2rs-large-flow-use-case-03 (work in progress),
February 2014.
[I-D.white-i2rs-use-case]
White, R., Hares, S., and A. Retana, "Protocol Independent
Use Cases for an Interface to the Routing System", draft-
white-i2rs-use-case-02 (work in progress), February 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.
[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.
[RFC4960] Stewart, R., "Stream Control Transmission Protocol", RFC
4960, September 2007.
13.2. Informative References
[RFC1104] Braun, H., "Models of policy based routing", RFC 1104,
June 1989.
Authors' Addresses
Sriganesh Kini (editor)
Ericsson
Email: sriganesh.kini@ericsson.com
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Ron Folkes
Juniper
Email: ronf@juniper.net
Jan Medved
Cisco
Email: jmedved@cisco.com
Ram Krishnan
Brocade
Email: ramk@brocade.com
Anoop Ghanwani
Dell
Email: anoop@alumni.duke.edu
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