| 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
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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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.
An autonomic addressing scheme has the following requirements:
We assume that each node has a unique domain name and a unique node name inside that domain, for example "node17.domain.com".
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].
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.
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.
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 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.
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.
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. and B. Liu, "A Reference Model for Autonomic Networking", Internet-Draft draft-behringer-anima-reference-model-02, June 2015. |
| [I-D.behringer-autonomic-control-plane] | Behringer, M., Bjarnason, S., BL, B. and T. Eckert, "An Autonomic Control Plane", Internet-Draft draft-behringer-autonomic-control-plane-00, 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", Internet-Draft draft-irtf-nmrg-autonomic-network-definitions-07, 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. |