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explains that this draft deals with the RFC8345 limitations #15

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explains that this draft deals with the RFC8345 limitations #15

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explains that this draft deals with the RFC8345 limitations
bclaise Oct 18, 2023
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editorial
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35 changes: 22 additions & 13 deletions draft-ogondio-opsawg-isis-topology.md
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Expand Up @@ -61,6 +61,8 @@ Network operators perform the capacity planning for their networks and run regul

This document defines a YANG data model representing an abstracted view of a network topology containing Intermediate System to Intermediate System (IS-IS). It covers the topology of IP/MPLS networks running IS-IS as Interior Gateway Protocol (IGP) protocol. The proposed YANG mode augments the "A YANG Data Model for Network Topologies" {{!RFC8345}} and"A YANG Data Model for Layer 3 Topologies" {{!RFC8346}} by adding IS-IS concepts. This YANG data model is used to export the IS-IS related topology directly from a network controller to an Operation Support System (OSS) tools.

Note that the YANG model is in this document strictly adhere to the concepts (and the YANG module) in "A YANG Data Model for Network Topologies" {{!RFC8345}} and"A YANG Data Model for Layer 3 Topologies" {{!RFC8346}}. While investigating the IS-IS topology, some limitations have discovered in {{!RFC8345}}, regarding how the digital map can be represented. Those limitations (and potential improvements) are covered in {{?I-D.draft-havel-opsawg-digital-map}}.

This document explains the scope and purpose of the IS-IS topology model and how the topology and service models fit together.
The YANG data model defined in this document conforms to the Network Management Datastore Architecture {{!RFC8342}}.

Expand Down Expand Up @@ -101,7 +103,7 @@ This information is required in the IP/MPLS planning process to properly assess

The standardization of an abstracted view of the IS-IS topology model as NorthBound Interface (NBI) of Software Defined Networking (SDN) controllers allows the inject this information into third party tools covering specialized cases.

The IS-IS topological model should export enough IS-IS information to permit these tools simulating the IP routing. By adding the traffic demand, ideally at the IP flow level, we can simulate the traffic growth and its effect on the routing. That is, simulating how IP-level traffic demands would be forwarded, after ISIS convergence is reached, and from there estimating, using appropriate mathematical models, related KPIs like the occupation in the links or end-to-end latencies.
The IS-IS topological model should export enough IS-IS information to permit these tools simulating the IP routing. By adding the traffic demand, ideally at the IP flow level, we can simulate the traffic growth and its effect on the routing. That is, simulating how IP-level traffic demands would be forwarded, after IS-IS convergence is reached, and from there estimating, using appropriate mathematical models, related KPIs like the occupation in the links or end-to-end latencies.

In summary, the network-wide view of the IS-IS topology enables multiple use cases:

Expand All @@ -114,7 +116,7 @@ In summary, the network-wide view of the IS-IS topology enables multiple use cas


{{!RFC9130}} specifies a YANG data model that can be used to configure and manage the IS-IS protocol on network elements. This data model covers the configuration of an IS-IS routing protocol instance, as well as the retrieval of IS-IS operational states.
{{!RFC9130}} is still expected to be used for individual network elements configuration and monitoring. On the other hand, the proposed YANG model in this document covers the abstracted view of the entire network topology containing Intermediate System to Intermediate System (IS-IS). As such, this model is available via the NBI of SDN controllers.
{{!RFC9130}} is still expected to be used for individual network elements configuration and monitoring. On the other hand, the proposed YANG model in this document covers the abstracted view of the entire network topology containing IS-IS. As such, this model is available via the NBI of SDN controllers.

## Relationship with Digital Map

Expand All @@ -128,15 +130,14 @@ As such the IGP topology of the Digital Map (in this case, IS-IS) is just one of

# Use of IETF-Topology for Representing an IP/MPLS network domain

IP/MPLS Networks can contain multiple domain IGP domains. We can define an IGP domain as the collection of nodes and links that participate in the same IGP process. The topology information of a domain can be structured according to ietf-network-topology
information model {{!RFC8345}}. For example, if BGP-LS is used to collect the information, the nodes and links that are announced with the same combination of AS number / are considered to belong to the same domain.
IP/MPLS Networks can contain multiple domain IGP domains. We can define an IGP domain as the collection of nodes and links that participate in the same IGP process. The topology information of a domain can be structured according to ietf-network-topology data model {{!RFC8345}}. For example, if BGP-LS is used to collect the information, the nodes and links that are announced with the same combination of AS number / are considered to belong to the same domain.

If a node and/or layer termination point participates in more than one IGP it will be present in multiple IGP domain networks.

The ietf-network instance MUST include the following properties to indicate it is a domain running an IGP instance:

A network-id that uniquely identifies such domain in the network.
The "network-types property should include the l3t:l3-unicast-topology, to indicate it is a network in which the nodes are capable of forwarding unicast packet. Also, this draft proposed to ade a new property, isis-topology, to indicate the topology being represented is running an IGP process.
The "network-types" property should include the l3t:l3-unicast-topology, to indicate it is a network in which the nodes are capable of forwarding unicast packet. Also, this draft proposed to add a new property, "isis-topology", to indicate the topology being represented is running the IS-IS IGP process.

Also, should the topology include information such as bandwidth, delay information or color, it must include tet:te-topology.
To include delay and bandwdith performance measurements , MUST include tet-pkt:te-packet under the previous property
Expand All @@ -146,7 +147,7 @@ The ietf-network-topology:link MUST be present, with one link per each IP adjace

# YANG Data Model for IS-IS Topology

The abstract (base) network data model is defined in the "ietf-network" module of {{!RFC8345}}. The ISIS-topology builds on the network data model defined in the "ietf-network" module {{!RFC8345}}, augmenting the nodes with IS-IS information, which anchor the links and are contained in nodes).
The abstract (base) network data model is defined in the "ietf-network" module of {{!RFC8345}}. The isis-topology builds on the network data model defined in the "ietf-network" module {{!RFC8345}}, augmenting the nodes with IS-IS information, which anchor the links and are contained in nodes).

There is a set of parameters and augmentations that are included at the node level. Each parameter and description are detailed following:

Expand All @@ -170,21 +171,29 @@ There is a second set of parameters and augmentations are included at the termin

~~~~
module: ietf-l3-isis-topology

augment /nw:networks/nw:network/nw:network-types:
+--rw isis-topology!
augment /nw:networks/nw:network/nw:node/l3t:l3-node-attributes:
+--rw isis-timer-attributes
| +--rw lsp-lifetime? string
| +--rw lsp-refresh-interval? string
| +--rw lsp-lifetime? uint16
| +--rw lsp-refresh-interval? uint16
+--rw isis-status
+--rw level? ietf-isis:level
+--rw area-address* ietf-isis:area-address
+--ro neighbours* inet:ip-address
augment .../nt:termination-point/l3t:l3-termination-point-attributes:
+--rw system-id? ietf-isis:system-id
+--ro neighbors* inet:ip-address
augment /nw:networks/nw:network/nt:link/l3t:l3-link-attributes:
+--rw isis-termination-point-attributes
+--rw interface-type? ietf-isis:interface-type
+--rw level? ietf-isis:level
+--rw metric? uint32
+--rw is-passive? boolean
augment /nw:networks/nw:network/nw:node/nt:termination-point/l3t:l3-termination-point-attributes:
+--rw isis-termination-point-attributes
+--rw interface-type? identityref
+--rw interface-type? ietf-isis:interface-type
+--rw level? ietf-isis:level
+--rw metric? uint64
+--rw metric? uint32
+--rw is-passive? boolean
~~~~
{: #fig-ietf-l3-isis-topology-tree title="IS-IS Topology tree diagram"}
Expand Down Expand Up @@ -244,7 +253,7 @@ module ietf-l3-isis-topology {
Editor: Samier Barguil
<mailto:[email protected]>
Editor: Victor Lopez
<mailto:[email protected]>";
<mailto:[email protected]>;
Editor: Benoit Claise
<mailto:[email protected]>";
description
Expand Down