Internet DRAFT - draft-kowal-lisp-policy-distribution
draft-kowal-lisp-policy-distribution
Network Working Group M. Kowal
Internet-Draft M. Portoles
Intended status: Experimental Cisco Systems
Expires: 1 April 2023 A. Jain
Juniper Networks
D. Farinacci
lispers.net
28 September 2022
LISP Transport for Policy Distribution
draft-kowal-lisp-policy-distribution-03
Abstract
This document describes the use of the Locator/ID Separation Protocol
(LISP) to encode and transport data models for the configuration of
LISP ITRs.
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 [RFC2119].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on 1 April 2023.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Definition of Terms . . . . . . . . . . . . . . . . . . . . . 2
3. Policy Distribution Use Cases . . . . . . . . . . . . . . . . 3
4. Policy Distribution: Packet Flow Description . . . . . . . . 3
4.1. Policy Distribution . . . . . . . . . . . . . . . . . . . 4
4.2. Policy Updates . . . . . . . . . . . . . . . . . . . . . 5
5. Mapping System Operations . . . . . . . . . . . . . . . . . . 6
6. Policy Distribution Process . . . . . . . . . . . . . . . . . 6
7. Policy Distribution Encoding . . . . . . . . . . . . . . . . 6
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
10.1. Normative References . . . . . . . . . . . . . . . . . . 7
10.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
When LISP ITRs are deployed with enough configuration to build a LISP
overlay, they may require additional configurations such as security,
QoS, and/or traffic forwarding policies. As networks continue to
grow, it can be challenging to ensure these configurations are
distributed to many ITRs and kept in sync. LISP network operators
may wish to re-use their existing LISP architecture to distribute
these configurations as opposed to configuring them by hand, using a
script, or investing in a configuration management system. The
configurations can be distributed via a mapping system that the
network operator manages or is managed by a third-party as part of a
managed service offering.
2. Definition of Terms
LISP related terms are defined as part of the LISP specification
[RFC6830], notably EID, RLOC, Map-Request, Map- Reply, Map-Notify,
Ingress Tunnel Router (ITR), Egress Tunnel Router (ETR), Map- Server
(MS) and Map-Resolver (MR).
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3. Policy Distribution Use Cases
The ITR could use the mapping system to receive configuration
policies for use cases such as:
* The RLOC interfaces of an ITR may be connected to WAN links that
are policed at sub-line rate by its upstream provider. Using the
mapping system, the ITR could receive and apply the QoS policies
that would shape traffic to the correct rate on each ITR RLOC
interface.
* ITRs use the mapping system to receive access-list (ACL)
configuration(s) that would allow them to restrict traffic from
authorized sources to authorized services.
* ITRs receive configurations that determine local forwarding
policies, such as specifying ITR RLOCs to be used for egress
forwarding on a per-application basis or RLOCs on different ITRs
within the same LISP site to maintain application symmetry.
* Baseline configurations for common services (e.g., DNS, SSH,
Syslog) can be maintained in a mapping system and distributed
across multiple ITRs.
Policy distribution is not meant to provide zero-touch provisioning
for ITRs within a LISP network. At a minimum, the ITR must have a
map resolver defined, IP connectivity to the map resolver, and one or
more distinguished names [I-D.ietf-lisp-name-encoding] defined for
receiving specific policies from the mapping system.
4. Policy Distribution: Packet Flow Description
The following figure illustrates a reference system used to support
packet flow descriptions in this section.
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+----------+ +-+---+
|controller|---------|MS/MR|
+----------+ +-----+
|
_..-._.--._...._.,.-|_.,--._.-_._.-.._
.-.' '.-.
( RLOC SPACE )
( )
'..'.-._.'--'._.'.-._.'.-._.'.-._.'.-._.'.--.'
/ \
(ifaceA) (ifaceB)
+-+--+--+ +-+--+--+
.| xTR A |.-. .| xTR B |.-.
( +-+--+--+ ) ( +-+--+--+ )
.' Site A ) .' Site B )
( . ( .
'--'._.'. ) '--'._.'. )
'--' '--'
Figure 1: Reference system for policy distribution
The reference system contains two sites, site A and site B, with
corresponding xTR-A and xTR-B providing encapsulation and
decapsulation services for the overlay traffic. xTR-A uses
interface-A to forward and receive encapsulated traffic through the
RLOC space; and xTR-B uses interface-B for it.
For packet flow purposes the reference system assumes that a network
controller provides the policies to a map-server.
When an ITR comes up, it requests it's designated policies with it's
map-server. The MS may have this policy configured by the
administrator via a network controller.
4.1. Policy Distribution
The following is an illustration of the sequence to distribute a
policy registered by the controller with the mapping system, down to
an ITR that requests its designated policies. In the example <ITR-A>
represents the hostname of the ITR that learns a policy using this
mechanism.
* The Mapping-System is either configured by an operator or learns a
mapping sent by a controller though a Map-Register. The Mapping
System learns the mapping: EID="policy-<ITR-A>" --> RLOC= "{
"shape":{ "interface":"ifaceA", "direction":"outbound",
"value":100Mbps }}". The EID is encoded as a Distinguished Name
and the RLOC as a JSON string.
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* ITR-A is configured to dynamically learn policies from the Mapping
System with the name "policy-ITR-A" (policy followed by its
hostname).
* ITR-A sends a Map-Request to the Mapping System with EID="policy-
<ITR-A>" encoded as a Distinguished Name. The Map-Request is sent
with the N-bit set.
* The Mapping System forwards the request to the appropriate Map-
Server. The Map-Server adds ITR-A to the subscription list of
EID="policy-<ITR-A>" and sends back a Map-Notify with the mapping
that the controller has registered.
* When ITR-A receives the Map-Notify installs the received policy
locally, to shape traffic sent over the RLOC facing interface.
* Note that when the map-server has multiple policies associated
with this ITR, it can send each one of the policies as an
additional locator record (following the same JSON format) in the
mapping. The locator count in the Map-Notify reflects the number
of policies distributed with the mapping.
4.2. Policy Updates
Policy distribution takes advantage of the LISP pubsub model to
ensure that router updates are properly distributed when policies
change. In such a case, and using the same reference sytem as above,
the information exchange is as follows:
* The controller sends a Map-Register to the Mapping System,
updating the policy mapping with: EID="policy-<ITR-A>" --> RLOC=
"{ "shape":{ "interface":"ifaceA", "direction":"outbound",
"value":200Mbps }}".
* When the corresponding Map-Server receives this update it checks
the list of ITRs subscribed for updates of EID="policy-<ITR-A>"
and finds out that ITR-A is subscribed.
* The Map-Server sends a Map-Notify to ITR-A with the updated
mapping information that has been registered.
* When ITR-A receives and validates the Map-Notify, it updates the
local policy, changing the shaping rate as specified in the new
JSON description. Note that if the JSON specifies the same policy
that is currently applied the notification is ignored.
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5. Mapping System Operations
The mapping system that is used for distributing policy
configurations can be managed by either the administrator who owns
and operates their own LISP sites or a third-party administrator who
offers LISP mapping system functionality as a managed service. A
controller or orchestrator could be used to update and optimize
policies within the mapping system based on network or ITR telemetry.
Within the mapping system, the administrator must define a
distinguished name that is specific to an ITR. The distinguished
name is associated with the specific policy configurations that the
ITR is to receive. Each ITR is configured with the minimal
requirements to perform a mapping request procedure as well as a
distinguished name that can be matched upon in the mapping system.
Map-Servers should be able to receive policy registrations through
the Map-Registration process. The Map-Registration must encode the
policy following the specification in the policy distribution
encoding section.
6. Policy Distribution Process
The ITR subscribes to its policy via the Map-Request procedure
defined in section 5 of [I-D.ietf-lisp-pubsub]. The PubSub procedure
is used to ensure that policies can be updated or audited after an
ITR has received them. Policies are published to the ITR from the
mapping system using the mapping notification procedure defined in
section 6 of [I-D.ietf-lisp-pubsub].
EID-to-RLOC mappings used for policy distribution are of the type EID
<Distinguished Name> to RLOC <JSON policy specification>. The EID is
a distinguished name uniquely identifying a router in the system,
while each RLOC record uses JSON encoding to specify the particular
policy (or policies) that this router needs to implement.
7. Policy Distribution Encoding
When the ITR is configured to receive a policy using a distinguished
name, the ITR sends a subscription for the EID record encoded as this
Distinguished Name. When a policy has been registered with the
Mapping System for this Distinguished Name, the ITR receives a
publication with a list of policies as RLOC records and encoded as
JSON strings (as defined in section 5.4 of [RFC8060].
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Example encoding for QoS policy that shapes traffic to 50 percent of
the line-rate: EID-Record encoded as distinguished name "policy-ce-
router1" RLOC-Record record encoded as JSON string
"{"shape":{"interface":"ethernet1","direction":"outbound",
"unit":"percent","value":50}}"
Example encoding for setting the ITR's NTP server to 10.10.10.10:
EID-Record encoded as distinguished name "policy-ce-router" RLOC-
Record record encoded as JSON string "{"NTP-address": "10.10.10.10"}"
Multiple ITRs can be configured to use multiple distinguished names
for receiving multiple sets policies. This allows for an ITR to
receive specific policies and many ITRs to receive policies that can
be broadly applied. Referring to the two examples above, an ITR can
be configured to use a distinguished name of "policy-ce-router1" to
receive a QoS configuration that is specific to that node while also
using a distinguished name of "policy-ce-router" to receive
configurations that are common to each ITR in the LISP network (e.g.,
NTP configuration). The use of multiple distinguished names per ITR
reduces the amount of configuration within the mapping system.
8. IANA Considerations
This memo includes no request to IANA.
9. Acknowledgements
Thanks to James Stankiewicz for his thorough comments and
suggestions.
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC6830] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, "The
Locator/ID Separation Protocol (LISP)", RFC 6830,
DOI 10.17487/RFC6830, January 2013,
<https://www.rfc-editor.org/info/rfc6830>.
[RFC8060] Farinacci, D., Meyer, D., and J. Snijders, "LISP Canonical
Address Format (LCAF)", RFC 8060, DOI 10.17487/RFC8060,
February 2017, <https://www.rfc-editor.org/info/rfc8060>.
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10.2. Informative References
[I-D.ietf-lisp-name-encoding]
Farinacci, D., "LISP Distinguished Name Encoding", Work in
Progress, Internet-Draft, draft-ietf-lisp-name-encoding-
00, 6 September 2022, <https://www.ietf.org/archive/id/
draft-ietf-lisp-name-encoding-00.txt>.
[I-D.ietf-lisp-pubsub]
Rodriguez-Natal, A., Ermagan, V., Cabellos, A., Barkai,
S., and M. Boucadair, "Publish/Subscribe Functionality for
LISP", Work in Progress, Internet-Draft, draft-ietf-lisp-
pubsub-09, 28 June 2021, <https://www.ietf.org/archive/id/
draft-ietf-lisp-pubsub-09.txt>.
Authors' Addresses
Michael Kowal
Cisco Systems
111 Wood Ave. South
Iselin, NJ 08830
United States of America
Email: mikowal@cisco.com
Marc Portoles Comeras
Cisco Systems
170 Tasman Drive
San Jose, CA 95134
United States of America
Email: mportole@cisco.com
Amit Jain
Juniper Networks
1133 Innovation Way
Sunnyvale, CA 94089
United States of America
Email: atjain@juniper.net
Dino Farinacci
lispers.net
San Jose, CA
United States of America
Email: farinacci@gmail.com
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