]> 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.

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.

isis_int ianaift:ipForward eth1 ianaift:ethernetCsmacd p2p ianaift:p2pOverLan isis_int eth1 false down down 2021-04-01T03:00:00+00:00 ]]>

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 Informative References IANA IANA

Examples If the underlying interface is a VLAN sub-interface, the ifStackTable should be defined as:

isis_int ianaift:ipForward eth1_valn1 ianaift:l2vlan p2p ianaift:p2pOverLan isis_int eth1_valn1 false down down 2021-04-01T03:00:00+00:00 ]]>

If the underlying interface is Link Aggregation Group (LAG), the ifStackTable should be defined as:

isis_int ianaift:ipForward eth1_lag1 ianaift:ieee8023adLag p2p ianaift:p2pOverLan isis_int eth1_lag1 false down down 2021-04-01T03:00:00+00:00 ]]>

If the P2P interface and underlying interface are both administratively up and the underlying interface operational status is up:

p2p ianaift:p2pOverLan isis_int eth1 up up ]]>

If the P2P interface and underlying interface are administratively up but the underlying interface operational status is down:

p2p ianaift:p2pOverLan isis_int eth1 up down ]]>

If the P2P interface is administratively down:

p2p ianaift:p2pOverLan isis_int eth1 down down ]]>

If the P2P interface is administratively up but the underlying interface is administratively down:

p2p ianaift:p2pOverLan isis_int eth1 up down ]]>

Acknowledgements The authors would like to thank for his reviews and valuable comments and suggestions.