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| | A YANG Data Model for OSPF Segment Routing for the MPLS Data Plane |
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This document defines a YANG data module that can be used to configure and manage OSPF Extensions for Segment Routing for the MPLS data plane. |
| | A YANG Data Model for IS-IS Segment Routing for the MPLS Data Plane |
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| | draft-ietf-isis-sr-yang-21.txt |
| | Date: |
22/01/2024 |
| | Authors: |
Stephane Litkowski, Yingzhen Qu, Pushpasis Sarkar, Helen Chen, Jeff Tantsura |
| | Working Group: |
Link State Routing (lsr) |
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This document defines a YANG data module that can be used to configure and manage IS-IS Segment Routing for MPLS data plane. |
| | Dynamic Flooding on Dense Graphs |
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Routing with link state protocols in dense network topologies can result in sub-optimal convergence times due to the overhead associated with flooding. This can be addressed by decreasing the flooding topology so that it is less dense. This document discusses the problem in some depth and an architectural solution. Specific protocol changes for IS-IS, OSPFv2, and OSPFv3 are described in this document. |
| | OSPF YANG Model Augmentations for Additional Features - Version 1 |
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This document defines YANG data modules augmenting the IETF OSPF YANG model to provide support for Traffic Engineering Extensions to OSPF Version 3 as defined in RF 5329, OSPF Two-Part Metric as defined in RFC 8042, OSPF Graceful Link Shutdown as defined in RFC 8379, OSPF Link-Local Signaling (LLS) Extensions for Local Interface ID Advertisement as defined in RFC 8510, OSPF MSD as defined in RFC 8476, OSPF Application-Specific Link Attributes as defined in RFC 8920, and OSPF Flexible Algorithm. |
| | YANG Model for OSPFv3 Extended LSAs |
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This document defines a YANG data model augmenting the IETF OSPF YANG model to provide support for OSPFv3 Link State Advertisement (LSA) Extensibility as defined in RFC 8362. OSPFv3 Extended LSAs provide extensible TLV-based LSAs for the base LSA types defined in RFC 5340. |
| | Flooding Topology Minimum Degree Algorithm |
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This document proposes an algorithm for a node to compute a flooding topology, which is a subgraph of the complete topology per underline physical network. When every node in an area automatically calculates a flooding topology by using a same algorithm and floods the link states using the flooding topology, the amount of flooding traffic in the network is greatly reduced. This would reduce convergence time with a more stable and optimized routing environment. |
| | Area Proxy for IS-IS |
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Link state routing protocols have hierarchical abstraction already built into them. However, when lower levels are used for transit, they must expose their internal topologies to each other, leading to scale issues. To avoid this, this document discusses extensions to the IS-IS routing protocol that allow level 1 areas to provide transit, yet only inject an abstraction of the level 1 topology into level 2. Each level 1 area is represented as a single level 2 node, thereby enabling greater scale. |
| | IS-IS Topology-Transparent Zone |
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| | draft-ietf-lsr-isis-ttz-09.txt |
| | Date: |
29/03/2024 |
| | Authors: |
Huaimo Chen, Richard LI, Yi Yang, N Anil, Yanhe Fan, Ning So, Vic liu, Mehmet Toy, Lei Liu, Kiran Makhijani |
| | Working Group: |
Link State Routing (lsr) |
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This document specifies a topology-transparent zone in an IS-IS area. A zone is a subset (block/piece) of an area, which comprises a group of routers and a number of circuits connecting them. It is abstracted as a virtual entity such as a single virtual node or zone edges mesh. Any router outside of the zone is not aware of the zone. The information about the circuits and routers inside the zone is not distributed to any router outside of the zone. |
| | Extensions to OSPF for Advertising Prefix Administrative Tags |
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It is useful for routers in OSPFv2 and OSPFv3 routing domains to be able to associate tags with prefixes. Previously, OSPFv2 and OSPFv3 were relegated to a single tag and only for AS External and Not-So- Stubby-Area (NSSA) prefixes. With the flexible encodings provided by OSPFv2 Prefix/Link Attribute Advertisement and OSPFv3 Extended LSAs, multiple administrative tags may be advertised for all types of prefixes. These administrative tags can be used for many applications including route redistribution policy, selective prefix prioritization, selective IP Fast-ReRoute (IPFRR) prefix protection, and many others. The ISIS protocol supports a similar mechanism that is described in RFC 5130. |
| | IS-IS YANG Model Augmentations for Additional Features - Version 1 |
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This document defines YANG data modules augmenting the IETF IS-IS YANG model to provide support for IS-IS Minimum Remaining Lifetime as defined in RFC 7987, IS-IS Application-Specific Link Attributes as defined in RFC 8919, IS-IS Flexible Algorithm as defined in RFC 9350, and Signaling Maximum SID Depth Using IS-IS as defined in RFC 8491. |
| | Applicability of IS-IS Multi-Topology (MT) for Segment Routing based Network Resource Partition (NRP) |
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Enhanced VPNs aim to deliver VPN services with enhanced characteristics, such as guaranteed resources, latency, jitter, etc., so as to support customers requirements for connectivity services with these enhanced characteristics. Enhanced VPN requires integration between the overlay VPN connectivity and the characteristics provided by the underlay network. A Network Resource Partition (NRP) is a subset of the network resources and associated policies on each of a connected set of links in the underlay network. An NRP could be used as the underlay to support one or a group of enhanced VPN services. In some network scenarios, each NRP can be associated with a unique logical network topology. This document describes a mechanism to build the SR-based NRPs using IS-IS Multi-Topology together with other well-defined IS-IS extensions. |
| | OSPF-GT (Generalized Transport) |
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OSPFv2 and OSPFv3 include a reliable flooding mechanism to disseminate routing topology and Traffic Engineering (TE) information within a routing domain. Given the effectiveness of these mechanisms, it is advantageous to use the same mechanism for dissemination of other types of information within the domain. However, burdening OSPF with this additional information will impact intra-domain routing convergence and possibly jeopardize the stability of the OSPF routing domain. This document presents mechanisms to advertise this non-routing information in separate OSPF Generalized Transport (OSPF-GT) instances. OSPF-GT is not constrained to the semantics as traditional OSPF. OSPF-GT neighbors are not required to be directly attached since they are never used to compute hop-by-hop routing. Consequently, independent sparse topologies can be defined to dissemenate non- routing information only to those OSPF-GT routers requiring it. |
| | Flexible Algorithms: Bandwidth,Delay,Metrics and Constraints |
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Many networks configure the link metric relative to the link capacity. High bandwidth traffic gets routed as per the link capacity. Flexible algorithms provide mechanisms to create constraint based paths in IGP. This draft documents a generic metric type and set of bandwidth related constraints to be used in Flexible Algorithms. |
| | Algorithm Related IGP-Adjacency SID Advertisement |
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Segment Routing architecture supports the use of multiple routing algorithms, i.e., different constraint-based shortest-path calculations can be supported. There are two standard algorithms: SPF and Strict-SPF, defined in Segment Routing architecture. There are also other user defined algorithms according to Flex-algo applicaiton. However, an algorithm identifier is often included as part of a Prefix-SID advertisement, that maybe not satisfy some scenarios where multiple algorithm share the same link resource. This document complement that the algorithm identifier can be also included as part of a Adjacency-SID advertisement. |
| | YANG Data Model for OSPF SRv6 |
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This document defines a YANG data model that can be used to configure and manage OSPFv3 Segment Routing over the IPv6 Data Plane. |
| | YANG Data Model for IS-IS SRv6 |
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This document defines a YANG data model that can be used to configure and manage IS-IS Segment Routing over the IPv6 Data Plane. |
| | IS-IS Fast Flooding |
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| | draft-ietf-lsr-isis-fast-flooding-09.txt |
| | Date: |
10/04/2024 |
| | Authors: |
Bruno Decraene, Les Ginsberg, Tony Li, Guillaume Solignac, Marek Karasek, Gunter Van de Velde, Tony Przygienda |
| | Working Group: |
Link State Routing (lsr) |
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Current Link State Protocol Data Unit (PDU) flooding rates are much slower than what modern networks can support. The use of IS-IS at larger scale requires faster flooding rates to achieve desired convergence goals. This document discusses the need for faster flooding, the issues around faster flooding, and some example approaches to achieve faster flooding. It also defines protocol extensions relevant to faster flooding. |
| | IS-IS Optimal Distributed Flooding for Dense Topologies |
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In dense topologies (such as data center fabrics based on the Clos and butterfly topologies, though not limited to those exclusively), IGP flooding mechanisms designed originally for sparse topologies can "overflood," or in other words generate too many identical copies of topology and reachability information arriving at a given node from other devices. This normally results in slower convergence times and higher resource utilization to process and discard the superfluous copies. The modifications to the flooding mechanism in the Intermediate System to Intermediate System (IS-IS) link state protocol described in this document reduce resource utilization significantly, while increaseing convergence performance in dense topologies. Beside reducing the extraneous copies it uses the dense topologies to "load-balance" flooding across different possible paths in the network to prevent build up of flooding hot-spots. Note that a Clos fabric is used as the primary example of a dense flooding topology throughout this document. However, the flooding optimizations described in this document apply to any arbitrary topology. |
| | IGP Flexible Algorithms Reverse Affinity Constraint |
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An IGP Flexible Algorithm (Flex-Algorithm) allows IGPs to compute constraint-based paths. This document extends IGP Flex-Algorithm with additional constraints. |
| | IGP Unreachable Prefix Announcement |
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In the presence of summarization, there is a need to signal loss of reachability to an individual prefix covered by the summary in order to enable fast convergence away from paths to the node which owns the prefix which is no longer reachable. This document describes how to use the existing protocol mechanisms in IS-IS and OSPF, together with the two new flags, to advertise such prefix reachability loss. |
| | Multi-part TLVs in IS-IS |
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| | draft-ietf-lsr-multi-tlv-01.txt |
| | Date: |
13/02/2024 |
| | Authors: |
Parag Kaneriya, Tony Li, Tony Przygienda, Shraddha Hegde, Chris Bowers, Les Ginsberg |
| | Working Group: |
Link State Routing (lsr) |
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New technologies are adding new information into IS-IS while deployment scales are simultaneously increasing, causing the contents of many critical TLVs to exceed the currently supported limit of 255 octets. Extensions exist that require significant IS-IS changes that could help address the problem, but a less drastic solution would be beneficial. This document codifies the common mechanism of extending the TLV content space through multiple TLVs. |
| | Prefix Flag Extension for OSPFv2 and OSPFv3 |
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Within OSPF, each prefix is advertised along with an 8-bit field of capabilities, by using the Prefix Options (OSPFv3) and the flag flield in the OSPFv2 Extended Prefix TLV (OSPFv2). However, for OSPFv3, all the bits of the Prefix Options have already been assigned, and for OSPFv2, there are not many undefined bits left in the OSPFv2 Extended Prefix TLV. This document solves the problem of insufficient existing flags, and defines the variable length Prefix Attribute Flags Sub-TLVs for OSPFv2 and OSPFv3 respectively for the extended flag fields. |
| | Advertising Infinity Links in OSPF |
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This document proposes the method to advertise links as unreachable in OSPF. In some scenarios, there are requirements to advertise unreachable links in OSPF for purposes other than building the normal Shortest Path Tree. |
| | Updates to Anycast Property advertisement for OSPFv2 |
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Both SR-MPLS prefix-SID and IPv4 prefix may be configured as anycast and as such the same value can be advertised by multiple routers. It is useful for other routers to know that the advertisement is for an anycast identifier. Each prefix is advertised along with an 8-bit field of capabilities,by using the flag flield in the OSPFv2 Extended Prefix TLV, but the definition of anycast flag to identify the prefix as anycast has not yet been defined. This document defines a new flag in the OSPFv2 Extended Prefix TLV Flags to advertise the anycast property. |