ifStackTable for the Point-to-Point (P2P) Interface over a LAN Type: Definition and Examples Ericsson
No.5 Lize East Street 100102 Beijing China harold.liu@ericsson.com
Ericsson
joel.halpern@ericsson.com
Ericsson
congjie.zhang@ericsson.com
RFC 5309 defines the Point-to-Point (P2P) circuit type, one of the two circuit types used in the link-state routing protocols, and highlights that it is important to identify the correct circuit type when forming adjacencies, flooding link-state database packets, and monitoring the link state. This document provides advice about the ifStack for the P2P interface over a LAN Type to facilitate operational control, maintenance, and statistics.
Status of This Memo This document is not an Internet Standards Track specification; it is published for informational purposes. This is a contribution to the RFC Series, independently of any other RFC stream. The RFC Editor has chosen to publish this document at its discretion and makes no statement about its value for implementation or deployment. Documents approved for publication by the RFC Editor are not candidates for any level of Internet Standard; see Section 2 of RFC 7841. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at .
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Table of Contents
  • .  Introduction
  • .  Requirements Language
  • .  Interface Stack Table for P2P Interface Type
    • .  P2P Interface: higher-layer-if and lower-layer-if
    • .  P2P Interface Statistics
    • .  P2P Interface Administrative State
  • .  Security Considerations
  • .  IANA Considerations
  • .  References
    • .  Normative References
    • .  Informative References
  • .  Examples
  • Acknowledgements
  • Authors' Addresses
Introduction defines the Point-to-Point (P2P) circuit type and highlights that it is important to identify the correct circuit type when forming adjacencies, flooding link-state database packets, and monitoring the link state. To simplify configuration and operational control, it is helpful to represent the fact that an interface is to be considered a P2P interface over a LAN type explicitly in the interface stack. This enables, for example, routing protocols to automatically inherit the correct operating mode from the interface stack without further configuration (i.e., there is no need to explicitly configure the P2P interface in routing protocols). It is helpful to map the P2P interface over a LAN type in the interface management stack table. If no entry specifies the lower layer of the P2P interface, then management tools lose the ability to retrieve and measure properties specific to lower layers. In standard network management protocols that make use of ifStackTables, the P2P interface over a LAN type is intended to be used solely as a means to signal that the upper-layer interface of link-data layer is a P2P interface. Thus, the upper and lower layers of P2P over a LAN type are expected to apply appropriate semantics. In general, the higher layer of a P2P over a LAN type SHOULD be "ipForward" (value 142 in ), and the lower layer of P2P over a LAN type SHOULD be any appropriate link-data layer of "ipForward". The assignment of 303 as the value for the p2pOverLan ifType was made by Expert Review (see and ). The purpose of this document is to serve as a reference for ifType 303 by suggesting how the ifStackTable for the P2P interface over a LAN type is to be used and providing examples. It should be noted that this document reflects the operating model used on some routers. Other routers that use different models may not represent a P2P as a separate interface.
Requirements Language 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 when, and only when, they appear in all capitals, as shown here.
Interface Stack Table for P2P Interface Type
P2P Interface: higher-layer-if and lower-layer-if If a device implements the IF-MIB , then each entry in the "/interfaces/interface" list (see "A YANG Data Model for Interface Management" ) in the operational state is typically mapped to one ifEntry as required in . Therefore, the P2P interface over a LAN type should also be fully mapped to one ifEntry by defining the "ifStackTable" ("higher-layer-if" and "lower-layer-if", defined in ). In the ifStackTable, the higher layer of the P2P interface over a LAN type SHALL be network layer "ipForward" to enable IP routing, and the lower layer of the P2P interface over a LAN type SHOULD be any link-data layer that can be bound to "ipForward", including "ethernetCsmacd", "ieee8023adLag", "l2vlan", and so on (defined in the iana-if-type YANG module ). The P2P interface over the LAN type ifStackTable can be defined along the lines of the following example, which complies with and . In the example, "lower-layer-if" takes "ethernetCsmacd", but, in fact, "lower-layer-if" can be any other available link-data layer. See for more examples.
<interface> <name>isis_int</name> <type>ianaift:ipForward</type> </interface> <interface> <name>eth1</name> <type>ianaift:ethernetCsmacd</type> </interface> <interface> <name>p2p</name> <type>ianaift:p2pOverLan</type> <higher-layer-if>isis_int</higher-layer-if> <lower-layer-if>eth1</lower-layer-if> <enabled>false</enabled> <admin-status>down</admin-status> <oper-status>down</oper-status> <statistics> <discontinuity-time> 2021-04-01T03:00:00+00:00 </discontinuity-time> <!-- counters now shown here --> </statistics> </interface>
P2P Interface Statistics Because multiple IP interfaces can be bound to one physical port, the statistics on the physical port SHOULD be a complete set that includes statistics of all upper-layer interfaces. Therefore, each P2P interface collects and displays traffic that has been sent to it via higher layers or received from it via lower layers.
P2P Interface Administrative State The P2P interface can be shut down independently of the underlying interface. If the P2P interface is administratively up, then the "oper-status" (defined in ) of that interface SHALL fully reflect the state of the underlying interface; if the P2P interface is administratively down, then the "oper-status" of that interface SHALL be down. Examples can be found in .
Security Considerations The writable attribute "admin-status" of the p2povervlan ifType is inherited from . Other objects associated with the p2povervlan ifType are read-only. With this in mind, the considerations discussed in otherwise apply to the p2povervlan ifType.
IANA Considerations In the "Interface Types (ifType)" registry, value 303 is assigned to p2pOverLan . As this document explains how the p2pOverLan (303) ifType is to be used, IANA has amended the reference for p2pOverLan (303) to point to this document (instead of ) and made a similar amendment in the YANG iana-if-type module (originally specified in ).
References Normative References Key words for use in RFCs to Indicate Requirement Levels In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. The Interfaces Group MIB This memo discusses the 'interfaces' group of MIB-II, especially the experience gained from the definition of numerous media-specific MIB modules for use in conjunction with the 'interfaces' group for managing various sub-layers beneath the internetwork-layer. It specifies clarifications to, and extensions of, the architectural issues within the MIB-II model of the 'interfaces' group. [STANDARDS-TRACK] Point-to-Point Operation over LAN in Link State Routing Protocols The two predominant circuit types used by link state routing protocols are point-to-point and broadcast. It is important to identify the correct circuit type when forming adjacencies, flooding link state database packets, and representing the circuit topologically. This document describes a simple mechanism to treat the broadcast network as a point-to-point connection from the standpoint of IP routing. This memo provides information for the Internet community. IANA Interface Type YANG Module This document defines the initial version of the iana-if-type YANG module. Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. A YANG Data Model for Interface Management This document defines a YANG data model for the management of network interfaces. It is expected that interface-type-specific data models augment the generic interfaces data model defined in this document. The data model includes definitions for configuration and system state (status information and counters for the collection of statistics). The YANG data model in this document conforms to the Network Management Datastore Architecture (NMDA) defined in RFC 8342. This document obsoletes RFC 7223. Informative References Interface Types (ifType) IANA YANG Module Names IANA Common YANG Data Types This document introduces a collection of common data types to be used with the YANG data modeling language. This document obsoletes RFC 6021. Guidelines for Writing an IANA Considerations Section in RFCs Many protocols make use of points of extensibility that use constants to identify various protocol parameters. To ensure that the values in these fields do not have conflicting uses and to promote interoperability, their allocations are often coordinated by a central record keeper. For IETF protocols, that role is filled by the Internet Assigned Numbers Authority (IANA). To make assignments in a given registry prudently, guidance describing the conditions under which new values should be assigned, as well as when and how modifications to existing values can be made, is needed. This document defines a framework for the documentation of these guidelines by specification authors, in order to assure that the provided guidance for the IANA Considerations is clear and addresses the various issues that are likely in the operation of a registry. This is the third edition of this document; it obsoletes RFC 5226.
Examples If the underlying interface is a VLAN sub-interface, the ifStackTable should be defined as:
<interface> <name>isis_int</name> <type>ianaift:ipForward</type> </interface> <interface> <name>eth1_valn1</name> <type>ianaift:l2vlan</type> </interface> <interface> <name>p2p</name> <type>ianaift:p2pOverLan</type> <higher-layer-if>isis_int</higher-layer-if> <lower-layer-if>eth1_valn1</lower-layer-if> <enabled>false</enabled> <admin-status>down</admin-status> <oper-status>down</oper-status> <statistics> <discontinuity-time> 2021-04-01T03:00:00+00:00 </discontinuity-time> <!-- counters now shown here --> </statistics> </interface>
If the underlying interface is Link Aggregation Group (LAG), the ifStackTable should be defined as:
<interface> <name>isis_int</name> <type>ianaift:ipForward</type> </interface> <interface> <name>eth1_lag1</name> <type>ianaift:ieee8023adLag</type> </interface> <interface> <name>p2p</name> <type>ianaift:p2pOverLan</type> <higher-layer-if>isis_int</higher-layer-if> <lower-layer-if>eth1_lag1</lower-layer-if> <enabled>false</enabled> <admin-status>down</admin-status> <oper-status>down</oper-status> <statistics> <discontinuity-time> 2021-04-01T03:00:00+00:00 </discontinuity-time> <!-- counters now shown here --> </statistics> </interface>
If the P2P interface and underlying interface are both administratively up and the underlying interface operational status is up:
<interface> <name>p2p</name> <type>ianaift:p2pOverLan</type> <higher-layer-if>isis_int</higher-layer-if> <lower-layer-if>eth1</lower-layer-if> <admin-status>up</admin-status> <oper-status>up</oper-status> </interface>
If the P2P interface and underlying interface are administratively up but the underlying interface operational status is down:
<interface> <name>p2p</name> <type>ianaift:p2pOverLan</type> <higher-layer-if>isis_int</higher-layer-if> <lower-layer-if>eth1</lower-layer-if> <admin-status>up</admin-status> <oper-status>down</oper-status> </interface>
If the P2P interface is administratively down:
<interface> <name>p2p</name> <type>ianaift:p2pOverLan</type> <higher-layer-if>isis_int</higher-layer-if> <lower-layer-if>eth1</lower-layer-if> <admin-status>down</admin-status> <oper-status>down</oper-status> </interface>
If the P2P interface is administratively up but the underlying interface is administratively down:
<interface> <name>p2p</name> <type>ianaift:p2pOverLan</type> <higher-layer-if>isis_int</higher-layer-if> <lower-layer-if>eth1</lower-layer-if> <admin-status>up</admin-status> <oper-status>down</oper-status> </interface>
Acknowledgements The authors would like to thank for his reviews and valuable comments and suggestions.
Authors' Addresses Ericsson
No.5 Lize East Street 100102 Beijing China harold.liu@ericsson.com
Ericsson
joel.halpern@ericsson.com
Ericsson
congjie.zhang@ericsson.com