Babel routing protocol B. Stark Internet-Draft AT&T Intended status: Informational April 5, 2018 Expires: October 7, 2018 Babel Information Model draft-ietf-babel-information-model-02 Abstract This Babel Information Model can be used to create data models under various data modeling regimes (e.g., YANG). It allows a Babel implementation (via a management protocol such as netconf) to report on its current state and may allow some limited configuration of protocol constants. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on October 7, 2018. Copyright Notice Copyright (c) 2018 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Stark Expires October 7, 2018 [Page 1] Internet-Draft Babel Information Model April 2018 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 1.2. Notation . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. The Information Model . . . . . . . . . . . . . . . . . . . . 5 3.1. Definition of babel-information-obj . . . . . . . . . . . 5 3.2. Definition of babel-constants-obj . . . . . . . . . . . . 6 3.3. Definition of babel-interfaces-obj . . . . . . . . . . . 7 3.4. Definition of babel-neighbors-obj . . . . . . . . . . . . 8 3.5. Definition of babel-security-obj . . . . . . . . . . . . 9 3.6. Definition of babel-routes-obj . . . . . . . . . . . . . 10 4. Common Objects . . . . . . . . . . . . . . . . . . . . . . . 11 4.1. Definition of babel-credential-obj . . . . . . . . . . . 11 4.2. Definition of babel-log-obj . . . . . . . . . . . . . . . 11 5. Extending the Information Model . . . . . . . . . . . . . . . 11 6. Security Considerations . . . . . . . . . . . . . . . . . . . 12 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 9.1. Normative References . . . . . . . . . . . . . . . . . . 12 9.2. Informative References . . . . . . . . . . . . . . . . . 12 Appendix A. Open Issues . . . . . . . . . . . . . . . . . . . . 13 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 14 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 16 1. Introduction Babel is a loop-avoiding distance-vector routing protocol defined in draft-ietf-babel-rfc6126bis [rfc6126bis]. draft-babel-7298bis [BABEL-HMAC] defines a security mechanism that allows Babel messages to be cryptographically authenticated, and draft-babel-dtls [BABEL-DTLS] defines a security mechanism that allows Babel messages to encrypted. This document describes an information model for Babel (including implementations using one of these security mechanisms) that can be used to created management protocol data models (such as a netconf [RFC6241] YANG data model). Due to the simplicity of the Babel protocol and the fact that it is designed to be used in non-professionally administered environments (such as home networks), most of the information model is focused on reporting status of the Babel protocol, and very little of that is considered mandatory to implement (conditional on a management protocol with Babel support being implemented). Some parameters may be configurable; however, it is up to the Babel implementation whether to allow any of these to be configured within its implementation. Where the implementation does not allow Stark Expires October 7, 2018 [Page 2] Internet-Draft Babel Information Model April 2018 configuration of these parameters, it may still choose to expose them as read-only. The Information Model is presented using a hierarchical structure. This does not preclude a data model based on this Information Model from using a referential or other structure. 1.1. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. 1.2. Notation This document uses a programming language-like notation to define the properties of the objects of the information model. An optional property is enclosed by square brackets, [ ], and a list property is indicated by two numbers in angle brackets, , where m indicates the minimal number of values, and n is the maximum. The symbol * for n means no upper bound. The object definitions use base types that are defined as follows: base64 An opaque array of bytes. boolean A type representing a boolean value. counter A non-negative integer that monotonically increases. Counters may have discontinuities and they are not expected to persist across restarts. credentials An opaque type representing credentials needed by a cryptographic mechanism to secure communication. Data models must expand this opaque type as needed and required by the security protocols utilized. datetime A type representing a date and time using the Gregorian calendar. The datetime format MUST conform to RFC 3339 [RFC3339]. int A type representing signed or unsigned integer numbers. This information model does not define a precision nor does it make a distinction between signed and unsigned number ranges. This type is also used to represent enumerations. Stark Expires October 7, 2018 [Page 3] Internet-Draft Babel Information Model April 2018 ip-address A type representing an IP address. This type supports both IPv4 and IPv6 addresses. string A type representing a human-readable string consisting of a (possibly restricted) subset of Unicode and ISO/IEC 10646 [ISO.10646] characters. uri A type representing a Uniform Resource Identifier as defined in STD 66 [RFC3986]. 2. Overview The Information Model is hierarchically structured as follows: information object includes implementation version, router id, this node seqno, enable flag parameters constants object (exactly one per information object) includes UDP port and optional multicast and unicast groups parameters interfaces object includes interface reference, Hello seqno and intervals, update interval, link type, external cost parameters neighbors object includes neighbor IP address, Hello history, cost parameters security object (per interface) includes supported and enabled security mechanisms, self credentials (credential object), trusted credentials (credential object) security object (common to all interfaces) includes supported and enabled security mechanisms, self credentials (credential object), trusted credentials (credential object) routes object includes route prefix, source router, reference to advertising neighbor, metric, sequence number, whether route is feasible, whether route is selected Following is a list of the data elements that an implementation can choose to allow to be configurable: o enable/disable babel o Constant: UDP port o Constant: IPv6 multicast group Stark Expires October 7, 2018 [Page 4] Internet-Draft Babel Information Model April 2018 o Constant: IPv4 multicast group o Interface: Link type o Interface: External cost (must be configurable if implemented, but implementation is optional) o Interface: enable/disable babel on this interface o Interface: enable/disable message log o Security: self credentials o Security: trusted credentials o Security: enable/disable security log Note that this overview is intended simply to be informative and is not normative. If there is any discrepancy between this overview and the detailed information model definitions in subsequent sections, the error is in this overview. 3. The Information Model 3.1. Definition of babel-information-obj object { string babel-implementation-version; boolean babel-enable; base64 babel-self-router-id; string babel-supported-link-types<1..*>; [int babel-self-seqno;] string babel-metric-comp-algorithms<1..*>; babel-constants-obj babel-constants; babel-interfaces-obj babel-interfaces<0..*>; babel-routes-obj babel-routes<0..*>; [babel-security-obj babel-security;] }babel-information-obj; babel-implementation-version: the version of this implementation of the Babel protocol babel-enable: if true, the babel implementation is running; if false, the babel implementation is not currently running; MAY be configurable to allow babel to be started or stopped Stark Expires October 7, 2018 [Page 5] Internet-Draft Babel Information Model April 2018 babel-self-router-id: the router-id used by this instance of the Babel protocol to identify itself; draft-ietf-babel-rfc6126bis [rfc6126bis] describes this as an arbitrary string of 8 octets babel-supported-link-types: set of values of supported link types where the following enumeration values MUST be supported: 1 = wireless, 2 = physical-layer ethernet, 99 = other babel-self-seqno: the current sequence number included in route updates for routes originated by this node babel-metric-comp-algorithms: a set of names of supported cost computation algorithms; possible values include "k-out-of-j", "ETX" babel-constants: a babel-constants object babel-interfaces: a set of babel-interface objects babel-security: a babel-security object that applies to all interfaces; if this object is implemented, it allows a security mechanism to be enabled or disabled in a manner that applies to all Babel messages on all interfaces babel-sources: a set of babel-source objects babel-routes: a set of babel-route objects; includes received and routes routes 3.2. Definition of babel-constants-obj object { int babel-udp-port; [ip-address babel-mcast-group-ipv6;] [ip-address babel-mcast-group-ipv4;] }babel-constants-obj; babel-udp-port: UDP port for sending and listening for Babel messages; default is 6696; MAY be configurable babel-mcast-group-ipv6: multicast group for sending and listening to multicast announcements on IPv6; default is ff02:0:0:0:0:0:1:6; MAY be configurable babel-mcast-group-ipv4: multicast group for sending and listening to multicast announcements on IPv4; default is 224.0.0.111; MAY be configurable Stark Expires October 7, 2018 [Page 6] Internet-Draft Babel Information Model April 2018 3.3. Definition of babel-interfaces-obj object { string babel-interface-reference; [boolean babel-interface-enable;] int babel-link-type; [int babel-mcast-hello-seqno;] [int babel-ucast-hello-seqno;] [int babel-mcast-hello-interval;] [int babel-ucast-hello-interval;] [int babel-update-interval;] [int babel-external-cost;] [boolean babel-message-log-enable;] [babel-log-obj babel-message-log<0..*>;] babel-neighbors-obj babel-neighbors<1..*>; [babel-security-obj babel-interface-security;] }babel-interfaces-obj; babel-interface-reference: reference to an interface object as defined by the data model (e.g., YANG, BBF TR-181); data model is assumed to allow for referencing of interface objects which may be at any layer (physical, Ethernet MAC, IP, tunneled IP, etc.); referencing syntax will be specific to the data model; if there is no set of interface objects available, this should be a string that indicates the interface name used by the underlying operating system babel-interface-enable: if true, babel sends and receives messages on this interface; if false, babel messages received on this interface are ignored and none are sent; MAY be configurable babel-link-type: indicates the type of link; integer values specify an enumeration of a supported link type where the following enumerations MUST be supported: 1 = wireless, 2 = physical-layer ethernet, 99 = other; additional values MAY be supported; MAY be configurable babel-mcast-hello-seqno: the current sequence number in use for multicast hellos on this interface babel-ucast-hello-seqno: the current sequence number in use for unicast hellos on this interface babel-mcast-hello-interval: the current multicast hello interval in use for this interface babel-ucast-hello-interval: the current unicast hello interval in use for this interface Stark Expires October 7, 2018 [Page 7] Internet-Draft Babel Information Model April 2018 babel-update-interval: the current update interval in use for this interface babel-external-cost: external input to cost of link of this interface (need to determine how to express this);MUST be configurable if implemented babel-message-log-enable: if true, logging of babel messages received on this interface is enabled; if false, babel messages are not logged; MUST be configurable, if implemented babel-message-log: log entries that have timestamp of a received Babel message and the entire received Babel message, including Ethernet frame and IP headers; an implementation must restrict the size of this log, but how and what size is implementation-specific babel-neighbors: a set of babel-neighbors objects babel-interface-security: a babel-security object that applies to this interface; if implemented, this allows security to be enabled only on specific interfaces or allows different security mechanisms to be enabled on different interfaces 3.4. Definition of babel-neighbors-obj object { ip-address babel-neighbor-address; [string babel-hello-mcast-history;] [string babel-hello-ucast-history;] int babel-txcost; int babel-hello-seqno; int babel-neighbor-ihu-interval; [int babel-rxcost] [int babel-cost] }babel-neighbors-obj; babel-neighbor-address: (IPv4 or v6) address the neighbor sends messages from babel-hello-mcast-history: the multicast Hello history of whether or not each of the 16 multicast Hello messages prior to babel- hello-seqno was received; represented as a 16 bit (4 hex digits) value where 1 = Hello received and 0 = Hello not received; see draft-ietf-babel-rfc6126bis [rfc6126bis] section A.1 babel-hello-ucast-history: the unicast Hello history of whether or not each of the 16 unicast Hello messages prior to babel-hello- seqno was received; represented as a 16 bit (4 hex digits) value Stark Expires October 7, 2018 [Page 8] Internet-Draft Babel Information Model April 2018 where 1 = Hello received and 0 = Hello not received; see draft- ietf-babel-rfc6126bis [rfc6126bis] section A.1 babel-txcost: transmission cost value from the last IHU packet received from this neighbor, or maximum value (infinity) to indicates the IHU hold timer for this neighbor has expired babel-hello-seqno: expected Hello sequence number babel-neighbor-ihu-interval: current IHU interval for this neighbor babel-rxcost: reception cost calculated for this neighbor; this value is usually derived from the Hello history, which may be combined with other data, such as statistics maintained by the link layer; the rxcost is sent to a neighbour in each IHU babel-cost: link cost is computed from the values maintained in the neighbour table: the statistics kept in the neighbour table about the reception of Hellos, and the txcost computed from received IHU packets 3.5. Definition of babel-security-obj object { string babel-security-supported; string babel-security-enabled-protocol; babel-credential-obj babel-security-self-cred<1..*>; babel-credential-obj babel-security-trust<1..*>; [boolean babel-credvalid-log-enable;] [babel-log-obj babel-credvalid-log<0..*>;] }babel-security-obj; babel-security-supported: list of supported security mechanisms babel-security-enabled-protocol: the currently enabled security protocol; empty if none is enabled babel-security-self-cred: credentials this router presents to participate in the enabled security protocol; ; adding and deleting credentials MAY be allowed babel-security-trust: a set of babel-credential-obj objects that identify the credentials of routers whose babel messages may be trusted or of a certificate authority (CA) whose signing of a router's credentials implies the router credentials can be trusted; how a security mechanism interacts with this list is determined by the mechanism; a security algorithm may do Stark Expires October 7, 2018 [Page 9] Internet-Draft Babel Information Model April 2018 additional validation of credentials, such as checking validity dates or revocation lists, so presence may not be sufficient to determine trust; adding and deleting credentials MAY be allowed babel-credvalid-log-enable: if true, logging of messages that include credentials used for authentication is enabled; if false, these messages are not logged; MUST be configurable, if implemented babel-credvalid-log: log entries that have the timestamp a message containing credentials used for peer authentication (e.g., DTLS Server Hello) was received on a Babel port, and the entire received message (including Ethernet frame and IP headers); an implementation must restrict the size of this log, but how and what size is implementation-specific 3.6. Definition of babel-routes-obj object { ip-address babel-route-prefix; int babel-route-prefix-length; base64 babel-route-router-id; [int babel-route-metric;] [int babel-route-announced-metric;] int babel-route-seqno; ip-address babel-route-next-hop; boolean babel-route-feasible; boolean babel-route-selected; }babel-routes-obj; babel-route-prefix: Prefix (expressed in IP address format) for which this route is advertised babel-route-prefix-length: Length of the prefix for which this route is advertised babel-route-router-id: router-id of the source router for which this route is advertised babel-route-metric: the metric with which this route was advertised by the neighbor, or maximum value (infinity) to indicate a recently retracted route; this metric will be 0 (zero) if the route was not received from a neighbor but was generated through other means; either babel-route-announced-metric or babel- route-metric MUST be provided babel-route-announced-metric: a calculated metric for this route; how the metric is calculated is implementation-specific; either Stark Expires October 7, 2018 [Page 10] Internet-Draft Babel Information Model April 2018 babel-route-announced-metric or babel-route-metric MUST be provided babel-route-seqno: the sequence number with which this route was advertised babel-route-next-hop: the next-hop address of this route; this will be empty if this route has no next-hop address babel-route-feasible: a boolean flag indicating whether this route is known to work; a route that is not feasible will never be selected babel-route-selected: a boolean flag indicating whether this route is selected, i.e., whether it is currently being used for forwarding and is being advertised 4. Common Objects 4.1. Definition of babel-credential-obj object { credentials babel-cred; }babel-credential-obj; babel-cred: a credential, such as an X.509 certificate, a public key, etc. used for signing and/or encrypting babel messages 4.2. Definition of babel-log-obj object { datetime babel-log-time; string babel-log-entry; }babel-log-obj; babel-log-time: the date and time (according to the device internal clock setting, which may be a time relative to boot time, acquired from NTP, configured by the user, etc.) when this log entry was created babel-log-entry: the logged message, as a string of utf-8 encoded hex characters 5. Extending the Information Model Implementations MAY extend this information model with other parameters or objects. For example, an implementation MAY choose to expose babel route filtering rules by adding a route filtering object Stark Expires October 7, 2018 [Page 11] Internet-Draft Babel Information Model April 2018 with parameters appropriate to how route filtering is done in that implementation. The precises means used to extend the information model would be specific to the data model the implementation uses to expose this information. 6. Security Considerations This document defines a set of information model objects and parameters that may be exposed to be visible from other devices, and some of which may be configured. Any mechanism or protocol that is used to transmit this information or allow for its configuration is also responsible for ensuring this is done so in a secure manner. 7. IANA Considerations This document makes no IANA requests. 8. Acknowledgements Juliusz Chroboczek's review has been very helpful in refining this information model. The language in the Notation section was mostly taken from RFC 8193 [RFC8193]. 9. References 9.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [rfc6126bis] Chroboczek, J., "The Babel Routing Protocol", Work in Progress, draft-ietf-babel-rfc6126bis, October 2017. 9.2. Informative References [BABEL-DTLS] Schinazi, D., "TBD", Work in Progress, rfc6347, March 2018. [BABEL-HMAC] Ovsienko, D., "Babel HMAC Cryptographic Authentication", Work in Progress, draft-ovsienko-babel-rfc7298bis, March 2018. Stark Expires October 7, 2018 [Page 12] Internet-Draft Babel Information Model April 2018 [ISO.10646] International Organization for Standardization, "Information Technology - Universal Multiple-Octet Coded Character Set (UCS)", ISO Standard 10646:2014, 2014. [RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet: Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002, . [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, DOI 10.17487/RFC3986, January 2005, . [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., and A. Bierman, Ed., "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, . [RFC8193] Burbridge, T., Eardley, P., Bagnulo, M., and J. Schoenwaelder, "Information Model for Large-Scale Measurement Platforms (LMAPs)", RFC 8193, DOI 10.17487/RFC8193, August 2017, . Appendix A. Open Issues This draft must be reviewed against draft-ietf-babel-rfc6126bis. [I feel like this has been adequately done, but I could be wrong.] Following are some issues where a conscious decision may be useful: 1. babel-interfaces-obj: Juliusz:"This needs further discussion, I fear some of these are implementation details." [In the absence of discussion, the current model stands. Note that all but link-type and the neighbors sub-object are optional; if an implementation does not have any of the optional elements then it simply doesn't have them and that's fine.] 2. Would it be useful to define some parameters for reporting statistics or logs? [2 logs are now included. If others are needed they need to be proposed.] 3. Would it be useful to define some parameters specifically for security anomalies? [The 2 logs should be useful in identifying security anomalies. If more is needed, someone needs to propose.] Stark Expires October 7, 2018 [Page 13] Internet-Draft Babel Information Model April 2018 4. I created a basic security model. It's useful for single (or no) active security mechanism (e.g., just HMAC, just DTLS, or neither); but not multiple active (both HMAC and DTLS -- which is not the same as HMAC of DTLS and would just mean that HMAC would be used on all unencrypted messages -- but right now the model doesn't allow for configuring HMAC of unencrypted messages for routers without DTLS, while DTLS is used if possible). OK? 5. Do we need a registry for the supported security mechanisms? [Given the current limited set, and unlikelihood of massive expansion, I don't think so. But we can if someone wants it.] 6. babel-external-cost may need more work. [if no comment, it will be left as is] 7. babel-hello-[mu]cast-history: the Hello history is formated as 16 bits, per A.1 of 6126bis. Is that a too implementation specific? [We also now have an optional-to-implement log of received messages, and I made these optional. So maybe this is ok?] 8. rxcost, txcost, cost: is it ok to model as integers, since 6126bis 2.1 says costs and metrics need not be integers. [I have them as integers unless someone insists on something else.] 9. Should babel link types have an IANA registry? [Right now, none is defined.] 10. For the security log, should it also log whether the credentials were considered ok? [Right now it doesn't and I think that's ok because if you log Hellos it was ok and if you don't it wasn't.] Closed Issues: Closed by defining base64 type and using it for all router IDs: "babel-self-router-id: Should this be an opaque 64-bit value instead of int?" Appendix B. Change Log Individual Drafts: v00 2016-07-07 EBD Initial individual draft version v01 2017-03-13 Addressed comments received in 2016-07-15 email from J. Chroboczek Working group drafts: Stark Expires October 7, 2018 [Page 14] Internet-Draft Babel Information Model April 2018 v00 2017-07-03 Addressed points noted with "oops" in https://www.ietf.org/proceedings/98/slides/slides-98-babel-babel- information-model-00.pdf v01 2018-01-02 Removed item from issue list that was agreed (in Prague) not to be an issue. Added description of data types under Notation section, and used these in all data types. Added babel- security and babel-trust. v02 2018-mm-dd - changed babel-version description to babel-implementation- version - replace optional babel-interface-seqno with optional babel- mcast-hello-seqno and babel-ucast-hello-seqno - replace optional babel-interface-hello-interval with optional babel-mcast-hello-interval and babel-ucast-hello-interval - remove babel-request-trigger-ack - remove "babel-router-id: router-id of the neighbor"; note that parameter had previously been removed but description had accidentally not been removed - added an optional "babel-cost" field to babel-neighbors object, since the spec does not define how exactly the cost is computed from rxcost/txcost - deleted babel-source-garbage-collection-time - change babel-lossy-link to babel-link-type and make this an enumeration; added at top level babel-supported-link-types so which are supported by this implementation can be reported - changes to babel-security-obj to allow self credentials to be one or more instances of a credential object; allowed trusted credentials to include CA credentials; made some parameter name changes - updated references and Introduction - added Overview section - deleted babel-sources-obj Stark Expires October 7, 2018 [Page 15] Internet-Draft Babel Information Model April 2018 - added feasible Boolean to routes - added section to briefly describe extending the information model. - deleted babel-route-neighbor - tried to make definition of babel-interface-reference clearer - added security and message logs Author's Address Barbara Stark AT&T Atlanta, GA US Email: barbara.stark@att.com Stark Expires October 7, 2018 [Page 16]