| Internet-Draft | MPLS-TE Topology YANG Model | July 2021 |
| Busi, et al. | Expires 13 January 2022 | [Page] |
This document describes a YANG data model for Multi-Protocol Label Switching (MPLS) with Traffic Engineering (MPLS-TE) networks.¶
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This document describes a YANG data model for Multi-Protocol Label Switching (MPLS) with Traffic Engineering (MPLS-TE) networks.¶
This document also defines a collection of common data types and groupings in YANG data modeling language for MPLS-TE networks. These derived common types and groupings are intended to be imported by the MPLS-TE topology model, defined in this document, as well as by the MPLS-TE tunnel model, defined in [I-D.ietf-teas-yang-te-mpls].¶
Multi-Protocol Label Switching - Transport Profile (MPLS-TP) is a profile of the MPLS protocol that is used in packet switched transport networks and operated in a similar manner to other existing transport technologies (e.g., OTN), as described in [RFC5921]. The YANG model defined in this document can also be for MPLS-TP networks.¶
A simplified graphical representation of the data model is used in Section 5.1 of this this document. The meaning of the symbols in these diagrams is defined in [RFC8340].¶
In this document, names of data nodes and other data model objects are prefixed using the standard prefix associated with the corresponding YANG imported modules, as shown in Table 1.¶
| Prefix | YANG module | Reference |
|---|---|---|
| rt-types | ietf-routing-types | [RFC8294] |
| tet | ietf-te-topology | [RFC8795] |
| tet-pkt | ietf-te-topology-packet | [I-D.ietf-teas-yang-l3-te-topo] |
| te-packet-types | ietf-te-packet-types | [I-D.ietf-teas-yang-l3-te-topo] |
| mte-types | ietf-mpls-te-types | This document |
| tet-mpls | ietf-te-mpls-topology | This document |
The module ietf-mpls-te-types contains the following YANG types and groupings which can be reused by MPLS-TE YANG models:¶
The MPLS-TE technology specific topology model augments the ietf-te- topology-packet YANG module, defined in [I-D.ietf-teas-yang-l3-te-topo], which in turns augment the generic ietf-te-topology YANG module, defined in [RFC8795], as shown in Figure 1.¶
+------------------+ o: augment
TE generic | ietf-te-topology |
+------------------+
o
|
|
|
+-------------------------+
Packet TE | ietf-te-topology-packet |
+-------------------------+
o
|
|
|
+-----------------------+
MPLS-TE | ietf-te-mpls-topology |
+-----------------------+
Given the guidance for augmentation in [RFC8795], the following technology-specific augmentations need to be provided:¶
augment /nw:networks/nw:network/nw:network-types/tet:te-topology
/tet-pkt:packet:
+--rw mpls-topology!
¶
Note: TE Bandwidth Augmentations for paths, LSPs and links are provided by the ietf-te-topology-packet module, defined in [I-D.ietf-teas-yang-l3-te-topo].¶
In MPLS-TE, the label allocation is done by NE, information about label values availability is not necessary to be provided to the controller. Moreover, MPLS-TE tunnels are currently established within a single domain.¶
Therefore this document does not define any MPLS-TE technology-specific augmentations, of the TE Topology model, for the TE label since no TE label related attributes should be instantiated for MPLS-TE Topologies.¶
Open issue: shall this module allows the setup of MPLS-TE multi-domain tunnels?¶
Multi-Protocol Label Switching - Transport Profile (MPLS-TP) is a profile of the MPLS protocol that is used in packet switched transport networks and operated in a similar manner to other existing transport technologies (e.g., OTN), as described in [RFC5921].¶
Therefore YANG model defined in this document can also be applicable for MPLS-TP networks.¶
However, as described in [RFC5921], MPLS-TP networks support bidirectional LSPs and require no ECMP and no PHP. When reporting the topology for an MPLS-TP network, additional information is required to indicate whether the network support these MPLS-TP characteristics.¶
It is worth noting that [RFC8795] is already capable to model TE topologies supporting either unidirectional or bidirectional LSPs: all bidirectional TE links can support bidirectional LSPs and all the links can support unidirectional LSPs and it is always possible to associated unidirectional LSPs as long as they belong to the same tunnel.¶
When setting up bidirectional LSPs (e.g., MPLS-TP LSPs) only bidirectional TE Links are selected by path computation.¶
In order to allow reporting that ECMP is not affecting forwarding the packets of a given LSP, the load-balancing-type attribute reports whether a LAG or TE Bundled Link performs load-balancing on a per-flow or per-top-label:¶
augment /nw:networks/nw:network/nt:link/tet:te:
+--rw load-balancing-type? mte-types:load-balancing-type
¶
When setting up LSPs which do not requires ECMP (e.g., MPLS-TP LSPs) only Links that are not part of a LAG or TE Bundle or that performs per-top-label load balancing are selected by path computation.¶
It is assumed that almost all the MPLS-TE nodes are capable to support Ultimate Hop Popping (UHP). However, if some interfaces are not able to support UHP, they can report it in the MPLS-TE topology:¶
augment /nw:networks/nw:network/nw:node/nt:termination-point
/tet:te:
+--ro uhp-incapable? empty
¶
When setting up LSPs which do not requires PHP (e.g., MPLS-TP LSPs) only the interfaces (LTPs) which are capable to support UHP in the destination node are selected by path computation.¶
<CODE BEGINS>file "ietf-mpls-te-types@2021-07-12.yang"
module ietf-mpls-te-types {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-mpls-te-types";
prefix "mte-types";
import ietf-routing-types {
prefix "rt-types";
}
organization
"Internet Engineering Task Force (IETF) TEAS WG";
contact
"WG Web: <https://datatracker.ietf.org/wg/teas/>
WG List: <mailto:teas@ietf.org>
Editor: Italo Busi
<mailto:italo.busi@huawei.com>
Editor: Haomian Zheng
<mailto:zhenghaomian@huawei.com>
Editor: Aihua Guo
<mailto:aihuaguo.ietf@gmail.com>
Editor: Xufeng Liu
<mailto:xufeng.liu.ietf@gmail.com>";
description
"This module defines technology-specific MPLS-TE types
data model.
Copyright (c) 2021 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 Simplified
BSD License set forth in Section 4.c of the IETF Trust's
Legal Provisions Relating to IETF Documents
(http://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 2021-07-12 {
description
"Initial Version";
reference
"draft-busizheng-teas-yang-te-mpls-topology";
}
/*
* Typedefs
*/
typedef load-balancing-type {
type enumeration {
enum per-flow {
description
"The load-balancing algorithm ensures that packets
characterized as the same flow (e.g. based on IP 5-tuple)
that egress on a LAG or a bundled TE link are forwarded
on the same component link.
Packets for different flows within the same LSP can be
forwarded on different component links.";
}
enum per-top-label {
description
"The load-balancing algorithm ensures incoming MPLS
packets with the same top MPLS label and that egress on
on a LAG or bundled TE link are forwarded on the same
component link.
Packets for different flows within the same LSP are
forwarded on the same component link.";
}
}
description
"The type of load balancing used on bundled links.";
} // typedef load-balancing-type
/*
* Groupings
*/
grouping te-mpls-label-hop {
description
"MPLS-TE Label Hop.";
leaf mpls-label {
type rt-types:mpls-label;
description
"MPLS Label.";
}
} // grouping te-mpls-label-hop
}
<CODE ENDS>
Figure 3 below shows the tree diagram of the YANG model defined in module ietf-te-mpls-topology.yang.¶
module: ietf-te-mpls-topology
augment /nw:networks/nw:network/nw:network-types/tet:te-topology
/tet-pkt:packet:
+--rw mpls-topology!
augment /nw:networks/nw:network/nt:link/tet:te:
+--rw load-balancing-type? mte-types:load-balancing-type
augment /nw:networks/nw:network/nw:node/nt:termination-point
/tet:te:
+--ro uhp-incapable? empty
<CODE BEGINS>file "ietf-te-mpls-topology@2021-07-12.yang"
module ietf-te-mpls-topology {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-te-mpls-topology";
prefix "tet-mpls";
import ietf-network {
prefix "nw";
}
import ietf-network-topology {
prefix "nt";
}
import ietf-te-topology {
prefix "tet";
}
import ietf-te-topology-packet {
prefix "tet-pkt";
}
import ietf-mpls-te-types {
prefix "mte-types";
}
organization
"Internet Engineering Task Force (IETF) TEAS WG";
contact
"WG Web: <https://datatracker.ietf.org/wg/teas/>
WG List: <mailto:teas@ietf.org>
Editor: Italo Busi
<mailto:italo.busi@huawei.com>
Editor: Haomian Zheng
<mailto:zhenghaomian@huawei.com>
Editor: Aihua Guo
<mailto:aihuaguo.ietf@gmail.com>
Editor: Xufeng Liu
<mailto:xufeng.liu.ietf@gmail.com>";
description
"This module defines technology-specific MPLS-TE topology
data model.
Copyright (c) 2021 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 Simplified
BSD License set forth in Section 4.c of the IETF Trust's
Legal Provisions Relating to IETF Documents
(http://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 2021-07-12 {
description
"Initial Version";
reference
"draft-busizheng-teas-yang-te-mpls-topology";
}
/*
* Augmentations
*/
augment "/nw:networks/nw:network/nw:network-types/"
+ "tet:te-topology/tet-pkt:packet" {
description
"Augment network types to include MPLS-TE Topology Type";
container mpls-topology {
presence
"Indicates an MPLS-TE Topology Type.";
description
"Its presence indicates an MPLS-TE Topology";
}
}
augment "/nw:networks/nw:network/nt:link/tet:te" {
when "../../nw:network-types/tet:te-topology/"
+ "tet-pkt:packet/tet-mpls:mpls-topology" {
description
"Augment MPLS-TE Topology.";
}
description
"Augment TE Link.";
leaf load-balancing-type {
type mte-types:load-balancing-type;
default 'per-flow';
description
"Indicates the type of load-balancing (per-flow or per-LSP)
performed by the bundled TE Link.
This leaf is not present when the TE Link is not bundled.";
} // leaf load-balancing-type
}
augment "/nw:networks/nw:network/nw:node/nt:termination-point/"
+ "tet:te" {
when "../../../nw:network-types/tet:te-topology/"
+ "tet-pkt:packet/tet-mpls:mpls-topology" {
description "Augment MPLS-TE Topology.";
}
description "Augment LTP.";
leaf uhp-incapable {
type empty;
config false;
description
"When present, indicates that the LTP is not capable to
support Ultimate Hop Popping (UHP).";
} // leaf uhp-incapable
}
}
<CODE ENDS>
To be added.¶
To be added.¶
The authors would also like to thank Tarek Saad, Vishnu Pavan Beeram, Rakesh Gandhi, Xufeng Liu, Igor Bryskin for their input on how to support MPLS-TP features (bidirectional LSPs, no ECMP, no PHP) using a common MPLS-TE topology model.¶
We thank Loa Andersson and Igor Bryskin for providing useful suggestions for this draft.¶
This document was prepared using kramdown.¶
Previous versions of this document was prepared using 2-Word-v2.0.template.dot.¶