RTGWG X. Ding Internet-Draft F. Zheng Intended status: Standards Track Huawei Expires: February 25, 2019 R. Wilton Cisco Systems August 24, 2018 YANG Data Model for ARP draft-ietf-rtgwg-arp-yang-model-00 Abstract This document defines a YANG data model to describe Address Resolution Protocol (ARP) configurations. The data model performs as a guideline for configuring ARP capabilities on a system. It is intended this model be used by service providers who manipulate devices from different vendors in a standard way. 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 February 25, 2019. 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 Ding, et al. Expires February 25, 2019 [Page 1] Internet-Draft ARP YANG model August 2018 the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2 1.2. Tree Diagrams . . . . . . . . . . . . . . . . . . . . . . 3 2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3 3. Design of the Data Model . . . . . . . . . . . . . . . . . . 4 3.1. ARP Caching . . . . . . . . . . . . . . . . . . . . . . . 4 3.2. proxy ARP . . . . . . . . . . . . . . . . . . . . . . . . 4 3.3. gratuitous ARP . . . . . . . . . . . . . . . . . . . . . 4 3.4. ietf-arp Module . . . . . . . . . . . . . . . . . . . . . 5 4. ARP YANG Module . . . . . . . . . . . . . . . . . . . . . . . 5 5. Data Model Examples . . . . . . . . . . . . . . . . . . . . . 12 5.1. Static ARP Entries . . . . . . . . . . . . . . . . . . . 12 5.2. ARP Dynamic Learning . . . . . . . . . . . . . . . . . . 12 6. Security Considerations . . . . . . . . . . . . . . . . . . . 13 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 14 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 8.1. Normative References . . . . . . . . . . . . . . . . . . 14 8.2. Informative References . . . . . . . . . . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 1. Introduction This document defines a YANG [RFC7950] data model for Address Resolution Protocol [RFC826] implementation and identification of some common properties within a device. Devices have common properties that need to be configured and monitored in a standard way. This document is intended to present universal ARP protocol configuration and many vendors can implement it. The data model convers configuration of system parameters of ARP, such as static ARP entries, timeout for dynamic ARP entries, interface ARP, proxy ARP, and so on. It also provides information about running state of ARP implementations. 1.1. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14, [RFC2119]. The following terms are defined in [RFC6241] and are not redefined here: Ding, et al. Expires February 25, 2019 [Page 2] Internet-Draft ARP YANG model August 2018 o client o configuration data o server o state data 1.2. Tree Diagrams A simplified graphical representation of the data model is presented in Section 3. o Brackets "[" and "]" enclose list keys. o Abbreviations before data node names: "rw" means configuration (read-write) and "ro" state data (read-only). o Symbols after data node names: "?" means an optional node, "!" means a presence container, and "*" denotes a list and leaf-list. o Parentheses enclose choice and case nodes, and case nodes are also marked with a colon (":"). o Ellipsis ("...") stands for contents of subtrees that are not shown. Tree diagrams used in this document use the notation defined in [RFC8340]. 2. Problem Statement This document defines a YANG [RFC7950] configuration data model that may be used to configure the ARP feature running on a system. Data model "ietf-ip" [I-D.ietf-netmod-rfc7277bis] covers the address mapping functionality. However, this functionality is strictly dependent on IPv4 networks, and many ARP related functionalities are missing, e.g. device global ARP entries and control, configuration related to dynamic ARP learning, proxy ARP, gratuitous ARP, etc. The data model makes use of the YANG "feature" construct which allows implementations to support only those ARP features that lie within their capabilities. It is intended this model be used by service providers who manipulate devices from different vendors in a standard way. Ding, et al. Expires February 25, 2019 [Page 3] Internet-Draft ARP YANG model August 2018 This model can be used to configure the ARP applications for discovering the link layer address associated with a given Internet layer address. 3. Design of the Data Model This data model intends to describe the processing that a protocol finds the hardware address, also known as Media Access Control (MAC) address, of a host from its known IP address. These tasks include, but are not limited to, adding a static entry in the ARP cache, configuring dynamic ARP learning, proxy ARP, gratuitous ARP. There are two kind of ARP configurations: global ARP configuration, which is across all interfaces on the device, and per interface ARP configuration. 3.1. ARP Caching ARP caching is the method of storing network addresses and the associated data-link addresses in memory for a period of time as the addresses are learned. This minimizes the use of valuable network resources to broadcast for the same address each time a datagram is sent. There are static ARP cache entries and dynamic ARP cache entries. Static entries are manually configured and kept in the cache table on a permanent basis. Dynamic entries are added by vendor software, kept for a period of time, and then removed. We can specify how long an entry remains in the ARP cache. If we specify a timeout of 0 seconds, entries are never cleared from the ARP cache. 3.2. proxy ARP Proxy ARP [RFC1027] can be configured to enable the switch to respond to ARP queries for network addresses by offering its own Ethernet media access control (MAC) address. With proxy ARP enabled, the switch captures and routes traffic to the intended destination. 3.3. gratuitous ARP Gratuitous ARP requests help detect duplicate IP addresses. A gratuitous ARP is a broadcast request for a router's own IP address. If a router or switch sends an ARP request for its own IP address and no ARP replies are received, the router- or switch-assigned IP address is not being used by other nodes. However, if a router or switch sends an ARP request for its own IP address and an ARP reply is received, the router- or switch-assigned IP address is already being used by another node. Ding, et al. Expires February 25, 2019 [Page 4] Internet-Draft ARP YANG model August 2018 3.4. ietf-arp Module This module has one top level container, ARP, which consists of two second level containers, which are used for static entries configuration and global parameters control. module: ietf-arp +--rw arp +--rw global-static-entries {global-static-entries}? | +--rw static-entry* [ip-address] | +--rw ip-address inet:ipv4-address-no-zone | +--rw mac-address yang:mac-address +--rw global-control +--rw enable-learning? boolean +--rw enable-proxy? boolean augment /if:interfaces/if:interface: +--rw arp-dynamic-learning +--rw expire-time? uint32 +--rw learn-disable? boolean +--rw proxy | +--rw mode enumeration +--rw probe | +--rw interval? uint8 | +--rw times? uint8 | +--rw unicast? boolean +--rw gratuitous | +--rw gratuitous-enable? boolean | +--rw interval? uint32 | +--rw drop? boolean +--ro statistics +--ro in-requests-pkts? uint16 +--ro in-replies-pkts? uint16 +--ro in-gratuitous-pkts? uint16 +--ro out-requests-pkts? uint16 +--ro out-replies-pkts? uint16 +--ro out-gratuitous-pkts? uint16 augment /if:interfaces/if:interface/ip:ipv4/ip:neighbor: +--ro remaining-expire-time? uint32 4. ARP YANG Module This section presents the ARP YANG module defined in this document. This YANG module imports typedefs from [RFC6991]. file "ietf-arp@2018-01-27.yang" module ietf-arp { Ding, et al. Expires February 25, 2019 [Page 5] Internet-Draft ARP YANG model August 2018 yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-arp"; prefix arp; import ietf-inet-types { prefix inet; reference "RFC 6991: INET Types Model"; } import ietf-yang-types { prefix yang; reference "RFC 6991: yang Types Model"; } import ietf-interfaces { prefix if; description "A Network Management Datastore Architecture (NMDA) compatible version of the ietf-interfaces module is required."; } import ietf-ip { prefix ip; description "A Network Management Datastore Architecture (NMDA) compatible version of the ietf-ip module is required."; } organization "IETF Routing Area Working Group (rtgwg)"; contact "WG Web: WG List: Editor: Xiaojian Ding dingxiaojian1@huawei.com Editor: Feng Zheng habby.zheng@huawei.com Editor: Robert Wilton rwilton@cisco.com"; description "Address Resolution Protocol (ARP) management, which includes static ARP configuration, dynamic ARP learning, ARP entry query, and packet statistics collection."; revision 2018-01-27 { description "Init revision"; Ding, et al. Expires February 25, 2019 [Page 6] Internet-Draft ARP YANG model August 2018 NOTE TO RFC EDITOR: Please replace the following reference to draft-ding-rtgwg-arp-yang-model-02 with RFC number when published (i.e. RFC xxxx). reference "draft-ding-rtgwg-arp-yang-model-02"; } /* * Features */ feature global-static-entries { description "This feature indicates that the device allows static entries to be configured globally."; } container arp { description "Address Resolution Protocol (ARP) management, which includes static ARP configuration, dynamic ARP learning, ARP entry query, and packet statistics collection."; container global-static-entries { if-feature "global-static-entries"; description "Set a global static ARP entry, which is independent of the interface."; list static-entry { key "ip-address"; description "List of ARP static entries that can be configured globally."; leaf ip-address { type inet:ipv4-address-no-zone; description "IP address, in dotted decimal notation."; } leaf mac-address { type yang:mac-address; mandatory true; description "MAC address in the format of H-H-H, in which H is a hexadecimal number of 1 to 4 bits."; } } } Ding, et al. Expires February 25, 2019 [Page 7] Internet-Draft ARP YANG model August 2018 container global-control { description "Set global control parameters, which are independent of interface."; leaf enable-learning { type boolean; default "true"; description "Enables or disables global dynamic ARP learning. If 'true', then enforcement is enabled. If 'false', then enforcement is disabled."; } leaf enable-proxy { type boolean; default "true"; description "Enables or disables global proxy. If 'true', then proxy is enabled. If 'false', then proxy is disabled."; } } augment "/if:interfaces/if:interface" { description "Augment interface configuration with parameters of ARP."; container arp-dynamic-learning { description "Support for ARP configuration on interfaces."; leaf expire-time { type timeticks { range "60..86400"; } units "second"; description "Aging time of a dynamic ARP entry."; } leaf learn-disable { type boolean; default "false"; description "Whether dynamic ARP learning is disabled on an interface. If the value is True, dynamic ARP learning is disabled. If the value is False, dynamic ARP learning is enabled."; } container proxy { description "Configuration parameters for proxy ARP"; leaf mode { Ding, et al. Expires February 25, 2019 [Page 8] Internet-Draft ARP YANG model August 2018 type enumeration { enum DISABLE { description "The system should not respond to ARP requests that do not specify an IP address configured on the local subinterface as the target address."; } enum REMOTE_ONLY { description "The system responds to ARP requests only when the sender and target IP addresses are in different subnets."; } enum ALL { description "The system responds to ARP requests where the sender and target IP addresses are in different subnets, as well as those where they are in the same subnet."; } } default "DISABLE"; description "When set to a value other than DISABLE, the local system should respond to ARP requests that are for target addresses other than those that are configured on the local subinterface using its own MAC address as the target hardware address. If the REMOTE_ONLY value is specified, replies are only sent when the target address falls outside the locally configured subnets on the interface, whereas with the ALL value, all requests, regardless of their target address are replied to."; reference "RFC1027: Using ARP to Implement Transparent Subnet Gateways"; } } container probe { description "Common configuration parameters for all ARP probe."; leaf interval { type uint8 { range "1..5"; } units "second"; description "Interval for detecting dynamic ARP entries."; } leaf times { type uint8 { range "0..10"; Ding, et al. Expires February 25, 2019 [Page 9] Internet-Draft ARP YANG model August 2018 } description "Number of aging probe attempts for a dynamic ARP entry. If a device does not receive an ARP reply message after the number of aging probe attempts reaches a specified number,thedynamic ARP entry is deleted."; } leaf unicast { type boolean; default "false"; description "Send unicast ARP aging probe messages for a dynamic ARP entry."; } } container gratuitous { description "Configure gratuitous ARP."; leaf enable { type boolean; default "false"; description "Enable or disable sending gratuitous-arp packet on interface."; } leaf interval { type uint32 { range "1..86400"; } units "second"; description "The interval of sending gratuitous-arp packet on the interface."; } leaf drop { type boolean; default "false"; description "Drop the receipt of gratuitous ARP packets on the interface."; } } container statistics { config false; description "IP ARP Statistics information on interfaces"; leaf in-requests-pkts { Ding, et al. Expires February 25, 2019 [Page 10] Internet-Draft ARP YANG model August 2018 type uint16; description "Total ARP requests received"; } leaf in-replies-pkts { type uint16; description "Total ARP replies received"; } leaf in-gratuitous-pkts { type uint16; description "Total gratuitous ARP received"; } leaf out-requests-pkts { type uint16; description "Total ARP requests sent"; } leaf out-replies-pkts { type uint16; description "Total ARP replies sent"; } leaf out-gratuitous-pkts { type uint16; description "Total gratuitous ARP sent"; } } } } augment "/if:interfaces/if:interface/ip:ipv4/ip:neighbor" { description "Augment neighbor list with parameters of ARP, eg., support for remaining expire time query on interfaces."; leaf remaining-expire-time { type uint32; config false; description "Remaining expire time of a dynamic ARP entry. "; } } } } Ding, et al. Expires February 25, 2019 [Page 11] Internet-Draft ARP YANG model August 2018 5. Data Model Examples This section presents a simple but complete example of configuring static ARP entries and dynamic learning, based on the YANG modules specified in Section 4. 5.1. Static ARP Entries Requirement: Enable static ARP entry global configuration (not rely on interface). 10.2.2.3 00e0-fc01-0000 Requirement: Enable static ARP entry configuration on interface (defined in draft [I-D.ietf-netmod-rfc7277bis]). 10.2.2.3 00e0-fc01-0000 GE1/0/1 5.2. ARP Dynamic Learning Ding, et al. Expires February 25, 2019 [Page 12] Internet-Draft ARP YANG model August 2018 Requirement: Enable ARP dynamic learning configuration. GE1/0/1 1200 false false 5 3 false false 60 false 6. Security Considerations The YANG module defined in this document is designed to be accessed via YANG based management protocols, such as NETCONF [RFC6241] and RESTCONF [RFC8040]. Both of these protocols have mandatory-to- implement secure transport layers (e.g., SSH, TLS) with mutual authentication. The NETCONF access control model (NACM) [RFC6536] provides the means to restrict access for particular users to a pre-configured subset of all available protocol operations and content. These are the subtrees and data nodes and their sensitivity/ vulnerability: There are a number of data nodes defined in this YANG module that are writable/creatable/deletable (i.e., config true, which is the default). These data nodes may be considered sensitive or vulnerable in some network environments. Write operations (e.g., edit-config) to these data nodes without proper protection can have a negative effect on network operations. Ding, et al. Expires February 25, 2019 [Page 13] Internet-Draft ARP YANG model August 2018 7. Acknowledgments The authors wish to thank Alex Campbell and Reshad Rahman, Qin Wu, many others for their helpful comments. 8. References 8.1. Normative References [I-D.ietf-netmod-rfc7223bis] Bjorklund, M., "A YANG Data Model for Interface Management", draft-ietf-netmod-rfc7223bis-03 (work in progress), January 2018. [I-D.ietf-netmod-rfc7277bis] Bjorklund, M., "A YANG Data Model for IP Management", draft-ietf-netmod-rfc7277bis-03 (work in progress), January 2018. [RFC1027] Carl-Mitchell, S. and J. Quarterman, "Using ARP to implement transparent subnet gateways", RFC 1027, DOI 10.17487/RFC1027, October 1987, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, July 2013, . [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016, . 8.2. Informative References [RFC0826] Plummer, D., "An Ethernet Address Resolution Protocol: Or Converting Network Protocol Addresses to 48.bit Ethernet Address for Transmission on Ethernet Hardware", STD 37, RFC 826, DOI 10.17487/RFC0826, November 1982, . Ding, et al. Expires February 25, 2019 [Page 14] Internet-Draft ARP YANG model August 2018 [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, . [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, . [RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, . Authors' Addresses Xiaojian Ding Huawei 101 Software Avenue, Yuhua District Nanjing, Jiangsu 210012 China Email: dingxiaojian1@huawei.com Feng Zheng Huawei 101 Software Avenue, Yuhua District Nanjing, Jiangsu 210012 China Email: habby.zheng@huawei.com Robert Wilton Cisco Systems Email: rwilton@cisco.com Ding, et al. Expires February 25, 2019 [Page 15]