Internet DRAFT - draft-jiang-anima-prefix-management
draft-jiang-anima-prefix-management
ANIMA WG S. Jiang, Ed.
Internet-Draft Z. Du
Intended status: Informational Huawei Technologies Co., Ltd
Expires: April 20, 2016 B. Carpenter
Univ. of Auckland
Q. Sun
China Telecom
October 18, 2015
Autonomic Prefix Management in Large-scale Networks
draft-jiang-anima-prefix-management-02
Abstract
This document describes an autonomic solution for prefix management
in large-scale networks.
Status of This Memo
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This Internet-Draft will expire on April 20, 2016.
Copyright Notice
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Intended User and Administrator Experience . . . . . . . 3
2.2. Analysis of Parameters and Information Involved . . . . . 3
2.2.1. Parameters each device can decide for itself . . . . 4
2.2.2. Information needed from policy intent . . . . . . . . 4
2.2.3. Comparison with current solutions . . . . . . . . . . 5
2.3. Interaction with other devices . . . . . . . . . . . . . 5
2.3.1. Information needed from other devices . . . . . . . . 5
2.3.2. Monitoring, diagnostics and reporting . . . . . . . . 6
3. Autonomic Prefix Management Solution . . . . . . . . . . . . 6
3.1. Behaviors to discover prefix providing device . . . . . . 6
3.2. Behaviors on prefix providing device . . . . . . . . . . 6
3.3. Prefix Requests Behaviors . . . . . . . . . . . . . . . . 7
3.4. Prefix log . . . . . . . . . . . . . . . . . . . . . . . 8
4. Autonomic Prefix Management Options . . . . . . . . . . . . . 8
4.1. Prefix Objective option . . . . . . . . . . . . . . . . . 8
5. Prefix Management Intent . . . . . . . . . . . . . . . . . . 8
5.1. Example of Prefix Management Intent . . . . . . . . . . . 9
6. Security Considerations . . . . . . . . . . . . . . . . . . . 10
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
9. Change log [RFC Editor: Please remove] . . . . . . . . . . . 10
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
This document proposes an autonomic solution for prefix management in
large-scale networks. The background to Autonomic Network (AN) is
described in [RFC7575] and [RFC7576]. A generic autonomic signaling
protocol (GRASP) is proposed by [I-D.ietf-anima-grasp], which would
be used by the proposed autonomic prefix management solution.
This document is dedicated to how to make IPv6 prefix management in
pure IPv6 large-scale networks as autonomic as possible. This
document for now is only considering service provider (ISP) networks.
Although there are similarities with large enterprise networks, the
requirements are a little different for the two use cases.
Note in draft: This version is preliminary. In particular, many
design details may be subject to change until the anima
specifications become agreed.
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2. Problem Statement
The autonomic networking use case considered here is autonomic IP
address management in large-scale networks.
Although DHCPv6 Prefix Delegation [RFC3633] has supported automated
delegation of IPv6 prefixes, prefix management is still largely
depending on human planning. In other words, there is no basic
information or policy to support autonomic decisions on the prefix
length that each router should request or be delegated, according to
its role in the network. Roles could be locally defined or could be
generic (edge router, interior router, etc.). Furthermore, the
current IPv6 prefix management by humans is rigid and static after
initial planning.
The problem to be solved by AN is how to dynamically and
autonomically manage IPv6 address space in large-scale networks, so
that IPv6 addresses can be used efficiently. The AN approach
discussed in this document is based on the assumption that there is a
generic discovery and negotiation protocol that enables direct
negotiation between intelligent IP routers. [I-D.ietf-anima-grasp]
is one of the attempts at such a protocol.
2.1. Intended User and Administrator Experience
The intended experience is, for the administrator(s) of a large-scale
network, that the management of IPv6 address space can be run with
minimum efforts, for both the network and network device initiation
stage and during running time. In the ideal scenario, the
administrator(s) only have to configure a single IPv6 prefix for the
whole network and the initial prefix length for each device role.
The actual address usage needs to be logged for potential offline
management operations including audit and security incident tracing.
2.2. Analysis of Parameters and Information Involved
For specific purposes of address management, a few parameters are
involved on each device (some of them can be pre-configured before
they are connected). They include:
o Identity of this device. It can be verified by the certification
authority (CA) that is maintained by the network administrator(s).
o Identity of a trust anchor which is certification authority (CA)
that is maintained by the network administrator(s).
o Role of this device.
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o An IPv6 prefix length for this device.
o An IPv6 prefix that is assigned to this device and its downstream
devices.
A few parameters are involved in the network as a whole. They are:
o Identity of a trust anchor which is a certification authority (CA)
that is maintained by the network administrator(s).
o Total IPv6 address space. It is one (or several) IPv6 prefix(es).
o The initial prefix length for each device role.
2.2.1. Parameters each device can decide for itself
This section identifies those of the above parameters that do not
need external information in order for the devices concerned to set
them to a reasonable value after bootstrap or after a network
disruption. There are few of these:
o Role of this device.
o Default IPv6 prefix length for this device.
o Identity of this device.
The device may be shipped from the manufacture with pre-configured
role and default prefix length.
2.2.2. Information needed from policy intent
This section identifies those parameters that need external
information about policy intent in order for the devices concerned to
set them to a non-default value.
o Non-default value for the IPv6 prefix length for this device.
This needs to be decided based on the role of this device.
o The initial prefix length for each device role.
o Identity of a trust anchor.
o Whether to allow the device request more address space.
o The policy when to request more address space, for example, the
address usage reaches a certain limit or percentage.
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2.2.3. Comparison with current solutions
This section briefly compares the above use case with current
solutions. Currently, the address management is still largely
depending on human planning. It is rigid and static after initial
planning. The address requests will fail if the configured address
space is used up.
Some functions, for autonomic and dynamic address management, may be
achievable by extending the existing protocols, for example,
extending DHCPv6-PD to request IPv6 address according to the device
role. However, defining uniform device roles may not be a practical
task. Some functions are not suitable to be achieved by any existing
protocols.
However, using a generic autonomic discovery and negotiation protocol
instead of specific solutions has the advantage that additional
parameters can be included in the autonomic solution without creating
new mechanisms. This is the principal argument for a generic
approach.
2.3. Interaction with other devices
2.3.1. Information needed from other devices
This section identifies those of the above parameters that need
external information from neighbor devices (including the upstream
devices). In many cases, two-way dialogue with neighbor devices is
needed to set or optimize them.
o Identity of a trust anchor.
o The device will need to discover a device, from which it can
acquire IPv6 address space.
o The initial prefix length for each device role, particularly for
its own downstream devices.
o The default value of the IPv6 prefix length may be overridden by a
non-default value.
o The device will need to request and acquire IPv6 prefix that is
assigned to this device and its downstream devices.
o The device may respond to prefix delegation request from its
downstream devices.
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o The device may require to be assigned more IPv6 address space, if
it used up its assigned IPv6 address space.
2.3.2. Monitoring, diagnostics and reporting
This section discusses what role devices should play in monitoring,
fault diagnosis, and reporting.
o The actual address assignments need to be logged for the potential
offline management operations.
o In general, the usage situation of address space should be
reported to the network administrators, in an abstract way, for
example, statistics or visualized report.
o A forecast of address exhaustion should be reported.
3. Autonomic Prefix Management Solution
This section introduces an autonomic prefix management solution. It
extends the generic discovery and negotiation protocol defined by
[I-D.ietf-anima-grasp]. The relevant options are defined in
Section 4.
3.1. Behaviors to discover prefix providing device
A device should decide the length of request prefix by the intent-
based mechanism, described in Section 5. If it used up its current
address resource, it could request more, which is not necessary to be
on the same scale as its initial resource.
A prefix requesting device that needs new or more address space
should firstly discover peer devices that may be able to provide
extra address space. The device should send out a GRASP Discovery
message that contains a Prefix Objective option Section 4.1, in which
the device also indicates whether it supports the DHCPv6 Prefix
Delegation (PD) [RFC3633] function and the length of requested
prefix.
3.2. Behaviors on prefix providing device
A peer device receiving a Discovery message with a Prefix Objective
option, if it is able to provide such a prefix, should respond with a
GRASP Response message. The Response message also carries a Prefix
Objective option, which also indicate whether the peer device
supports the PD function and the available prefix length matching the
request. If the peer device does not have enough resource, it may
silently drop the Discovery message or return a GRASP Response
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message, which contains a longer prefix length (smaller address
space) that it can provide. A divert option may also be added into
the GRASP Response message. This divert option indicates another
device that may provide the prefix. The diverted device is typically
an upstream gateway router, but it could in theory be any device that
might have unused prefix space.
A gateway router in a hierarchical network topology is normally
responsible to provide prefixes for routers within its subnet. In
the case that it does not have enough resource for the downstream
requesting router, it should return a GRASP Response message, which
contains a longer prefix length (smaller address space) that this
gateway router may provide. In this case too, a divert option may be
added into the GRASP Response message. The diverted device is
typically another upstream gateway router.
A resource shortage may cause the gateway router to request more
resource from its upstream device. This would be another independent
GND discovery and negotiation process. During the processing time,
the gateway router should send a Confirm-waiting Message to the
initial requesting router. When the new resource becomes available,
the gateway router responds with a GRASP Response message with the
prefix length matching the request.
The algorithm to choose which prefixes to assign on the prefix
providing devices is an implementation choice out of document scope.
3.3. Prefix Requests Behaviors
Upon receiving the GRASP Response message that indicates the
requesting prefix length is accepted, the requesting device may
request the prefix using DHCPv6 PD, if both itself and the response
device support PD.
Upon receiving the GRASP Response message that indicates the
requesting prefix length is not possible, but a longer prefix length
is available, the requesting device may request the longer prefix
using DHCPv6 PD, if both itself and the response device support PD.
If the GRASP Response message carries a divert option, the requesting
device may sent an unicast GRASP Discovery message to the diverted
device to find out whether that device can provide the requested
length prefix.
[Author's note: undecided whether we should support prefix delegation
using the GRASP protocol. This would have some partial overlap with
DHCPv6 PD. But it seems more consistent as a solution.]
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3.4. Prefix log
Within the autonomic prefix management, all the prefix assignment is
done by devices without human intervention. It is even more
important to record all the prefix assignment history. However, the
logging and reporting process is out of document scope.
4. Autonomic Prefix Management Options
This section defines the GRASP options that are used to support
autonomic prefix management.
4.1. Prefix Objective option
The Prefix Objective option carries the PD support flag and the
prefix length. The format of the Prefix Objective option is
described as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix_Obj_Option | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|PD_Support_Flag| Prefix_Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code Prefix_Obj_Option (TBA1).
option-len 2, length of option content in octets.
PD_Support_Flag Indicates whether the message sender supports
DHCPv6 Prefix Delegation function, 1 for support,
0 for no support, as client or server accordingly.
This flag must not be set to any other values.
Prefix_Length Indicate the prefix length that the message sender
requests or is willing to provide.
5. Prefix Management Intent
With in a single administrative domain, the network operator could
manage all their devices with role set. If so, there is possibility
to configure/manage the prefix length for every device in a simple
way.
The network operator could only manage the default prefix length for
each type of role. A prefix management intent, which contains all
mapping information of device roles and their default prefix lengths,
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should be flooded in the network, through the Autonomic Control Plane
(ACP) [I-D.ietf-anima-autonomic-control-plane]. The intent flooding
mechanism is out of document scope.
Upon receiving the prefix management intent, every device can decide
its default prefix length by matching its own role.
5.1. Example of Prefix Management Intent
The prefix management intent in this document is used to carry
mapping information of device roles and their default prefix lengths
in an autonomic domain. For example, an IPRAN operator wants to
configure the prefix length of RNC Site Gateway (RSG) as 34, the
prefix length of Aggregation Site Gateway (ASG) as 44, and the prefix
length of Cell Site Gateway (CSG) as 56. She/he may input the
following intent into the autonomic network:
{"autonomic_intent":
[
{"model_version": "1.0"},
{"intent_type": "Network management"},
{"autonomic_domain": "Customer_X_intranet"},
{"intent_name": "Prefix management"},
{"intent_version": 73},
{"Timestamp": "20150606 00:00:00"},
{"Lifetime": "Permanent"},
{"signature": "XXXXXXXXXXXXXXXXXXX"},
{"content":
[
{"role": [{"role_name": "RSG"},
{"role_characteristic":
[{"prefix_length": "34"}]}
]},
{"role": [{"role_name": "ASG"},
{"role_characteristic":
[{"prefix_length": "44"}]}
]},
{"role": [{"role_name": "CSG"},
{"role_characteristic":
[{"prefix_length": "56"}]}
]}
]
}
]
}
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6. Security Considerations
Relevant security issues are discussed in [I-D.ietf-anima-grasp].
The security mechanism in this document is established on a Public
Key Infrastructure (PKI) system [RFC3647] that is maintained by the
network administrator(s).
It is RECOMMENDED that DHCPv6 PD, if used, should be operated using
DHCPv6 authentication or Secure DHCPv6.
7. IANA Considerations
This document defines one new GRASP option. The IANA is requested to
assign a value for this option from the GRASP Option Codes table of
the GRASP Parameters registry as defined by [I-D.ietf-anima-grasp]
(if approved).
o The Prefix Objective option (TBA1), described in Section 4.1.
8. Acknowledgements
Valuable comments were received from Michael Behringer and Chongfeng
Xie.
This document was produced using the xml2rfc tool [RFC2629].
9. Change log [RFC Editor: Please remove]
draft-jiang-anima-prefix-management-00: original version, 2014-10-25.
draft-jiang-anima-prefix-management-01: add intent example and
coauthor Zongpeng Du, 2015-05-04.
draft-jiang-anima-prefix-management-02: update references and the
format of the prefix management intent, 2015-10-14.
10. References
[I-D.ietf-anima-autonomic-control-plane]
Behringer, M., Bjarnason, S., BL, B., and T. Eckert, "An
Autonomic Control Plane", draft-ietf-anima-autonomic-
control-plane-01 (work in progress), October 2015.
[I-D.ietf-anima-grasp]
Bormann, C., Carpenter, B., and B. Liu, "A Generic
Autonomic Signaling Protocol (GRASP)", draft-ietf-anima-
grasp-01 (work in progress), October 2015.
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[RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
DOI 10.17487/RFC2629, June 1999,
<http://www.rfc-editor.org/info/rfc2629>.
[RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
Host Configuration Protocol (DHCP) version 6", RFC 3633,
DOI 10.17487/RFC3633, December 2003,
<http://www.rfc-editor.org/info/rfc3633>.
[RFC3647] Chokhani, S., Ford, W., Sabett, R., Merrill, C., and S.
Wu, "Internet X.509 Public Key Infrastructure Certificate
Policy and Certification Practices Framework", RFC 3647,
DOI 10.17487/RFC3647, November 2003,
<http://www.rfc-editor.org/info/rfc3647>.
[RFC7575] Behringer, M., Pritikin, M., Bjarnason, S., Clemm, A.,
Carpenter, B., Jiang, S., and L. Ciavaglia, "Autonomic
Networking: Definitions and Design Goals", RFC 7575,
DOI 10.17487/RFC7575, June 2015,
<http://www.rfc-editor.org/info/rfc7575>.
[RFC7576] Jiang, S., Carpenter, B., and M. Behringer, "General Gap
Analysis for Autonomic Networking", RFC 7576,
DOI 10.17487/RFC7576, June 2015,
<http://www.rfc-editor.org/info/rfc7576>.
Authors' Addresses
Sheng Jiang (editor)
Huawei Technologies Co., Ltd
Q14, Huawei Campus, No.156 Beiqing Road
Hai-Dian District, Beijing, 100095
P.R. China
Email: jiangsheng@huawei.com
Zongpeng Du
Huawei Technologies Co., Ltd
Q14, Huawei Campus, No.156 Beiqing Road
Hai-Dian District, Beijing, 100095
P.R. China
Email: duzongpeng@huawei.com
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Brian Carpenter
Department of Computer Science
University of Auckland
PB 92019
Auckland 1142
New Zealand
Email: brian.e.carpenter@gmail.com
Qiong Sun
China Telecom
No.118, Xizhimennei Street
Beijing 100035
P. R. China
Email: sunqiong@ctbri.com.cn
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