SPRING Working Group Madhukar Anand Internet-Draft Sanjoy Bardhan Intended Status: Informational Ramesh Subrahmaniam Infinera Corporation Expires: September 21, 2016 March 20, 2016 Packet-Optical Integration in Segment Routing draft-anand-spring-poi-sr-00 Abstract This document illustrates a way to integrate a new class of nodes and links in segment routing to represent networks in an opaque way for further extensibility of the link-state protocols that help with segment routing. An instance of the opaque definition would be optical networks that are typically transport centric. In the IP centric network, this will help in defining a common control protocol for packet optical integration that will include optical paths as opaque 'segments' or sub-paths as an augmentation to the defined extensions of segment routing. This opaque option defines a general mechanism to allow for future extensibility of 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 RFC 2119 [RFC2119]. Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/1id-abstracts.html Anand et al., Expires September 21, 2016 [Page 1] Internet-Draft draft-anand-spring-poi-sr-00 March 20, 2016 The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html Copyright and License Notice Copyright (c) 2016 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 . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Reference Taxonomy . . . . . . . . . . . . . . . . . . . . . . 3 3. Use case - Packet Optical Integration . . . . . . . . . . . . . 3 4. Mechanism overview . . . . . . . . . . . . . . . . . . . . . . 5 5. IS-IS extensions for supporting the opaque adjacency segment . 6 6. OSPF extensions for supporting the opaque adjacency segment . 8 7. OSPFv3 extensions for supporting the opaque adjacency segment . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 8. BGP-LS extensions for supporting the opaque adjacency segment . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 8.1 Link Attribute TLVs . . . . . . . . . . . . . . . . . . . . 11 8.2 Opaque Adjacency SID TLV . . . . . . . . . . . . . . . . . . 12 9. PCEP-LS extensions for supporting the opaque adjacency segment . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 10. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 11. Security Considerations . . . . . . . . . . . . . . . . . . . 14 12 IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 13 References . . . . . . . . . . . . . . . . . . . . . . . . . . 14 13.1 Normative References . . . . . . . . . . . . . . . . . . . 14 13.2 Informative References . . . . . . . . . . . . . . . . . . 15 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15 Anand et al., Expires September 21, 2016 [Page 2] Internet-Draft draft-anand-spring-poi-sr-00 March 20, 2016 1 Introduction Packet and optical transport networks have evolved independently with different control plane mechanisms that have to be provisioned and maintained separately. Consequently, coordinating packet and optical networks for delivering services such as end-to-end traffic engineering or failure response has proved challenging. To address this challenge, a unified control and management paradigm that provides an incremental path to complete packet-optical integration while leveraging existing signaling and routing protocols in either domains is needed. This document introduces such a paradigm based on Segment Routing (SR) [I-D.ietf-spring-segment-routing]. This document introduces a new type of segment, Opaque Adjacency Segment. Opaque Adjacency Segment can be used to model abstracted paths through the optical transport domain and integrate it with the packet network for delivering end-to-end services. In addition, this also introduces a notion of a Packet optical gateway (POG). These are nodes in the network that map packet services to the optical domain that originate and terminate these opaque adjacency segments. Given an opaque adjacency, a POG will expand it to a path in the optical transport network. 2. Reference Taxonomy POG - Packet optical gateway Device SR Edge Router - The Edge Router which is the first SR capable device CE - Customer Edge Device that is outside of the SR domain PCE - Path Computation Engine Controller - A network controller 3. Use case - Packet Optical Integration Many operators build and operate their networks that are both multi- layer and multi-domain. Services are built around these layers and domains to provide end-to-end services. Due to the nature of the different domains, such as packet and optical, the management and service creation has always been problematic and time consuming. With segment routing, enabling a head-end node to select a path and embed the information in the packet is a powerful construct that would be Anand et al., Expires September 21, 2016 [Page 3] Internet-Draft draft-anand-spring-poi-sr-00 March 20, 2016 used in the Packet Optical Gateways (POG). The path is usually constructed for each domain that may be manually derived or through a stateful PCE which is run specifically in that domain. P1---------O1---------P2---------O2---------P3---------O3---------P4 Figure 1: Representation of a packet-optical path In Figure 1 above, the nodes represent a packet optical network. P1, P2, P3 and P4 are packet optical devices that are connected via optical paths O1, O2 and O3. Nodes P1 and P4 are edge devices that have customer facing devices (denoted as Border POGs) and P2 and P3 are core nodes (denoted as Transit POGs) in the network. A packet service is established by specifying a path between P1 and P4. Note that in defining this path, we will need to specify both the nodes and the links that make up this service. POGs advertise themselves along with their adjacencies and the domains they belong to. To leverage segment routing to define the above service, the ingress node P1 would append all outgoing packets in a SR header consisting of the SIDs that constitute the path. In the packet domain this would mean P1 would send its packets towards P4 using the segment list {P2, P4}. The operator would need to use a different mechanism in the optical domain to set up the optical paths denoted by O1, O2 and O3. Each POG would announce the active optical path as an opaque adjacency - for example, in the case of P1, the optical path O1 would represent an optical path that includes the optical nodes Om and On as shown on Figure 2. This path is not known to the packet SR domain and is only relevant to the optical domain D between P1 and P2. A PCE that is run in Domain D would be responsible for calculating path O1. |-----Om--------On-----| P1----| (D) |------P2 |-----Ox---------Oy----| Figure 2: POG with multiple optical paths through an optical domain Similarly, the transit POGs P2 and P3 in Figure 1 would announce opaque adjacencies O2 and O3. The border POG would include the optical paths O1, O2 and O3 to the segment list for P1 to P4. The expanded segment list would read as {O1, P2, O2, P3, O3, P4}. There are potentially two locations for Borders POGs - one that has last-mile access nodes and the other being Data Center Interconnect nodes. The POGs that are in the core of the network which connect with long haul optical networks are usually Transit POGs. Anand et al., Expires September 21, 2016 [Page 4] Internet-Draft draft-anand-spring-poi-sr-00 March 20, 2016 +------------------------+ | | +--------------+----' PCE or Controller |----+---------------+ | | | | | | | | +------------------------+ | | | | | | | | .-----. | | | | ( ) | | +-------+ +-------+ .--( )--. +-------+ +-------+ | SR | |Packet | ( ) |Packet | | SR | | Edge | |Optical|-( Optical Transport )_ |Optical| | Edge | |Router | ... |Gateway| ( Domain ) |Gateway| ... |Router | +---+.--+ +-------+ ( ) +-------+ +---+.--+ | '--( )--' | ,--+. ( ) ,-+-. ( CE ) '-----' ( CE ) `---' `---' Figure 3. Reference Topology for Opaque Adjacency Segment 4. Mechanism overview The current proposal assumes that the SR domains run standard IGP protocols to discover the topology and distribute labels without any modification. There are also no modifications to the control plane mechanisms in the Optical transport domains. The mechanism for supporting the opaque adjacency segment is as follows. 1. Firstly, the Packet Optical Gateway (POG) devices announce themselves in the SR domain. This is indicated by advertising a new SR node capability flag. The exact extensions to support this capability are described in the subsequent sections of this document. 2. Then, the POG devices announce paths to other POGs through the optical transport domain as an opaque adjacency segment (opaque adjacency SID) in the SR domain. The paths are announced with an appropriate transit domain type, optical transport domain ID, and a label to be used to bind to the opaque adjacency segment. The Anand et al., Expires September 21, 2016 [Page 5] Internet-Draft draft-anand-spring-poi-sr-00 March 20, 2016 appropriate IGP segment routing extensions to carry this information is described in the subsequent sections of this document. 3. The opaque adjacency segment can also optionally be announced with a set of attributes that characterizes the path in the optical transport domain between the two POG devices. For instance, those attributes could define the OTN mapping used (e.g., ODU4, ODU3,ODU3e1....ODU1), timeslots (1-8 or 4,6,7 or 1-2,5), or optical path protection schemes. 4. The POG device is also responsible for programming its forwarding table to map every opaque adjacency label entry into an appropriate forwarding action relevant in the optical domain, such as mapping it to a label-switched path. 5. The opaque adjacency segment is communicated to the PCE or Controller using extensions to BGP-LS or PCEP-LS as described in subsequent sections of this document. 6. Finally, the PCE or Controller then uses the opaque adjacency segment label to influence the path leaving the SR domain into the optical domain, thereby defining the end-to-end path for a given service. 5. IS-IS extensions for supporting the opaque adjacency segment A new IS-IS sub-TLV is defined: the Opaque Adjacency Segment Identifier sub-TLV (Opaque-Adj-SID sub-TLV). The Opaque-Adj-SID sub- TLV is an optional sub-TLV carrying the opaque adjacency SID with flags and fields that may be used, in future extensions of Segment Routing, for carrying other types of Opaque Adjacency SIDs. Multiple Opaque-Adj-SID sub-TLVs MAY be associated with a pair of POG devices to represent multiple paths within the optical domain with perhaps different characteristics. Anand et al., Expires September 21, 2016 [Page 6] Internet-Draft draft-anand-spring-poi-sr-00 March 20, 2016 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Flags | Weight | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Domain ID |Opaque Sub Type| Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Remote POG System ID | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Packet-Optical Label | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Where: Type: TBD, suggested value 33 Length: variable. Flags: 1 octet field of following flags: V - Value flag. If set, then the packet-optical label carries a value. By default the flag is SET. L - Local. Local Flag. If set, then the value/index carried by the Adj-SID has local significance. By default the flag is SET. 0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+ |V|L| +-+-+-+-+-+-+-+-+ Other bits: Reserved. These MUST be zero when sent and are ignored when received. Weight: TBD Domain ID: An identifier for the transport domain Opaque Sub Type: TBD Remote POG System-ID: 6 octets of IS-IS System-ID of length "ID Length" as defined in [ISO10589]. Packet-Optical Label : according to the V and L flags, it contains either: * A 3 octet local label where the 20 rightmost bits are used for encoding the label value. In this case the V and L flags MUST be set. Anand et al., Expires September 21, 2016 [Page 7] Internet-Draft draft-anand-spring-poi-sr-00 March 20, 2016 * A 4 octet index defining the offset in the label space advertised by this router. In this case V and L flags MUST be unset. Further, to communicate the Packet-Optical Gateway capability of the device, we introduce a new flag O in the SR Node Capabilities sub-TLV: 0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+ |I|V|H|O| | +-+-+-+-+-+-+-+-+ I, V, H flags are defined in [I-D.ietf-isis-segment-routing-extensions]. O-Flag: If set, then the router is capable of performing Packet Optical Gateway function. 6. OSPF extensions for supporting the opaque adjacency segment A new OSPF sub-TLV is defined: the Opaque Adjacency Segment Identifier sub-TLV (Opaque-Adj-SID sub-TLV). The Opaque-Adj-SID sub-TLV is an optional sub-TLV of the Extended Link TLV carrying the opaque adjacency SID with flags and fields that may be used, in future extensions of Segment Routing, for carrying other types of Opaque Adjacency SIDs. Multiple Opaque-Adj-SID sub-TLVs MAY be associated with a pair of POG devices to represent multiple paths within the optical domain with perhaps different characteristics. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flags | Reserved | MT-ID | Weight | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Domain ID |Opaque Sub Type| Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Remote POG Router-ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Packet-Optical Label | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Anand et al., Expires September 21, 2016 [Page 8] Internet-Draft draft-anand-spring-poi-sr-00 March 20, 2016 where: Type: TBD, suggested value 3 Length: variable. Flags: 1 octet field of following flags: V - Value flag. If set, then the optical label carries a value. By default the flag is SET. L - Local. Local Flag. If set, then the value/index carried by the Adj-SID has local significance. By default the flag is SET. 0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+ |V|L| +-+-+-+-+-+-+-+-+ Other bits: Reserved. These MUST be zero when sent and are ignored when received. MT-ID: Multi-Topology ID (as defined in [RFC4915]). Weight: TBD Domain ID: An identifier for the transport domain Opaque Sub Type: TBD Remote POG Router-ID: 4 octets of OSPF Router-ID Packet-Optical Label : according to the V and L flags, it contains either: * A 3 octet local label where the 20 rightmost bits are used for encoding the label value. In this case the V and L flags MUST be set. * A 4 octet index defining the offset in the label space advertised by this router. In this case V and L flags MUST be unset. Further, to communicate the Packet-Optical Gateway capability of the device, we introduce an new optical informational capability bit in the Router Information capabilities TLV (as defined in [RFC4970]). Bit-24 - Optical - If set, then the router is capable of performing Packet Optical Gateway function. Anand et al., Expires September 21, 2016 [Page 9] Internet-Draft draft-anand-spring-poi-sr-00 March 20, 2016 7. OSPFv3 extensions for supporting the opaque adjacency segment The Opaque-Adj-SID Sub-TLV is an optional Sub-TLV of the Router-Link TLV as defined in [I-D.ietf-ospf-ospfv3-lsa-extend]. It MAY appear multiple times in Router-Link TLV. Multiple Opaque-Adj-SID sub-TLVs MAY be associated with a pair of POG devices to represent multiple paths within the optical domain with perhaps different characteristics. The Opaque-Adj-SID Sub-TLV has the following format: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flags | Weight | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Domain ID |Opaque Sub Type| Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Remote POG Router-ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Packet-Optical Label | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ where: Type: TBD, suggested value 6 Length: variable. Flags: 1 octet field of following flags: V - Value flag. If set, then the optical label carries a value. By default the flag is SET. L - Local. Local Flag. If set, then the value/index carried by the Adj-SID has local significance. By default the flag is SET. 0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+ |V|L| +-+-+-+-+-+-+-+-+ Other bits: Reserved. These MUST be zero when sent and are ignored when received. Weight: TBD Anand et al., Expires September 21, 2016 [Page 10] Internet-Draft draft-anand-spring-poi-sr-00 March 20, 2016 Domain ID: An identifier for the transport domain Opaque Sub Type: TBD Remote POG Router-ID: 4 octets of OSPFv3 Router-ID Packet-Optical Label : according to the V and L flags, it contains either: * A 3 octet local label where the 20 rightmost bits are used for encoding the label value. In this case the V and L flags MUST be set. * A 4 octet index defining the offset in the label space advertised by this router. In this case V and L flags MUST be unset. Further, to communicate the Packet-Optical Gateway capability of the device, we introduce an new optical informational capability bit in the Router Information capabilities TLV (as defined in [RFC4970]). Bit-24 - Optical - If set, then the router is capable of performing Packet Optical Gateway function. 8. BGP-LS extensions for supporting the opaque adjacency segment 8.1 Link Attribute TLVs The following new Link Attribute TLVs are defined: +-----------+----------------------------+----------+---------------+ | TLV Code | Description | Length | Section | | Point | | | | +-----------+----------------------------+----------+---------------+ | 1101 | Opaque Adjacency Segment | variable | | | | Identifier (Opq-Adj-SID)TLV| | | +-----------+----------------------------+----------+---------------+ Table 1: BGP-LS Link Attribute TLVs These TLVs can ONLY be added to the Link Attribute associated with the link whose local node originates the corresponding SR TLV. The Opaque adjacency segment TLV allows a node to advertise an opaque adjacency within a single IGP domain. Anand et al., Expires September 21, 2016 [Page 11] Internet-Draft draft-anand-spring-poi-sr-00 March 20, 2016 8.2 Opaque Adjacency SID TLV The Opaque Adjacency SID (Opq-Adj-SID) TLV has the following format: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Flags | Weight | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Domain ID |Opaque Sub Type| Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Remote POG System ID/Router-ID | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Packet-Optical Label | +---------------------------------------------------------------+ Where: Type: TBD, suggested value 1101. Length: Variable. Flags: 1 octet field of following flags as defined in the previous sections for IS-IS and OSPF. Weight: TBD. Domain ID: An identifier for the optical transport domain Opaque Sub Type : TBD Remote POG Router-ID/System-ID: 4 octets of OSPF Router-ID or 6 Octets of IS-IS System ID. Packet-Optical Label: 4 octet field carrying the label as defined in the previous sections for IS-IS and OSPF. 9. PCEP-LS extensions for supporting the opaque adjacency segment Changes similar to BGP-LS are needed for supporting the opaque adjacency segment in PCEP-LS. Details TBD. Anand et al., Expires September 21, 2016 [Page 12] Internet-Draft draft-anand-spring-poi-sr-00 March 20, 2016 10. Summary The motivation for introducing an opaque adjacency segment that is separate from an IGP adjacency segment is to distinguish between a real IGP adjacency (which is typically a symmetric relationship between the devices that share a route flooding domain), and a relationship between devices in potentially two different domains such as packet and optical domains with no real IGP adjacency. Further, the opaque adjacency segment can carry optional information that is of significance only in the optical domain, and hence, opaque, to the IGPs. This is specifically useful if the optical domain is bridging the same IGP domain, then, the POG can attach both the adjacency SID and the opaque adjacency SID to influence the end-to-end path in the packet and optical domains respectively. Anand et al., Expires September 21, 2016 [Page 13] Internet-Draft draft-anand-spring-poi-sr-00 March 20, 2016 11. Security Considerations This document does not introduce any new security considerations. 12 IANA Considerations TBD. 13 References 13.1 Normative References [I-D.ietf-spring-segment-routing] Filsfils, C., Previdi, S., Decraene, B., Litkowski, S., and r. rjs@rob.sh, "Segment Routing Architecture", draft- ietf-spring-segment-routing-04 (work in progress), July 2015. [I-D.ietf-isis-segment-routing-extensions] Previdi, S., Filsfils, C., Bashandy, A., Gredler, H., Litkowski, S., Decraene, B., and J. Tantsura, "IS-IS Extensions for Segment Routing", draft-ietf-isis-segment- routing-extensions-05 (work in progress), June 2015. [I-D.ietf-ospf-segment-routing-extensions] Psenak, P., Previdi, S., Filsfils, C., Gredler, H., Shakir, R., Henderickx, W., and J. Tantsura, "OSPF Extensions for Segment Routing", draft-ietf-ospf-segment- routing-extensions-05 (work in progress), June 2015. [RFC4915] L. Nguyen, P. Psenak, S. Mirtorabi, P. Pillay-Esnault, and A. Roy, "Multi-Topology (MT) Routing in OSPF.", RFC4915, . [I-D.ietf-ospf-ospfv3-segment-routing-extensions] Psenak, P., Previdi, S., Filsfils, C., Gredler, H., Shakir, R., Henderickx, W., and J. Tantsura, "OSPFv3 Extensions for Segment Routing", draft-ietf-ospf-ospfv3- segment-routing-extensions-03 (work in progress), June 2015. [I-D.ietf-idr-ls-distribution] Gredler, H., Medved, J., Previdi, S., Farrel, A., and S. Anand et al., Expires September 21, 2016 [Page 14] Internet-Draft draft-anand-spring-poi-sr-00 March 20, 2016 Ray, "North-Bound Distribution of Link-State and TE Information using BGP", draft-ietf-idr-ls-distribution-13 (work in progress), October 2015. [RFC4970] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and S. Shaffer, "Extensions to OSPF for Advertising Optional Router Capabilities", RFC 4970, DOI 10.17487/RFC4970, July 2007, . 13.2 Informative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . Authors' Addresses Madhukar Anand Infinera Corporation 169 W Java Dr, Sunnyvale, CA 94089 Email: manand@infinera.com Sanjoy Bardhan Infinera Corporation 169 W Java Dr, Sunnyvale, CA 94089 Email: sbardhan@infinera.com Ramesh Subrahmaniam Infinera Corporation 169 W Java Dr, Sunnyvale, CA 94089 Email: RSubrahmaniam@@infinera.com Anand et al., Expires September 21, 2016 [Page 15]