| ANIMA | T. Eckert, Ed. |
| Internet-Draft | Huawei |
| Intended status: Informational | M. Behringer |
| Expires: August 9, 2018 | February 5, 2018 |
Using Autonomic Control Plane for Stable Connectivity of Network OAM
draft-ietf-anima-stable-connectivity-10
OAM (Operations, Administration and Maintenance - as per BCP161, (RFC6291) processes for data networks are often subject to the problem of circular dependencies when relying on connectivity provided by the network to be managed for the OAM purposes.
Provisioning while bringing up devices and networks tends to be more difficult to automate than service provisioning later on, changes in core network functions impacting reachability cannot be automated because of ongoing connectivity requirements for the OAM equipment itself, and widely used OAM protocols are not secure enough to be carried across the network without security concerns.
This document describes how to integrate OAM processes with an autonomic control plane in order to provide stable and secure connectivity for those OAM processes. This connectivity is not subject to aforementioned circular dependencies.
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This Internet-Draft will expire on August 9, 2018.
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OAM (Operations, Administration and Maintenance - as per BCP161, [RFC6291]) for data networks is often subject to the problem of circular dependencies when relying on the connectivity service provided by the network to be managed. OAM can easily but unintentionally break the connectivity required for its own operations. Avoiding these problems can lead to complexity in OAM. This document describes this problem and how to use an autonomic control plane to solve it without further OAM complexity:
The ability to perform OAM on a network device requires first the execution of OAM necessary to create network connectivity to that device in all intervening devices. This typically leads to sequential, 'expanding ring configuration' from a NOC (Network Operations Center). It also leads to tight dependencies between provisioning tools and security enrollment of devices. Any process that wants to enroll multiple devices along a newly deployed network topology needs to tightly interlock with the provisioning process that creates connectivity before the enrollment can move on to the next device.
When performing change operations on a network, it likewise is necessary to understand at any step of that process that there is no interruption of connectivity that could lead to removal of connectivity to remote devices. This includes especially change provisioning of routing, forwarding, security and addressing policies in the network that often occur through mergers and acquisitions, the introduction of IPv6 or other mayor re-hauls in the infrastructure design. Examples include change of an IGP or areas, PA (Provider Aggregatable) to PI (Provider Independent) addressing, or systematic topology changes (such as L2 to L3 changes).
All these circular dependencies make OAM complex and potentially fragile. When automation is being used, for example through provisioning systems, this complexity extends into that automation software.
In the late 1990s and early 2000, IP networks became the method of choice to build separate OAM networks for the communications infrastructure within Network Providers. This concept was standardized in ITU-T G.7712/Y.1703 and called "Data Communications Networks" (DCN). These were (and still are) physically separate IP(/MPLS) networks that provide access to OAM interfaces of all equipment that had to be managed, from PSTN (Public Switched Telephone Network) switches over optical equipment to nowadays Ethernet and IP/MPLS production network equipment.
Such DCN provide stable connectivity not subject to aforementioned problems because they are a separate network entirely, so change configuration of the production IP network is done via the DCN but never affects the DCN configuration. Of course, this approach comes at a cost of buying and operating a separate network and this cost is not feasible for many providers, most notably smaller providers, most enterprises and typical IoT networks (Internet of Things).
One of the goals of the IETF ANIMA (Autonomic Networking Integrated Model and Approach ) working group is the specification of a secure and automatically built inband management plane that provides similar stable connectivity as a DCN, but without having to build a separate DCN. It is clear that such 'in-band' approach can never achieve fully the same level of separation, but the goal is to get as close to it as possible.
This goal of this document is to discuss how such an inband management plane can be used to support the DCN-like OAM use-case, leverage its stable connectivity and details the options of deploying it incrementally - short and long term.
The evolving ANIMA working groups specification [I-D.ietf-anima-autonomic-control-plane] ) calls this inband management plane the "Autonomic Control Plane" (ACP). The discussions in this document are not depending on the specification of that ACP, but only on a set of high level constraints decided early on in the work for the ACP. Unless being specific about details of the ACP, this document uses the term "Generalized ACP" (GACP) and is applicable to any designs that meet those high level constraints. For example - but not limited to - variations of the ACP protocol choices.
The high level constraints of a GACP assumed and discussed in this document are as follows:
The GACP must be built autonomic and its function must not be disruptable by operator or automated (NMS/SDN) configuration/provisioning actions. These are allowed to only impact the "data-plane". This aspect is not currently covered in this document. Instead, it focusses on the impact of the above constraints: IPv6 only, dual connectivity and security.
The ANI is the "Autonomic Networking Infrastructure" consisting of secure zero touch Bootstrap (BRSKI - [I-D.ietf-anima-bootstrapping-keyinfra]), GeneRic Autonomic Signaling Protocol (GRASP - [I-D.ietf-anima-grasp]), and Autonomic Control Plane (ACP - [I-D.ietf-anima-autonomic-control-plane]). Refer to [I-D.ietf-anima-reference-model] for an overview of the ANI and how its components interact and [RFC7575] for concepts and terminology of ANI and autonomic networks.
This section describes stable connectivity for centralized OAM via the GACP, for example via the ACP with or without a complete ANI, starting by what we expect to be the most easy to deploy short-term option. It then describes limitation and challenges of that approach and their solutions/workarounds to finish with the preferred target option of autonomic NOC devices in Section 2.1.6.
This order was chosen because it helps to explain how simple initial use of a GACP can be, how difficult workarounds can become (and therefore what to avoid), and finally because one very promising long-term solution alternative is exactly like the most easy short-term solution only virtualized and automated.
In the most common case, OAM will be performed by one or more applications running on a variety of centralized NOC systems that communicate with network devices. We describe differently advanced approaches to leverage a GACP for stable connectivity. There is a wide range of options, some of which are simple, some more complex.
Three stages can be considered:
In the most simple candidate deployment case, the GACP extends all the way into the NOC via one or more "GACP-edge-devices". See also section 6.1 of [I-D.ietf-anima-autonomic-control-plane]. These devices "leak" the (otherwise encrypted) GACP natively to NMS hosts. They act as the default routers to those NMS hosts and provide them with IPv6 connectivity into the GACP. NMS hosts with this setup need to support IPv6 (see e.g. [RFC6434]) but require no other modifications to leverage the GACP.
Note that even though the GACP only uses IPv6, it can of course support OAM for any type of network deployment as long as the network devices support the GACP: The data-plane can be IPv4 only, dual-stack or IPv6 only. It is always separate from the GACP, therefore there is no dependency between the GACP and the IP version(s) used in the data-plane.
This setup is sufficient for troubleshooting such as SSH into network devices, NMS that performs SNMP read operations for status checking, software downloads into autonomic devices, provisioning of devices via NETCONF and so on. In conjunction with otherwise unmodified OAM via separate NMS hosts it can provide a good subset of the stable connectivity goals. The limitations of this approach are discussed in the next section.
Because the GACP provides 'only' for IPv6 connectivity, and because addressing provided by the GACP does not include any topological addressing structure that operations in a NOC often relies on to recognize where devices are on the network, it is likely highly desirable to set up DNS (Domain Name System - see [RFC1034]) so that the GACP IPv6 addresses of autonomic devices are known via domain names that include the desired structure. For example, if DNS in the network was set up with names for network devices as devicename.noc.example.com, and the well-known structure of the data-plane IPv4 addresses space was used by operators to infer the region where a device is located in, then the GACP address of that device could be set up as devicename_<region>.acp.noc.example.com, and devicename.acp.noc.example.com could be a CNAME to devicename_<region>.acp.noc.example.com. Note that many networks already use names for network equipment where topological information is included, even without a GACP.
This simple connectivity of non-autonomic NMS hosts suffers from a range of challenges (that is, operators may not be able to do it this way) or limitations (that is, operator cannot achieve desired goals with this setup). The following list summarizes these challenges and limitations. The following sections describe additional mechanisms to overcome them.
Note that these challenges and limitations exist because GACP is primarily designed to support distributed ASA (Autonomic Service Agent, a piece of autonomic software) in the most lightweight fashion, but not mandatorily require support for additional mechanisms to best support centralized NOC operations. It is this document that describes additional (short term) workarounds and (long term) extensions.
These four problems can be tackled independently of each other by solution improvements. Combining some of these solutions improvements together can lead towards a candidate long term solution.
Simultaneous connectivity to both GACP and data-plane can be achieved in a variety of ways. If the data-plane is IPv4-only, then any method for dual-stack attachment of the NOC device/application will suffice: IPv6 connectivity from the NOC provides access via the GACP, IPv4 will provide access via the data-plane. If as explained above in the simple case, an autonomic device supports native attachment to the GACP, and the existing NOC setup is IPv4 only, then it could be sufficient to attach the GACP device(s) as the IPv6 default router to the NOC subnet and keep the existing IPv4 default router setup unchanged.
If the data-plane of the network is also supporting IPv6, then the most compatible setup for NOC devices is to have two IPv6 interfaces. One virtual ((e.g. via IEEE 802.1Q) or physical interface connecting to a data-plane subnet, and another into an GACP connect subnet. See section 8.1 of [I-D.ietf-anima-autonomic-control-plane] for more details. That document also specifies how the NOC devices can receive auto configured addressing and routes towards the ACP connect subnet if it supports [RFC6724] and [RFC4191].
Configuring a second interface on a NOC host may be impossible or be seen as undesired complexity. In that case the GACP edge device needs to provide support for a "Combined ACP and data-plane interface" as also described in section 8.1 of [I-D.ietf-anima-autonomic-control-plane]. This setup may not work with auto configuration and all NOC host network stacks due to limitations in those network stacks. They need to be able to perform RFC6724 source address selection rule 5.5 including caching of next-hop information.
For security reasons, it is not considered appropriate to connect a non-GACP router to a GACP connect interface. The reason is that the GACP is a secured network domain and all NOC devices connecting via GACP connect interfaces are also part of that secure domain - the main difference is that the physical link between the GACP edge device and the NOC devices is not authenticated/encrypted and therefore, needs to be physically secured. If the secure GACP was extendable via untrusted routers then it would be a lot more difficult to verify the secure domain assertion. Therefore the GACP edge devices are not supposed to redistribute routes from non-GACP routers into the GACP.
One architectural expectation for the GACP as described in Section 1.3 is that all devices that want to use the GACP do support IPv6. Including NMS hosts. Note that this expectation does not imply any requirements against the data-plane, especially no need to support IPv6 in it. The data-plane could be IPv4 only, IPv6 only, dual stack or it may not need to have any IP host stack on the network devices.
The implication of this architectural decision is the potential need for short-term workarounds when the operational practices in a network do not yet meet these target expectations. This section explains when and why these workarounds may be operationally necessary and describes them. However, the long term goal is to upgrade all NMS hosts to native IPv6, so the workarounds described in this section should not be considered permanent.
Most network equipment today supports IPv6 but it is by far not ubiquitously supported in NOC backend solutions (HW/SW), especially not in the product space for enterprises. Even when it is supported, there are often additional limitations or issues using it in a dual stack setup or the operator mandates for simplicity single stack for all operations. For these reasons an IPv4 only management plane is still required and common practice in many enterprises. Without the desire to leverage the GACP, this required and common practice is not a problem for those enterprises even when they run dual stack in the network. We discuss these workarounds here because it is a short term deployment challenge specific to the operations of a GACP.
To connect IPv4 only management plane devices/applications with a GACP, some form of IP/ICMP translation of packets IPv4<->IPv6 is necessary. The basic mechanisms for this are defined in SIIT ([RFC7915]). There are multiple solutions using this mechanism. To understand the possible solutions, we consider the requirements:
Because of these requirements, the necessary and sufficient set of solutions are those that provide 1:1 mapping of IPv6 GACP addresses into IPv4 space and 1:1 mapping of IPv4 NMS host space into IPv6 (for use in the GACP). This means that stateless SIIT based solutions are sufficient and preferred.
Note that GACP devices may use multiple IPv6 addresses in the GACP. For example, [I-D.ietf-anima-autonomic-control-plane] section 6.10 defines multiple useful addressing sub-schemes supporting this option. All those addresses may then need to be reachable through the IPv6/IPv4 address translation.
The need to allocate for every GACP device one or multiple IPv4 addresses should not be a problem if - as we assume - the NMS hosts can use private IPv4 address space ([RFC1918]). Nevertheless even with RFC1918 address space it is important that the GACP IPv6 addresses can efficiently be mapped into IPv4 address space without too much waste.
The currently most flexible mapping scheme to achieve this is [RFC7757] because it allows configured IPv4 <-> IPv6 prefix mapping. Assume the GACP uses the ACP "Zone Addressing" Sub-Scheme and there are 3 registrars. In the Zone Addressing Sub-Scheme, there is for each registrar a constant /112 prefix for which in RFC7757 an EAM (Explicit Address Mapping) into a /16 (e.g.: RFC1918) prefix into IPv4 can be configured. Within the registrars /112 prefix, Device-Numbers for devices are sequentially assigned: with V-bit effectively two numbers are assigned per GACP device. This also means that if IPv4 address space is even more constrained, and it is known that a registrar will never need the full /15 extent of Device-Numbers, then a longer than /112 prefix can be configured into the EAM to use less IPv4 space.
When using the ACP "Vlong Addressing" Sub-Scheme, it is unlikely that one wants or need to translate the full /8 or /16 bits of addressing space per GACP device into IPv4. In this case, the EAM rules of dropping trailing bits can be used to map only N bits of the V-bits into IPv4. This does imply though that only V-addresses that differ in those high-order N V-bits can be distinguished on the IPv4 side.
Likewise, the IPv4 address space used for NMS hosts can easily be mapped into an address prefix assigned to a GACP connect interface.
A full specification of a solution to perform SIIT in conjunction with GACP connect following the considerations below is outside the scope of this document.
To be in compliance with security expectations, SIIT has to happen on the GACP edge device itself so that GACP security considerations can be taken into account. E.g.: that IPv4 only NMS hosts can be dealt with exactly like IPv6 hosts connected to a GACP connect interface.
Note that prior solutions such as NAT64 ([RFC6146]) may equally be useable to translate between GACP IPv6 address space and NMS Hosts IPv4 address space, and that as workarounds this can also be done on non GACP Edge Devices connected to a GACP connect interface. The details vary depending on implementation because the options to configure address mappings vary widely. Outside of EAM, there are no standardized solutions that allow for mapping of prefixes, so it will most likely be necessary to explicitly map every individual (/128) GACP device address to an IPv4 address. Such an approach should use automation/scripting where these address translation entries are created dynamically whenever a GACP device is enrolled or first connected to the GACP network.
Overall, the use of NAT is especially subject to the ROI (Return On Investment) considerations, but the methods described here may not be too different from the same problems encountered totally independent of GACP when some parts of the network are to introduce IPv6 but NMS hosts are not (yet) upgradeable.
As mentioned above, a GACP is not expected to have high performance because its primary goal is connectivity and security, and for existing network device platforms this often means that it is a lot more effort to implement that additional connectivity with hardware acceleration than without - especially because of the desire to support full encryption across the GACP to achieve the desired security.
Some of these issues may go away in the future with further adoption of a GACP and network device designs that better tender to the needs of a separate OAM plane, but it is wise to plan for even long-term designs of the solution that does NOT depend on high-performance of the GACP. This is opposite to the expectation that future NMS hosts will have IPv6, so that any considerations for IPv4/NAT in this solution are temporary.
To solve the expected performance limitations of the GACP, we do expect to have the above describe dual-connectivity via both GACP and data-plane between NOC application devices and devices with GACP. The GACP connectivity is expected to always be there (as soon as a device is enrolled), but the data-plane connectivity is only present under normal operations but will not be present during e.g. early stages of device bootstrap, failures, provisioning mistakes or during network configuration changes.
The desired policy is therefore as follows: In the absence of further security considerations (see below), traffic between NMS hosts and GACP devices should prefer data-plane connectivity and resort only to using the GACP when necessary, unless it is an operation known to be so much tied to the cases where the GACP is necessary that it makes no sense to try using the data-plane. An example are SSH connections from the NOC into a network device to troubleshoot network connectivity. This could easily always rely on the GACP. Likewise, if an NMS host is known to transmit large amounts of data, and it uses the GACP, then its performance need to be controlled so that it will not overload the GACP performance. Typical examples of this are software downloads.
There is a wide range of methods to build up these policies. We describe a few:
Ideally, a NOC system would learn and keep track of all addresses of a device (GACP and the various data-plane addresses). Every action of the NOC system would indicate via a "path-policy" what type of connection it needs (e.g. only data-plane, GACP-only, default to data-plane, fallback to GACP,...). A connection policy manager would then build connection to the target using the right address(es). Shorter term, a common practice is to identify different paths to a device via different names (e.g. loopback vs. interface addresses). This approach can be expanded to GACP uses, whether it uses NOC system local names or DNS. We describe example schemes using DNS:
DNS can be used to set up names for the same network devices but with different addresses assigned: One name (name.noc.example.com) with only the data-plane address(es) (IPv4 and/or IPv6) to be used for probing connectivity or performing routine software downloads that may stall/fail when there are connectivity issues. One name (name-acp.noc.example.com) with only the GACP reachable address of the device for troubleshooting and probing/discovery that is desired to always only use the GACP. One name with data-plane and GACP addresses (name-both.noc.example.com).
Traffic policing and/or shaping at the GACP edge in the NOC can be used to throttle applications such as software download into the GACP.
Using different names mapping to different (subset of) addresses can be difficult to set up and maintain, especially also because data-plane addresses may change due to reconfiguration or relocation of devices. The name based approach alone can also not well support policies for existing applications and long-lived flows to automatically switch between ACP and data-plane in the face of data-plane failure and recovery. A solution would be GACP node host transport stacks supporting the following requirements:
Protocols like MPTCP (Multipath TCP -see [RFC6824]) and SCTP ([RFC4960]) can already support part of these requirements. MPTCP for example supports signaling of addresses in a TCP backward compatible fashion, establishment of additional flows (called subflows in MPTCP) and having primary and fallback subflows via MP_PRIO signalling. The details if or how MPTCP, SCTP and/or other approaches potentially with extensions and/or (shim) layers on top of them can best provide a complete solution for the above requirements is subject to further work outside the scope of this document.
Setting up connectivity between the NOC and autonomic devices when the NOC device itself is non-autonomic is as mentioned in the beginning a security issue. It also results as shown in the previous paragraphs in a range of connectivity considerations, some of which may be quite undesirable or complex to operationalize.
Making NMS hosts autonomic and having them participate in the GACP is therefore not only a highly desirable solution to the security issues, but can also provide a likely easier operationalization of the GACP because it minimizes NOC-special edge considerations - the GACP is simply built all the way automatically, even inside the NOC and only authorized and authenticate NOC devices/applications will have access to it.
Supporting the ACP according to [I-D.ietf-anima-autonomic-control-plane] all the way into an application device requires implementing the following aspects in it: AN bootstrap/enrollment mechanisms, the secure channel for the ACP and at least the host side of IPv6 routing setup for the ACP. Minimally this could all be implemented as an application and be made available to the host OS via e.g. a tap driver to make the ACP show up as another IPv6 enabled interface.
Having said this: If the structure of NMS hosts is transformed through virtualization anyhow, then it may be considered equally secure and appropriate to construct (physical) NMS host system by combining a virtual GACP enabled router with non-GACP enabled NOC-application VMs via a hypervisor, leveraging the configuration options described in the previous sections but just virtualizing them.
When combining GACP and data-plane connectivity for availability and performance reasons, this too has an impact on security: When using the GACP, the traffic will be mostly encryption protected, especially when considering the above described use of application devices with GACP. If instead the data-plane is used, then this is not the case anymore unless it is done by the application.
The simplest solution for this problem exists when using GACP capable NMS hosts, because in that case the communicating GACP capable NMS host and the GACP network device have credentials they can mutually trust (same GACP domain). In result, data-plane connectivity that does support this can simply leverage TLS/DTLS ([RFC5246])/([RFC6347]) with those GACP credentials for mutual authentication - and does not incur new key management.
If this automatic security benefit is seen as most important, but a "full" GACP stack into the NMS host is unfeasible, then it would still be possible to design a stripped down version of GACP functionality for such NOC hosts that only provides enrollment of the NOC host with the GACP cryptographic credentials but without directly participating in the GACP encryption method. Instead, the host would just leverage TLS/DTLS using its GACP credentials via the data-plane with GACP network devices as well as indirectly via the GACP with the above mentioned GACP connect into the GACP.
When using the GACP itself, TLS/DTLS for the transport layer between NMS hosts and network device is somewhat of a double price to pay (GACP also encrypts) and could potentially be optimized away, but given the assumed lower performance of the GACP, it seems that this is an unnecessary optimization.
If we consider what potentially could be the most lightweight and autonomic long term solution based on the technologies described above, we see the following direction:
Today, many distributed protocols implement their own unique security mechanisms.
KARP (Keying and Authentication for Routing Protocols, see [RFC6518]) has tried to start to provide common directions and therefore reduce the re-invention of at least some of the security aspects, but it only covers routing-protocols and it is unclear how well it is applicable to a potentially wider range of network distributed agents such as those performing distributed OAM. The common security of a GACP can help in these cases.
Furthermore, GRASP ([I-D.ietf-anima-grasp]) can run on top of a GACP as a security and transport substrate and provide common local & remote neighbor discovery and peer negotiation mechanism, further allowing to unifying & reuse future protocol designs.
The GACP is intended to be IPv6 only, and the prior explanations in this document show that this can lead to some complexity when having to connect IPv4 only NOC solutions, and that it will be impossible to leverage the GACP when the OAM agents on a GACP network device do not support IPv6. Therefore, the question was raised whether the GACP should optionally also support IPv4.
The decision not to include IPv4 for GACP as something that is considered in the use cases in this document is because of the following reasons:
In SP networks that have started to support IPv6, often the next planned step is to consider moving out IPv4 from a native transport to just a service on the edge. There is no benefit/need for multiple parallel transport families within the network, and standardizing on one reduces OPEX and improves reliability. This evolution in the data-plane makes it highly unlikely that investing development cycles into IPv4 support for GACP will have a longer term benefit or enough critical short-term use-cases. Support for IPv6-only for GACP is purely a strategic choice to focus on the known important long term goals.
In other types of networks as well, we think that efforts to support autonomic networking is better spent in ensuring that one address family will be supported so all use cases will long-term work with it, instead of duplicating effort into IPv4. Especially because auto-addressing for the GACP with IPv4 would be more complex than in IPv6 due to the IPv4 addressing space.
In this section, we discuss only security considerations not covered in the appropriate sub-sections of the solutions described.
Even though GACPs are meant to be isolated, explicit operator misconfiguration to connect to insecure OAM equipment and/or bugs in GACP devices may cause leakage into places where it is not expected. Mergers/Acquisitions and other complex network reconfigurations affecting the NOC are typical examples.
GACP addresses are ULA addresses. Using these addresses also for NOC devices as proposed in this document is not only necessary for above explained simple routing functionality but it is also more secure than global IPv6 addresses. ULA addresses are not routed in the global Internet and will therefore be subject to more filtering even in places where specific ULA addresses are being used. Packets are therefore less likely to leak to be successfully injected into the isolated GACP environment.
The random nature of a ULA prefix provides strong protection against address collision even though there is no central assignment authority. This is helped by the expectation that GACPs are never expected to connect all together, but only few GACPs may ever need to connect together, e.g. when mergers and acquisitions occur.
Note that the GACP constraints demands that only packets from connected subnet prefixes are permitted from GACP connect interfaces, limiting the scope of non-cryptographically secured transport to a subnet within a NOC that instead has to rely on physical security (only connect trusted NOC devices to it).
To help diagnose packets that unexpectedly leaked for example from another GACP (that was meant to be deployed separately), it can be useful to voluntarily list your own the ULA GACP prefixes on some site(s) on the Internet and hope that other users of GACPs do the same so that you can look up unknown ULA prefix packets seen in your network. Note that this does not constitute registration. https://www.sixxs.net/tools/grh/ula/ was a site to list ULA prefixes but it is not open for new listings anymore since the mid of 2017. The authors are not aware of other active Internet sites to list ULA use.
Note that there is a provision in [RFC4193] for non-locally assigned address space (L bit = 0), but there is no existing standardization for this, so these ULA prefixes must not be used.
According to [RFC4193] section 4.4, PTR records for ULA addresses should not be installed into the global DNS (no guaranteed ownership). Hence also the need to rely on voluntary lists (and in prior paragraph) to make the use of an ULA prefix globally known.
Nevertheless, some legacy OAM applications running across the GACP may rely on reverse DNS lookup for authentication of requests (e.g.: TFTP for download of network firmware/config/software). Operators may therefore need to use a private DNS setup for the GACP ULA addresses. This is the same setup that would be necessary for using RFC1918 addresses in DNS. See for example [RFC1918] section 5, last paragraph. In [RFC6950] section 4, these setups are discussed in more detail.
Any current and future protocols must rely on secure end-to-end communications (TLS/DTLS) and identification and authentication via the certificates assigned to both ends. This is enabled by the cryptographic credentials mechanisms of the GACP.
If DNS and especially reverse DNS are set up, then it should be set up in an automated fashion when the GACP address for devices are assigned. In the case of the ACP, DNS resource record creation can be linked to the autonomic registrar backend so that the DNS and reverse DNS records are actually derived from the subject name elements of the ACP device certificates in the same way as the autonomic devices themselves will derive their ULA addresses from their certificates to ensure correct and consistent DNS entries.
If an operator feels that reverse DNS records are beneficial to its own operations but that they should not be made available publically for "security" by concealment reasons, then the case of GACP DNS entries is probably one of the least problematic use cases for split-DNS: The GACP DNS names are only needed for the NMS hosts intending to use the GACP - but not network wide across the enterprise.
This document requests no action by IANA.
This work originated from an Autonomic Networking project at cisco Systems, which started in early 2010 including customers involved in the design and early testing. Many people contributed to the aspects described in this document, including in alphabetical order: BL Balaji, Steinthor Bjarnason, Yves Herthoghs, Sebastian Meissner, Ravi Kumar Vadapalli. The author would also like to thank Michael Richardson, James Woodyatt and Brian Carpenter for their review and comments. Special thanks to Sheng Jiang and Mohamed Boucadair for their thorough review.