Futurewei

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Telefonica

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Intel Corporation

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Internet DMM Working Group L3 Tunnel Attachment circuit as a Service Delivery of network services over a Layer 3 tunnel assumes that the appropriate setup is provisioned over links that connect the customer termination points and provider network. The required setup to allow successful data exchange over these links is referred to as an attachment circuit (AC) while the underlying link for carrying network services is referred to as "bearer", in this case a Layer 3 UDP tunnel. This document specifies an extension for UDP tunnel as Layer 3 bearer to the YANG service data model for AC.

Connectivity services provided by networks to customers ensure the transfer of data between termination points via a provider network. The objectives of the connectivity service can be negotiated and agreed between customers and network providers. To facilitate data transfer within the provider network, it is assumed that the appropriate setup is provisioned over links that connect customer termination points and provider network (usually via Provider Edges (PEs)). This is referred to as attachment circuit (AC) and the underlying link defined in this document is a UDP tunnel as Layer 3 bearer. In general, a bearer can be described as a physical or logical link that connects a customer node (or site) to a provider network. describes further details on the description of the bearer service and the attachment circuit service. specifies YANG data models for the bearer service and the attachment circuit service. Layer 3 UDP tunnel as bearer is not defined in the ACaaS specification and is an extension defined in this document. An example of Layer 3 UDP tunnel as a bearer is in 5G networks where a GTP-U (UDP) bearer is used to transport datagrams of a mobile end-user between 3GPP user plane functions. describes the "ietf-ac-udpt" YANG module for Layer 3 UDP tunnel service. describes the UDP tunnel YANG data model. An example of UDP Tunnel with source port number to identify bearers at the transport network Provider Edge (PE) is provided in .

Attachment Circuit Customer Edge General Packet Radio Service (GPRS) Tunneling Protocol - User plane (3GPP) Gateway Network Slice Controller Provider Edge Service Function Service Management and Orchestration Transport Network User Datagram Protocol UDP tunnel as a bearer for data flows.

defines a YANG service model for AC based on underlying bearers. A bearer is a logical link with the appropriate level of resources, QoS and priority for the data traffic it carries. This document extends the YANG service model for AC in to support UDP tunnel as the underlying bearer. The 'l3-service' and 'l3-tunnel-service' in the AC structure in is used to configure the relevant layer 3 tunnel properties of a UDP tunnel AC. IPv4 and IPv6 properties of the UDP tunnel AC are provided in the "ip-connection" container (Section 5.2.5.2 of ). The extension below adds source port number and range for the UDP tunnel. The meanings of the symbols in the YANG tree diagram are defined in "YANG Tree Diagrams" .

module: ietf-ac-udpt augment /ac-svc:attachment-circuits/ac-svc:ac/ac-svc:ip-connection /ac-svc:l3-service/ac-svc:l3-tunnel-service /ac-svc:l3-tunnel-service: +--rw (udp-port)? +--:(port-range-or-operator) +--rw source-port-range-or-operator +--rw (port-range-or-operator)? +--:(range) | +--rw lower-port inet:port-number | +--rw upper-port inet:port-number +--:(operator) +--rw operator? operator +--rw port inet:port-number

'l3-tunnel-service' in Section 5.2.5.2 of is extended in this document to specify UDP source port number or a range port numbers. Also, this document defines a new identity (called 'udp') based on the base identity 'l3-tunnel-type' defined in Section 4.2 of .

The "ietf-ac-udp-tunnel" module uses types and groupings defined in , , and .

file "ietf-ac-udp-tunnel@2025-09-18.yang" module ietf-ac-udp-tunnel { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-ac-udp-tunnel"; prefix ac-udpt; import ietf-ac-common { prefix ac-common; reference "RFC 9833: A Common YANG Data Model for Attachment Circuits"; } import ietf-ac-svc { prefix ac-svc; reference "RFC 9834: YANG Data Models for Bearers and 'Attachment Circuits'-as-a-Service (ACaaS)"; } import ietf-packet-fields { prefix packet-fields; reference "RFC 8519: YANG Data Model for Network Access Control Lists (ACLs), Section 4.2"; } organization "IETF DMM (Distributed Mobility Management)"; contact "WG Web: WG List: Author: John Kaippallimalil "; description "This YANG module defines a YANG model for augmenting the ACaaS service model with UDP Encapsulation as Layer 3 tunnel service. Copyright (c) 2025 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). All revisions of IETF and IANA published modules can be found at the YANG Parameters registry group (https://www.iana.org/assignments/yang-parameters). This version of this YANG module is part of RFC XXXX; see the RFC itself for full legal notices."; revision 2025-09-18 { description "Initial revision."; reference "RFC XXXX: A YANG Data Model for Attachment Circuit as a Service with UDP Tunnel Support"; } identity udp { base ac-common:l3-tunnel-type; description "UDP Encapsulation."; reference "RFC 8085: UDP Usage Guidelines, Section 3.1.11"; } augment "/ac-svc:attachment-circuits/ac-svc:ac" + "/ac-svc:ip-connection/ac-svc:l3-service" + "/ac-svc:l3-tunnel-service/ac-svc:l3-tunnel-service" { when "derived-from-or-self(./ac-svc:type, 'ac-udpt:udp')" { description "Only applicable if l3 service type is UDP encapsulation."; } description "Augments Layer 3 AC service with required data nodes for UDP encapsulation support."; choice udp-port { description "Choice of specifying the source port number or referring to a group of port numbers."; container source-port-range-or-operator { description "Indicates a set of source ports numbers."; uses packet-fields:port-range-or-operator; } } } } ]]>

Note to RFC Editor: Replace "RFC XXXX" with the RFC number to be assigned to this document.

Thanks to Mohamed Boucadair for the review and comments. Lionel Morand helped with the review and Yang structures in this document. Thanks to Linda and Tianji for the reivew and suggested updates.

This section is modeled after the template described in Section 3.7 of . The "ietf-ac-udp-tunnel" YANG module defines a data model that is designed to be accessed via YANG-based management protocols, such as NETCONF and RESTCONF . These YANG-based management protocols (1) have to use a secure transport layer (e.g., SSH , TLS , and QUIC ) and (2) have to use mutual authentication. Servers MUST verify that requesting clients are entitled to access and manipulate a given bearer or AC. For example, a given customer must not have access to bearers (attachment circuits) of other customers. The Network Configuration Access Control Model (NACM) 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. The data nodes in the YANG model in this document inherits from , and the security constraints to the data structures there apply. Data nodes defined in the ietf-ac-udp-tunnel YANG module 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. The 'udp-port' information may be used to track a customer of the slice service and may be considered a violation of the customer-provider trust relationship.

IANA is requested to register the following URI in the "ns" subregistry within the "IETF XML Registry" : URI: urn:ietf:params:xml:ns:yang:ietf-ac-udp-tunnel Registrant Contact: The IESG. XML: N/A; the requested URI is an XML namespace. IANA is requested to register the following YANG module in the "YANG Module Names" subregistry within the "YANG parameters" registry. Name: ietf-ac-udp-tunnel Maintained by IANA? N Namespace: urn:ietf:params:xml:ns:yang:ietf-ac-udp-tunnel Prefix: ac-udp-tunnel Reference: RFC XXXX

3rd Generation Partnership Project (3GPP)

This example is adapted from Appendix A.7 of where details of the topology and service are described. describes the end-to-end network topology as well as orchestration scope:

• The topology is made up of two sites ("site1" and "site2"), interconnected via a Transport Network (e.g., IP/MPLS network). An SF is deployed within each site in a dedicated IP subnet.
• A 5G Service Management and Orchestration (SMO) is responsible for the deployment of SFs and the indirect management of a local Gateway (i.e., CE).
• An IETF Network Slice Controller (NSC) is responsible for the deployment of IETF Network Slices across the Transport Network.

<---------+--------> <----+----> Site1 Transport Network Site2 .--------------. | | .---. .---. .---. .---. | | | | .---. .---. |SF1+----------------+PE1| |PE2+---------------|SF2| '---' |GW1| ^ | | | | ^ |GW2| '---' '---' | '-+-' '-+-' | '---' | | | | | '--------------' | | | | | UDP Tunnel Bearer: UDP Tunnel Bearer: bearerX@site1 bearerX@site2 ]]>

describes the logical connectivity enforced with IETF Network slice and ACaaS models with UDP tunnel bearer identified by the UDP source port number.

AS 65550 .---. .--------. .---. |SF1| 192.0.2.0/30 | | 192.0.2.4/30 |SF2| '-+-' .---. .-+-. .-+-. .---. '-+-' | | |.1 .2| | | |.6 .5| | | --+-----+GW1+-----------+PE1| |PE2+-----------+GW2+-----+-- | |udp-src-prt| | | |udp-src-prt| | '---' 5678 '-+-' '-+-' 7890 '---' 198.51.100.0/24 | | 203.0.113.0/24 '--------' sdp1 sdp2 <--------------------> <-----------> <------------------> Attachment Network Slice Attachment * "ac1" properties: - bearer-reference: bearerX@site1 - udp-src-prt: 5678 - CE address (SF1): 198.51.100.0/24 - PE address: 192.0.2.2/30 - Routing: static 198.51.100.0/24 via 192.0.2.1 tag primary_UP_slice * "ac2" properties: - bearer-reference: bearerY@site2 - udp-src-prt: 7890 - CE address (SF2): 203.0.113.0/24 - PE address: 192.0.2.6/30 - Routing: BGP local-as: 65536 (Provider ASN) peer-as: 65550 (customer ASN) remote-address: 192.0.2.5 (Customer address) ]]>

is an adaptation of A.7, Figure 41 in with a UDP Tunnel bearer identified by the source port number.

is an adaptation of A.7, Figure 42 in that shows the message body of that response to a GET request received from the controller.

is derived from A.7, Figure 43 in . shows the message body of the request to create a Slice Service bound to the ACs created using . Only references to these ACs are included in the Slice Service request.