| Internet-Draft | AC Glue for VPN Models | November 2023 |
| Boucadair, et al. | Expires 31 May 2024 | [Page] |
The document specifies a module that updates existing service and network VPN modules with the required information to bind specific services to ACs that are created using the Attachment Circuit (AC) service and network models.¶
This note is to be removed before publishing as an RFC.¶
Discussion of this document takes place on the Operations and Management Area Working Group Working Group mailing list (opsawg@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/opsawg/.¶
Source for this draft and an issue tracker can be found at https://github.com/boucadair/attachment-circuit-model.¶
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Copyright (c) 2023 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 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.¶
The document specifies a YANG module (Section 5) that updates existing service and network Virtual Private Network (VPN) modules with the required information to bind specific services to Attachment Circuits (ACs) that are created using the AC service model [I-D.ietf-opsawg-teas-attachment-circuit], specifically the following modules are augmented:¶
Likewise, the document augments the L2NM and L3NM with references to the ACs that are managed using the AC network model [I-D.ietf-opsawg-ntw-attachment-circuit].¶
The YANG data model in this document conforms to the Network Management Datastore Architecture (NMDA) defined in [RFC8342].¶
An example to illustrate the use of the model is provided in Appendix A.¶
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 meanings of the symbols in the YANG tree diagrams are defined in [RFC8340].¶
This document uses terms defined in [I-D.ietf-opsawg-teas-attachment-circuit].¶
LxSM refers to both the L2SM and the L3SM.¶
LxNM refers to both the L2NM and the L3NM.¶
Figure 1 depicts two target topology flavors that involve ACs. These topologies have the following characteristics:¶
A Customer Edges (CEs) can be either a physical device or a logical entity. Such logical entity is typically a software component (e.g., a virtual service function that is hosted within the provider's network or a third-party infrastructure). A CE is seen by the network as a peer Service Attachment Point (SAP) [RFC9408].¶
An AC service request may include one or multiple ACs, which may be associated to a single CE or multiple CEs.¶
CEs may be either dedicated to one single connectivity service or host multiple connectivity services (e.g., CEs with roles of service functions [RFC7665]).¶
A network provider may bind a single AC to one or multiple peer SAPs (e.g., CE#1 and CE#2 are tagged as peer SAPs for the same AC). For example, and as discussed in [RFC4364], multiple CEs can be attached to a PE over the same attachment circuit. This scenario is typically implemented when the Layer 2 infrastructure between the CE and the network is a multipoint service.¶
A single CE may terminate multiple ACs, which can be associated with the same bearer or distinct bearers.¶
Customers may request protection schemes in which the ACs associated with their endpoints are terminated by the same PE (e.g., CE#3), distinct PEs (e.g., CE#34), etc. The network provider uses this request to decide where to terminate the AC in the network provider network and also whether to enable specific capabilities (e.g., Virtual Router Redundancy Protocol (VRRP)).¶
The procedure to provision a service in a service provider network may depend on the practices adopted by a service provider. This includes the flow put in place for the provisioning of advanced network services and how they are bound to an attachment circuit. For example, a single attachment circuit may be used to host multiple connectivity services. In order to avoid service interference and redundant information in various locations, a service provider may expose an interface to manage ACs network-wide. Customers can then request a bearer or an attachment circuit to be put in place, and then refer to that bearer or AC when requesting VPN services that are bound to the bearer or AC.¶
Figure 2 shows the positioning of the AC service model is the overall service delivery process.¶
[RFC8299] specifies that a "site-network-access" attachment is achieved through a "bearer" with an "ip-connection" on top. From that standpoint, a "site-network-access" is mapped to an attachment circuit with both Layer 2 and 3 properties as per [I-D.ietf-opsawg-teas-attachment-circuit]. [RFC8466] specifies that a "site-network-access" represents an logical layer 2 connection to a site. A "site-network-access" can thus be mapped to an attachment circuit with Layer 2 properties [I-D.ietf-opsawg-teas-attachment-circuit]. Similarly, "vpn-network-access" defined in both [RFC9182] and [RFC9282] is mapped to an attachment circuit as per [I-D.ietf-opsawg-teas-attachment-circuit] or [I-D.ietf-opsawg-ntw-attachment-circuit].¶
As such, ACs created using the "ietf-ac-svc" module [I-D.ietf-opsawg-teas-attachment-circuit] can be referenced in other VPN-related modules (e.g., L2SM, L3SM, L2NM, and L3NM). Also, ACs managed using "ietf-ac-ntw" [I-D.ietf-opsawg-ntw-attachment-circuit] can be referenced in VPN-related network modules (mainly, L2NM and L3NM). The required augmentations to that aim as shown in Figure 3.¶
augment /l2vpn-svc:l2vpn-svc/l2vpn-svc:sites/l2vpn-svc:site
/l2vpn-svc:site-network-accesses:
+--rw ac-svc-ref* ac-svc:attachment-circuit-reference
augment /l3vpn-svc:l3vpn-svc/l3vpn-svc:sites/l3vpn-svc:site
/l3vpn-svc:site-network-accesses:
+--rw ac-svc-ref* ac-svc:attachment-circuit-reference
augment /l2nm:l2vpn-ntw/l2nm:vpn-services/l2nm:vpn-service
/l2nm:vpn-nodes/l2nm:vpn-node/l2nm:vpn-network-accesses:
+--rw ac-svc-ref* ac-svc:attachment-circuit-reference
+--rw ac-ntw-ref* ac-ntw:attachment-circuit-reference
augment /l3nm:l3vpn-ntw/l3nm:vpn-services/l3nm:vpn-service
/l3nm:vpn-nodes/l3nm:vpn-node/l3nm:vpn-network-accesses:
+--rw ac-svc-ref* ac-svc:attachment-circuit-reference
+--rw ac-ntw-ref* ac-ntw:attachment-circuit-reference
<CODE BEGINS> file ietf-ac-glue@2023-11-13.yang
module ietf-ac-glue {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-ac-glue";
prefix ac-glue;
import ietf-l3vpn-svc {
prefix l3vpn-svc;
reference
"RFC 8299: YANG Data Model for L3VPN Service Delivery";
}
import ietf-l2vpn-svc {
prefix l2vpn-svc;
reference
"RFC 8466: A YANG Data Model for Layer 2 Virtual Private
Network (L2VPN) Service Delivery";
}
import ietf-l3vpn-ntw {
prefix l3nm;
reference
"RFC 9182: A YANG Network Data Model for Layer 3 VPNs";
}
import ietf-l2vpn-ntw {
prefix l2nm;
reference
"RFC 9291: A YANG Network Data Model for Layer 2 VPNs";
}
import ietf-ac-svc {
prefix ac-svc;
reference
"RFC SSSS: YANG Service Data Models for Attachment Circuits";
}
import ietf-ac-ntw {
prefix ac-ntw;
reference
"RFC NNNN: A Network YANG Data Model for Attachment Circuits";
}
organization
"IETF OPSAWG (Operations and Management Area Working Group)";
contact
"WG Web: <https://datatracker.ietf.org/wg/opsawg/>
WG List: <mailto:opsawg@ietf.org>
Editor: Mohamed Boucadair
<mailto:mohamed.boucadair@orange.com>
Author: Richard Roberts
<mailto:rroberts@juniper.net>
Author: Samier Barguil
<mailto:ssamier.barguil_giraldo@nokia.com>
Author: Oscar Gonzalez de Dios
<mailto:oscar.gonzalezdedios@telefonica.com>";
description
"This YANG module defines a YANG model for augmenting the LxSM
and the LxNM with attachment circuit references.
Copyright (c) 2023 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).
This version of this YANG module is part of RFC XXXX; see the
RFC itself for full legal notices.";
revision 2023-11-13 {
description
"Initial revision.";
reference
"RFC XXXX: A YANG Data Model for Augmenting VPN Service
and Network Models with Attachment Circuits";
}
grouping ac-svc-glue {
description
"A set of service-specific AC-related data.";
leaf-list ac-svc-ref {
type ac-svc:attachment-circuit-reference;
description
"A reference to the AC as exposed at the service that
was provisionned using the ACaaS module.";
}
}
grouping ac-glue {
description
"A set of AC-related data.";
leaf-list ac-svc-ref {
type ac-svc:attachment-circuit-reference;
description
"A reference to the AC as exposed at the service that
was provisionned using the ACaaS module.";
}
leaf-list ac-ntw-ref {
type ac-ntw:attachment-circuit-reference;
description
"A reference to the AC that was provisionned
using the AC network module.";
}
}
augment "/l2vpn-svc:l2vpn-svc"
+ "/l2vpn-svc:sites/l2vpn-svc:site"
+ "/l2vpn-svc:site-network-accesses" {
description
"Augments VPN network access with AC provisioning details.";
uses ac-svc-glue;
}
augment "/l3vpn-svc:l3vpn-svc"
+ "/l3vpn-svc:sites/l3vpn-svc:site"
+ "/l3vpn-svc:site-network-accesses" {
description
"Augments VPN network access with AC provisioning details.";
uses ac-svc-glue;
}
augment "/l2nm:l2vpn-ntw/l2nm:vpn-services/l2nm:vpn-service"
+ "/l2nm:vpn-nodes/l2nm:vpn-node"
+ "/l2nm:vpn-network-accesses" {
description
"Augments VPN network access with AC provisioning details.";
uses ac-glue;
}
augment "/l3nm:l3vpn-ntw/l3nm:vpn-services/l3nm:vpn-service"
+ "/l3nm:vpn-nodes/l3nm:vpn-node"
+ "/l3nm:vpn-network-accesses" {
description
"Augments VPN network access with AC provisioning details.";
uses ac-glue;
}
}
<CODE ENDS>¶
The YANG module specified in this document defines 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 Network Configuration 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-ac-glue" module:¶
Some of the readable data nodes in this YANG module may be considered sensitive or vulnerable in some network environments. It is thus important to control read access (e.g., via get, get-config, or notification) to these data nodes. These are the subtrees and data nodes and their sensitivity/vulnerability in the "ietf-ac-glue" module:¶
IANA is requested to register the following URI in the "ns" subregistry within the "IETF XML Registry" [RFC3688]:¶
URI: urn:ietf:params:xml:ns:yang:ietf-ac-glue 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" registry [RFC6020] within the "YANG Parameters" registry group.¶
Name: ietf-ac-glue Namespace: urn:ietf:params:xml:ns:yang:ietf-ac-glue Prefix: ac-glue Maintained by IANA? N Reference: RFC xxxx¶
Let's consider the example depicted in Figure 4 with two customer terminating points (CE1 and CE2). Let's also assume that the bearers to attach these CEs to the provider network are already in place. References to the identify these bearers are shown in the figure.¶
.-----. .--------------. .-----.
.----. | PE1 +===+ +===+ PE2 | .----.
| CE1+------+"450"| | MPLS | |"451"+------+ CE2|
'----' ^ '-----' | | '-----' ^ '----'
| | Core | |
Bearer:1234 '--------------' Bearer:5678
The AC service model [I-D.ietf-opsawg-teas-attachment-circuit] can be used by the provider to manage and expose the ACs over existing bearers as shown in Figure 5.¶
{
"ietf-ac-svc:attachment-circuits":{
"ac-group-profile":[
{
"name":"an-ac-profile",
"l2-connection":{
"encapsulation":{
"encap-type":"ietf-vpn-common:dot1q",
"dot1q":{
"tag-type":"ietf-vpn-common:c-vlan",
"cvlan-id":550
}
}
},
"service":{
"mtu":1550,
"svc-pe-to-ce-bandwidth":{
"pe-to-ce-bandwidth":[
{
"bw-type":"ietf-vpn-common:bw-per-port",
"cir":"20480000"
}
]
},
"svc-ce-to-pe-bandwidth":{
"ce-to-pe-bandwidth":[
{
"bw-type":"ietf-vpn-common:bw-per-port",
"cir":"20480000"
}
]
},
"qos":{
"qos-profile":{
"qos-profile":[
{
"profile":"QoS_Profile_A",
"direction":"ietf-vpn-common:both"
}
]
}
}
}
}
],
"ac":[
{
"name":"ac-1",
"description":"First attachment",
"ac-group-profile":["an-ac-profile"],
"l2-connection":{
"bearer-reference":"1234"
}
},
{
"name":"ac-2",
"description":"Second attachment",
"ac-group-profile": ["an-ac-profile"],
"l2-connection":{
"bearer-reference":"5678"
}
}
]
}
}
Let's now consider that the customer wants to request a VPLS service between the sites as shown in Figure 6.¶
|---------- VPLS "1543" ----------|
.-----. .--------------. .-----.
.----. AC1 | PE1 +===+ +===+ PE2 | AC2 .----.
| CE1+------+"450"| | MPLS | |"451"+------+ CE2|
'----' ^ '-----' | | '-----' ^ '----'
| | Core | |
Bearer:1234 '--------------' Bearer:5678
To that aim, existing ACs are referenced during the creation of the VPLS instance using the L2NM and the "ietf-ac-glue" as shown in Figure 7.¶
{
"ietf-l2vpn-ntw:l2vpn-ntw": {
"vpn-services": {
"vpn-service": [
{
"vpn-id": "1543",
"vpn-name": "CORPO-EXAMPLE",
"customer-name": "EXAMPLE",
"vpn-type": "ietf-vpn-common:vpls",
"vpn-service-topology": "ietf-vpn-common:hub-spoke",
"bgp-ad-enabled": false,
"signaling-type": "ietf-vpn-common:ldp-signaling",
"global-parameters-profiles": {
"global-parameters-profile": [
{
"profile-id": "simple-profile",
"ce-vlan-preservation": true,
"ce-vlan-cos-preservation": true
}
]
},
"vpn-nodes": {
"vpn-node": [
{
"vpn-node-id": "450",
"ne-id": "2001:db8:5::1",
"role": "ietf-vpn-common:hub-role",
"status": {
"admin-status": {
"status": "ietf-vpn-common:admin-up"
}
},
"active-global-parameters-profiles": {
"global-parameters-profile": [
{
"profile-id": "simple-profile"
}
]
},
"signaling-option": {
"ldp-or-l2tp": {
"t-ldp-pw-type": "vpls-type",
"pw-peer-list": [
{
"peer-addr": "2001:db8:50::1",
"vc-id": "1543"
}
]
}
},
"vpn-network-accesses": {
"ietf-ac-glue:ac-svc-ref": ["ac-1"]
}
},
{
"vpn-node-id": "451",
"ne-id": "2001:db8:50::1",
"role": "ietf-vpn-common:spoke-role",
"status": {
"admin-status": {
"status": "ietf-vpn-common:admin-up"
}
},
"active-global-parameters-profiles": {
"global-parameters-profile": [
{
"profile-id": "simple-profile"
}
]
},
"signaling-option": {
"ldp-or-l2tp": {
"t-ldp-pw-type": "vpls-type",
"pw-peer-list": [
{
"peer-addr": "2001:db8:5::1",
"vc-id": "1543"
}
]
}
},
"vpn-network-accesses": {
"ietf-ac-glue:ac-svc-ref": ["ac-2"]
}
}
]
}
}
]
}
}
}
Note that before implementing the VPLS creation request, the provider service orchestrator may first check if the VPLS service can be provided to the customer using the target delivery locations. The orchestrator will use the SAP model [RFC9408] as exemplified in Figure 8. This example assumes that the query concerns only PE1. A similar query can be issued for PE2.¶
{
"ietf-sap-ntw:service":[
{
"service-type":"ietf-vpn-common:vpls",
"sap":[
{
"sap-id":"sap#1",
"peer-sap-id":[
"ce-1"
],
"description":"A parent SAP",
"attachment-interface":"GE0/6/1",
"interface-type":"ietf-sap-ntw:phy",
"role":"ietf-sap-ntw:uni",
"allows-child-saps":true,
"sap-status":{
"status":"ietf-vpn-common:op-up"
}
}
]
}
]
}
The response in Figure 8 indicates that the VPLS service can be delivered to CE1. [I-D.ietf-opsawg-ntw-attachment-circuit] can be also used to access AC-related details that are bound to the target SAP (Figure 9).¶
=============== NOTE: '\' line wrapping per RFC 8792 ================
{
"ietf-sap-ntw:service":[
{
"service-type":"ietf-vpn-common:vpls",
"sap":[
{
"sap-id":"sap#1",
"peer-sap-id":[
"ce-1"
],
"description":"A parent SAP",
"attachment-interface":"GE0/6/1",
"interface-type":"ietf-sap-ntw:phy",
"role":"ietf-sap-ntw:uni",
"allows-child-saps":true,
"sap-status":{
"status":"ietf-vpn-common:op-up"
}
},
{
"sap-id":"sap#11",
"description":"A child SAP",
"parent-termination-point":"GE0/6/4",
"attachment-interface":"GE0/6/4.2",
"interface-type":"ietf-sap-ntw:logical",
"encapsulation-type":"ietf-vpn-common:vlan-type",
"sap-status":{
"status":"ietf-vpn-common:op-up"
},
"ietf-ac-ntw:ac":[
{
"name":"ac-11",
"ac-svc-ref":"ac-1",
"peer-sap-id":[
"ce-1"
],
"status":{
"admin-status":{
"status":"ietf-vpn-common:admin-up"
},
"oper-status":{
"status":"ietf-vpn-common:op-up"
}
},
"l2-connection":{
"encapsulation":{
"encap-type":"ietf-vpn-common:dot1q",
"dot1q":{
"tag-type":"ietf-vpn-common:c-vlan",
"cvlan-id":550
}
},
"bearer-reference":"1234"
},
"service":{
"mtu":1550,
"svc-pe-to-ce-bandwidth":{
"pe-to-ce-bandwidth":[
{
"cir":"20480000"
}
]
},
"svc-ce-to-pe-bandwidth":{
"ce-to-pe-bandwidth":[
{
"cir":"20480000"
}
]
},
"qos":{
"qos-profile":{
"qos-profile":[
{
"profile":"QoS_Profile_A",
"direction":"ietf-vpn-common:\
both"
}
]
}
}
}
}
]
}
]
}
]
}
Thanks to Bo Wu for the review and comments.¶