RTGWG F. Zheng Internet-Draft B. Wu, Ed. Intended status: Standards Track Huawei Expires: 1 January 2025 R. Wilton, Ed. Cisco Systems F. Zhang, Ed. Y. Zhu China Telecom X. Ding 30 June 2024 A YANG Data Model for ARP draft-ietf-rtgwg-arp-yang-model-04 Abstract This document defines a YANG data model for the management of the Address Resolution Protocol (ARP). It extends the basic ARP functionality contained in the ietf-ip YANG data model, defined in RFC 8344, to provide management of optional ARP features and statistics. 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 1 January 2025. Copyright Notice Copyright (c) 2024 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. Zheng, et al. Expires 1 January 2025 [Page 1] Internet-Draft ARP YANG model June 2024 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 Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Tree Diagrams . . . . . . . . . . . . . . . . . . . . . . 4 2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 4 3. Design of the Data Model . . . . . . . . . . . . . . . . . . 4 3.1. ARP Dynamic Learning . . . . . . . . . . . . . . . . . . 4 3.2. Proxy ARP . . . . . . . . . . . . . . . . . . . . . . . . 5 3.3. Gratuitous ARP . . . . . . . . . . . . . . . . . . . . . 5 3.4. ARP Data Model . . . . . . . . . . . . . . . . . . . . . 5 4. ARP YANG Module . . . . . . . . . . . . . . . . . . . . . . . 6 5. Data Model Examples . . . . . . . . . . . . . . . . . . . . . 11 5.1. Configured static ARP Entry . . . . . . . . . . . . . . . 11 5.2. Configuration of proxy ARP and gratuitous ARP . . . . . . 12 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 7. Security Considerations . . . . . . . . . . . . . . . . . . . 14 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 15 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 15 9.1. Normative References . . . . . . . . . . . . . . . . . . 15 9.2. Informative References . . . . . . . . . . . . . . . . . 16 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 17 A.1. Configuration of a Static ARP Entry . . . . . . . . . . . 17 A.2. Configuration of Proxy ARP and Gratuitous ARP . . . . . . 17 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18 1. Introduction Basic ARP functionality is supported by the ietf-ip YANG data model, defined in [RFC8344]. This document defines a YANG [RFC7950] data model that extends the basic ARP YANG support to also cover optional ARP features, and ARP related statistics to aid network monitoring and troubleshooting. This model defines YANG configuration and operational state data nodes both for ARP related functionality formally specified in other RFCs (such as [RFC8344] and [RFC1027]), and also for common ARP behaviour that is often supported on network devices. The YANG modules in this document conform to the Network Management Datastore Architecture (NMDA) [RFC8342]. Zheng, et al. Expires 1 January 2025 [Page 2] Internet-Draft ARP YANG model June 2024 Editorial Note: (To be removed by RFC Editor) This draft contains several placeholder values that need to be replaced with finalized values at the time of publication. Please apply the following replacements: * "XXXX" --> the assigned RFC value for this draft both in this draft and in the YANG models under the revision statement. * The "revision" date in model, in the format XXXX-XX-XX, needs to be updated with the date the draft gets approved. The date also needs to get reflected on the line with . 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] [RFC8174] when, and only when, they appear in all capitals, as shown here. The following terms are defined in [RFC8342] and are not redefined here: * client * server * configuration data * system state * state data * intended configuration * running configuration datastore * operational state datastore The following terms are defined in [RFC7950] and are not redefined here: * augment * data model Zheng, et al. Expires 1 January 2025 [Page 3] Internet-Draft ARP YANG model June 2024 * data node The terminology for describing YANG data models is found in [RFC7950]. 1.2. Tree Diagrams Tree diagrams used in this document follow the notation defined in [RFC8340]. 2. Problem Statement Neither ARP [RFC0826] nor Proxy-ARP [RFC1027] defines standard network management configuration models. Instead, network equipment vendors have implemented their own bespoke configuration interfaces and models. Network operators benefit from having common network management models defined that can be implemented by multiple network equipment manufacturers. This simplifies the operation and management of network devices. Some, but not all, required ARP functionality has been defined in "ietf-ip" ([RFC8344]). Providing a standard YANG model that models these optional ARP features, which are fairly widely implemented by network equipment manufacturers, and used by network operators, is beneficial to the general goal of interoperability in the networking industry. 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, configuring dynamic ARP learning, proxy ARP, and gratuitous ARP. There are two kinds of ARP configurations: global ARP configuration, which is across all interfaces on the device, and per interface ARP configuration. 3.1. ARP Dynamic Learning As defined in [RFC0826], 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. Zheng, et al. Expires 1 January 2025 [Page 4] Internet-Draft ARP YANG model June 2024 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 which are defined in the ipv4 neighbor list for each interface in [RFC8344]. 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, defined in [RFC1027], allows a router to respond to ARP requests on behalf of another machine that is not on the same local subnet, offering its own Ethernet media access control (MAC) address. By replying in such a way, the router then takes responsibility for routing packets to the intended destination. In the case of certain data center network virtualization, as specified in [RFC8014], the proxy ARP can be extended to intercept all ARP requests, including source and target IP addresses in different subnets, and those ARP requests in the same subnet to suppress ARP handling. 3.3. Gratuitous ARP Gratuitous ARP enables a device to send an ARP Request packet using its own IP address as the destination address. Gratuitous ARP provides the following functions: * Checks duplicate IP addresses: [RFC5227] uses gratuitous ARP to help detect IP conflicts. When a device receives an ARP request containing a source IP that matches its own, then it knows there is an IP conflict. * Advertises a new MAC address: Also in [RFC5227], if the MAC address of a host changes because its network adapter is replaced, the host sends a gratuitous ARP packet to notify all hosts of the change before the ARP entry is aged out. * Notifies an active/standby switchover in a [RFC5798] VRRP backup group: After an active/standby switchover, the master router sends a gratuitous ARP packet in the VRRP backup group to notify the switchover. 3.4. ARP Data Model This document defines the YANG module "ietf-arp", which has the following structure: Zheng, et al. Expires 1 January 2025 [Page 5] Internet-Draft ARP YANG model June 2024 module: ietf-arp +--rw arp +--rw dynamic-learning? boolean augment /if:interfaces/if:interface/ip:ipv4: +--rw arp +--rw expiry-time? uint32 +--rw dynamic-learning? boolean +--rw proxy-arp | +--rw mode? enumeration +--rw gratuitous-arp | +--rw enable? boolean | +--rw interval? uint32 +--ro statistics +--ro in-requests-pkts? yang:counter32 +--ro in-replies-pkts? yang:counter32 +--ro in-gratuitous-pkts? yang:counter32 +--ro out-requests-pkts? yang:counter32 +--ro out-replies-pkts? yang:counter32 +--ro out-gratuitous-pkts? yang:counter32 augment /if:interfaces/if:interface/ip:ipv4/ip:neighbor: +--ro remaining-expiry-time? uint32 4. ARP YANG Module This section presents the ARP YANG module defined in this document. This module imports definitions from Common YANG Data Types [RFC6991], A YANG Data Model for Interface Management [RFC8343], and A YANG Data Model for IP Management [RFC8344]. file "ietf-arp@2024-06-30.yang" module ietf-arp { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-arp"; prefix arp; import ietf-yang-types { prefix yang; reference "RFC 6991: Common YANG Data Types"; } import ietf-interfaces { prefix if; reference "RFC 8343: A Yang Data Model for Interface Management"; } import ietf-ip { Zheng, et al. Expires 1 January 2025 [Page 6] Internet-Draft ARP YANG model June 2024 prefix ip; reference "RFC 8344: A Yang Data Model for IP Management"; } organization "IETF Routing Area Working Group (rtgwg)"; contact "WG Web: WG List: Author: Feng Zheng Editor: Bo Wu Editor: Robert Wilton Editor: Fan Zhang Author: Yongqing Zhu Author: Xiaojian Ding 5. Data Model Examples This section presents two simple ARP configuration examples: 5.1. Configured static ARP Entry This example illustrates the configuration for a static ARP entry for peer 192.0.2.1 with MAC address 00:00:5E:00:53:AB using the model defined in [RFC8344]. Zheng, et al. Expires 1 January 2025 [Page 11] Internet-Draft ARP YANG model June 2024 eth0 ianaift:ethernetCsmacd 192.0.2.1 00:00:5E:00:53:AB 5.2. Configuration of proxy ARP and gratuitous ARP This example illustrates the configuration of ARP entry expiry time, proxy ARP in 'remote-only' mode, and enabling gratuitous ARP with an interval of 10 minutes. Zheng, et al. Expires 1 January 2025 [Page 12] Internet-Draft ARP YANG model June 2024 eth0 ianaift:ethernetCsmacd 1200 remote-only true 600 6. IANA Considerations This document registers a URI in the IETF XML registry [RFC3688]. Following the format in [RFC3688], the following registration is requested to be made: URI: urn:ietf:params:xml:ns:yang:ietf-arp Registrant Contact: The RTGWG WG of the IETF. XML: N/A, the requested URI is an XML namespace. This document registers a YANG module in the YANG Module Names registry [RFC6020]. Name: ietf-arp Namespace: urn:ietf:params:xml:ns:yang:ietf-arp Prefix: arp Reference: RFC XXXX Zheng, et al. Expires 1 January 2025 [Page 13] Internet-Draft ARP YANG model June 2024 7. Security Considerations The YANG module specified in this document defines a schema for data that is designed to be accessed via network management protocols such as NETCONF [RFC6241] or RESTCONF [RFC8040] . The lowest NETCONF layer is the secure transport layer, and the mandatory-to-implement secure transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS [RFC8446]. The NETCONF Access Control Model (NACM) [RFC8341] provides the means to restrict access for particular NETCONF or RESTCONF users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content. 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) and delete operations to these data nodes without proper protection or authentication can have a negative effect on network operations.These are the subtrees and data nodes and their sensitivity/vulnerability in the "ietf-arp" module: * /ietf-arp/dynamic-learning This leaf is used to enable ARP dynamic learning on all interfaces. ARP dynamic learning could allow an attacker to inject spoofed traffic into the network, e.g. denial-of-service attack. * arp/dynamic-learning This leaf is used to enable ARP dynamic learning on a single interface. ARP dynamic learning could allow an attacker to inject spoofed traffic into the network, e.g. denial-of-service attack. * interface/ipv4/arp/proxy-arp These leaves are used to enable proxy ARP on an interface. They could allow traffic to be mis-configured (denial-of-service attack). * interface/ipv4/arp/gratuitous-arp Zheng, et al. Expires 1 January 2025 [Page 14] Internet-Draft ARP YANG model June 2024 These leaves are used to enable sending gratuitous ARP packet on an interface. This configuration could allow an attacker to inject spoofed traffic into the network, e.g. man-in-the-middle attack. The default value for this data node is device specific, and hence users of this model MUST understand whether or not gratutious ARP is enabled and whether this could constitute a security risk. 8. Acknowledgments The authors wish to thank Alex Campbell, Reshad Rahman, Qin Wu, Tom Petch, Jeffrey Haas, and others for their helpful comments. 9. References 9.1. Normative 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, . [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, . [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, . [RFC5227] Cheshire, S., "IPv4 Address Conflict Detection", RFC 5227, DOI 10.17487/RFC5227, July 2008, . [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, . [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011, . Zheng, et al. Expires 1 January 2025 [Page 15] Internet-Draft ARP YANG model June 2024 [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, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., and R. Wilton, "Network Management Datastore Architecture (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018, . [RFC8343] Bjorklund, M., "A YANG Data Model for Interface Management", RFC 8343, DOI 10.17487/RFC8343, March 2018, . [RFC8344] Bjorklund, M., "A YANG Data Model for IP Management", RFC 8344, DOI 10.17487/RFC8344, March 2018, . [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, . 9.2. Informative References [RFC5798] Nadas, S., Ed., "Virtual Router Redundancy Protocol (VRRP) Version 3 for IPv4 and IPv6", RFC 5798, DOI 10.17487/RFC5798, March 2010, . [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, . [RFC8014] Black, D., Hudson, J., Kreeger, L., Lasserre, M., and T. Narten, "An Architecture for Data-Center Network Virtualization over Layer 3 (NVO3)", RFC 8014, DOI 10.17487/RFC8014, December 2016, . Zheng, et al. Expires 1 January 2025 [Page 16] Internet-Draft ARP YANG model June 2024 [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, . [RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, March 2018, . Appendix A. Examples This section presents two simple ARP configuration examples: A.1. Configuration of a Static ARP Entry This example illustrates the configuration for a static ARP entry for peer 192.0.2.1 with MAC address 00:00:5E:00:53:AB using the model defined in [RFC8344]. eth0 ianaift:ethernetCsmacd 192.0.2.1 00:00:5E:00:53:AB A.2. Configuration of Proxy ARP and Gratuitous ARP This example illustrates the configuration of ARP entry expiry time, proxy ARP in 'remote-only' mode, and enabling gratuitous ARP with an interval of 10 minutes. Zheng, et al. Expires 1 January 2025 [Page 17] Internet-Draft ARP YANG model June 2024 eth0 ianaift:ethernetCsmacd 1200 remote-only true 600 Authors' Addresses Feng Zheng Huawei 101 Software Avenue, Yuhua District Nanjing Jiangsu, 210012 China Email: habby.zheng@huawei.com Bo Wu (editor) Huawei Email: lana.wubo@huawei.com Robert Wilton (editor) Cisco Systems Email: rwilton@cisco.com Fan Zhang (editor) China Telecom Zheng, et al. Expires 1 January 2025 [Page 18] Internet-Draft ARP YANG model June 2024 Email: zhangf52@chinatelecom.cn Yongqing Zhu China Telecom Email: zhuyq8@chinatelecom.cn Xiaojian Ding Email: wjswsl@163.com Zheng, et al. Expires 1 January 2025 [Page 19]