SPRING Working Group S. Litkowski Internet-Draft Orange Business Service Intended status: Standards Track Y. Qu Expires: January 21, 2016 Cisco Systems P. Sarkar Juniper Networks J. Tantsura Ericsson July 20, 2015 YANG Data Model for Segment Routing draft-ietf-spring-sr-yang-00 Abstract This document defines a YANG data model ([RFC6020]) for segment routing ([I-D.ietf-spring-segment-routing]) configuration and operation. This YANG model is intended to be used on network elements to configure or operate segment routing. This document defines also generic containers that SHOULD be reused by IGP protocol modules to support segment routing. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on January 21, 2016. Litkowski, et al. Expires January 21, 2016 [Page 1]
Internet-Draft sr-yang-cfg July 2015 Copyright Notice Copyright (c) 2015 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 (http://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 Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Tree diagram . . . . . . . . . . . . . . . . . . . . . . 3 2. Design of the Data Model . . . . . . . . . . . . . . . . . . 3 3. Configuration . . . . . . . . . . . . . . . . . . . . . . . . 5 4. IGP Control plane configuration . . . . . . . . . . . . . . . 6 4.1. IGP interface configuration . . . . . . . . . . . . . . . 6 4.1.1. Adjacency SID properties . . . . . . . . . . . . . . 6 4.1.1.1. Bundling . . . . . . . . . . . . . . . . . . . . 6 4.1.1.2. Protection . . . . . . . . . . . . . . . . . . . 7 5. States . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 6. Notifications . . . . . . . . . . . . . . . . . . . . . . . . 7 7. YANG Module . . . . . . . . . . . . . . . . . . . . . . . . . 8 8. Security Considerations . . . . . . . . . . . . . . . . . . . 20 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 20 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 11. Normative References . . . . . . . . . . . . . . . . . . . . 21 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21 1. Introduction This document defines a YANG data model for segment routing configuration and operation. This document does not define the IGP extensions to support segment routing but defines generic groupings that SHOULD be reused by IGP extension modules. The reason of this design choice is to not require implementations to support all IGP extensions. For example, an implementation may support IS-IS extension but not OSPF. Litkowski, et al. Expires January 21, 2016 [Page 2]
Internet-Draft sr-yang-cfg July 2015 1.1. Tree diagram A simplified graphical representation of the data model is presented in Section 2. The meaning of the symbols in these diagrams is as follows: o Brackets "[" and "]" enclose list keys. o Curly braces "{" and "}" contain names of optional features that make the corresponding node conditional. o Abbreviations before data node names: "rw" means configuration (read-write), and "ro" state data (read-only). o Symbols after data node names: "?" means an optional node and "*" denotes a "list" or "leaf-list". o Parentheses enclose choice and case nodes, and case nodes are also marked with a colon (":"). o Ellipsis ("...") stands for contents of subtrees that are not shown. 2. Design of the Data Model As the module definition is just starting, it is expected that there will be changes as the module matures. module: ietf-segment-routing augment /rt:routing/rt:routing-instance: +--rw segment-routing +--rw transport-type? identityref +--rw bindings | +--rw mapping-server {mapping-server}? | | +--rw policy* [name] | | +--rw name string | | +--rw ipv4 | | | +--rw mapping-entry* [prefix] | | | +--rw prefix inet:ipv4-prefix | | | +--rw value-type? enumeration | | | +--rw start-sid uint32 | | | +--rw range? uint32 | | +--rw ipv6 | | +--rw mapping-entry* [prefix] | | +--rw prefix inet:ipv6-prefix | | +--rw value-type? enumeration | | +--rw start-sid uint32 Litkowski, et al. Expires January 21, 2016 [Page 3]
Internet-Draft sr-yang-cfg July 2015 | | +--rw range? uint32 | +--rw connected-prefix-sid-map | +--rw ipv4 | | +--rw ipv4-prefix-sid* [prefix] | | +--rw prefix inet:ipv4-prefix | | +--rw value-type? enumeration | | +--rw start-sid uint32 | | +--rw range? uint32 | | +--rw last-hop-behavior? enumeration {sid-last-hop-behavior}? | +--rw ipv6 | +--rw ipv6-prefix-sid* [prefix] | +--rw prefix inet:ipv6-prefix | +--rw value-type? enumeration | +--rw start-sid uint32 | +--rw range? uint32 | +--rw last-hop-behavior? enumeration {sid-last-hop-behavior}? +--rw srgb* [lower-bound upper-bound] +--rw lower-bound uint32 +--rw upper-bound uint32 augment /rt:routing-state/rt:routing-instance: +--ro segment-routing +--ro node-capabilities | +--ro transport-planes* [transport-plane] | | +--ro transport-plane identityref | +--ro segment-stack-push-limit? uint8 | +--ro readable-label-stack-depth? uint8 +--ro label-blocks* | +--ro lower-bound? uint32 | +--ro upper-bound? uint32 | +--ro size? uint32 | +--ro free? uint32 | +--ro used? uint32 +--ro global-sid-list +--ro sid* [target sid source source-protocol binding-type] +--ro target string +--ro sid uint32 +--ro algorithm? uint8 +--ro source inet:ip-address +--ro used? boolean +--ro source-protocol leafref +--ro binding-type enumeration notifications: +---n segment-routing-global-sid-collision | +--ro received-target? string | +--ro original-target? string | +--ro index? uint32 | +--ro routing-protocol? leafref +---n segment-routing-index-out-of-range Litkowski, et al. Expires January 21, 2016 [Page 4]
Internet-Draft sr-yang-cfg July 2015 +--ro received-target? string +--ro received-index? uint32 +--ro routing-protocol? leafref 3. Configuration This module augments the "/rt:routing/rt:routing-instance:" with a segment-routing container. This container defines all the configuration parameters related to segment-routing for this particular routing-instance. The segment-routing configuration is split in global routing-instance configuration and interface configuration. The global configuration includes : o segment-routing transport type : The underlying transport type for segment routing. The version of the model limits the transport type to an MPLS dataplane. The transport-type is only defined once for a particular routing-instance and is agnostic to the control plane used. Only a single transport-type is supported in this version of the model. o bindings : Defines prefix to SID mappings. The operator can control advertisement of Prefix-SID independently for IPv4 and IPv6. Two types of mappings are available : * Mapping-server : maps non local prefixes to a segment ID. Configuration of bindings does not automatically allow advertisement of those bindings. Advertisement must be controlled by each routing-protocol instance (see Section 4). Multiple mapping policies may be defined. * Connected prefixes : maps connected prefixes to a segment ID. Advertisement of the mapping will be done by IGP when enabled for segment routing (see Section 4). The SID value can be expressed as an index (default), or an absolute value. The "last-hop-behavior" configuration dictates the PHP behavior: "explicit-null", "php", or "non-php". o SRGB (Segment Routing Global Block): Defines a list of label blocks represented by a pair of lower-bound/upper-bound labels. The SRGB is also agnostic to the control plane used. So all routing-protocol instance will have to advertise the same SRGB. Litkowski, et al. Expires January 21, 2016 [Page 5]
Internet-Draft sr-yang-cfg July 2015 4. IGP Control plane configuration Support of segment-routing extensions for a particular IGP control plane is done by augmenting routing-protocol configuration with segment-routing extensions. This augmentation SHOULD be part of separate YANG modules in order to not create any dependency for implementations to support all protocol extensions. This module defines groupings that SHOULD be used by IGP segment routing modules. The "controlplane-cfg" grouping defines the generic global configuration for the IGP. The "enabled" leaf enables segment-routing extensions for the routing-protocol instance. The "bindings" container controls the routing-protocol instance's advertisement of local bindings and the processing of received bindings. 4.1. IGP interface configuration The interface configuration is part of the "igp-interface-cfg" grouping and includes Adjacency SID properties. 4.1.1. Adjacency SID properties 4.1.1.1. Bundling This section is a first proposal on how to use S-bit in Adj-SID to create bundles. Authors would like to trigger discussion based on this first proposal. In case of parallel IP links between routers, an additional Adjacency SID may be advertised representing more than one adjacency (i.e., a bundle of adjacencies). The "advertise-adj-group-sid" configuration controls whether or not an additional adjacency SID is advertised. The "advertise-adj-group-sid" would be a list of "group-id". The "group-id" will permit to identify interfaces that must be bundled together. Litkowski, et al. Expires January 21, 2016 [Page 6]
Internet-Draft sr-yang-cfg July 2015 +-------+ +------+ | | ------- L1 ---- | | | R1 | ------- L2 ---- | R2 | | | ------- L3 ---- | | | | ------- L4 ---- | | +-------+ +------+ In the figure above, R1 and R2 are interconnected by four links. A routing protocol adjacency is established on each link. Operator would like to create segment-routing Adj-SID that represent some bundles of links. We can imagine two different bundles : L1/L2 and L2/L3. To achieve this behavior, the service provider will configure a "group-id" X for both interfaces L1 and L2 and a "group-id" Y for both interfaces L3 and L3. This will result in R1 advertising an additional Adj-SID for each adjacency, for example a Adj-SID with S flag set and value of 400 will be added to L1 and L2. A Adj-SID with S flag set and value of 500 will be added to L3 and L4. As L1/L2 and L3/L4 does not share the same "group-id", a different SID value will be allocated. 4.1.1.2. Protection The "advertise-protection" defines how protection for an interface is advertised. It does not control the activation or deactivation of protection. If the "single" option is used, a single Adj-SID will be advertised for the interface. If the interface is protected, the B-Flag for the Adj-SID advertisement will be set. If the "dual" option is used and if the interface is protected, two Adj-SIDs will be advertised for the interface adjacencies. One Adj-SID will always have the B-Flag set and the other will have the B-Flag clear. This option is intended to be used in the case of traffic engineering where a path must use either protected segments or non-protected segments. 5. States The operational states contains information reflecting the usage of allocated SRGB labels. It also includes a list of all global SIDs, their associated bindings, and other information such as the source protocol and algorithm. 6. Notifications The model proposes two notifications for segment-routing. Litkowski, et al. Expires January 21, 2016 [Page 7]
Internet-Draft sr-yang-cfg July 2015 o segment-routing-global-sid-collision: Raised when a control plane advertised index is already associated with another target (in this version, the only defined targets are IPv4 and IPv6 prefixes). o segment-routing-index-out-of-range: Raised when a control plane advertised index fall outside the range of SRGBs configured for the network device. 7. YANG Module <CODE BEGINS> file "ietf-segment-routing@2015-06-22.yang" module ietf-segment-routing { namespace "urn:ietf:params:xml:ns:" + "yang:ietf-segment-routing"; prefix sr; import ietf-inet-types { prefix "inet"; } import ietf-routing { prefix "rt"; } organization "IETF SPRING Working Group"; contact "WG List: <mailto:spring@ietf.org> Editor: Stephane Litkowski <mailto:stephane.litkowski@orange.com> Acee Lindem <mailto:acee@cisco.com> Yingzhen Qu <mailto:yiqu@cisco.com> Pushpasis Sarkar <mailto:psarkar@juniper.net> Ing-Wher Chen <mailto:ing-wher.chen@ericsson.com> Jeff Tantsura <jeff.tantsura@ericsson.com> "; Litkowski, et al. Expires January 21, 2016 [Page 8]
Internet-Draft sr-yang-cfg July 2015 description "The YANG module defines a generic configuration model for Segment routing common across all of the vendor implementations."; revision 2015-06-22 { description " * Prefix SID config moved to connected-prefix-sid-map in global SR cfg rather than IGP. "; reference "draft-litkowski-spring-sr-yang-01"; } revision 2015-04-23 { description " * Node flag deprecated from prefixSID * SR interface cfg moved to protocol * Adding multiple binding policies for SRMS "; reference ""; } revision 2015-02-27 { description "Initial"; reference "draft-litkowski-spring-sr-yang-00"; } /* Identities */ identity segment-routing-transport { description "Base identity for segment routing transport."; } identity segment-routing-transport-mpls { base segment-routing-transport; description "This identity represents MPLS transport for segment routing."; } /* Features */ feature mapping-server { description "Support of SRMS."; } feature sid-last-hop-behavior { description Litkowski, et al. Expires January 21, 2016 [Page 9]
Internet-Draft sr-yang-cfg July 2015 "Configurable last hop behavior."; } /* Groupings */ grouping controlplane-cfg { container segment-routing { leaf enabled { type boolean; default false; description "Enables segment-routing protocol extensions."; } container bindings { container advertise { leaf-list policies { type string; description "List of policies to be advertised."; } description "Authorize the advertise of local mappings in binding TLV."; } leaf receive { type boolean; default true; description "Authorize the reception and usage of binding TLV."; } description "Control of binding advertisement and reception."; } description "segment routing global config."; } description "Defines protocol configuration."; } grouping sid-value-type { leaf value-type { type enumeration { enum index { Litkowski, et al. Expires January 21, 2016 [Page 10]
Internet-Draft sr-yang-cfg July 2015 description "The value will be interpreted as an index."; } enum absolute { description "The value will become interpreted as an absolute value."; } } default index; description "This leaf defines how value must be interpreted."; } description "Defines how the SID value is expressed."; } grouping ipv4-sid-cfg { leaf prefix { type inet:ipv4-prefix; description "connected prefix sid."; } uses sid-value-type; leaf start-sid { type uint32; mandatory true; description "Value associated with prefix. The value must be interpreted in the context of value-type."; } leaf range { type uint32; description "Describes how many SIDs could be allocated."; } description "This grouping defines cfg of prefix SID."; Litkowski, et al. Expires January 21, 2016 [Page 11]
Internet-Draft sr-yang-cfg July 2015 } grouping ipv6-sid-cfg { leaf prefix { type inet:ipv6-prefix; description "connected prefix sid."; } uses sid-value-type; leaf start-sid { type uint32; mandatory true; description "Value associated with prefix. The value must be interpreted in the context of value-type."; } leaf range { type uint32; description "Describes how many SIDs could be allocated."; } description "This grouping defines cfg of prefix SID."; } grouping last-hop-behavior { leaf last-hop-behavior { if-feature sid-last-hop-behavior; type enumeration { enum explicit-null { description "Use explicit-null for the SID."; } enum no-php { description "Do no use PHP for the SID."; } enum php { description "Use PHP for the SID."; } Litkowski, et al. Expires January 21, 2016 [Page 12]
Internet-Draft sr-yang-cfg July 2015 } description "Configure last hop behavior."; } description "Defines last hop behavior"; } grouping igp-interface-cfg { container segment-routing { container adjacency-sid { list advertise-adj-group-sid { key group-id; leaf group-id { type uint32; description "The value is an internal value to identify a group-ID. Interfaces with the same group-ID will be bundled together. "; } description "Control advertisement of S flag. Enable to advertise a common Adj-SID for parallel links."; } leaf advertise-protection { type enumeration { enum "single" { description "A single Adj-SID is associated with the adjacency and reflects the protection configuration."; } enum "dual" { description "Two Adj-SIDs will be associated with the adjacency if interface is protected. In this case one will be enforced with backup flag set, the other will be enforced to backup flag unset. In case, protection is not configured, a single Adj-SID will be advertised with backup flag unset."; Litkowski, et al. Expires January 21, 2016 [Page 13]
Internet-Draft sr-yang-cfg July 2015 } } description "If set, the Adj-SID refers to an adjacency being protected."; } description "Defines the adjacency SID properties."; } description "container for SR interface cfg."; } description "Grouping for IGP interface cfg."; } /* Cfg */ augment "/rt:routing/rt:routing-instance" { description "This augments routing-instance configuration with segment-routing."; container segment-routing { leaf transport-type { type identityref { base segment-routing-transport; } default "segment-routing-transport-mpls"; description "Dataplane to be used."; } container bindings { container mapping-server { if-feature mapping-server; list policy { key name; leaf name { type string; description "Name of the mapping policy."; } container ipv4 { list mapping-entry { key prefix; uses ipv4-sid-cfg; description "Mapping entries."; } Litkowski, et al. Expires January 21, 2016 [Page 14]
Internet-Draft sr-yang-cfg July 2015 description "IPv4 mapping entries."; } container ipv6 { list mapping-entry { key prefix; uses ipv6-sid-cfg; description "Mapping entries."; } description "IPv6 mapping entries."; } description "Definition of mapping policy."; } description "Configuration of mapping-server local entries."; } container connected-prefix-sid-map { container ipv4 { list ipv4-prefix-sid { key prefix; uses ipv4-sid-cfg; uses last-hop-behavior; description "List of prefix SID mapped to IPv4 local prefixes."; } description "Parameters associated with IPv4 prefix SID"; } container ipv6 { list ipv6-prefix-sid { key prefix; uses ipv6-sid-cfg; uses last-hop-behavior; description "List of prefix SID mapped to IPv6 local prefixes."; } description "Parameters associated with IPv6 prefix SID"; } description "Prefix SID configuration."; } Litkowski, et al. Expires January 21, 2016 [Page 15]
Internet-Draft sr-yang-cfg July 2015 description "List of bindings."; } list srgb { key "lower-bound upper-bound"; ordered-by user; leaf lower-bound { type uint32; description "Lower value in the block."; } leaf upper-bound { type uint32; description "Upper value in the block."; } description "List of global blocks to be advertised."; } description "segment routing global config."; } } /* Operational states */ augment "/rt:routing-state/rt:routing-instance" { description "This augments the operational states with segment-routing."; container segment-routing { container node-capabilities { list transport-planes { key transport-plane; leaf transport-plane { type identityref { base segment-routing-transport; } description "Transport plane supported"; } description "List of supported transport planes."; } leaf segment-stack-push-limit { type uint8; Litkowski, et al. Expires January 21, 2016 [Page 16]
Internet-Draft sr-yang-cfg July 2015 description "Describes the number of segments that can be pushed by the node."; } leaf readable-label-stack-depth { type uint8; description "Number of MPLS labels that can be read in the stack."; } description "Shows the SR capability of the node."; } list label-blocks { leaf lower-bound { type uint32; description "Lower bound of the label block."; } leaf upper-bound { type uint32; description "Upper bound of the label block."; } leaf size { type uint32; description "Number of indexes in the block."; } leaf free { type uint32; description "Number of indexes free in the block."; } leaf used { type uint32; description "Number of indexes used in the block."; } description "List of labels blocks currently in use."; } container global-sid-list { list sid { key "target sid source source-protocol binding-type"; ordered-by system; Litkowski, et al. Expires January 21, 2016 [Page 17]
Internet-Draft sr-yang-cfg July 2015 leaf target { type string; description "Defines the target of the binding. It can be a prefix or something else."; } leaf sid { type uint32; description "Index associated with the prefix."; } leaf algorithm { type uint8; description "Algorithm to be used for the prefix SID."; } leaf source { type inet:ip-address; description "IP address of the router than own the binding."; } leaf used { type boolean; description "Defines if the binding is used in forwarding plane."; } leaf source-protocol { type leafref { path "/rt:routing-state/rt:routing-instance/" + "rt:routing-protocols/rt:routing-protocol/rt:name"; } description "Rtg protocol that owns the binding"; } leaf binding-type { type enumeration { enum prefix-sid { description "Binding is learned from a prefix SID."; } enum binding-tlv { description "Binding is learned from a binding TLV."; Litkowski, et al. Expires January 21, 2016 [Page 18]
Internet-Draft sr-yang-cfg July 2015 } } description "Type of binding."; } description "Binding."; } description "List of prefix and SID associations."; } description "Segment routing operational states."; } } /* Notifications */ notification segment-routing-global-sid-collision { leaf received-target { type string; description "Target received in the controlplane that caused SID collision."; } leaf original-target { type string; description "Target already available in database that have the same SID as the received target."; } leaf index { type uint32; description "Value of the index used by two different prefixes."; } leaf routing-protocol { type leafref { path "/rt:routing-state/rt:routing-instance/" + "rt:routing-protocols/rt:routing-protocol/rt:name"; } description "Routing protocol reference that received the event."; } description "This notification is sent when a new mapping is learned Litkowski, et al. Expires January 21, 2016 [Page 19]
Internet-Draft sr-yang-cfg July 2015 , containing mapping where the SID is already used. The notification generation must be throttled with at least a 5 second gap. "; } notification segment-routing-index-out-of-range { leaf received-target { type string; description "Target received in the controlplane that caused SID collision."; } leaf received-index { type uint32; description "Value of the index received."; } leaf routing-protocol { type leafref { path "/rt:routing-state/rt:routing-instance/" + "rt:routing-protocols/rt:routing-protocol/rt:name"; } description "Routing protocol reference that received the event."; } description "This notification is sent when a binding is received, containing a segment index which is out of the local configured ranges. The notification generation must be throttled with at least a 5 second gap. "; } } <CODE ENDS> 8. Security Considerations TBD. 9. Acknowledgements Authors would like to thank Derek Yeung, Acee Lindem, Greg Hankins, Hannes Gredler, Uma Chunduri, Jeffrey Zhang, Shradda Hedge for their contributions. Litkowski, et al. Expires January 21, 2016 [Page 20]
Internet-Draft sr-yang-cfg July 2015 10. IANA Considerations TBD. 11. Normative References [I-D.ietf-spring-segment-routing] Filsfils, C., Previdi, S., Decraene, B., Litkowski, S., and R. Shakir, "Segment Routing Architecture", draft-ietf- spring-segment-routing-03 (work in progress), May 2015. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, October 2010. Authors' Addresses Stephane Litkowski Orange Business Service Email: stephane.litkowski@orange.com Yingzhen Qu Cisco Systems Email: yiqu@cisco.com Pushpasis Sarkar Juniper Networks Email: psarkar@juniper.net Jeff Tantsura Ericsson Email: jeff.tantsura@ericsson.com Litkowski, et al. Expires January 21, 2016 [Page 21]