| ANIMA | M. Behringer |
| Internet-Draft | Cisco Systems |
| Intended status: Standards Track | October 16, 2015 |
| Expires: April 18, 2016 |
An Autonomic IPv6 Addressing Scheme
draft-behringer-anima-autonomic-addressing-02
This document describes a generic IPv6 addressing scheme which is suitable for self-managing Autonomic Control Plane. The scheme allows for a flat address hierarchy as well as optionally, when required, the definition of aggregatable zones.
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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.
In an autonomic network each node receives a domain-unique identifier, which consists of a domain name and a unique node-ID in that domain. We introduce an addressing scheme and an algorithm that allows the calculation of a unique IPv6 ULA address from those parameters. In other words, once a device has a unique node-ID 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 the Autonomic Control Plane (ACP; see [I-D.ietf-anima-autonomic-control-plane]). It is for communication inside the domain only, specifically to support self-management functions. It may be used for OAM functions inside the ACP as well, as described in [I-D.eckert-anima-stable-connectivity].
We assume that each node has a unique domain name and a unique node ID inside that domain. The fundamental concepts for autonomic addressing are:
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:
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.
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.]
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:
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. See Section 5 for a description of the zone bits.
51 13 64-V ?
+------------------------+---------+----------------------------+---+
| (base scheme) | Zone ID | Device ID | V |
+------------------------+---------+----------------------------+---+
Figure 3: Addressing Scheme 2
The fields are defined as follows: [Editor's note: The lengths of the fields is for discussion.]
In addition the scheme 1 (Section 4.1), 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.
The "zone ID" allows for the introduction of structure in the addressing scheme.
Zone = zero is the default addressing scheme in an autonomic domain. Every autonomic node MUST respond to its ACP address with zone=0. Used on its own this leads to a non-hierarchical address scheme, which is suitable for networks up to a certain size. In this case, the addresses primarily act as identifiers for the nodes, and aggregation is not possible.
If aggregation is required, the 13 bit value allows for up to 8191 zones. The allocation of zone numbers may either happen automatically through a to-be-defined algorithm; or it could be configured and maintained manually. [We could divide the zone space into manual and automatic space - to be discussed.]
If a device learns through an autonomic method or through configuration that it is part of a zone, it MUST also respond to its ACP address with that zone number. In this case the ACP loopback is configured with two ACP addresses: One for zone 0 and one for the assigned zone. This method allows for a smooth transition between a flat addressing scheme and an hierarchical one.
(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.)
Note: Another way to introduce hierarchy is to use sub-domains in the naming scheme. The node names "node17.subdomainA.example.com" and "node4.subdomainB.example.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.
The type field in the base addressing scheme should be maintained by IANA.
tbc
The following people have been involved in developing this scheme: Toerless Eckert, Steinthor Bjarnason, BL Balaji, Ravi Kumar Vadapalli.
| [I-D.behringer-anima-reference-model] | Behringer, M., Carpenter, B., Eckert, T., Ciavaglia, L., Liu, B., Jeff, J. and J. Strassner, "A Reference Model for Autonomic Networking", Internet-Draft draft-behringer-anima-reference-model-03, June 2015. |
| [I-D.eckert-anima-stable-connectivity] | Eckert, T. and M. Behringer, "Using Autonomic Control Plane for Stable Connectivity of Network OAM", Internet-Draft draft-eckert-anima-stable-connectivity-01, March 2015. |
| [I-D.ietf-anima-autonomic-control-plane] | Behringer, M., Bjarnason, S., BL, B. and T. Eckert, "An Autonomic Control Plane", Internet-Draft draft-ietf-anima-autonomic-control-plane-01, October 2015. |
| [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", Internet-Draft draft-irtf-nmrg-autonomic-network-definitions-07, March 2015. |
| [RFC4193] | Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast Addresses", RFC 4193, DOI 10.17487/RFC4193, October 2005. |
| [RFC7404] | Behringer, M. and E. Vyncke, "Using Only Link-Local Addressing inside an IPv6 Network", RFC 7404, DOI 10.17487/RFC7404, November 2014. |