ANIMA                                                      T.T.E. Eckert
Internet-Draft                                                 Futurewei
Intended status: Standards Track                            M. Boucadair
Expires: 5 September 2022                                   C. Jacquenet
                                                            M. Behringer
                                                            4 March 2022

Autoconfiguration of infrastructure services in ACP networks via DNS-SD
                               over GRASP


   This document defines standards that enable autoconfiguration of
   fundamental centralized or decentralized network infrastructure
   services on ACP network nodes via GRASP.  These are primarily the
   services required for initial bootstrapping of a network but will
   persist through the lifecycles of the network.  These services
   include secure remote access to zero-touch bootstrapped ANI devices
   via SSH/Netconf with Radius/Diameter authentication and authorization
   and provides lifecycle autoconfiguration for other crucial services
   such as syslog, NTP (clock synchronization) and DNS for operational

Status of This Memo

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   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on 5 September 2022.

Copyright Notice

   Copyright (c) 2022 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
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   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Overview  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.2.  ACP nodes supporting services autoconfiguration . . . . .   3
     1.3.  Use of ACP GRASP for autoconfiguration  . . . . . . . . .   4
     1.4.  GRASP parameters  . . . . . . . . . . . . . . . . . . . .   5
   2.  Services  . . . . . . . . . . . . . . . . . . . . . . . . . .   8
     2.1.  Syslog  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     2.2.  NTP . . . . . . . . . . . . . . . . . . . . . . . . . . .  11
     2.3.  DNS for operations  . . . . . . . . . . . . . . . . . . .  12
     2.4.  Radius  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     2.5.  Diameter  . . . . . . . . . . . . . . . . . . . . . . . .  14
     2.6.  SSH server  . . . . . . . . . . . . . . . . . . . . . . .  15
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .  15
   4.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  16
   5.  Change log [RFC Editor: Please remove]  . . . . . . . . . . .  16
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  16
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .  16
     6.2.  Informative References  . . . . . . . . . . . . . . . . .  17
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  18

1.  Introduction

1.1.  Overview

   This document defines to support the autoconfiguration of Autonomic
   Control Plane (ACP, [RFC8994]) nodes for fundamental decentralized
   network services via DNS-SD GRASP, utilizing a new proposal mapping
   of DNS-SD ([RFC6763]) onto GRASP as its hop-by-hop multicast
   transport and encoding of messages.

   One key purpose of this autoconfiguration is the seamless step from
   zero-touch bootstrap in ANI devices over to a securely remotely
   manageable ACP node.

   Bootstrapping ANI devices via BRSKI into a running ACP can be seen as
   so-called "Day-0" bootstrap.  If devices do not have BRSKI, then this
   "Day-0" may include pre-staging of devices with the required ACP

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   domain credentials.  The mechanisms described in this document then
   start with what maybe could be called "Day-1" bootstrap: Auto-
   configuring the required functions for remote, secure access to ANI/
   ACP devices.

   The services identified to be required for "Day-1" start with
   bootstrapping NTP clock synchronization across ACP/ANI nodes
   sufficient to validate certificates used across the ACP,
   establishment of user/role based authentication via Radius or
   diameter, autoconfiguration of the required remote-access methods to
   remotely access ACP/ANI nodes, SSH and NetConf with user/role based
   authentication.  Last, but not least, in the absence of better
   registration mechanisms, syslog, which is also proposed to be
   autoconfigured via the mechanisms of this document can also serve as
   a "Day-1" mechanism to inform other sysems about the status of ACP/
   ANI devices.

   All autoconfiguration provided for Day-1 stays valuable and continues
   to operate through the lifetime of the ANI/ACP devices, so called
   "Day-N" services.  This allows especially to change decentralized
   servers such as diameter/radius/NTP/syslog servers in case of
   failures, load-balancing or when moving devices to different
   locations in the network where better local server instances should
   be used.

   [RFC8368] was written on the simple assumption that all server
   instances for services described in this document, NTP, Radius/
   Diameter, Syslog and so on are located in a so called 'Network
   Operations Center'.  This was at the writing of [RFC8368] how this
   was done and called in various, mostly Enterprise networks, but is
   today not necessarily a good way to capture all possible deployment
   options.  For example, server instances can today with distributed
   Point of Presence (POP) and edge data-centers much easier
   decentralized for resilience, performance and cost.  Therefore, this
   document avoids limiting its applicability to just one "NOC"
   deployment option.

1.2.  ACP nodes supporting services autoconfiguration

   This document introduces the term ACPna nodes to indicate nodes
   supporting ACP that also support the requirements described in this
   document: ACP (n)oc (a)utoconfigurable.

   If an ACPna node supports zero-touch bootstrap of the ACP where no
   configuration is possible before the ACP is enabled, then the
   services autoconfiguration features described in this document SHOULD
   be enabled by default on such an ACPna node after this zero-touch
   bootstrap, because the autoconfiguration of these services can be the

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   only method for the ACPna node to become operationally accessible
   from OAM systems so that it can further be configured.  ANI nodes are
   nodes supporting ACP and BRSKI ([RFC8995]).  BRSKI bootstrap is an
   instance of such a zero-touch bootstrap requiring auto-enablement of
   autoconfiguration after zero-toch bootstrap.

   If an ACPna node was not zero-touch bootstrapped, then
   autoconfiguration SHOULD be enabled whenever ACP is enabled but may
   be separately configurable.

1.3.  Use of ACP GRASP for autoconfiguration

   Autoconfiguration of ACNna services utilizes the ACP instance of
   GRASP, ([RFC8990] as defined in [RFC8994].  It leverages and extends
   the GRASP objective definitions of [I-D.eckert-anima-grasp-dnssd].
   Thos objective elements allow to create DNS-SD compatible service
   announcements with flexible priority/weight and distance based
   selection across multiple service instances and per-service

   Nodes supporting a particular service announce it via the appropriate
   GRASP objective into ACP GRASP.  The nodes therefore need to have
   access to the ACP, either directly because they are ACP nodes or
   because they use the ACP connect function (see [RFC8994]).  ACPna
   nodes receive these announcements and auto-configure the services
   tied to them.  In most instances, the service announcement is from
   server that a client instance on the ACPna node connects to, for
   example a syslog server in the POP/NOC or other location with
   compute.  In another instance, the service is that of an
   authentication service and the ACPna nodes will enable a server
   instance that leverages the authentication service elsewhere in the

   Note: Currently, this document does not define the option of an mDNS/
   DNS-SD -> ACP GRASP gateway function to enable service nodes without
   GRASP implementations to utilize mDNS/DNS-SD to announce their
   services and then expect an appropriate translation function to
   convert these announcements into GRASP objectives.  This document
   does define all the GRASP objectives so that that it would be
   possible to define such a gateway function, but some loss of
   functionality would exist.  For once, GRASP does support network
   distance based service selection (e.g., select a server from the
   closest service node location), whereas no such mechanism exists in
   DNS-SD.  In addition, this documen believes that support of GRASP
   software to announce services from service systems is very easy to

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1.4.  GRASP parameters

   Unless otherwise described, all GRASP objective announcements
   described in this document SHOULD default to the following GRASP
   parameters.  These parameters MAY all be configurable on the service

   *  M_FLOOD GRASP message, periodicially sent once every 60 second.
      Random phase vs. full minutes (so different service announcements
      are distributed over time in the network).

   *  ttl of 210000 msec (3.5 times 60 seconds).

   *  locator-option is the ACP address of the announcing node unless
      the nnouncement is done from a third-party, for exmple if the
      announcing server does not support GRASP but GRASP is run on
      another service node.

   *  objective-name is 'SRV.<name>', where <name> is an [RFC6335]
      registered service name for the service in question.

   *  objective-flags is sync-only, loop-count is 255.

   *  objective-value MUST comply with the requirements of

        [M_FLOOD, 12340815, h'fd89b714f3db0000200000064000001', 210000,
            ["SRV.syslog", 4, 255,
                { rfcXXXX: {
                    &(sender-loop-count:1) => 255,
                    &(srv-element:2) => {
                        &(msg-type:1)  => &(describe: 0),
                        &(service:2)   => "syslog",
                        &(instance:3)  => "east-coast-primary",
                        &(priority:5)  => 0,
                        &(weight:6)    => 65535,
                        &(kvpairs:7)   => { "replicate" => 2 },
                        &(range:8)     => 2,
                } }
                 h'fd89b714f3db0000200000064000001', TLS12, 514]

                        Figure 1: SRV.syslog example

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   The above example shows the default values for a "syslog" service
   announcement using the objective-value elements defined in
   [I-D.eckert-anima-grasp-dnssd].  SRV.syslog is the standard objective
   name for the "syslog" service, as is SRV.<any> for the <any> service.
   The announcer of this objective also provides the syslog service as
   it is announcing its own address in the locator option.  It provides
   syslog on the standard syslog TCP port 514 using TLS12.

   The DNS-SD equivalent service attributes are carried in the srv-
   element.  The msg-type indicates that this objective is a service
   announcement.  The instance of "" indicates that this service
   annuncement for the ACP itself, and not for e.g. the data-plane.  It
   is shown here just for illustration purposes and can be left out in
   encoding because it is the default.  Likewise, the service element is
   redundant and shown only for illustrative purposes.  Priority and
   weight have the same semantic as in DNS-SD SRV records.  In this
   case, the service announcement indicates the highest priority (0) and
   the highest weight (65535).  Kvpairs includes service specific

   Going beyond the capabilities, the range parameter indicates that the
   client of this service should select this announced service not only
   by priority/weight but primarily by the distance in terms of network
   hop-count between this service announcer and the client: The client
   is expected to select the best service announcement by priority adn
   weight only between alternatives that are not more than two network
   hops apart in distance to the client.  Otherwise the client should
   pick the closer one.

   To allow the client to know the distance to a service announcement,
   the sender-loop-count parameter is included in the announcement.  It
   MUST be set by the sender to the same value (255 in this example) as
   the loop-count in the GRASP header.  The loop-count in the header is
   hop-by-hop reduced.  When the GRASP message arrives at the client,
   the difference between sender-loop-count and loop-count is the
   distance to the service announcer in hops.

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    ; Following GRASP header definitions from GRASP
    flood-message = [M_FLOOD, session-id, initiator, ttl,
                     +[objective, (locator-option / [])]]
    objective = ["SRV.<rfc6335-name>", objective-flags, loop-count,

    objective-flags = sync-only  ; as in GRASP spec
    sync-only       = 4          ; M_FLOOD only requires synchronization
    loop-count      = 255        ; recommended
    ; Following GRASP objective-value definitions from GRASP DNS-SD
    objective-value = { 1*elements }
    elements        = ( @rfcXXXX: { 1*relement } )
    relement      //= ( &(sender-loop-count:1) => 1..255 )
    relement      //= ( &(srv-element:2) => context-element )
    context-element  =  {
        ?( &(private:0)      => any),
        ?( &(msg-type:1      => msg-type),
        ?( &(service:2)      => tstr),
        *( &(instance:3)     => tstr),
        ?( &(domain:4)       => tstr),
        ?( &(priority:5)     => 0..65535 ),
        ?( &(weight:6)       => 0..65535 ),
        *( &(kvpairs:7)      => { *(tstr: any) },
        ?( &(range:8)        => 0..255 ),
        *( &(clocator:9)     => clocator),
    TLS12 = 257

                  Figure 2: GRASP service definition

   The above picture shows the complete CDDL defition of a GRASP M_FLOOD
   message indicating a service together with the objective-value
   encoding.  Som of the context-element options are not used in this
   document (TBD - remove before going RFC).

   The value 257 is defined to indicate TLS12 ([RFC5246]) to be used in
   the protocol field of GRASP locators to indicate that a TCP port is
   intended to be used with TLS version 1.2.  Values 1..255 are reserved
   for IP protocol numbers.

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2.  Services

2.1.  Syslog

   ACPna nodes SHOULD support autoconfiguring of syslog via the
   SRV.syslog objective.

   When an ACPna node discovers one or more SRV.syslog announcements
   across the ACP, it SHOULD perform syslog operations to the best
   available discovered server.

   Local configuration of syslog on the ACPna node SHOULD have no impact
   on the autoconfigured syslog operations, or else, misconfiguration
   could cause to failure of the autoconfigured syslog operations.
   Instead, configured syslog operations should just operate as ships-
   in-the-night to the GRASP learned autoconfigured syslog operations.

   Severity of syslog messages SHOULD be 5 (Notice) (see [RFC5424]), and
   all messages that are necessary to support normal remote operations
   of the node should be assigned severities higher (numerically lower)
   or equal to 5/Notice.

   Syslog service announcements SHOULD include the instance option,
   indicating the unique name of the service instance described by the
   GRASP objective.  This serves diagnostics and avoids having to
   identify service instances by the address(es) in the locator-options.
   In the example Figure 1, the instance name is "east-coast-primary".

   The syslog facility value is a choice of the ACPna node, the
   autoconfigured syslog server must be able to deal with any syslog
   facility code received.  If an ACPna node has no pre-established
   standard for the facility-code, then the value of local7 (23) MAY be

   For resilience, it may be appropriate to receive syslog messages on
   more than one server.  A server can indicate this via the "replicate"
   keyword in the GRASP objective-value kvpair element.  The value of
   the "replicate" keyword indicates the maximum number of syslog
   servers that the client SHOULD autoconfigure syslog to.  After
   selecting the best service announcement, the client looks up the
   value N of the "replicate" keyword of that best servers announcement
   and selects the best N-1 service announcements and ultimately logs to
   all N.  ACPna nodes SHOULD support autoconfigured syslog to up to 3
   servers simultaneously.

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   Autoconfigured syslog SHOULD support TLS1.2, TCP and UDP.  Because
   ACP provides encryption, use of just TCP instead of TLS should be
   sufficient and may achieve higher performance.  Use of UDP should be
   avoided because of the potential to loose packets and not supporting
   congestion control.

   If a syslog server supports more than one transport option (TLS1.2,
   TCP, UDP), it SHOULD announce them via a single GRASP objective and
   list them via clocator options of the srv-element because the
   locator-option in the GRASP header (as shown in example Figure 1)
   allows only one locator-option.  The order of the clocator options in
   the indicates the preference of the server.  From this list, the
   client supports the first option supported also by the client and
   ignore the others.  The context of the clocator would normally be "",
   indicating that the locator-option address is reachable via the ACP.

   Instead of (or in addition to) using multiple clocator options, a
   server can also announce multiple SRV.syslog objectives, but in that
   case each of them would be considered to be a different service
   instance considered by the the client when selecting the (set of)
   best service instances.  If a service announcement indicates via the
   "replicate" keyword that the client should log to three service
   instances, and announce three separate SRV.syslog objectives, each
   one with a different locator-option, then the client might select to
   log to all three of them - instead of - which is more likely the
   desired option - for the client to log to actually three different
   servers.  Hence the use of multiple clocator options that are
   examined by clients only after server selection is done.

   When a client uses TLS, it MUST use its ACP domain certificate for
   authentication.  Likewise, the syslog server MUSTS use its ACP domain

   Logging by default uses the ACP, in the clocator option, this is
   indicated via a context value of "".  Servers may also indicate
   support for logging across the data-plane, which may provide higher
   performance but may fail if reachability in the data-plane does not
   exist, so care must be taken when announcing this option.  For
   example, in managed MPLS/VPN networks where the ACP extends across P/
   PE and CE devices, the global routing table on a CE device is often
   not the same as that on P/PE devices, and therefore CE devices may
   not be able to log to "0".  In this case, the syslog server should
   instead announce a deployment choosen name for the context, such as
   "VRF0".  Clients would only take such a clocator into account if
   there is a local configuration that maps the context name to a
   routing table.  In this example, only P/PE nodes would have this
   configuration, therefore allowing the CE nodes to ignore this
   clocator; And if this clocator was the only locator-option in the

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   GRASP objective, then the whole objective MUST be ignored by the
   client when selecting the best possible service instance.  Note that
   for contexts other than the ACP (""), both IPv4 and IPv6 are
   possible, depending on what version(s) of IP are deployed in the

   Failure to connect to a choosen service instance SHOULD be taken into
   accounts by clients when selecting service instances to log to.  For
   UDP locator-options, ICMP/ICMPv6 error indications are such
   connection failures.  For TCP/TLS connections, connection failure
   includes TCP and TLS failures as well as keepalive failures.  When
   failures occur, clients should attempt to re-connect with exponential
   timeouts, starting with 5 seconds and staying at 320 seconds or until
   the GRASP service announcement expires and is not refreshed.

   When connecting to a server fails, the ACPna client SHOULD connect to
   the next best available server in the meantime.  ACPna client SHOULD
   support connecting to up to four service instances if any connections
   fail.  If for example the client is logging to two service instances
   because 2 is indicated in the "replicate" option of the service
   announcements, and one fails, the client will attempt to re-connect
   to it while in parallel establishing syslog connection to a third-
   best service-instance.

   When establishing connection to a new syslog service instance, ACPna
   clients SHOULD log with severity 5 an indication of this event,
   indicating its own ACP address, the ACP address and if existing
   instance name of the new syslog service instance and the reason.
   Like any other autoconfigured syslog message, this would go to all
   syslog connections and therefore show up on the redundant syslog
   servers, allowing to recognize failure of connectivity to another
   syslog server - and tracing of client logs across syslog servers if
   the client changes them.


   ACP: fd89:b714:f3db::0200:0000:6400:0042 start logging to:
   fd89:b714:f3db::0200:0000:6400:0001/east-coast-primary,TLS reason:
   starting up

   ACP: fd89:b714:f3db::0200:0000:6400:0042 start logging to:
   fd89:b714:f3db::0200:0000:6400:0001/east-coast-primary,TLS reason:
   new better service instance

   ACP: fd89:b714:f3db::0200:0000:6400:0042 stop logging to:
   fd89:b714:f3db::0200:0000:6400:0001/east-coast-secondary,TLS reason:
   connection failure

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   When failures to deliver syslog messages to ANY syslog servers
   happen, clients SHOULD track the this and indicate loss of messages
   via the next working syslog connection.  Note that due to the
   possibility of ICMP/ICMPv6 errors, only the successful delivery of
   messages via TLS or TCP should be tracked.  TBD: need to check if
   this can reasonably be recommended, pending on availability of e.g.
   TAPS API spec to know whethrer a TCP write was sent and acknowledged
   by the receiver (given how there are no reply messages in syslog).

2.2.  NTP

   Time synchronization is one of the most fundamental functionality for
   network devices for a variety of functions to work and also for
   diagnostics to be comparable across the network.  If problems
   propagate fast across the network, the client generated timestamp of
   events in syslog messages (or other diagnostics function) allows to
   trace event propagation and decude causality.  This may require
   network clock synchronization in the order of milliseconds, something
   which is easily achievable in todays network devices via NTP.

   ACPna nodes SHOULD support autoconfiguration of clock synchronization
   through NTP ([RFC5905]) with the following autoconfiguration

   The GRASP objective for NTP is SRV.ntp.  This does not distinguish
   between NTPv4 and NTPv3 because NTPv4 is fully backward compatible
   with NTPv3, so server and client will negotiate between these two

   The kvpair key "stratum" has a numeric value and indicates the
   stratum or level of a server in a synchronization tree.  The value of
   1 indicates the root of the distribution tree.  Servers that
   synchronize from the master have a stratum of 2, and so on.

   The kvpair key "minpoll" indicates the lowest periodic polling that
   the client will perform against the server.  Announcing a large
   numeric value allows for a server to reduce the amount of NTP
   messages from clients, but slows down convergence time of
   clientsnumber of service instances that simultaneously bootstrap.

   The kvpair key "key" indicates the NTPv3 authentication mechanism.
   When present, clients MUST use the value as the key to perform NTPv3
   (MD5) hash authentication of message with this service instance.
   Note that the encryption of the ACP serves as protection of
   distributing such a cleartext symmetric key via GRASP to clients.

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   TBD: Understand NTPv4 autokey and define appropriate kvpair to enable
   auto-configuring it, especially when the service instance
   announcement indicates the use of the data-plane.

   The autoconfiguration described in the following paragraphs is for
   leafs of the clock distribution graph, e.g., nodes that do only aim
   to obtain synchronized time from a server.  Configuration of the
   server hierarchy is left to explicit configuration.

   Clients SHOULD select service instance(s) with the worst (highest)
   stratum value.  In the face of multiple equal options, clients have
   to pick the best ones based on the standard selection criteria
   priority/weight and range, allowing for distributed NTP server
   deployment by e.e., setting range to 1, or via centralized deployment
   with multiple servers, setting range to 255 and priority/weight
   accordingly.  Making the stratum the primary selection criteria
   allows in the future to also introduce autoconfiguration of servers
   in the NTP clock distribution tree without incurring the problem that
   a large number of clients would then select higher stratum servers
   (and overload them).

   Like most other autoconfigured services, the autoconfigured NTP time
   synchronization SHOULD take precedence over explicit configured NTP
   options to ensure that time synchronization is not subject to
   misconfiguration of individual nodes (but only subject to
   misconfiguration of servers).

   The kvpair "TZ" option allows to signal the time zone of the ACP
   network to clients.  Its value is a string indicating the time zone
   of all nodes in the ACP network.  Care must be taken not to use this
   option in networks extending across multiple time zones.  Because
   time zone distribution does not work automatically across larger
   networks with multiple time zones, overriding the signalled time zone
   SHOULD be possible through local configuration.

   TBD: references for time zone spec standards and also for DST rule

2.3.  DNS for operations

   Availability of DNS names for network operations/troubleshooting is
   today mostly an convenience in network operations, but with IPv6
   evolving the need to use DNS names even in CLI based network
   diagnostics is raising - because IPv6 addresses often are more
   difficult to memorize by operators.  More and more network features
   also support configurtion that instead of addresses include domain
   names or URLs, and ultimately, any non-fully autoconfigured functions
   should rather rely on domain-names and URLs instead of just addresses

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   for greater flexibility and relilability in the face of address

   In thw face of this, ACPna nodes SHOULD support autoconfiguration of
   DNS for operational purposes.  "For operation purposes" implies that
   the use of of the autoconfigured DNS servers SHOULD NOT be used for
   DNS services offered to users of the data plane, such as DNS proxy
   services.  This would cause the ACP to effectively carry user
   traffic, whenever a client DNS request to an ACPna node with a DNS
   proxy would be forwrded to an autoconfigured server via the ACP.

   The GRASP objective name for such OAM use of DNS is OAM-DNS.  It is
   explicitly not SRV.dns to highlight that this instance of DNS is
   coped for operational purposes only to isolate it from user issues
   (performance across the ACP and attacks).  Utilizing different DNS
   contexts also allows to set up split-horizon DNS where all the
   operationally relevant DNS names are only made available via the DNS
   servers or zones available across the ACP.

   The value of the "search-list" kvpair option is a ";" (semicolon)
   separated list of domain name prefixes that should be searched by the
   client for non-FQDN that they need to resolve. "local-arpa" is the
   prefix to use for reverse IPv4/IPv6 address lookups.  If for example
   "local-arpa" is set to "", then the clients should
   first look up IPv4/IPv6 addresses in ""/"in-" before resorting to lookup in the Internet
   global ""/"".  For RFC1918/ULA addresses, no
   fallback to the global reverse lookup prefixes should be done.

   ACPna nodes SHOULD look up their name via a reverse lookup of their
   ACP address, and then auto-configure this name.

   There are no service specifics for the selection of DNS servers.  A
   ACPna node simply uses the standard priority/weight/range options to
   select a DNS server.  It MAY prefer a server with TCP locator-option
   simply because that allows in most cases faster discovery of
   connectivity problems than a UDP connection.

   TBD: Note that it is fairly easy to re-use the autoconfiguration
   scheme described here to provide auto-configuration of DNS for user
   DNS services with the help of the ACP.  The objective name would have
   to be changed and the clocators would have to indicate a data-plane
   context, so that user requests are carried across the data-plane from
   DNS proxies to DNS servers.  It is unclear if this service should be
   described in this document though.

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2.4.  Radius

   Radius [RFC2865] is a protocol used for AAA service - Authentication,
   Authorization and Accounting.  Autodiscovery of Radius servers across
   the ACP for ACPna nodes serves the purpose to enable authentication
   and authorization of other ACPna autoconfigured services such as
   below described Section 2.6.

   ACPna nodes MUST support Radius and/or Diameter autoconfiguration if
   they support any of the autoconfigured services depending on such an
   authentication service.

   The GRASP objective naem is SRV.radius.  The UDP or TCP port of the
   locator-option in the GRASP header or the clocator option indicate
   the UDP or TCP port of the Radius servers authentication connection.
   The context of a clocator MUST be "" to indicate the ACP - because
   the Radius connections MUST pass across the ACP to be protected
   against eavesdropping - and the radius security methods described
   here are not sufficiently secure to allow passing them across the

   The kvpair "secret_key" string value indicates the secret key to use
   on the connection to the Radius server.  The optional "acct_port"
   numeric value indicate the UDP/TCP port of any accounting connection
   supported by the radius server.  The protocol (UDP vs. TCP) is the
   same as the one in the choosen locator-option/clocator.

   There are no service specific selection rules.  TCP is preferred for
   faster recognition of a failed server and reselection of an
   alternative server.

   The specific data/authentication/authorization configuration required
   on the Radius server depends on the OAM service authenticated/
   authorized and is described in its section in this document.

   TBD: Should we define AVpair or different objective names to
   distinguish what services canb e authenticated ? Would be easier if
   we found another service than SSH/Netconf.

2.5.  Diameter

   TBD.  Alternative to Radius.  Author would welcome suggesting what
   parameters are relevant for a diameter authentication service.

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2.6.  SSH server

   ACPna nodes supporting SSH server functionality for remote management
   access via CLI, NETCONF or other methods SHOULD auto-enable SSH
   server functionality across the ACP whenever they are aware from ACP
   GRASP of RADIUS (Section 2.4) or DIAMETER (Section 2.5)
   authentication servers.  ACPna nodes that support ACPna SSH server
   functionality MUST support authentication via either RADIUS and/or

   If both protocols are supported by the ACPna node, the ACPna node
   SHOULD select the authentication server based on the service priority
   parameters across both protocols.  E.g., if a RADIUS server has a
   higher priority in GRASP than the DIAMETER server, the ACPna node
   should authenticate against the RADIUS server.

   When valid authentication server(s) are discovered, the SSH server is
   autoconfigured.  It SHOULD only listen to the standard SSH port with
   the ACP address of the node but not be reachable from the data-plane.
   It MUST NOT be modifyable by configuration (only by auto-
   configuration).  If autoconfiguration of an SSH server on the
   standard SSH port conflicts with explicitly configured SSH server for
   the data-plane due to software limitations or complexity, the
   autoconfigured SSH server MAY be started on a node-type specific and
   not dynamically selected port number.  This port number must be well-
   known to OAM operations as there is no method provided to signal it
   to the SSH client side.

   Note that this document does not define any standards for the exact
   message options for authentication or authorization.  Especially
   authorization, such as privilege level that permits to change
   configuration is likely using vendor specific methods, and Radius/
   Diameter servers must be capable to recognize the type of client as
   they had to without this autoconfiguration.

3.  Security Considerations

   There is no protection against "unauthorized" ACP nodes to generate
   service announcements, because there is no authorization scheme in
   GRASP.  Discovery of unauthorized announcers is easy though because
   the service announcements are flooded across the ACP and are
   therefore easily visible on nodes that may specifically oberve
   announcements to discover unauthorized ones.

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   A possible framework to define authorization could rely on defining
   roles for ACP nodes either through additional parameters in thei ACP
   domain certificate or following initial provisioning, and then lock
   down the ability for later configuration to enable services (and
   their GRASP announcements) to only those included in the role
   assigned to the node.  This is outside the scope of this document.

4.  Acknowledgments

   Thanks to Ignas Bagdonas for deployment / applicability / terminology
   input and to Balaji BL, Ravi Kumar Vadapalli for their original
   implementation of the concept.

5.  Change log [RFC Editor: Please remove]


      01: Refresh.

      00: Renaming from 'noc-autoconfig' after a long discussion with
      Ignas Bagdonas: replaced all mention of NOC with "infrastructure /
      decentralized" services, because the term NOC seems to be a
      terminology that does not well match how it is called in many type
      of networks.

   draft-eckert-anima-noc-autoconfig (2018)

      00: Initial version.

6.  References

6.1.  Normative References

              Eckert, T., Boucadair, M., Jacquenet, C., and M. H.
              Behringer, "DNS-SD Compatible Service Discovery in GeneRic
              Autonomic Signaling Protocol (GRASP)", Work in Progress,
              Internet-Draft, draft-eckert-anima-grasp-dnssd-02, 12 July
              2021, <

   [RFC2865]  Rigney, C., Willens, S., Rubens, A., and W. Simpson,
              "Remote Authentication Dial In User Service (RADIUS)",
              RFC 2865, DOI 10.17487/RFC2865, June 2000,

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   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246,
              DOI 10.17487/RFC5246, August 2008,

   [RFC5424]  Gerhards, R., "The Syslog Protocol", RFC 5424,
              DOI 10.17487/RFC5424, March 2009,

   [RFC5905]  Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,
              "Network Time Protocol Version 4: Protocol and Algorithms
              Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010,

   [RFC6335]  Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S.
              Cheshire, "Internet Assigned Numbers Authority (IANA)
              Procedures for the Management of the Service Name and
              Transport Protocol Port Number Registry", BCP 165,
              RFC 6335, DOI 10.17487/RFC6335, August 2011,

   [RFC6763]  Cheshire, S. and M. Krochmal, "DNS-Based Service
              Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013,

   [RFC8368]  Eckert, T., Ed. and M. Behringer, "Using an Autonomic
              Control Plane for Stable Connectivity of Network
              Operations, Administration, and Maintenance (OAM)",
              RFC 8368, DOI 10.17487/RFC8368, May 2018,

   [RFC8990]  Bormann, C., Carpenter, B., Ed., and B. Liu, Ed., "GeneRic
              Autonomic Signaling Protocol (GRASP)", RFC 8990,
              DOI 10.17487/RFC8990, May 2021,

   [RFC8994]  Eckert, T., Ed., Behringer, M., Ed., and S. Bjarnason, "An
              Autonomic Control Plane (ACP)", RFC 8994,
              DOI 10.17487/RFC8994, May 2021,

6.2.  Informative References

   [RFC8995]  Pritikin, M., Richardson, M., Eckert, T., Behringer, M.,
              and K. Watsen, "Bootstrapping Remote Secure Key
              Infrastructure (BRSKI)", RFC 8995, DOI 10.17487/RFC8995,
              May 2021, <>.

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Authors' Addresses

   Toerless Eckert
   Futurewei Technologies USA Inc.
   2220 Central Expressway
   Santa Clara,  95050
   United States of America

   Mohamed Boucadair
   35000 Rennes

   Christian Jacquenet

   Michael H. Behringer

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