--- 1/draft-ietf-lsr-isis-ttz-00.txt 2020-10-03 21:13:10.964253411 -0700 +++ 2/draft-ietf-lsr-isis-ttz-01.txt 2020-10-03 21:13:11.008254525 -0700 @@ -1,61 +1,61 @@ Internet Engineering Task Force H. Chen Internet-Draft R. Li Intended status: Experimental Futurewei -Expires: March 18, 2021 Y. Yang +Expires: April 6, 2021 Y. Yang IBM A. Kumar S N RtBrick Y. Fan Casa Systems N. So V. Liu M. Toy Verizon L. Liu Fujitsu K. Makhijani Futurewei - September 14, 2020 + October 3, 2020 IS-IS Topology-Transparent Zone - draft-ietf-lsr-isis-ttz-00.txt + draft-ietf-lsr-isis-ttz-01.txt Abstract - This document presents a topology-transparent zone in an area. A - zone is a 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. + This document specifies a topology-transparent zone in an 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. 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 https://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 March 18, 2021. + This Internet-Draft will expire on April 6, 2021. Copyright Notice Copyright (c) 2020 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 (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents @@ -64,149 +64,165 @@ 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 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 4 - 3. Zone Abstraction . . . . . . . . . . . . . . . . . . . . . . 4 + 3. Zone Abstraction . . . . . . . . . . . . . . . . . . . . . . 5 4. Topology-Transparent Zone . . . . . . . . . . . . . . . . . . 5 4.1. Zone as a Single Node . . . . . . . . . . . . . . . . . . 5 4.1.1. An Example of Zone as a Single Node . . . . . . . . . 5 4.1.2. Zone Leader Election . . . . . . . . . . . . . . . . 7 4.1.3. LS Generation for Zone as a Single Node . . . . . . . 8 - 4.1.4. Adjacency Establishment and Termination . . . . . . . 8 - 4.1.5. Computation of Routes . . . . . . . . . . . . . . . . 10 - 4.1.6. Extensions to Protocols . . . . . . . . . . . . . . . 11 - 4.2. Zone as Edges Full Mesh . . . . . . . . . . . . . . . . . 14 - 4.2.1. Extensions to IS-IS . . . . . . . . . . . . . . . . . 14 - 4.3. Advertisement of LSs . . . . . . . . . . . . . . . . . . 15 - 4.3.1. Advertisement of LSs within Zone . . . . . . . . . . 15 - 4.3.2. Advertisement of LSs through Zone . . . . . . . . . . 16 - 5. Seamless Migration . . . . . . . . . . . . . . . . . . . . . 16 - 5.1. Transfer Zone to a Single Node . . . . . . . . . . . . . 16 - 5.2. Roll Back from Zone as a Single Node . . . . . . . . . . 16 - 6. Operations . . . . . . . . . . . . . . . . . . . . . . . . . 19 - 7. Security Considerations . . . . . . . . . . . . . . . . . . 19 - 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 - 9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 20 - 10. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 20 - 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 20 - 11.1. Normative References . . . . . . . . . . . . . . . . . . 20 - 11.2. Informative References . . . . . . . . . . . . . . . . . 21 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21 + 4.1.4. Adjacency Establishment . . . . . . . . . . . . . . . 8 + 4.1.5. Computation of Routes . . . . . . . . . . . . . . . . 9 + 4.2. Extensions to Protocols . . . . . . . . . . . . . . . . . 9 + 4.2.1. Zone ID TLV . . . . . . . . . . . . . . . . . . . . . 9 + 4.3. Zone as Edges Full Mesh . . . . . . . . . . . . . . . . . 11 + 4.3.1. Updating LSPs for Zone as Edges' Mesh . . . . . . . . 12 + 4.4. Advertisement of LSPs . . . . . . . . . . . . . . . . . . 12 + 4.4.1. Advertisement of LSPs within Zone . . . . . . . . . . 12 + 4.4.2. Advertisement of LSPs through Zone . . . . . . . . . 13 + 5. Seamless Migration . . . . . . . . . . . . . . . . . . . . . 13 + 5.1. Transfer Zone to a Single Node . . . . . . . . . . . . . 13 + 5.2. Roll Back from Zone as a Single Node . . . . . . . . . . 14 + 6. Operations . . . . . . . . . . . . . . . . . . . . . . . . . 15 + 6.1. Configuring Zone . . . . . . . . . . . . . . . . . . . . 15 + 6.2. Transferring Zone to Node . . . . . . . . . . . . . . . . 16 + 6.3. Rolling back Node to Zone . . . . . . . . . . . . . . . . 16 + + 7. Security Considerations . . . . . . . . . . . . . . . . . . 17 + 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 + 9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 17 + 10. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 18 + 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 18 + 11.1. Normative References . . . . . . . . . . . . . . . . . . 18 + 11.2. Informative References . . . . . . . . . . . . . . . . . 19 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19 1. Introduction - [ISO10589] describes two levels of areas, which are level 1 and level - 2 areas in IS-IS. There are scalability issues in using areas as the - number of routers in a network becomes larger and larger. + [ISO10589] describes two levels of areas in IS-IS, level 1 and level + 2 areas. There are scalability issues in using areas as the number + of routers in a network becomes larger and larger. - Through splitting the network into multiple areas, we may extend the - network further. However, dividing a network from one area into - multiple areas or from a number of existing areas to even more areas - is a very challenging and time consuming task since it is involved in - significant network architecture changes. + Through splitting the network into multiple level 1 areas connected + by level 2, we may extend the network further. However, dividing a + network from one area into multiple areas or from a number of + existing areas to even more areas can be a challenging and time + consuming task since it involves significant network architecture + changes. These issues can be resolved by using topology-transparent zone - (TTZ), which abstracts a zone (i.e., a block/piece of an area) as a - single virtual node or zone edges' mesh with minimum efforts and - minimum service interruption. Note that a zone can be an area (i.e., - the entire piece of an area). + (TTZ), which abstracts a zone (i.e., a subset of an area) as a single + virtual node or zone edges' mesh with minimum efforts and minimum + service interruption. Note that a zone can be an entire area. - This document presents a topology-transparent zone and describes - extensions to IS-IS for supporting the topology-transparent zone. + This document presents a topology-transparent zone and specifies + extensions to IS-IS that support topology-transparent zones. 1.1. 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]. + document are to be interpreted as described in [RFC2119] [RFC8174] + when, and only when, they appear in all capitals, as shown here. 1.2. Terminology - LSP: A Link State Protocol Data Unit (PDU) in IS-IS. - - LS: A Link Sate, which is short for LSP in IS-IS. - TTZ: A Topology-Transparent Zone. - Zone: A block or piece of an area. In a special case, a zone is an - area (i.e., the entire piece of an area). + Zone: A subset (block or piece) of an area. In a special case, a + zone is an entire area. Zone External Node: A node outside of a zone. - Zone Internal Node: A node of a zone without any connection to a + Zone Internal Node: A node within a zone without any connection to a node outside of the zone. - Zone Edge/Border: A node of a zone connecting to a node outside of - the zone. + Zone Edge/Border Node: A node that is part of a zone connecting to a + node outside of the zone. Zone Node: A zone internal node or a zone edge/border node (i.e., a - node of a zone). + node that is part of a zone). - Zone Link: A link connecting zone nodes (i.e., a link of a zone). + Zone Link: A link connecting zone nodes (i.e., a link that is part + of a zone). - Zone Neighbor: A node outside of a zone that is a neighbor of a - zone edge/border. + Zone Neighbor Node: A node outside of a zone that is a neighbor of + a zone edge/border node. + + CLI: Command Line Interface. + + LSP: A Link State Protocol Data Unit (PDU) in IS-IS. An LSP + contains link state information. In general, a router/node + originates multiple LSPs, distinguished by LSP fragment number, + to carry the link state information about it and the links + attached to it. + + LS: Link State. In general, the LS for a node is all the LSPs that + the node originates. The LS for a zone is the set of LSPs that + all the nodes in the zone originate to carry the information + about them and the links attached to them inside the zone. 2. Requirements - Topology-Transparent Zone (TTZ) may be deployed for resolving some + A Topology-Transparent Zone (TTZ) may be deployed to resolve some critical issues such as scalability in existing networks and future - networks. The requirements for TTZ are listed as follows: + networks. The requirements for a TTZ are as follows: o TTZ MUST be backward compatible. When a TTZ is deployed on a set of routers in a network, the routers outside of the TTZ in the - network do not need to know or support TTZ. + network do not need to know or support the TTZ. - o TTZ MUST support at least one more levels of network hierarchies, - in addition to the hierarchies supported by existing routing - protocols. + o TTZ MUST support at least one more levels of network hierarchy, in + addition to the hierarchies supported by existing IS-IS. - o Abstracting a zone as a virtual entity, which is a single virtual - node or zone edges' mesh, SHOULD be smooth with minimum service - interruption. + o Abstracting a zone as a TTZ virtual entity, which is a single + virtual node or zone edges' mesh, SHOULD be smooth with minimum + service interruption. - o De-abstracting (or say rolling back) a virtual entity to a zone - SHOULD be smooth with minimum service interruption. + o De-abstracting (or say rolling back) a TTZ virtual entity to a + zone SHOULD be smooth with minimum service interruption. - o Users SHOULD be able to easily set up an end to end service + o Users SHOULD be able to easily set up an end-to-end service crossing TTZs. - o The configuration for a TTZ in a network SHOULD be minimum. + o The configuration for a TTZ in a network SHOULD be minimal. - o The changes on the existing protocols for supporting TTZ SHOULD be - minimum. + o The changes on the existing protocols to support TTZ SHOULD be + minimal. 3. Zone Abstraction A zone can be abstracted as a single virtual node or the zone edges' full mesh. - When a zone is abstracted as a single virtual node, this single node - is connected to all the neighbors of the zone, and is in the same - area as the neighbors. + When a zone is abstracted as a single virtual node, this node appears + to be connected to all the neighbors of the zone, and to be in the + same area as those neighbors. When a zone is abstracted as its edges' full mesh, there is a full mesh connections among the edges and each edge is also connected to its neighbors outside of the zone. 4. Topology-Transparent Zone A Topology-Transparent Zone (TTZ) comprises an Identifier (ID) and a - piece/block of an area such as a Level 2 area in IS-IS. It is - abstracted as a single virtual node or its edges' full mesh. TTZ and - zone will be used exchangably below. + subset (piece/block) of an area such as a Level 2 area in IS-IS. It + is abstracted as a single virtual node or its edges' full mesh. TTZ + and zone as well as node and router will be used interchangeably + below. 4.1. Zone as a Single Node After a zone is abstracted as a single virtual node having a virtual node ID, every node outside of the zone sees a number of links connected to this single node. Each of these links connects a zone neighbor. The link states inside the zone are not advertised to any node outside of the zone. The virtual node ID may be derived from the zone ID. @@ -309,583 +325,489 @@ A node in a zone is elected as a leader for the zone, which is the node with the highest priority (and the highest node ID when there are more than one nodes having the same highest priority) in the zone. The leader election mechanism described in [I-D.ietf-lsr-dynamic-flooding] may be used to elect the leader for the zone. 4.1.3. LS Generation for Zone as a Single Node - The leader for the zone originates an LS (i.e., an LSP in IS-IS) for - the zone as a single virtual node and sends it to its neighbors. + The leader for the zone originates the LS (i.e., set of LSPs) for the + zone as a single virtual node and sends it to its neighbors. - The LS comprises all the links connecting the zone neighbors. The LS - ID is the ID of the virtual node for the zone. The Source ID or - Advertising Node/Router ID is the ID of the virtual node. + This LS comprises all the adjacencies between the virtual node and + the zone neighbors. The System ID of each LSP ID is the ID of the + virtual node for the zone. The Source ID or Advertising Node/Router + ID is the ID of the virtual node. - In addition, the LS may contain the stub links for the routes such as - the loopback addresses inside the zone to be accessed by zone - external nodes (i.e., nodes outside of the zone). + In addition, this LS may contain the IP prefixes such as the loopback + IP addresses inside the zone to be accessed by zone external nodes + (i.e., nodes outside of the zone). These IP prefixes are included in + the IP internal reachability TLV. -4.1.4. Adjacency Establishment and Termination +4.1.4. Adjacency Establishment - A zone edge node, acting as a single virtual node for the zone, forms - an adjacency with a node outside of the zone in a way described - below. + A zone edge node X, acting as a proxy for the single virtual node for + the zone, forms an adjacency between the virtual node and a node Y + that is outside of the zone and in node X's area as described below. - Case 1 for a new adjacency (i.e., no adjacency exists between the - edge and the node outside of the zone also called zone neighbor): + For a new adjacency (i.e., no adjacency exists between X and Y): - The edge node originates and sends the zone neighbor every protocol - packet such as Hello, which contains the virtual node ID as Source - ID. + Every IS-IS protocol packet, such as Hello, that edge node X + originates and sends node Y, uses the virtual node ID as Source ID. - When the edge node synchronizes its link state database (LSDB) with - the zone neighbor, it sends the zone neighbor the information about - all the link states except for the link states belonging to the zone - that are hidden from any node outside of the zone. + When node X synchronizes its link state database (LSDB) with node Y, + it sends Y all the link state information except for the link state + belonging to the zone that is hidden from the nodes outside of the + zone. - At the end of the LSDB synchronization, the LS for the zone as the + At the end of the LSDB synchronization, the LS for the zone as a single virtual node is originated by the zone leader and distributed - to the zone neighbor. This LS contains the links connecting all the - zone neighbors, including this newly formed zone neighbor. + to node Y. This LS contains the adjacencies between the virtual node + and all the zone neighbors, including this newly formed zone neighbor + Y. - Case 2 for an existing adjacency (i.e., an adjacency already exists - between the zone edge and the zone neighbor): + For an existing adjacency (i.e., an adjacency already exists between + X and Y): - At first, the edge acting as virtual node creates a new adjacency - between the virtual node for the zone and the zone external node in a + At first, edge node X acting as a proxy for the virtual node creates + a new adjacency between the virtual node for the zone and node Y in a normal way. It sends Hellos and other packets containing the virtual - node ID as Source ID to the zone external node. The zone external - node establishes the adjacency with the virtual in the normal way. - - And then, the edge terminates the existing adjacency between the edge - and the external node after the zone has been transferred to the - virtual node. It stops sending Hellos for the adjacency to the zone - external node. Without receiving Hellos from the edge node for a - given time such as hold-timer interval, the zone external node - removes the adjacency to the edge node. Even though this adjacency - terminates, the edge node keeps the link to the external node in its - LS. - - In another option, the zone edge sends Hellos to the zone neighbor - with additional information, including a flag T-bit set to one and a - TLV with the virtual node ID. This information requests the zone - neighbor to transfer the existing adjacency to the new adjacency - smoothly through working together with the zone edge in following - steps. - - Zone Edge Zone Neighbor - (Transfer Zone - to Virtual Node) Hello(T=1, Virtual ID) - ----------------------> OK for Transfer - Adjacency - Hello(T=1, Virtual ID) - Remote Ready for <---------------------- - Transfer - Hello(Source=Virtual ID) - Start Transfer -----------------------> Transfer to New - Adjacency - Hello - Transfer to New <----------------------- - Adjacency . . . - - Step 1: When "Transfer Zone to Virtual Node" is triggered, the zone - edge sends the zone neighbor a Hello containing additional - information T=1 and Virtual node ID. - - Step 2: After receiving the Hello with T=1 and virtual node ID from - the zone edge, the zone neighbor sends the zone edge a Hello with - T=1 and virtual node ID, which means ok for transfer to the new - adjacency. - - Step 3: The edge sends the zone neighbor a Hello containing the - virtual node ID as Source ID after receiving the Hello with T=1 - and virtual node ID from the zone neighbor, which starts to - transfer to the new adjacency. - - Step 4: The zone neighbor changes the existing adjacency to the new - adjacency after receiving the Hello containing the virtual node ID - as Source ID from the zone edge; and sends the zone edge a Hello - without the additional information, which means that it - transferred to the new adjacency. - - Step 5: The zone edge changes the existing adjacency to the new - adjacency after receiving the Hello without the additional - information from the zone neighbor; and continues to send the zone - neighbor a Hello containing the virtual node ID as Source ID. At - this point, the old adjacency is transferred to the new one. - - For the zone neighbor, changing the existing adjacency to the new one - includes: - - o Changing the existing adjacency ID from the edge node ID to the - virtual node ID through either removing the existing adjacency and - adding a new adjacency with the virtual node ID or just changing - the existing adjacency ID from the edge node ID to the virtual - node ID, - - o Removing the link to the zone edge node from its LS and adding a - new link to the virtual node (or just changing the link to the - edge node to the link to the virtual node in its LS), and - - o Continuing sending the zone edge Hellos without additional - information. - - For the zone edge, changing the existing adjacency to the new one - includes: + node ID as Source ID to node Y. Node Y establishes an adjacency with + the virtual node in the normal way. - o Keeping the link to the zone neighbor in its LS, and + Then, node X terminates the existing adjacency between node X and + node Y after the zone has transitioned to be the virtual node. It + stops sending Hellos for the adjacency to node Y. Without receiving + Hellos from node X for a given time such as hold-timer interval, node + Y removes the adjacency to node X. Even though this adjacency + terminates, node X keeps the link to node Y in its LS. - o Continuing sending the zone neighbor Hellos containing the virtual - node ID as Source ID. + In the case where node Y is not in node X's area, is in the backbone + and connected to node X, node X, acting as a proxy for the virtual + node, creates a new adjacency between the virtual node and node Y in + a normal way and sends the LS for the virtual node to node Y if the + zone includes all the nodes in its area. 4.1.5. Computation of Routes - After a zone edge migrates to zone as a virtual node, it computes the - routes (i.e., shortest paths to the destinations) in the zone using - the zone topology (i.e., the topology of the zone without the virtual - node). - - For the routes outside of the zone, it computes them using the zone - topology, the topology outside of the zone without the virtual node - and the connections between each zone edge and its zone neighbor. - - After a zone internal node migrates to zone as a virtual node, it - computes the routes using the zone topology, the topology outside of - the zone without the virtual node and the connections between each - zone edge and its zone neighbor. - -4.1.6. Extensions to Protocols + After a zone is transferred/migrated to a single virtual node, every + zone node computes the routes (i.e., shortest paths to the + destinations) using the zone topology, the connections between each + zone edge and its zone neighbor, and the topology outside of the zone + without the virtual node. The metric of a link outside of the zone + is one order of magnitude larger than the metric of a link inside the + zone. - The following TLVs are defined in IS-IS. +4.2. Extensions to Protocols - o Adjacent Node ID TLV: containing an adjacent node ID, to which an - adjacency is transferred or rolled back. In case of transfer, the - TLV contains the virtual node ID; in case of roll back, the TLV - contains the edge node ID. + The following TLV is defined in IS-IS. - o Zone TLV: containing a zone ID, a flags field and optional sub- + o Zone ID TLV: containing a zone ID, a flags field and optional sub- TLVs. -4.1.6.1. Adjacent Node ID TLV - - The format of Adjacent Node ID TLV is illustrated below. - - 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 (TBD1) | Length (8) | Virtual/Edge Node ID | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Virtual/Edge Node ID (Continue) | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Flags |N|T| - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - - Type (1 byte): To be assigned by IANA. - - Length (1 byte): Its value is 8. - - Virtual/Edge Node ID (6 bytes): An adjacent node ID, to which an - adjacency is transferred or rolled back. - - Flags field (16 bits): two new flag bits are defined as follows: - - o T-bit: Short for Transfer Adjacency bit. The T-bit set to one - indicates a request for transferring to a new 'virtual' adjacency - from the existing adjacency and the new adjacency is identified by - the virtual node ID (or say abstract node ID). - - o N-bit: Short for Roll Back to Normal Adjacency bit. The N-bit set - to one indicates a request for rolling back to a Normal adjacency - from the existing 'virtual' adjacency and the normal adjacency is - identified by the edge node ID. - -4.1.6.2. Zone TLV +4.2.1. Zone ID TLV - The format of IS-IS Zone TLV is illustrated below. It may be added - into an LSP or a Hello PDU for a zone node. When a node in a zone - receives a CLI command triggering zone information distribution for - migration, it updates its LSP by adding an IS-IS Zone TLV with T set - to 1. When a node in a zone receives a CLI command activating - migration zone to an abstracted entity, it sets M to 1 in the Zone - TLV in its LSP. + The format of IS-IS Zone ID TLV is illustrated below. It may be + added into an LSP for a zone node. 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 (TBD2) | Length | Zone ID | + | Type (TBD1) | Length | Zone ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Zone ID (Continue) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Flags |E|Z|S| OP | Sub TLVs | + | RESV |E| OP | Sub TLVs | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + ~ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - Figure 3: IS-IS Zone TLV + Figure 3: IS-IS Zone ID TLV - Type (1 byte): To be assigned by IANA. + Type (1 byte): TBD1. - Length (1 byte): Its value is variable. + Length (1 byte): Its value is variable with a minimum of 8. A value + larger than 8 means that sub-TLVs are present. If length is less + than 8, the TLV MUST be ignored. Zone ID (6 bytes): It is the identifier (ID) of a zone. - Flags field (16 bits): Three flag bits E, Z and S, and OP of 3 bits - are defined. + Flags field (16 bits): one flag bit E, OP of 3 bits, and a reserved + subfield are as follows: + RESV: Reserved. MUST be send as zero and ignored on receipt. E = 1: Indicating a node is a zone edge node - Z = 1: Indicating a node has migrated to Zone as a virtual entity - S = 1: Indicating the virtual entity is a Single virtual node + E = 0: Indicating a node is a zone internal node - When a zone node originates an LS containing a zone TLV, it MUST set - flag E to 1 if it is a zone edge node and to 0 if it is a zone- - internal node. It MUST set flag Z to 1 after it has migrated to zone - as a virtual entity and to 0 before it migrates zone to the virtual - entity or after it rolls back from zone as a virtual entity. When - the entity abstracted from a zone is a Single virtual node, flag S - MUST be set to 1. + When a Zone ID is configured on a zone node (refer to Section 6.1), + the node updates its LSP by adding an IS-IS Zone ID TLV with the Zone + ID. If it is a zone internal node, the TLV has its flag E = 0; + otherwise (i.e., it is a zone edge node) the TLV has its flag E = 1 + and may include a Zone ISN Sub TLV containing the zone links + configured. Every link of a zone internal node is a zone link. If + every link of a zone edge node is a zone link, the TLV with E = 1 + does not include any Zone ISN Sub TLV; otherwise (i.e., some of its + links are zone links), it includes the Zone ISN Sub TLV containing + the zone links. OP Value Meaning (Operation) 0x001 (T): Advertising Zone Topology Information for Migration - 0x010 (M): Migrating Zone to a Virtual Entity + 0x010 (M): Migrating Zone to a Virtual Entity such as Virtual Node 0x011 (N): Advertising Normal Topology Information for Rollback 0x100 (R): Rolling Back from the Virtual Entity The value of OP indicates one of the four operations above. When any - of the other values is received, it is ignored. + of the other values is received, the TLV MUST be ignored. - When a node in a zone receives a CLI command triggering zone - information distribution for migration, it updates its LSP by adding - an IS-IS Zone TLV with T set to 1. When a node in a zone receives a - CLI command activating migration zone to a virtual entity, it sets M - to 1 in the Zone TLV in its LSP. + When a zone node, such as the zone leader, receives a command via + management, such as a CLI command, to advertise zone information for + migration, or determines to advertise, it sets OP = T (i.e., 0x001) + in the Zone ID TLV of its LSP. When a zone node receives a command + to migrate zone to a virtual entity, or determines to migrate, it + sets OP = M (i.e., 0x010) in the Zone ID TLV of its LSP. When a zone + node receives a command to advertise Normal topology information for + roll back, it sets OP = N (i.e., 0x011) in the Zone ID TLV of its + LSP. When a zone node receives a command to roll back or determines + to roll back, it sets OP = R (i.e., 0x100) in the Zone ID TLV of its + LSP. - Two new sub-TLVs are defined, which may be added into an IS-IS Zone - TLV in an LSP. One is Zone IS Neighbor sub-TLV, or Zone ISN sub-TLV - for short. The other is Zone ES Neighbor sub-TLV, or Zone ESN sub- + Two new sub-TLVs are defined, which may be added to an IS-IS Zone ID + TLV. One is the Zone IS Neighbor sub-TLV, or Zone ISN sub-TLV for + short. The other is the Zone ES Neighbor sub-TLV, or Zone ESN sub- TLV for short. A Zone ISN sub-TLV contains the information about a - number of IS neighbors in the zone connected to a zone edge router. - It has the format below. + number of IS neighbors in the zone connected to a zone edge node. It + has the format below. 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 (TBD) | Length |DefaultMetric(i| DelayMetric(i)| - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - |ExpenseMetric(i| ErrorMetric(i)| Neighbor ID(i) | + | Type (TBD) | Length | Neighbor ID(i) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + | | + + +-----------------------------------------------+ + | | Metric (i) | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 4: Zone ISN Sub TLV A Zone ISN Sub TLV has 1 byte of Type, 1 byte of Length of - n*(IDLength + 4), which is followed by n tuples of Default Metric, - Delay Metric, Expense Metric, Error Metric and Neighbor ID. + n*(IDLength + 3), which is followed by n tuples of Neighbor ID and + Metric. A Zone ESN sub-TLV contains the information about a number of ES neighbors in the zone connected to a zone edge node. It has the format below. 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 (TBD) | Length |Default Metric | DelayMetric | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - |Expense Metric | Error Metric | Neighbor ID(i) | + | Type (TBD) | Length | Neighbor ID(i) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + | | + + +-----------------------------------------------+ + | | Metric (i) | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 5: Zone ESN Sub TLV -4.2. Zone as Edges Full Mesh - - OSPF Topology-Transparent Zone [RFC8099] describes the zone as edges' - full mesh and the extensions to OSPF for supporting zone as edges' - full mesh. Based on these extensions, IS-IS is extended by a few new - TLVs or Sub-TLVs. - -4.2.1. Extensions to IS-IS - -4.2.1.1. Updating LSPs for Zone - - A zone internal node adds an IS-IS Zone TLV into its LSP after it - receives an LSP containing an IS-IS Zone TLV with T = 1 or a CLI - command triggering zone information distribution for migration. The - TLV has a zone ID set to the ID of the zone and E bit in Flags set to - 0 indicating zone internal node. The node floods its LSP to its - neighbors in the zone. - - When a node inside the zone receives an LSP containing an IS-IS Zone - TLV from a neighboring node in the zone, it stores the LSP and floods - the LSP to the other neighboring nodes in the zone. +4.3. Zone as Edges Full Mesh +4.3.1. Updating LSPs for Zone as Edges' Mesh For every zone edge node, it updates its LSP in three steps and floods the LSP to all its neighbors. - At first, the zone edge node adds an IS-IS Zone TLV into its LSP - after it receives an LSP containing an IS-IS Zone TLV with T = 1 or a - CLI command triggering zone information distribution for migration. - The TLV has a zone ID set to the ID of the zone, E bit in Flags set - to 1 indicating zone edge node and a Zone ISN Sub TLV. The Sub TLV - contains the information about the zone IS neighbors connected to the - zone edge node. In addition, the TLV may has a Zone ESN Sub TLV - comprising the information about the zone end systems connected to - the zone edge node. - - Secondly, it adds each of the other zone edge nodes as an IS neighbor - into the Intermediate System Neighbors TLV in the LSP after it - receives an LSP containing an IS-IS Zone TLV with M = 1 or a CLI + At first, it adds each of the other zone edge nodes as an IS neighbor + into the Intermediate System Neighbors TLV in its LSP after it + receives an LSP containing an IS-IS Zone ID TLV with OP = M or a command activating migration zone to an abstracted entity. The metric to the neighbor is the metric of the shortest path to the edge node within the zone. - In addition, it adds a Prefix Neighbors TLV into its LSP. The TLV - contains a number of address prefixes in the zone to be reachable + In addition, it adds an IP internal reachability TLV into its LSP. + The TLV contains a number of IP prefixes in the zone to be reachable from outside of the zone. And then it removes the IS neighbors corresponding to the IS - neighbors in the Zone TLV (i.e., in the Zone ISN sub TLV) from - Intermediate System Neighbors TLV in the LSP, and the ES neighbors - corresponding to the ES neighbors in the Zone TLV (i.e., in the Zone - ESN sub TLV) from End System Neighbors TLV in the LSP. This SHOULD - be done after it receives the LSPs for virtualizing zone from the - other zone edges for a given time. + neighbors in the Zone ID TLV (i.e., in the Zone ISN sub TLV) from + Intermediate System Neighbors TLV in its LSP, and the ES neighbors + corresponding to the ES neighbors in the Zone ID TLV (i.e., in the + Zone ESN sub TLV) from End System Neighbors TLV in the LSP. This + SHOULD be done after it receives the LSPs for virtualizing zone from + the other zone edges for a given time. -4.3. Advertisement of LSs +4.4. Advertisement of LSPs - LSs can be divided into a couple of classes according to their - Advertisements. The first class of LSs is advertised within a zone. + LSPs can be divided into a couple of classes according to their + Advertisements. The first class of LSPs is advertised within a zone. The second is advertised through a zone. -4.3.1. Advertisement of LSs within Zone +4.4.1. Advertisement of LSPs within Zone - Any LS about a link state in a zone is advertised only within the + Any LSP about a link state in a zone is advertised only within the zone. It is not advertised to any router outside of the zone. For - example, a router LS generated for a zone internal router is - advertised only within the zone. + example, a LSP generated for a zone internal node is advertised only + within the zone. - Any network LS generated for a broadcast network in a zone is - advertised only within the zone. It is not advertised outside of the - zone. + Any LSP generated for a broadcast network in a zone is advertised + only within the zone. It is not advertised outside of the zone. - After migrating to zone as a single virtual node or edges' full mesh, - every zone edge MUST NOT advertise any LS belonging to the zone or - any information in a LS belonging to the zone to any node outside of - the zone. The zone edge determines whether an LS is about a zone - internal link state by checking if the advertising router of the LS - is a zone internal router. + After migrating to a zone as a single virtual node or edges' full + mesh, every zone edge MUST NOT advertise any LSP belonging to the + zone or any information in a LSP belonging to the zone to any node + outside of the zone. The zone edge determines whether an LSP is + about a zone internal link state by checking if the originating node + of the LSP is a zone internal node. - For any zone LS originated by a node within the zone, every zone edge + For any LSP originated by a node within the zone, every zone edge node MUST NOT advertise it to any node outside of the zone. -4.3.2. Advertisement of LSs through Zone +4.4.2. Advertisement of LSPs through Zone - Any LS about a link state outside of a zone received by a zone edge + Any LSP about a link state outside of a zone received by a zone edge is advertised using the zone as transit. For example, when a zone - edge node receives an LS from a node outside of the zone, it floods - the LS to its neighbors both inside and outside of the zone. This LS - may be any LS such as a router LSA that is advertised within an OSPF - area. + edge node receives an LSP from a node outside of the zone, it floods + the LSP to its neighbors both inside and outside of the zone. - The nodes in the zone continue to flood the LS. When another zone - edge receives the LS, it floods the LS to its neighbors both inside + The nodes in the zone continue to flood the LSP. When another zone + edge receives the LSP, it floods the LSP to its neighbors both inside and outside of the zone. 5. Seamless Migration This section presents the seamless migration between a zone and its - single virtual node. The seamless migration between a zone and its - edges' full mesh for IS-IS is similar to that described in OSPF - Topology-Transparent Zone [RFC8099] for OSPF. + single virtual node. 5.1. Transfer Zone to a Single Node - After transfer a Zone to a Single Virtual Node is triggered, the zone - is abstracted as a single virtual node in two steps: + Transferring a zone to a single virtual node smoothly takes a few + steps or stages. - Step 1: Every zone edge node works together with each of its zone - neighbor nodes to create a new adjacency between the virtual node - and the neighbor node in the way described in Section 4.1.4 for - Adjacency Establishment and Termination procedure for case 2. - After creating the adjacency, each of the zone neighbor nodes - update its LS by adding the adjacency/link into its LS. + At first, a user configures the zone on every node of the zone (refer + to Section 6.1). Every zone node updates its LSP by including a Zone + ID TLV. For a zone edge node, the TLV has the Zone ID configured, + its flag E = 1 and a Zone ISN Sub TLV containing the zone links + configured. For a zone internal node, the TLV has the Zone ID + configured and its flag E = 0. - Step 2: The zone leader originates an LS for the virtual node after - receiving the updated LSes originated by all the zone neighbor - nodes, where the updated LSes contain all the zone neighbors. + Second, after finishing the configuration of the zone, a user may + issue a command, such as a CLI command, on a zone node, such as the + zone leader, to trigger transferring the zone to the single virtual + node. When the node receives the command, it updates its LSP by + setting OP = T in its Zone ID TLV, which is distributed to every zone + node. After receiving the Zone ID TLV with OP = T, every zone edge + node, acting as a proxy of the virtual node, establishes a new + adjacency between the virtual node and each of its zone neighbor + nodes. - Step 3: After receiving the LS for the virtual node, every zone edge - does not send any LS inside the zone to any zone neighbors. It - advertises its LS without any links inside the zone to the nodes - outside of the zone and terminates its adjacency to each of its - zone neighbors in the way described in Section 4.1.4 for Adjacency - Establishment and Termination procedure for case 2. + The command may be replaced by the determination made by a zone node, + such as the zone leader. After determining that the configuration of + the zone is finished for a given time such as 10 seconds, it updates + its LSP by setting OP = T in its Zone ID TLV. The configuration is + complete if every zone link configured is bidirectional. For every + zone internal node configured with the Zone ID, there is an LSP + containing its Zone ID TLV with E = 0 in the LSDB, which indicates + that each link from the node (one direction) is a zone link. For + every zone edge node, each of its zone links configured from the edge + node (one direction) is included in its LSP containing its Zone ID + TLV with E = 1 and Zone ISN Sub TLV in the LSDB. + + Third, after receiving the updated LSPs from all the zone neighbor + nodes, the zone leader checks if all the new adjacencies between the + virtual node and the zone neighbor nodes have been established. If + so, it originates an LS for the virtual node and updates its LSP + (i.e., the LSP for itself zone leader) by setting OP = M in its Zone + ID TLV, which is distributed to every zone node. + + After receiving the Zone ID TLV with OP = M, every zone node migrates + to zone as virtual node. Every zone edge node does not send any LS + inside the zone to any zone neighbors. It advertises its LSP without + any zone links to the nodes outside of the zone or purges its LSP + outside of the zone, terminates its adjacency to each of its zone + neighbors, but contains the adjacency in its LSP that is distributed + within the zone. Every zone node computes the routes according to + Section 4.1.5. 5.2. Roll Back from Zone as a Single Node - After roll back from Zone as a Signle Virtual Node is triggered, - rolling back is done in following steps: + After abstracting a zone to a single virtual node, we may want to + roll back the node to the zone smoothly in some cases. The process + of rolling back has a few steps or stages. - Step 1: Every zone edge creates an adjacency to each of its zone - neighbors in a normal way. + At first, a user issues a command, such as a CLI command, on a zone + node, such as the zone leader, to start (or prepare) for roll back. + When receiving the command, the node updates its LSP by setting OP = + N in its Zone ID TLV, which will be distributed to every node in the + zone. After receiving the Zone ID TLV with OP = N, every zone edge + node establishes a normal adjacency between the edge node and each of + its zone neighbor nodes, and advertises the link state of the zone + over the adjacency if it crosses the adjacency, but holds off its LSP + containing the normal adjacency. - Step 2: After all the adjacencies between the zone edges and the - zone neighbors are created, the zone leader updates the LS for the - virtual node by changing every link metric to the maximum metric - in the LS. + Second, a user may issue a command, such as a CLI command, on a zone + node, such as the zone leader, to roll back from the virtual node to + the zone if the following conditions are met. - Step 3: Every zone edge sends its LS with the links inside the zone - and all the LSes inside the zone to its zone neighbors. Every - zone edge acting as the virtual node terminates the adjacency - between the virtual node and each of its zone neighbors through - stopping Hellos to the neighbors. + Condition 1: All the normal adjacencies between every zone edge node + and each of its zone neighbor nodes have been established. - In another option, rolling back is done as follows: + Condition 2: All the link state about the zone that is supposed to + be advertised outside of the zone has been advertised. - Step 1: Using the procedure described in the following, every zone - edge rolls back the existing virtual adjacency between the edge - node acting as the virtual node and the zone neighbor node to a - normal adjacency between the edge node and the neighbor. + After receiving the command, the node updates its LSP by setting OP = + R in its Zone ID TLV, which is distributed to every zone node. After + receiving the Zone ID TLV with OP = R, - Step 2: The zone leader may flush the LS for the virtual node. - Every zone edge sends Hello and other packets to its zone - neighbors, where the packets contain the edge node ID as Source - ID. + o every zone edge node, acting as a proxy of the virtual node, + terminates the adjacency between the virtual node and each of its + zone neighbor nodes and advertises its LSP containing the normal + adjacencies between it and each of its zone neighbor nodes; - The procedure below smoothly rolls back the existing virtual - adjacency between the edge node acting as the virtual node and the - zone neighbor node to a normal adjacency between the edge node and - the neighbor node. + o The zone leader purges the LS for the virtual node abstracted from + the zone; and - The edge node sends the neighbor node Hellos with additional - information, including a flag N-bit set to one and a TLV with the - edge node ID such as the Adjacent Node ID TLV with the edge node ID. - This information requests the neighbor node to roll back the existing - virtual adjacency to the normal adjacency smoothly through working - together with the edge node. + o Every zone node rolls back to normal. - The following steps will roll back the existing virtual adjacency to - the normal one: + The command may be replaced by the determination made by a zone node, + such as the zone leader. After determining that all the conditions + are met, it updates its LSP by setting OP = R in its Zone ID TLV, + which is distributed to every zone node. - zone Edge zone Neighbor - (Roll Back to - Normal Adjacency) Hello (N=1, Edge ID) - ----------------------> OK to Roll Back to - Normal Adjacency - Hello (N=1, Edge ID) - Remote Ready for <---------------------- - Rolling Back - Hello(Source=Edge ID) - Start Roll Back -----------------------> Roll Back to - Normal Adjacency - Hello - Roll Back to <----------------------- - Normal Adjacency . . . + Condition 1 is met if it has its LSDB containing the link from each + zone neighbor node to its zone edge node. That is that for every + link from a zone neighbor node to the virtual node in the LSDB, there + is a corresponding link from the zone neighbor to a zone edge node. - Step 1: When "Roll Back from Zone as a Single Node" is triggered, - the edge node sends the neighbor node a Hello with the additional - information N=1 and Edge ID as normal adjacency ID in order to - roll back to the normal adjacency from the virtual adjacency. + Condition 2 is met after Condition 1 has been met for a given time, + such as maximum LSP advertisement time (MaxLSPAdvTime) crossing a + network. We may assume that MaxLSPAdvTime is 5 seconds. - Step 2: After receiving the Hello with the additional information - from the edge node, the neighbor node sends the edge node a Hello - with the additional information (i.e., N=1 and Edge ID as normal - adjacency ID), which means ok for rolling back to the normal - adjacency. +6. Operations - Step 3: The edge sends the neighbor a Hello containing the edge node - ID as Source ID after receiving the Hello with the additional - information from the neighbor, which starts to roll back to the - normal adjacency. +6.1. Configuring Zone - Step 4: The neighbor node changes the existing adjacency to the - normal adjacency after receiving the Hello containing the edge - node ID as Source ID from the edge node; and sends the edge node a - Hello without the additional information, which means that it - rolled back to the normal adjacency. + In general, a zone is a subset of an area and has a zone ID. It + consists of some zone internal nodes and zone edge nodes. To + configure it, a user configures this zone ID on every zone internal + node and on every zone link of each zone edge node. - Step 5: The edge node changes the existing adjacency to the normal - adjacency after receiving the Hello without the additional - information from the neighbor node; and continues to send the - neighbor Hello containing the edge node ID as Source ID. At this - point, the virtual adjacency is rolled back to the normal - adjacency. + A node configured with the zone ID has all its links to be the zone + links. The zone internal nodes and all their links plus the zone + edge nodes and their zone links constitute the zone. - For the neighbor node, changing the existing virtual adjacency to the - normal one includes: + In a special case, a zone is an entire area and has a zone ID. All + the links in the area are the zone links of the zone. To configure + this zone, a user configures the zone ID on every zone node. - o Changing the existing adjacency ID from the virtual node ID to the - edge node ID through either removing the existing adjacency and - adding a new adjacency with the edge node ID or just changing the - existing adjacency ID from the virtual node ID to the edge node - ID, +6.2. Transferring Zone to Node - o Removing the link to the virtual node from its LS and adding a new - link to the edge node (or just changing the link to the virtual - node to the link to the edge node in its LS), and + Transferring a zone to a single virtual node smoothly may take a few + steps or stages. - o Continuing sending the edge node Hellos without additional - information. + At first, a user configures the zone on every node of the zone. - For the edge node, changing the existing virtual adjacency to the - normal one includes: + After finishing the configuration of the zone, the user may issue a + command, such as a CLI command, on a zone node, such as the zone + leader, to trigger transferring the zone to the node. When receiving + the command, the node distributes it to every zone node. After + receiving it, every zone edge node, acting as a proxy of the virtual + node, establishes a new adjacency between the virtual node and each + of its zone neighbor nodes. - o Sending its LS to the neighbor, and + If automatic transferring zone to node is enabled, the user does not + need to issue the command. A zone node, such as the zone leader, + will distribute the "command" to every zone node after determining + that the configuration of the zone has been finished. - o Continuing sending the neighbor node Hellos containing the edge - node ID as Source ID without additional information. + Then, all the zone nodes, including the zone leader, zone edge nodes + and zone internal nodes, work together to make the zone to appear as + a single virtual node smoothly in a couple of steps. -6. Operations +6.3. Rolling back Node to Zone - The Operations on TTZ described in OSPF Topology-Transparent Zone - [RFC8099] are for Zone as Edges Full Mesh in OSPF. They can be used - for Zone as Edges Full Mesh in IS-IS. They can also be used for Zone - as a Single Virtual Node in IS-IS. + After abstracting a zone to a single virtual node, we may want to + roll back the node to the zone smoothly in some cases. The process + of rolling back has a few steps or stages. + + At first, a user issues a command, such as a CLI command, on a zone + node, such as the zone leader, to start (or prepare) for roll back. + When receiving the command, the node distributes it to every node in + the zone. After receiving it, every zone edge node establishes a + normal adjacency between the edge node and each of its zone neighbor + nodes, and advertises the link state of the zone over the adjacency + if it crosses the adjacency, but holds off its LSP containing the + normal adjacency. + + Second, a user may issue a command, such as a CLI command, on a zone + node, such as the zone leader, to roll back from the virtual node to + the zone if it is ready for roll back. + + After receiving the command, the node distributes it to every node in + the zone. After receiving it, all the zone nodes work together to + roll back from the virtual node to the zone. + + If automatic roll back Node to Zone is enabled, the user does not + need to issue the command. A zone node, such as the zone leader, + will distribute the "command" to every zone node after determining + that it is ready for roll back. 7. Security Considerations The mechanism described in this document does not raise any new security issues for the IS-IS protocols. 8. IANA Considerations Under the registry name "IS-IS TLV Codepoints", IANA is requested to - assign new registry types for Adjacent Node ID, Zone ID and Zone - Options as follows: + assign a new registry type for Zone ID as follows: +==============+===================+=====================+ | TLV Type | TLV Name | reference | +==============+===================+=====================+ - | 26(suggested)| Adjacent Node ID | This document | + | TBD1 | Zone ID | This document | +--------------+-------------------+---------------------+ - | 27(suggested)| Zone | This document | + + IANA is requested to create a new sub-registry "Adjacent Node ID Sub- + TLVs" on the IANA IS-IS TLV Codepoints web page as follows: + + +==============+===================+=====================+ + | Type | Name | reference | + +==============+===================+=====================+ + | 0 | Reserved | + +--------------+-------------------+---------------------+ + | 1 | Zone ISN | This document | + +--------------+-------------------+---------------------+ + | 2 | Zone ESN | This document | + +--------------+-------------------+---------------------+ + | 3 - 255 | Unassigned | +--------------+-------------------+---------------------+ 9. Contributors Alvaro Retana Futurewei Raleigh, NC USA Email: alvaro.retana@futurewei.com 10. Acknowledgement The authors would like to thank Acee Lindem, Abhay Roy, Christian Hopps, Dean Cheng, Russ White, Tony Przygienda, Wenhu Lu, Lin Han, - Kiran Makhijani, Padmadevi Pillay Esnault, and Yang Yu for their - valuable comments on TTZ. + Donald Eastlake, Tony Li, Robert Raszuk, Padmadevi Pillay Esnault, + and Yang Yu for their valuable comments on TTZ. 11. References 11.1. Normative References [I-D.ietf-lsr-dynamic-flooding] Li, T., Psenak, P., Ginsberg, L., Chen, H., Przygienda, T., Cooper, D., Jalil, L., Dontula, S., and G. Mishra, "Dynamic Flooding on Dense Graphs", draft-ietf-lsr- dynamic-flooding-07 (work in progress), June 2020. @@ -922,20 +844,24 @@ [RFC7142] Shand, M. and L. Ginsberg, "Reclassification of RFC 1142 to Historic", RFC 7142, DOI 10.17487/RFC7142, February 2014, . [RFC8099] Chen, H., Li, R., Retana, A., Yang, Y., and Z. Liu, "OSPF Topology-Transparent Zone", RFC 8099, DOI 10.17487/RFC8099, February 2017, . + [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC + 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, + May 2017, . + 11.2. Informative References [Clos] Clos, C., "A Study of Non-Blocking Switching Networks", The Bell System Technical Journal Vol. 32(2), DOI 10.1002/j.1538-7305.1953.tb01433.x, March 1953, . [RFC5307] Kompella, K., Ed. and Y. Rekhter, Ed., "IS-IS Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS)", RFC 5307, DOI 10.17487/RFC5307, October 2008,