ANIMA M. Behringer
Internet-Draft Cisco Systems
Intended status: Standards Track June 18, 2015
Expires: December 20, 2015
An Autonomic IPv6 Addressing Scheme
draft-behringer-anima-autonomic-addressing-01
Abstract
This document describes a generic IPv6 addressing scheme which is
suitable for autonomic nodes, where node addressing must not depend
on a centrally managed scheme. It assumes a unique domain name and
device name, and automatically derives a unique IPv6 address from
those. The scheme allows for a flat address hierarchy as well as
optionally, when required, the definition of zones which are
aggregatable.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements and Assumptions . . . . . . . . . . . . . . . . 2
3. Fundamental Concepts of Autonomic Addressing . . . . . . . . 3
4. The Base Addressing Scheme . . . . . . . . . . . . . . . . . 4
5. Possible Sub-Schemes . . . . . . . . . . . . . . . . . . . . 4
5.1. Sub-Scheme 1 . . . . . . . . . . . . . . . . . . . . . . 5
5.2. Sub-Scheme 2 . . . . . . . . . . . . . . . . . . . . . . 5
6. Address Hierarchy . . . . . . . . . . . . . . . . . . . . . . 6
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
8. Security Considerations . . . . . . . . . . . . . . . . . . . 7
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
In an Autonomic Network, as defined in
[I-D.irtf-nmrg-autonomic-network-definitions], and specified in more
detail in [I-D.behringer-anima-reference-model], one of the design
goals is to minimise central functions. Address management
traditionally is a centralised function, where addresses are assigned
to nodes. In this document we assume that each node has already been
assigned with a unique node name, and a domain name. We introduce an
addressing scheme and an algorithm that allows the calculation of a
unique IPv6 ULA address inside a domain. In other words, once a
device has a unique node and domain name, this addressing scheme and
algorithm allows for distributed self-management of addressing inside
a network.
The addressing scheme described here is specifically designed for
both the data plane of a network, as well as the Autonomic Control
Plane (ACP; see [I-D.behringer-autonomic-control-plane]). It is for
communication inside the domain only, specifically to support self-
management functions.
2. Requirements and Assumptions
An autonomic addressing scheme has the following requirements:
o Zero-touch for simple networks: Simple networks should have
complete self-management of addressing, and not require any
central address management, tools, or address planning.
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o Low-touch for complex networks: If complex networks require
operator input for autonomic address management, it should be
limited to high level guidance only, expressed in Intent.
o Flexibility: The addressing scheme must be flexible enough for
nodes to be able to move around, for the network to grow, split
and merge.
o Robustness: It should be as hard as possible for an administrator
to negatively affect addressing (and thus connectivity) in the
autonomic context.
o Support for virtualization: Autonomic Nodes may support Autonomic
Service Agents in different virtual machines or containers. The
addressing scheme should support this architecture.
o Simplicity: To make engineering simpler, and to give the human
administrator an easy way to trouble-shoot autonomic functions.
o Scale: The proposed scheme should work in any network of any size.
o Upgradability: The scheme must be able to support different
addressing concepts in the future.
We assume that each node has a unique domain name and a unique node
name inside that domain, for example "node17.domain.com".
3. Fundamental Concepts of Autonomic Addressing
IPv6 only: Autonomic processes should use exclusively IPv6, for
simplicity reasons.
Usage: Autonomic addresses are exclusively used for self-management
functions inside a trusted domain. They are not used for user
traffic. Communications with entities outside the trusted domain use
another address space, for example normally managed routable address
space.
Separation: Autonomic address space is used separately from user
address space and other address realms. This supports the robustness
requirement.
Loopback-only: Only loopback interfaces of autonomic nodes carry a
routable address; all other interfaces exclusively use IPv6 link
local for autonomic functions. The usage of IPv6 link local
addressing is discussed in [RFC7404].
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Use-ULA: For loopback interfaces of autonomic nodes, we use Unique
Local Addresses (ULA), as specified in [RFC4193]. An alternative
scheme was discussed, using assigned ULA addressing. The consensus
was to use standard ULA, because it was deemed to be sufficient.
No external connectivity: They do not provide access to the Internet.
If a node requires further reaching connectivity, it should use
another, traditionally managed address scheme in parallel.
4. The Base Addressing Scheme
The Base ULA addressing scheme for autonomic nodes has the following
format:
8 40 3 77
+--+--------------+------+------------------------------------------+
|FD| hash(domain) | Type | (sub-scheme) |
+--+--------------+------+------------------------------------------+
Figure 1: Base Addressing Scheme
The first 48 bits follow the ULA scheme, as defined in [RFC4193], to
which a type field is added:
o "FD" identifies a locally defined ULA address.
o The "global ID" is set here to be a hash of the domain name, which
results in a pseudo-random 40 bit value. It is calculated as the
first 40 bits of the MD5 hash of the domain name, in the example
"domain.com".
o Type: Set to 000 (3 zero bits). This field allows different
address sub-schemes in the future. The goal is to start with a
minimal number of sub-scheme initially, but to allow for
extensions later if and when required. This addresses the
"upgradability" requirement. Assignment of types for this field
should be maintained by IANA.
5. Possible Sub-Schemes
The sub-schemes listed here are not intended to be all supported
initially, but are listed for discussion. The final document should
define ideally only a single sub-scheme for now, and leave the other
"types" for later assignment.
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5.1. Sub-Scheme 1
51 13 64
+------------------------+---------+--------------------------------+
| (base scheme) | Zone ID | Device ID |
+------------------------+---------+--------------------------------+
Figure 2: Addressing Scheme 1
The fields are defined as follows: [Editor's note: The lengths of the
fields is for discussion.]
o Zone ID: If set to all zero bits: Flat addressing scheme. Any
other value indicates a zone. See section Section 6 on how this
field is used in detail.
o Device ID: A unique value for each device.
The device ID is derived as follows: In an Autonomic Network, a
registrar is enrolling new devices. As part of the enrolment process
the registrar assigns a number to the device, which is unique for
this registrar, but not necessarily unique in the domain. The 64 bit
device ID is then composed as:
o 48 bit: Registrar ID, a number unique inside the domain that
identifies the registrar which assigned the name to the device. A
MAC address of the registrar can be used for this purpose.
o 16 bit: Device ID, a number which is unique for a given registrar,
to identify the device. This can be a sequentially assigned
number.
The "device ID" itself is unique in a domain (i.e., the Zone-ID is
not required for uniqueness). Therefore, a device can be addressed
either as part of a flat hierarchy (zone ID = 0), or with an
aggregation scheme (any other zone ID). A address with zone-ID could
be interpreted as an identifier, with another zone-ID as a locator.
5.2. Sub-Scheme 2
51 13 64-V ?
+------------------------+---------+----------------------------+---+
| (base scheme) | Zone ID | Device ID | V |
+------------------------+---------+----------------------------+---+
Figure 3: Addressing Scheme 2
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The fields are defined as follows: [Editor's note: The lengths of the
fields is for discussion.]
o Zone ID: As in sub-scheme 1.
o Device ID: As in sub-scheme 1.
o V: Virtualization bit(s): 1 or more bits that indicate a virtual
context on an autonomic node.
In addition the scheme 1 (Section 5.1), this scheme allows the direct
addressing of specific virtual containers / VMs on an autonomic node.
An increasing number of hardware platforms have a distributed
architecture, with a base OS for the node itself, and the support for
hardware blades with potentially different OSs. The VMs on the
blades could be considered as separate autonomic nodes, in which case
it would make sense to be able to address them directly. Autonomic
Service Agents (ASAs) could be instantiated in either the base OS, or
one of the VMs on a blade. This addressing scheme allows for the
easy separation of the hardware context.
The location of the V bit(s) at the end of the address allows to
announce a single prefix for each autonomic node, while having
separate virtual contexts addressable directly.
6. Address Hierarchy
The "zone ID" allows for the definition of a simple address
hierarchy. If set to zero, the address scheme is flat. In this
case, the addresses primarily act as identifiers for the nodes. Used
like this, aggregation is not possible.
If aggregation is required, the 13 bit value allows for up to 8191
zones. (Theoretically, the 13 bits for the zone ID would allow also
for two levels of zones, introducing a sub-hierarchy. We do not
think this is required at this point, but a new type could be used in
the future to support such a scheme.)
Another way to introduce hierarchy is to use sub-domains in the
naming scheme. The node names "node17.subdomainA.domain.com" and
"node4.subdomainB.domain.com" would automatically lead to different
ULA prefixes, which can be used to introduce a routing hierarchy in
the network, assuming that the subdomains are aligned with routing
areas.
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7. IANA Considerations
The type field in the base addressing scheme should be maintained by
IANA.
8. Security Considerations
tbc
9. Acknowledgements
The following people have been involved in developing this scheme:
Toerless Eckert, Steinthor Bjarnason, BL Balaji, Ravi Kumar
Vadapalli.
10. References
[I-D.behringer-anima-reference-model]
Behringer, M., Carpenter, B., Eckert, T., Ciavaglia, L.,
and B. Liu, "A Reference Model for Autonomic Networking",
draft-behringer-anima-reference-model-02 (work in
progress), June 2015.
[I-D.behringer-autonomic-control-plane]
Behringer, M., Bjarnason, S., BL, B., and T. Eckert, "An
Autonomic Control Plane", draft-behringer-autonomic-
control-plane-00 (work in progress), June 2014.
[I-D.irtf-nmrg-autonomic-network-definitions]
Behringer, M., Pritikin, M., Bjarnason, S., Clemm, A.,
Carpenter, B., Jiang, S., and L. Ciavaglia, "Autonomic
Networking - Definitions and Design Goals", draft-irtf-
nmrg-autonomic-network-definitions-07 (work in progress),
March 2015.
[RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
Addresses", RFC 4193, October 2005.
[RFC7404] Behringer, M. and E. Vyncke, "Using Only Link-Local
Addressing inside an IPv6 Network", RFC 7404, November
2014.
Author's Address
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Michael H. Behringer
Cisco Systems
Building D, 45 Allee des Ormes
Mougins 06250
France
Email: mbehring@cisco.com
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