IS-IS

This document specifies extensions to the Path Computation Element Communication Protocol (PCEP) to enhance support for Segment Routing (SR) with a focus on the use of Segment Identifiers (SIDs) and SR-Algorithms in Traffic Engineering (TE). The SR-Algorithm associated with a SID defines the path computation algorithm used by Interior Gateway Protocols (IGPs). It introduces mechanisms for PCEP peers to signal the SR-Algorithm associated with SIDs by encoding this information in Explicit Route Object (ERO) and Record Route Object (RRO) subobjects, enables SR-Algorithm constraints for path computation, and defines new metric types for the METRIC object. This document updates RFC 8664 and RFC 9603 to allow such extensions.

Summarization is often used in multi-area or multi-domain networks to improve network efficiency and scalability. With summarization in place, there is a need to signal loss of reachability to an individual prefix covered by the summary. This enables fast convergence by steering traffic, when applicable, away from the node which owns the prefix and is no longer reachable.

This document specifies protocol mechanisms in IS-IS and OSPF, together with two new flags, to advertise such prefix reachability loss.

The term "OSPF" in this document is used to refer to both OSPFv2 and OSPFv3.

An IGP Flexible Algorithm (Flex-Algorithm) enables the computation of constraint-based paths within an IGP domain, allowing operators to influence path selection according to administrative policies. This document defines an extension to Flex-Algorithm that allows the inclusion or exclusion of links from path computation based on Administrative Groups (also known as link affinities) associated with the reverse direction of the path under computation.

This document updates RFCs 9350 and 9843 by introducing the new IANA registry that specifies the ordered set of rules that are used to prune links from the topology during the Flex-Algorithm path computation.

This document defines a YANG data model that can be used to manage IS-IS extensions for Segment Routing (SR) over the MPLS data plane.

New technologies are adding new information into IS-IS while deployment scales are simultaneously increasing. This causes the contents of many critical TLVs to exceed the currently supported limit of 255 octets. This document codifies the common mechanism of extending the TLV content space through multiple TLVs.

Many networks configure the IGP link metric relative to the link capacity, and high bandwidth traffic gets routed per the link capacity. Flexible Algorithms provide mechanisms to create constraint-based paths in an IGP. This specification documents a generic metric-type and a set of bandwidth-related constraints to be used in Flexible Algorithms.

This document updates RFC 9350.

Satellite networks present some interesting challenges for packet networking. The entire topology is continually in motion, with links far less reliable than what is common in terrestrial networks. Some changes to link connectivity can be anticipated due to orbital dynamics.

This document proposes a scalable routing architecture for satellite networks based on existing routing protocols and mechanisms that is enhanced with scheduled link connectivity change information. This document proposes no protocol changes.

This document presents the author's view and is neither the product of the IETF nor a consensus view of the community.

Current Link State 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.

The MPLS ping and traceroute mechanisms described in RFC 8029 and the related extensions for Segment Routing (SR) defined in RFC 8287 are highly valuable for validating control plane and data plane synchronization. In certain environments, only some intermediate or transit nodes may have been upgraded to support these validation procedures. A straightforward MPLS ping and traceroute mechanism allows traversal of any path without validation of the control plane state. RFC 8029 supports this mechanism with the Nil Forwarding Equivalence Class (FEC). The procedures outlined in RFC 8029 are primarily applicable when the Nil FEC is used as an intermediate FEC in the FEC stack. However, challenges arise when all labels in the label stack are represented using the Nil FEC.

This document introduces a new Type-Length-Value (TLV) as an extension to the existing Nil FEC. It describes MPLS ping and traceroute procedures using the Nil FEC with this extension to address and overcome these challenges.

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, thereby leading to scaling issues.

To avoid such issues, this document discusses extensions to the IS-IS routing protocol that allow Level 1 (L1) areas to provide transit but only inject an abstraction of the Level 1 topology into Level 2 (L2). Each Level 1 area is represented as a single Level 2 node, thereby enabling a greater scale.

Routing with link-state protocols in dense network topologies can result in suboptimal 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.

RFC 5029, "Definition of an IS-IS Link Attribute Sub-TLV", defines an IANA registry called "IS-IS Neighbor Link-Attribute Bit Values". This document changes the registration procedure for that registry from "Standards Action" to "Expert Review". This document updates RFC 5029.

This document extends IGP Flexible Algorithm so that it can be used with regular IPv4 and IPv6 forwarding.

Existing traffic-engineering-related link attribute advertisements have been defined and are used in RSVP-TE deployments. Since the original RSVP-TE use case was defined, additional applications (e.g., Segment Routing Policy and Loop-Free Alternates) that also make use of the link attribute advertisements have been defined. In cases where multiple applications wish to make use of these link attributes, the current advertisements do not support application-specific values for a given attribute, nor do they support an indication of which applications are using the advertised value for a given link. This document introduces link attribute advertisements that address both of these shortcomings.

This document obsoletes RFC 8919.

This document describes a backward-compatible, optional IS-IS extension that allows the creation of IS-IS flood reflection topologies. Flood reflection permits topologies in which IS-IS Level 1 (L1) areas provide transit-forwarding for IS-IS Level 2 (L2) areas using all available L1 nodes internally. It accomplishes this by creating L2 flood reflection adjacencies within each L1 area. Those adjacencies are used to flood L2 Link State Protocol Data Units (LSPs) and are used in the L2 Shortest Path First (SPF) computation. However, they are not ordinarily utilized for forwarding within the flood reflection cluster. This arrangement gives the L2 topology significantly better scaling properties than prevalently used flat designs. As an additional benefit, only those routers directly participating in flood reflection are required to support the feature. This allows for incremental deployment of scalable L1 transit areas in an existing, previously flat network design, without the necessity of upgrading all routers in the network.

IGP protocols historically compute the best paths over the network based on the IGP metric assigned to the links. Many network deployments use RSVP-TE or Segment Routing - Traffic Engineering (SR-TE) to steer traffic over a path that is computed using different metrics or constraints than the shortest IGP path. This document specifies a solution that allows IGPs themselves to compute constraint-based paths over the network. This document also specifies a way of using Segment Routing (SR) Prefix-SIDs and SRv6 locators to steer packets along the constraint-based paths.

Flexible Algorithm is a solution that allows some routing protocols (e.g., OSPF and IS-IS) to compute paths over a network based on user-defined (and hence, flexible) constraints and metrics. The computation is performed by routers participating in the specific network in a distributed manner using a Flexible Algorithm Definition (FAD). This definition is provisioned on one or more routers and propagated through the network by OSPF and IS-IS flooding.

Border Gateway Protocol - Link State (BGP-LS) enables the collection of various topology information from the network. This document defines extensions to the BGP-LS address family to advertise the FAD as a part of the topology information from the network.

The Segment Routing (SR) architecture allows a flexible definition of the end-to-end path by encoding it as a sequence of topological elements called "segments". It can be implemented over the MPLS or the IPv6 data plane. This document describes the IS-IS extensions required to support SR over the IPv6 data plane.

This document updates RFC 7370 by modifying an existing registry.

This document describes extensions to the Intermediate System to Intermediate System (IS-IS) protocol to support Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS) Traffic Engineering (TE) for multiple Autonomous Systems (ASes). It defines IS-IS extensions for the flooding of TE information about inter-AS links, which can be used to perform inter-AS TE path computation.

No support for flooding information from within one AS to another AS is proposed or defined in this document.

This document builds on RFC 5316 by adding support for IPv6-only operation.

This document obsoletes RFC 5316.

This document defines a YANG data model that can be used to configure and manage the IS-IS protocol on network elements.

This document defines a YANG module for managing the reverse metric extension to the Intermediate System to Intermediate System (IS-IS) intra-domain routing information exchange protocol.

This document defines a YANG data model that can be used to configure and manage Bidirectional Forwarding Detection (BFD).

The YANG modules in this document conform to the Network Management Datastore Architecture (NMDA) (RFC 8342). This document updates "YANG Data Model for Bidirectional Forwarding Detection (BFD)" (RFC 9127).

Extensions have been defined for link-state routing protocols that enable distribution of application-specific link attributes for existing as well as newer applications such as Segment Routing (SR). This document defines extensions to the Border Gateway Protocol - Link State (BGP-LS) to enable the advertisement of these application-specific attributes as a part of the topology information from the network.

Seamless Bidirectional Forwarding Detection (S-BFD) defines a simplified mechanism to use Bidirectional Forwarding Detection (BFD) with large portions of negotiation aspects eliminated, thus providing benefits such as quick provisioning as well as improved control and flexibility to network nodes initiating the path monitoring. The link-state routing protocols (IS-IS and OSPF) have been extended to advertise the S-BFD Discriminators.

This document defines extensions to the BGP - Link State (BGP-LS) address family to carry the S-BFD Discriminators' information via BGP.

This document introduces new IP Flow Information Export (IPFIX) code points to identify which traffic is being forwarded based on which MPLS control plane protocol is used within a Segment Routing domain. In particular, this document defines five code points for the IPFIX mplsTopLabelType Information Element for Path Computation Element (PCE), IS-IS, OSPFv2, OSPFv3, and BGP MPLS Segment Routing extensions.

This document defines a YANG data model that can be used to configure and manage Bidirectional Forwarding Detection (BFD).

The YANG modules in this document conform to the Network Management Datastore Architecture (NMDA) (RFC 8342).

Multiprotocol Label Switching (MPLS) has defined a mechanism to load-balance traffic flows using Entropy Labels (EL). An ingress Label Switching Router (LSR) cannot insert ELs for packets going into a given Label Switched Path (LSP) unless an egress LSR has indicated via signaling that it has the capability to process ELs, referred to as the Entropy Label Capability (ELC), on that LSP. In addition, it would be useful for ingress LSRs to know each LSR's capability for reading the maximum label stack depth and performing EL-based load-balancing, referred to as Entropy Readable Label Depth (ERLD). This document defines a mechanism to signal these two capabilities using IS-IS and Border Gateway Protocol - Link State (BGP-LS).

Segment Routing (SR) allows for a flexible definition of end-to-end paths by encoding paths as sequences of topological subpaths, called "segments". These segments are advertised by routing protocols, e.g., by the link-state routing protocols (IS-IS, OSPFv2, and OSPFv3) within IGP topologies.

This document defines extensions to the Border Gateway Protocol - Link State (BGP-LS) address family in order to carry SR information via BGP.

The key to the extensibility of the Intermediate System to Intermediate System (IS-IS) protocol has been the handling of unsupported and/or invalid Type-Length-Value (TLV) tuples. Although there are explicit statements in existing specifications, deployment experience has shown that there are inconsistencies in the behavior when a TLV that is disallowed in a particular Protocol Data Unit (PDU) is received.

This document discusses such cases and makes the correct behavior explicit in order to ensure that interoperability is maximized.

This document updates RFCs 5305 and 6232.

This document describes a mechanism for a restarting router to signal to its neighbors that it is restarting, allowing them to reestablish their adjacencies without cycling through the DOWN state while still correctly initiating database synchronization.

This document additionally describes a mechanism for a router to signal its neighbors that it is preparing to initiate a restart while maintaining forwarding-plane state. This allows the neighbors to maintain their adjacencies until the router has restarted but also allows the neighbors to bring the adjacencies down in the event of other topology changes.

This document additionally describes a mechanism for a restarting router to determine when it has achieved Link State Protocol Data Unit (LSP) database synchronization with its neighbors and a mechanism to optimize LSP database synchronization while minimizing transient routing disruption when a router starts.

This document obsoletes RFC 5306.

Segment Routing (SR) allows for a flexible definition of end-to-end paths within IGP topologies by encoding paths as sequences of topological sub-paths, called "segments". These segments are advertised by the link-state routing protocols (IS-IS and OSPF).

This document describes the IS-IS extensions that need to be introduced for Segment Routing operating on an MPLS data plane.

There are deployments where the Layer 3 interface on which IS-IS operates is a Layer 2 interface bundle. Existing IS-IS advertisements only support advertising link attributes of the Layer 3 interface. If entities external to IS-IS wish to control traffic flows on the individual physical links that comprise the Layer 2 interface bundle, link attribute information about the bundle members is required.

This document introduces the ability for IS-IS to advertise the link attributes of Layer 2 (L2) Bundle Members.

A micro-loop is a packet-forwarding loop that may occur transiently among two or more routers in a hop-by-hop packet-forwarding paradigm.

This document analyzes the impact of using different link state IGP implementations in a single network with respect to micro-loops. The analysis is focused on the Shortest Path First (SPF) delay algorithm but also mentions the impact of SPF trigger strategies.

In certain networks, such as, but not limited to, financial information networks (e.g., stock market data providers), network-performance criteria (e.g., latency) are becoming as critical to data-path selection as other metrics.

This document describes extensions to IS-IS Traffic Engineering Extensions (RFC 5305). These extensions provide a way to distribute and collect network-performance information in a scalable fashion. The information distributed using IS-IS TE Metric Extensions can then be used to make path-selection decisions based on network performance.

Note that this document only covers the mechanisms with which network-performance information is distributed. The mechanisms for measuring network performance or acting on that information, once distributed, are outside the scope of this document.

This document obsoletes RFC 7810.

This document describes a mechanism to allow IS-IS routing to quickly and accurately shift traffic away from either a point-to-point or multi-access LAN interface during network maintenance or other operational events. This is accomplished by signaling adjacent IS-IS neighbors with a higher reverse metric, i.e., the metric towards the signaling IS-IS router.

This document defines a way for an Intermediate System to Intermediate System (IS-IS) router to advertise multiple types of supported Maximum SID Depths (MSDs) at node and/or link granularity. Such advertisements allow entities (e.g., centralized controllers) to determine whether a particular Segment ID (SID) stack can be supported in a given network. This document only defines one type of MSD: Base MPLS Imposition. However, it defines an encoding that can support other MSD types. This document focuses on MSD use in a network that is Segment Routing (SR) enabled, but MSD may also be useful when SR is not enabled.

This document defines IS-IS extensions to support multicast forwarding using the Bit Index Explicit Replication (BIER) architecture.

This document specifies IS-IS autoconfiguration mechanisms. The key components are IS-IS System ID self-generation, duplication detection, and duplication resolution. These mechanisms provide limited IS-IS functions and are therefore suitable for networks where plug-and-play configuration is expected.

This document describes a mechanism that allows a single router to share one or more circuits among multiple Intermediate System to Intermediate System (IS-IS) routing protocol instances.

Multiple instances allow the isolation of resources associated with each instance. Routers will form instance-specific adjacencies. Each instance can support multiple topologies. Each topology has a unique Link State Database (LSDB). Each Protocol Data Unit (PDU) will contain a new Type-Length-Value (TLV) identifying the instance and the topology (or topologies) to which the PDU belongs.

This document obsoletes RFC 6822.

This document defines a new optional Intermediate System to Intermediate System (IS-IS) TLV named CAPABILITY, formed of multiple sub-TLVs, which allows a router to announce its capabilities within an IS-IS level or the entire routing domain. This document obsoletes RFC 4971.

Corruption of the Remaining Lifetime field in a Link State Protocol Data Unit (LSP) can go undetected. In certain scenarios, this may cause or exacerbate flooding storms. It is also a possible denial-of-service attack vector. This document defines a backwards-compatible solution to this problem.

This document defines a means of advertising one or more Seamless Bidirectional Forwarding Detection (S-BFD) Discriminators using the IS-IS Router CAPABILITY TLV.

This document describes an extension to the IS-IS routing protocol to advertise node administrative tags. This optional capability allows tagging and grouping of the nodes in an IS-IS domain. The node administrative tags can be used to express and apply locally defined network policies, thereby providing a very useful operational capability. Node administrative tags may be used by either IS-IS itself or other applications consuming information propagated via IS-IS.

IEEE 802.1Qca Path Control and Reservation (PCR) specifies explicit path control via IS-IS in Layer 2 networks in order to move beyond the shortest path capabilities provided by IEEE 802.1aq Shortest Path Bridging (SPB). IS-IS PCR provides capabilities for the establishment and control of explicit forwarding trees in a Layer 2 network domain. This document specifies the sub-TLVs for IS-IS PCR.

This document introduces new sub-TLVs to support advertisement of IPv4 and IPv6 prefix attribute flags and the source router ID of the router that originated a prefix advertisement.

In existing specifications, the route preferences for IPv4/IPv6 Extended Reachability TLVs are not explicitly stated. There are also inconsistencies in the definition of how the up/down bit applies to route preference when the prefix advertisement appears in Level 2 Link State Protocol Data Units (LSPs). This document addresses these issues.

Since the publication of the TRILL (Transparent Interconnection of Lots of Links) base protocol in 2011, active development and deployment of TRILL have revealed errata in RFC 6325 and areas that could use clarifications or updates. RFC 7177, RFC 7357, and an intended replacement of RFC 6439 provide clarifications and updates with respect to adjacency, the TRILL ESADI (End Station Address Distribution Information) protocol, and Appointed Forwarders, respectively. This document provides other known clarifications, corrections, and updates. It obsoletes RFC 7180 (the previous "TRILL clarifications, corrections, and updates" RFC), and it updates RFCs 6325, 7177, and 7179.

This document analyzes the current state of the Intermediate System to Intermediate System (IS-IS) protocol according to the requirements set forth in "Keying and Authentication for Routing Protocols (KARP) Design Guidelines" (RFC 6518) for both manual and automated key management protocols.

This document defines the Extended Sequence Number TLV to protect Intermediate System to Intermediate System (IS-IS) PDUs from replay attacks.

This document recommends some editorial changes to the IANA "IS-IS TLV Codepoints" registry to more accurately document the state of the protocol. It also sets out new guidelines for Designated Experts to apply when reviewing allocations from the registry.

Intermediate System to Intermediate System (IS-IS) provides efficient and reliable flooding of information to its peers; however, the current flooding scopes are limited to either area scope or domain scope. There are existing use cases where support of other flooding scopes is desirable. This document defines new Protocol Data Units (PDUs) that provide support for new flooding scopes as well as additional space for advertising information targeted for the currently supported flooding scopes. This document also defines extended Type-Length-Values (TLVs) and sub-TLVs that are encoded using 16-bit fields for Type and Length.

The protocol extensions defined in this document are not backwards compatible with existing implementations and so must be deployed with care.

The IETF Transparent Interconnection of Lots of Links (TRILL) protocol provides optimal pair-wise data frame forwarding without configuration in multi-hop networks with arbitrary topology and link technology; it also provides support for multipathing of both unicast and multicast traffic. This document specifies the data formats and code points for the IS-IS extensions to support TRILL. These data formats and code points may also be used by technologies other than TRILL. This document obsoletes RFC 6326.

This memo reclassifies RFC 1142, "OSI IS-IS Intra-domain Routing Protocol", to Historic status. This memo also obsoletes RFC 1142.

This document describes the manner in which generic application information (i.e., information not directly related to the operation of the Intermediate System to Intermediate System (IS-IS) protocol) should be advertised in IS-IS Link State Protocol Data Units (LSPs) and defines guidelines that should be used when flooding such information.

In this document, we analyze the applicability of the Loop-Free Alternate (LFA) method of providing IP fast reroute in both the core and access parts of Service Provider networks. We consider both the link and node failure cases, and provide guidance on the applicability of LFAs to different network topologies, with special emphasis on the access parts of the network. This document is not an Internet Standards Track specification; it is published for informational purposes.

802.1aq Shortest Path Bridging (SPB) has been standardized by the IEEE as the next step in the evolution of the various spanning tree and registration protocols. 802.1aq allows for true shortest path forwarding in a mesh Ethernet network context utilizing multiple equal cost paths. This permits it to support much larger Layer 2 topologies, with faster convergence, and vastly improved use of the mesh topology. Combined with this is single point provisioning for logical connectivity membership, which includes point-to-point, point-to-multipoint, and multipoint-to-multipoint variations. This memo documents the IS-IS changes required to support this IEEE protocol and provides some context and examples. [STANDARDS-TRACK]

At present, an IS-IS purge does not contain any information identifying the Intermediate System (IS) that generates the purge. This makes it difficult to locate the source IS.

To address this issue, this document defines a TLV to be added to purges to record the system ID of the IS generating it. Since normal Link State Protocol Data Unit (LSP) flooding does not change LSP contents, this TLV should propagate with the purge.

This document updates RFC 5301, RFC 5304, and RFC 5310. [STANDARDS-TRACK]

IANA maintains the "IS-IS TLV Codepoints" registry. This registry documents which TLVs can appear in different types of IS-IS Protocol Data Units (PDUs), but does not document which TLVs can be found in zero Remaining Lifetime Link State PDUs (LSPs), a.k.a. purges. This document extends the existing registry to record the set of TLVs that are permissible in purges and updates the rules for generating and processing purges in the presence of authentication. This document updates RFC 3563, RFC 5304, and RFC 5310. [STANDARDS-TRACK]

This document describes a type-length-value (TLV) for use in the IS-IS routing protocol that allows for the proper use of the Bidirectional Forwarding Detection (BFD) protocol. There exist certain scenarios in which IS-IS will not react appropriately to a BFD-detected forwarding plane failure without use of either this TLV or some other method. [STANDARDS-TRACK]

This document specifies the Intermediate System to Intermediate System (IS-IS) extensions necessary to support link state routing for any protocols running directly over Layer-2. While supporting this concept involves several pieces, this document only describes extensions to IS-IS. Furthermore, the Type, Length, Value pairs (TLVs) described in this document are generic Layer-2 additions, and specific ones as needed are defined in the IS-IS technology-specific extensions. We leave it to the systems using these IS-IS extensions to explain how the information carried in IS-IS is used. [STANDARDS- TRACK]

This document specifies a method for exchanging IPv6 traffic engineering information using the IS-IS routing protocol. This information enables routers in an IS-IS network to calculate traffic-engineered routes using IPv6 addresses. [STANDARDS-TRACK]

This document proposes an extension to Intermediate System to Intermediate System (IS-IS) to allow the use of any cryptographic authentication algorithm in addition to the already-documented authentication schemes, described in the base specification and RFC 5304. IS-IS is specified in International Standards Organization (ISO) 10589, with extensions to support Internet Protocol version 4 (IPv4) described in RFC 1195.

Although this document has been written specifically for using the Hashed Message Authentication Code (HMAC) construct along with the Secure Hash Algorithm (SHA) family of cryptographic hash functions, the method described in this document is generic and can be used to extend IS-IS to support any cryptographic hash function in the future. [STANDARDS-TRACK]

This document describes a simplified method for extending the Link State PDU (LSP) space beyond the 256 LSP limit. This method is intended as a preferred replacement for the method defined in RFC 3786. [STANDARDS-TRACK]

This document describes extensions to the OSPF version 2 and 3 protocols to support Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS) Traffic Engineering (TE) for multiple Autonomous Systems (ASes). OSPF-TE v2 and v3 extensions are defined for the flooding of TE information about inter-AS links that can be used to perform inter-AS TE path computation.

No support for flooding information from within one AS to another AS is proposed or defined in this document. [STANDARDS-TRACK]

RFC 2763 defined a simple and dynamic mechanism for routers running IS-IS to learn about symbolic hostnames. RFC 2763 defined a new TLV that allows the IS-IS routers to flood their name-to-systemID mapping information across the IS-IS network.

This document obsoletes RFC 2763. This document moves the capability provided by RFC 2763 to the Standards Track. [STANDARDS-TRACK]

This document describes extensions to the Intermediate System to Intermediate System (IS-IS) protocol to support optimal routing within a two-level domain. The IS-IS protocol is specified in ISO 10589, with extensions for supporting IPv4 (Internet Protocol) specified in RFC 1195. This document replaces RFC 2966.

This document extends the semantics presented in RFC 1195 so that a routing domain running with both level 1 and level 2 Intermediate Systems (IS) (routers) can distribute IP prefixes between level 1 and level 2, and vice versa. This distribution requires certain restrictions to ensure that persistent forwarding loops do not form. The goal of this domain-wide prefix distribution is to increase the granularity of the routing information within the domain. [STANDARDS-TRACK]

The IS-IS routing protocol (Intermediate System to Intermediate System, ISO 10589) requires reliable protocols at the link layer for point-to-point links. As a result, it does not use a three-way handshake when establishing adjacencies on point-to-point media. This paper defines a backward-compatible extension to the protocol that provides for a three-way handshake. It is fully interoperable with systems that do not support the extension.

Additionally, the extension allows the robust operation of more than 256 point-to-point links on a single router.

This extension has been implemented by multiple router vendors; this paper is provided to the Internet community in order to allow interoperable implementations to be built by other vendors. [STANDARDS-TRACK]

This document describes the authentication of Intermediate System to Intermediate System (IS-IS) Protocol Data Units (PDUs) using the Hashed Message Authentication Codes - Message Digest 5 (HMAC-MD5) algorithm as found in RFC 2104. IS-IS is specified in International Standards Organization (ISO) 10589, with extensions to support Internet Protocol version 4 (IPv4) described in RFC 1195. The base specification includes an authentication mechanism that allows for multiple authentication algorithms. The base specification only specifies the algorithm for cleartext passwords. This document replaces RFC 3567.

This document proposes an extension to that specification that allows the use of the HMAC-MD5 authentication algorithm to be used in conjunction with the existing authentication mechanisms. [STANDARDS-TRACK]

This document describes extensions to the Intermediate System to Intermediate System (IS-IS) protocol to support Traffic Engineering (TE). This document extends the IS-IS protocol by specifying new information that an Intermediate System (router) can place in Link State Protocol Data Units (LSP). This information describes additional details regarding the state of the network that are useful for traffic engineering computations. [STANDARDS-TRACK]

This document specifies encoding of extensions to the IS-IS routing protocol in support of Generalized Multi-Protocol Label Switching (GMPLS). [STANDARDS-TRACK]

This document specifies a method for exchanging IPv6 routing information using the IS-IS routing protocol. The described method utilizes two new TLVs: a reachability TLV and an interface address TLV to distribute the necessary IPv6 information throughout a routing domain. Using this method, one can route IPv6 along with IPv4 and OSI using a single intra-domain routing protocol. [STANDARDS-TRACK]

The two predominant circuit types used by link state routing protocols are point-to-point and broadcast. It is important to identify the correct circuit type when forming adjacencies, flooding link state database packets, and representing the circuit topologically. This document describes a simple mechanism to treat the broadcast network as a point-to-point connection from the standpoint of IP routing. This memo provides information for the Internet community.

This document describes an extension to the IS-IS protocol to add operational capabilities that allow for ease of management and control over IP prefix distribution within an IS-IS domain. This document enhances the IS-IS protocol by extending the information that an Intermediate System (IS) router can place in Link State Protocol (LSP) Data Units for policy use. This extension will provide operators with a mechanism to control IP prefix distribution throughout multi-level IS-IS domains. [STANDARDS-TRACK]

This document describes an optional mechanism within Intermediate System to Intermediate Systems (IS-ISs) used today by many ISPs for IGP routing within their clouds. This document describes how to run, within a single IS-IS domain, a set of independent IP topologies that we call Multi-Topologies (MTs). This MT extension can be used for a variety of purposes, such as an in-band management network "on top" of the original IGP topology, maintaining separate IGP routing domains for isolated multicast or IPv6 islands within the backbone, or forcing a subset of an address space to follow a different topology. [STANDARDS-TRACK]

There are various circumstances where it is highly desirable for a Path Computation Client (PCC) to be able to dynamically and automatically discover a set of Path Computation Elements (PCEs), along with information that can be used by the PCC for PCE selection. When the PCE is a Label Switching Router (LSR) participating in the Interior Gateway Protocol (IGP), or even a server participating passively in the IGP, a simple and efficient way to announce PCEs consists of using IGP flooding. For that purpose, this document defines extensions to the Intermediate System to Intermediate System (IS-IS) routing protocol for the advertisement of PCE Discovery information within an IS-IS area or within the entire IS-IS routing domain. [STANDARDS-TRACK]

This document defines a sub-TLV called "Link-attributes" carried within the TLV 22 and used to flood some link characteristics. [STANDARDS-TRACK]

The setup of a full mesh of Multi-Protocol Label Switching (MPLS) Traffic Engineering (TE) Label Switched Paths (LSP) among a set of Label Switch Routers (LSR) is a common deployment scenario of MPLS Traffic Engineering either for bandwidth optimization, bandwidth guarantees or fast rerouting with MPLS Fast Reroute. Such deployment may require the configuration of a potentially large number of TE LSPs (on the order of the square of the number of LSRs). This document specifies Interior Gateway Protocol (IGP) routing extensions for Intermediate System-to-Intermediate System (IS-IS) and Open Shortest Path First (OSPF) so as to provide an automatic discovery of the set of LSRs members of a mesh in order to automate the creation of such mesh of TE LSPs. [STANDARDS-TRACK]

This memo defines a portion of the Management Information Base (MIB) for use with network management protocols in the Internet community. Specifically, this document describes a MIB for the Intermediate System to Intermediate System (IS-IS) Routing protocol when it is used to construct routing tables for IP networks. [STANDARDS-TRACK]

This document discusses a number of differences between the Intermediate System to Intermediate System (IS-IS) protocol used to route IP traffic as described in RFC 1195 and the protocol as it is deployed today. These differences are discussed as a service to those implementing, testing, and deploying the IS-IS Protocol to route IP traffic. A companion document describes the differences between the protocol described in ISO 10589 and current practice. This memo provides information for the Internet community.

This document discusses a number of differences between the Intermediate System to Intermediate System (IS-IS) protocol as described in ISO 10589 and the protocol as it is deployed today. These differences are discussed as a service to those implementing, testing, and deploying the IS-IS Protocol. A companion document discusses differences between the protocol described in RFC 1195 and the protocol as it is deployed today for routing IP traffic. This memo provides information for the Internet community.

This document contains the text of the agreement signed between ISOC/IETF and ISO/IEC JTC1/SC6 regarding cooperative development of the IS-IS routing protocol. The agreement includes definitions of the related work scopes for the two organizations, request for creation and maintenance of an IS-IS registry by IANA, as well as collaboration guidelines. This memo provides information for the Internet community.

This draft describes an optional extension to IS-IS protocol, used

today by several ISPs for routing within their clouds. IS-IS is an

interior gateway routing protocol developed originally by OSI and

used with IP extensions as IGP. IS-IS originally does not provide

CSNP and PSNP checksums, relying on the underlying layers to verify

the integrity of information provided. Experience with the protocol

shows that this precondition does not always hold and scenarios

can be imagined that impact protocol functionality. This document

introduces a new optional TLV providing checksums.

This draft describes implementation codepoints within

IS-IS [ISO90 , Cal90a , Cal90b ] used today by several ISPs for

routing within their clouds. IS-IS is an interior gateway routing

protocol developed originally by OSI and used with IP extensions as

IGP. This draft summarizes all TLV codepoints that are being used by

the protocol and its pending extensions.

This document describes a simple, interoperable mechanism that can be employed in Intermediate System to Intermediate System (IS-IS) networks in order to decrease the data loss associated with deterministic blackholing of packets during transient network conditions. The mechanism proposed here requires no IS-IS protocol changes and is completely interoperable with the existing IS-IS specification. This memo provides information for the Internet community.

This document describes a mechanism to reduce redundant packet transmissions for the Intermediate System to Intermediate System (IS-IS) Routing protocol, as described in ISO 10589. This memo provides information for the Internet community.

This memo specifies an integrated routing protocol, based on the OSI Intra-Domain IS-IS Routing Protocol, which may be used as an interior gateway protocol (IGP) to support TCP/IP as well as OSI. This allows a single routing protocol to be used to support pure IP environments, pure OSI environments, and dual environments. This specification was developed by the IS-IS working group of the Internet Engineering Task Force. [STANDARDS-TRACK]