RIFT J. Head, Ed.
Internet-Draft T. Przygienda
Intended status: Standards Track C. Barth
Expires: 29 December 2022 Juniper Networks
27 June 2022
RIFT Auto-Flood Reflection
draft-head-rift-auto-fr-01
Abstract
This document specifies procedures where RIFT can automatically
provision IS-IS Flood Reflection topologies by leveraging its native
no-touch ZTP architecture.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Design Considerations . . . . . . . . . . . . . . . . . . . . 3
3. Auto-FR Device Roles . . . . . . . . . . . . . . . . . . . . 4
3.1. All Participating Nodes . . . . . . . . . . . . . . . . . 4
3.2. Flood Reflectors . . . . . . . . . . . . . . . . . . . . 4
3.3. Flood Reflectors Clients . . . . . . . . . . . . . . . . 4
4. Auto-FR Variable Derivation . . . . . . . . . . . . . . . . . 5
4.1. RIFT System ID . . . . . . . . . . . . . . . . . . . . . 5
4.2. Auto-FR Version . . . . . . . . . . . . . . . . . . . . . 5
4.3. Flood Reflection Cluster ID . . . . . . . . . . . . . . . 6
4.4. Flood Reflection Preference . . . . . . . . . . . . . . . 6
4.5. IS-IS System ID . . . . . . . . . . . . . . . . . . . . . 6
4.6. IS-IS NET Address . . . . . . . . . . . . . . . . . . . . 6
4.7. Loopback Address . . . . . . . . . . . . . . . . . . . . 7
4.7.1. Leaf Nodes as Flood Reflector Clients . . . . . . . . 7
4.7.2. ToF Nodes as Flood Reflectors . . . . . . . . . . . . 7
4.7.2.1. Flood Reflector Election Procedures . . . . . . . 8
5. RIFT Requirements . . . . . . . . . . . . . . . . . . . . . . 8
5.1. RIFT FSM / LIE Validation Requirements . . . . . . . . . 8
5.2. RIFT Node-TIE Advertisements . . . . . . . . . . . . . . 9
6. Operational Considerations . . . . . . . . . . . . . . . . . 9
6.1. RIFT Underlay and IS-IS Flood Reflection Topology . . . . 9
6.2. Auto-FR Analytics . . . . . . . . . . . . . . . . . . . . 11
6.2.1. Auto-FR Analytics (Global) Key/Value Pair . . . . . . 12
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
8. Security Considerations . . . . . . . . . . . . . . . . . . . 13
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
10.1. Normative References . . . . . . . . . . . . . . . . . . 13
Appendix A. Thrift Models . . . . . . . . . . . . . . . . . . . 14
A.1. common.thrift . . . . . . . . . . . . . . . . . . . . . . 14
A.2. encoding.thrift . . . . . . . . . . . . . . . . . . . . . 15
A.3. auto_flood_reflection_kv.thrift . . . . . . . . . . . . . 16
Appendix B. Auto-FR Variable Derivation . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22
1. Introduction
[RIFT] is a protocol that focuses heavily on operational simplicity.
It natively supports Zero Touch Provisioning (ZTP) functionality that
allows each node to automatically derive its place in the topology
and configure itself accordingly when properly cabled as a Clos, Fat-
Tree, or other similarly structured variant.
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IS-IS Flood Reflection [IS-IS-FR] is a mechanism that enables flat
single-area Level 2 IS-IS topologies to scale well beyond their
typical properties when deployed in similar topological structures
by:
1. Reducing the number of required links and adjacencies.
2. Reducing the size of the Link-State Database.
3. Reducing the amount of flooding.
4. Reducing the number of SPF computations.
5. Reducing the maximum SPF computation time.
RIFT Auto-Flood Reflection (Auto-FR) combines these technologies by
using RIFT's ZTP functionality in order to automatically provision
IS-IS Flood Reflection topologies in a completely distributed
fashion.
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].
2. Design Considerations
IS-IS Flood Reflection operates using Flood Reflectors at the top of
the fabric and Flood Reflector Clients at the bottom of the fabric.
Any nodes in the middle are not required to support Flood Reflection
functionality, nor do they need to support Auto-FR.
Nodes in a Flood Reflection topology require specific variables for
deployment. For example, a Cluster ID that is unique to the
particular fabric or loopback addresses that are unique to a
particular node. RIFT has enough topological information to derive
these variables with the appropriate scope in a distributed fashion
automatically.
Once the Flood Reflection topology is built, RIFT Key-Value TIEs can
be used to distribute operational state information to allow for
cluster-wide validation without any additional tooling.
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3. Auto-FR Device Roles
Auto-FR requires that each node understands its given role within the
scope of the Flood Reflection deployment, so each node derives the
necessary variables and resulting configuration.
3.1. All Participating Nodes
Not all nodes have to participate in Auto-FR, however, if a node does
assume an Auto-FR role, it MUST derive the following variables:
*Flood Reflection Cluster ID*
The Flood Reflection Cluster ID us to distinguish reflection
domains (similar to the Cluster ID use in BGP Route
Reflection).
*IPv6 Loopback Address*
Unique IPv6 loopback address.
*IS-IS System ID*
The IS-IS System Identifier used in deriving the IS-IS NET
Address.
*IS-IS NET Address*
The IS-IS NET Address used to uniquely identify an IS-IS node.
3.2. Flood Reflectors
This section defines an Auto-FR role whereby some ToF (Top-of-Fabric)
nodes act as IS-IS Flood Reflectors. It is expected that Flood
Reflectors will establish Level 2 IS-IS adjacencies with Flood
Reflector Clients in the same area, in the same fabric. The typical
Flood Reflector requirements do not change, however, determining
which specific values to use requires further consideration.
ToF nodes performing Flood Reflector functionality MUST derive the
following variables:
*IPv6 Flood Reflector Loopback Address*
Unique IPv6 loopback address.
3.3. Flood Reflectors Clients
Although no specific variables for Flood Reflector Clients are
described at this time, the generic role is specified as a
placeholder for future enhancements.
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*Future Consideration*
Future Consideration
4. Auto-FR Variable Derivation
As previously mentioned, not all nodes are required to derive all
variables in a network. For example, spine nodes may only be
required for transit traffic and not need to support Auto-FR at all.
All variables are derived from RIFT's FSM or ZTP mechanism, so no
additional flooding other than RIFT's typical flooding is required.
It is also important to mention that all variable derivation is in
some way based on the RIFT System ID and/or Cluster ID and MUST
comply precisely with calculation methods specified in the Auto-FR
Variable Derivation section to allow interoperability between
different implementations. All necessary foundational code elements
are also mentioned there.
4.1. RIFT System ID
The 64-bit RIFT System ID that uniquely identifies a node as defined
in [RIFT]. This not derived specifically for Auto-FR, but for all
RIFT nodes and is used in the derivation procedures described in this
section.
4.2. Auto-FR Version
This section describes extensions to both the RIFT LIE and Node-TIE
packet schemas in the form of a 16-bit value that identifies the
Auto-FR Version. Auto-FR capable nodes MUST support this extension,
but MAY choose not to advertise it in LIEs and Node-TIEs when Auto-FR
is not being utilized.
The complete encoding.thrift schema documented in [RIFT] describes
both major and minor protocol/schema versions. Auto-FR Version
calculation is done by multiiplying a static value of 256 by the
major version then adding the minor version, that is to say - 256 *
MAJOR + MINOR.
This section also describes an extension to the NodeCapabilities
schema indicating whether or not a node supports Auto-FR.
The appendix (Appendix A) details necessary changes to the LIEPacket,
NodeTIEElement, and NodeCapabilities Thrift schemas.
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4.3. Flood Reflection Cluster ID
This section describes extensions to both the RIFT LIE and Node-TIE
packet schemas in the form of a 32-bit value that identifies the
Auto-FR Cluster ID. Auto-FR capable nodes MUST support this
extension, but MAY choose not to advertise it in LIEs and Node-TIEs
when Auto-FR is not being utilized.
Deployments using more than one Auto-FR cluster MUST use different
Cluster IDs. Failure to do so may cause sub-optimal routing as L1/L2
nodes from different clusters would belong to the same subnet.
A Cluster ID with a value of 0 is considered invalid and MUST NOT be
used for any purpose.
The appendix (Appendix A) details necessary changes to the LIEPacket
and NodeTIEElement Thrift schemas.
4.4. Flood Reflection Preference
This section describes extensions to the Node-TIE packet schema in
the form of a 32-bit value that indicates a Flood Reflection
Preference value to be used during Flood Reflector election
procedures with the higher value being preferred. Auto-FR capable
nodes MUST support this extension.
The appendix (Appendix A) details necessary changes to the
NodeTIEElement Thrift schemas.
4.5. IS-IS System ID
Auto-FR nodes MUST derive a unique 8-byte IS-IS System ID for use in
deriving the IS-IS NET Address. Calculation is done using the 8-byte
RIFT System ID and 4-byte Cluster ID.
In order for nodes to derive an IS-IS System ID, the following
algorithms are required - auto_fr_cidsid2isissid (Figure 9) and
auto_fr_v6hash (Figure 14).
4.6. IS-IS NET Address
Auto-FR nodes MUST derive a unique 10-byte IS-IS NET (Network Entity
Title) Address to uniquely identify itself within the Flood
Reflection topology. The 1st byte (which indicates the AFI) MUST
have a value of "49". The last byte (i.e. the NSEL) MUST have a
value of 0. Remaining calculation is done using the 8-byte RIFT
System ID and 4-byte Cluster ID.
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In order for nodes to derive an IS-IS NET Address, the following
algorithms are required - auto_fr_cidsid2isisnet (Figure 8) and
auto_fr_cidsid2isissid (Figure 9).
4.7. Loopback Address
Auto-FR nodes MUST derive a ULA-scoped IPv6 loopback address to be
used in IS-IS. Calculation is done using the 6-bytes of reserved ULA
space, the 4-byte Cluster ID, and the node's 8-byte RIFT System ID.
Derivation of the IS-IS System ID varies slightly depending upon the
node's location/role in the fabric and will be described in
subsequent sections.
4.7.1. Leaf Nodes as Flood Reflector Clients
Leaf Nodes acting as Flood Reflector Clients MUST derive their
loopback address according to the specific section describing the
algorithm. Calculation is done using the 6-bytes of reserved ULA
space, the 4-byte Cluster ID, and the 8-byte RIFT System ID.
In order for leaf nodes to derive IPv6 loopbacks, the following
algorithms are required - auto_fr_cidsidv6loopback (Figure 11) and
auto_fr_v6prefixcidsid2loopback (Figure 15).
IPv4 addresses MAY be supported, but it should be noted that they
have a higher likelihood of collision. The appendix contains the
required auto_fr_cidsid2v4loopback (Figure 10) algorithm to support
IPv4 loopback derivation.
4.7.2. ToF Nodes as Flood Reflectors
ToF nodes acting as Flood Reflectors MUST derive their loopback
address according to the specific section describing the algorithm.
Calculation is done using the 6-bytes of reserved ULA space, the
4-byte Cluster ID, and the 8-byte RIFT System ID.
In order for ToF nodes to derive IPv6 loopbacks, the following
algorithms are required - auto_fr_cidsidv6loopback (Figure 11),
auto_fr_v6prefixcidsid2loopback (Figure 15), and
auto_fr_cidfrpref2frloopback (Figure 7).
IPv4 addresses MAY be supported, but it should be noted that they
have a higher likelihood of collision. The appendix contains the
required auto_fr_cidsid2v4loopback (Figure 10) algorithm to support
IPv4 loopback derivation.
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4.7.2.1. Flood Reflector Election Procedures
Each ToF performs the election independently based on the RIFT System
IDs and a Flood Reflection preference value of other ToF nodes in the
fabric obtained via southbound reflection. The Flood Reflector
election procedures are defined as follows:
1. Highest System ID with the highest preference.
2. Lowest System ID with the highest preference.
3. 2nd highest System ID with the 2nd highest preference.
4. etc.
This ordering is necessary to prevent a single node with either the
highest or lowest System ID from triggering changes to flood
reflector loopback addresses as it would result in all IS-IS
adjacencies flapping.
For example, if ToF01 (System ID: 002c6af5a281c000 / FR Preference:
100) and ToF02 (System ID: 002c6bf5788fc000 / FR Preference: 1) went
through the election process, ToF02 would be elected due to it having
the highest System ID. If a ToF determines that it is elected as a
Flood Reflector, it uses the knowledge of its position in the list to
derive Flood Reflector IPv6 loopback address.
A topology MUST elect at least 1 ToF node as an IS-IS Flood
Reflector, but SHOULD elect 3. The election process varies depending
upon whether or not the topology is comprised of a single plane or
multiple planes. The multiplane election procedure will be described
in a future version of this document.
The algorithm shown in "auto_fr_sids2frs" (Figure 12) is required to
perform the Flood Reflector election procedures.
5. RIFT Requirements
5.1. RIFT FSM / LIE Validation Requirements
RIFT FSM adjacency rules MUST consider Auto-FR Version (Section 4.2)
and Auto-FR Cluster ID (Section 4.3) values so that nodes that do not
support Auto-FR can interoperate with nodes that do. The LIE
validation is extended with the following clause and if it is not
met, miscabling should be declared:
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(if auto_flood_reflection_version is not advertised by either node OR
if auto_flood_reflection_version is identical on both nodes)
AND
(auto_flood_reflection_cluster_id is not advertised by either node OR
auto_flood_reflection_cluster_id is identical on both nodes)
5.2. RIFT Node-TIE Advertisements
All nodes utilizing Auto-FR MUST advertise their Auto-FR Version
(Section 4.2), Flood Reflection Cluster ID (Section 4.3), and Flood
Reflection Preference (Section 4.4) values in at least one Node-TIE
in each direction (i.e. North and South).
6. Operational Considerations
To fully realize the benefits of Auto-FR, it may help to describe the
high-level method. Simply put, RIFT automatically provisions the
underlay and Auto-FR provisions the Flood Reflection topology. The
goal of this section is to draw simple lines between general fabric
concepts, RIFT, and Auto-FR and how they fit into current network
designs and practices.
This section also describes a set of optional Key-Value TIEs
[RIFT-KV] that leverages the variables that have already been derived
to provide further operational enhancement to the operator.
6.1. RIFT Underlay and IS-IS Flood Reflection Topology
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+-----------------+ +-----------------+
| ToF-01 | | ToF-02 |
| L1 / L2 | | L1 / L2 | ]----------------------+
| Flood Reflector | | Flood Reflector | |
+-+--+------+--+--+ +-+--+------+--+--+ |
| | | | | | | | |
+---------------------+ | | | | | | | |
| | | | | | | +---------------------+ |
| +-----------)------)--)--------+ | | | |
| | | | | +-------+ | | |
| | | | | | | | |
| | | | +---)--------------)-----------+ | |
| | | | | | | | |
| | +--+ +------)----+ +--+ | | |
| | | | | | | | |
| | | +---+ | | | | | Level 2 Mesh of
| | | | | | | | | Flood Reflection
+-+------------+-+ +-+------------+-+ +-+------------+-+ +-+------------+-+ | Adjacencies
| Spine-1-1 | | Spine-1-2 | | Spine-2-1 | | Spine-2-2 | | Between ToFs/Leafs
| L1 | | L1 | | L1 | | L1 | |
| N/A | | N/A | | N/A | | N/A | |
+--+----------+--+ +--+----------+--+ +--+----------+--+ +--+----------+--+ |
| | | | | | | | |
| +----------)---+ | | +----------)---+ | |
| | | | | | | | |
| +----------+ | | | +----------+ | | |
| | | | | | | | |
+--+----------+--+ +------+------+--+ +--+----------+--+ +------+------+--+ |
| Leaf-1-1 | | Leaf-1-2 | | Leaf-2-1 | | Leaf-2-2 | |
| L1 / L2 | | L1 / L2 | | L1 / L2 | | L1 / L2 | ]-+
| FR Client | | FR Client | | FR Client | | FR Client |
+--+-------------+ +--------------+-+ +--+-------------+ +----------------+
| |
| |
| |
| |
+--+-------------+ +--+-----------+-+
| Node A | | Node Z |
| L2 | | L2 |
+----------------+ +----------------+
Figure 1: Auto-FR Example Topology
Figure 1 illustrates a typical 5-stage Clos IP fabric. Each node is
named and labelled in such a way that conveys:
1. The node's generic placement within the context of the RIFT
underlay
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2. The node's level(s) within the IS-IS area.
3. The node's role within the IS-IS Flood Reflection topology.
Table 1 should help further align these concepts.
+----------------+-------------+------------------------+
| RIFT Placement | IS-IS Level | IS-IS FR Role |
+================+=============+========================+
| ToF Nodes | L1/L2 | Flood Reflector |
+----------------+-------------+------------------------+
| Spine Nodes | L1 | N/A |
+----------------+-------------+------------------------+
| Leaf Nodes | L1/L2 | Flood Reflector Client |
+----------------+-------------+------------------------+
Table 1: Role Associations
Connections between various nodes can be understood in two different
ways:
1. Lines between ToF and leaf nodes are Level 2 IS-IS Flood
Reflection adjacencies.
2. Lines between spine and leaf are part of the physically connected
underlay.
3. Lines between ToF and spine are part of the physically connected
underlay.
It is important to remember that Auto-FR is not altering the way in
which IS-IS Flood Reflection operates in any way, it simply takes
existing deployment scenarios and simplifies the provisioning
process.
6.2. Auto-FR Analytics
Leaf nodes MAY optionally advertise analytics information about the
Auto-FR fabric to ToF nodes using RIFT Key-Value TIEs [RIFT-KV].
This may be helpful in that validation and troubleshooting activities
can be performed on the ToF nodes rather than manually verifying the
state separately on multiple leaf nodes.
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6.2.1. Auto-FR Analytics (Global) Key/Value Pair
This Key/Value pair describes node level information within the
context of the Flood Reflection topology. The RIFT System ID of the
advertising leaf node MUST be used to differentiate the node among
other nodes in the fabric.
The Auto-FR Analytics (Global) Key/Value pair MUST be advertised with
the 3rd and 4th bytes of the Key Identifier consisting of all 0s.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Well-Known | Auto-FR Analytics (Global) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (Auto-FR Role, |
| Flood Reflection Cluster ID, |
| Established IS-IS FR Adjacencies, |
| Established IS-IS FR L1 Shortcut Adjacencies, |
| Total IS-IS FR Adjacencies, |
| Total IS-IS FR L1 Shortcut Adjacencies,) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Auto-FR Global Key/Value Pair
*where:*
*Auto-FR Role:*
A REQUIRED value indicating the node's Auto-FR role within the
fabric.
*0:* Illegal value, MUST NOT be used.
*1:* Auto-FR Flood Reflector Client
*2:* Auto-FR Flood Reflector
*Auto-FR Cluster ID*
A REQUIRED 32-bit integer indicating the Auto-FR Cluster ID of
the local node.
*Established IS-IS Flood Reflector Adjacency Count:*
A RECOMMENDED 16-bit integer indicating the number of IS-IS
Level 2 Flood Reflector adjacencies in the "Up" state on the
local node.
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*Functional IS-IS Level 1 Shortcut Count*
A RECOMMENDED 16-bit integer indicating the number of
functional IS-IS Level 1 "shortcuts" on the local node.
*Total IS-IS Flood Reflector Adjacency Count:*
A RECOMMENDED 16-bit integer indicating the total number of IS-
IS Level 2 Flood Reflector adjacencies on the local node
regardless of state.
*Total IS-IS Level 1 Shortcut Count*
A RECOMMENDED 16-bit integer indicating the total number of IS-
IS Level 1 "shortcuts" the local node regardless of state.
Implementations leveraging Thrift for Key-Value functionality SHOULD
refer to the auto_flood_reflection_kv.thrift (Appendix A.3) schema in
the appendix.
7. IANA Considerations
This section requests the following suggested values from the RIFT
Well-Known Key-Type Registry.
+-------+----------------+------------------------------+-----------+
| Value | Key-Identifier | Description | Status/ |
| | | | Reference |
+=======+================+==============================+===========+
| 5 | Auto-FR | Key/Value pair | This |
| | Analytics | containing operational | document. |
| | (Global) | state of a Flood | |
| | | Reflector Client node. | |
+-------+----------------+------------------------------+-----------+
Table 2: Auto-FR Suggested Value(s) for RIFT Well-Known Key-Type
Registry
8. Security Considerations
This document introduces no new security concerns to RIFT or other
specifications referenced in this document as RIFT natively secures
LIE and TIE packets as described in [RIFT].
9. Acknowledgements
This section will be used to acknowledge major contributors.
10. References
10.1. Normative References
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[IS-IS-FR] Przygienda, A., Bowers, C., Lee, Y., Sharma, A., and R.
White, "IS-IS Flood Reflection", Work in Progress, draft-
ietf-lsr-isis-flood-reflection-07, November 2021.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", June
2017, <https://www.rfc-editor.org/info/rfc8126>.
[RIFT] Przygienda, T., Sharma, A., Thubert, P., Rijsman, B., and
D. Afanasiev, "RIFT: Routing in Fat Trees", Work in
Progress, draft-ietf-rift-rift-15, December 2021.
[RIFT-KV] Head, J. and T. Przygienda, "RIFT Key/Value Structure and
Registry", Work in Progress, draft-ietf-rift-kv-registry-
01, June 2022.
Appendix A. Thrift Models
This section contains the normative Thrift models required to support
Auto-FR. Per the main [RIFT] specification, all signed values MUST
be interpreted as unsigned values.
A.1. common.thrift
This section specifies extensions to RIFT common.thrift model.
These extensions are REQUIRED in order to support Auto-FR.
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...
enum AutoFRModel {
TunnelMode = 0,
NoTunnelMode = 1,
}
const AutoFRModel default_autofr_model = AutoFRModel.TunnelMode
typedef i32 FloodReflectionClusterIDType
const FloodReflectionClusterIDType IllegalClusterID = 0
const FloodReflectionClusterIDType DefaultClusterID = 1
/// preference to become FR, higher is better
typedef i32 FloodReflectionPreferenceType
const FloodReflectionPreferenceType MinFloodReflectionPreference = 0
...
Figure 3: RIFT Auto-FR: common.thrift
A.2. encoding.thrift
This section specifies extensions to RIFT encoding.thrift model.
These extensions are REQUIRED in order to support Auto-FR.
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struct NodeCapabilities {
...
/** indicates whether auto-flood-reflection feature is implemented on this node (but not necessarily enabled). */
20: optional bool auto_flood_reflection_support = false;
...
}
struct LIEPacket {
...
/** It provides optional version of FR ZTP as 256 * MAJOR + MINOR, indicates support for auto FR */
40: optional i16 auto_flood_reflection_version;
41: optional common.FloodReflectionClusterIDType auto_flood_reflection_cluster_id;
...
}
struct NodeTIEElement {
...
/** All Auto FR elements MUST be present in at least one TIE in each direction if auto FR is running. */
/** It provides optional version of FR ZTP as 256 * MAJOR + MINOR, indicates support for auto FR */
30: optional i16 auto_flood_reflection_version;
/** cluster ID of Auto FR */
31: optional common.FloodReflectionClusterIDType auto_flood_reflection_cluster_id;
/** preference to become FR */
32: optional common.FloodReflectionPreferenceType auto_flood_reflection_preference;
...
}
Figure 4: RIFT Auto-FR: encoding.thrift
A.3. auto_flood_reflection_kv.thrift
This section defines auto_flood_reflection_kv.thrift as a method of
supporting Auto-FR analytics functionality.
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include "common.thrift"
namespace py auto_flood_reflection_kv
namespace rs models
const i8 AutoFRWellKnownKeyType = 2
typedef i16 AutoFRCounterType
typedef i32 AutoFRLongCounterType
const i8 GlobalAutoFRTelemetryKV = 5
/** We don't need the full role structure, only an indication of the node's basic role */
enum AutoFRRole {
ILLEGAL = 0,
auto_fr_leaf = 1,
auto_fr_reflector = 2,
}
/** Per the according RIFT draft the key comes from the well known space.
Part of the key is used as Fabric-ID.
1st byte MUST be = "Well-Known"
2nd byte MUST be = "Auto-FR Analytics (Global) KV",
3rd/4th bytes MUST be = all 0s
*/
struct AutoFRTelemetryGlobalKV {
/** Only values that the ToF cannot derive itself should be flooded. */
1: required set<AutoFRRole> auto_fr_roles,
2: required common.FloodReflectionClusterIDType cluster_id,
3: optional AutoFRCounterType established_isis_fr_adjacencies_count,
4: optional AutoFRCounterType established_isis_l1_shortcut_adjacencies_count,
5: optional AutoFRCounterType total_isis_fr_adjacencies_count,
6: optional AutoFRCounterType total_isis_l1_shortcut_adjacencies_count,
}
Figure 5: RIFT Auto-FR: auto_flood_reflection_kv.thrift
Appendix B. Auto-FR Variable Derivation
This section contains the normative variable derivation algorithms
that are REQUIRED to support Auto-FR.
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/// indicates how many FRs we're computing in AUTO FR
pub const MAX_AUTO_FR_FRS: usize = 3;
/// indicates the cluster has no ID, used in computations to omit effects of cluster ID
pub const NO_CLUSTER_ID: FloodReflectionClusterIDType = 0;
/// unique v6 prefix for all nodes starts with this
pub fn auto_fr_v6pref(cid: FloodReflectionClusterIDType) -> String {
format!("FD00:{:04X}:B1", cid)
}
/// how many bytes in a v6pref for different purposes
pub const AUTO_FR_V6PREFLEN: usize = 8 * 5;
/// unique v6 prefix for flood reflector purposes starts like this
pub fn auto_fr_v6frpref(cid: FloodReflectionClusterIDType) -> String {
format!("FD00:{:04X}:B2", cid)
}
/// unique v4 prefix for IRB purposes
pub const AUTO_FR_V4LOOPBACKNET: u8 = 10;
pub const AUTO_FR_V4LOOPBACKMASK : usize = 8;
Figure 6: RIFT Auto-FR: auto_fr_const_structs_types
/// auto FR V6 loopback for FRs
pub fn auto_fr_cidfrpref2frloopback(cid: FloodReflectionClusterIDType,
preference: u8) -> Result<Ipv6Addr, ServiceErrorType> {
auto_fr_v6prefixcidsid2loopback(&auto_fr_v6frpref(cid), cid, (1 + preference) as _)
}
Figure 7: RIFT Auto-FR: auto_fr_cidfrpref2frloopback
pub fn auto_fr_cidsid2isisnet(cid: FloodReflectionClusterIDType, sid: UnsignedSystemID) -> Vec<u8> {
let mut r = vec![0x49]; // magic AFI
// area ID derived from cluster ID
r.extend(&cid.to_ne_bytes().iter().fold(0x77u16,
|prev, val| (prev ^ (val.rotate_right(4) as u16))).to_ne_bytes());
// ISIS ID derived from system ID + cid/sid
r.extend(auto_fr_cidsid2isissid(cid, sid).into_iter());
// selector non v-node
r.push(0);
r
}
Figure 8: RIFT Auto-FR: auto_fr_cidsid2isisnet
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/// ISIS system ID derivation
pub fn auto_fr_cidsid2isissid(
cid: FloodReflectionClusterIDType,
sid: UnsignedSystemID) -> Vec<u8> {
let sb = auto_fr_v6hash(cid, sid);
vec![sb[0],
sb[1],
sb[2],
sb[3],
sb[4] ^ sb[5].rotate_right(4),
sb[6] ^ sb[7].rotate_right(4),
]
}
Figure 9: RIFT Auto-FR: auto_fr_cidsid2isissid
/// v4 loopback address derivation for every node in auto-fr, returns address and
/// subnet mask length.
pub fn auto_fr_cidsid2v4loopback(cid: FloodReflectionClusterIDType, sid: UnsignedSystemID) -> (IPv4Address, u8) {
let mut derived = sid.to_ne_bytes().iter()
.fold(0 as IPv4Address, |p, e| (p << 4) ^ (*e as IPv4Address));
derived ^= cid as IPv4Address;
// use the byte we loose for entropy
derived ^= derived >> (32 - AUTO_FR_V4LOOPBACKMASK);
// and sanitize for loopback range, we nuke 8 bits out
derived &= (!U32MASKS[AUTO_FR_V4LOOPBACKMASK]) as IPv4Address;
let m = ((AUTO_FR_V4LOOPBACKNET as IPv4Address) << (32 - AUTO_FR_V4LOOPBACKMASK)) | derived;
(m as _, AUTO_FR_V4LOOPBACKMASK as _)
}
Figure 10: RIFT Auto-FR: auto_fr_cidsid2v4loopback
/// V6 loopback derivation for every node in auto fr
pub fn auto_fr_cidsidv6loopback(cid: FloodReflectionClusterIDType,
sid: UnsignedSystemID) -> Result<Ipv6Addr, ServiceErrorType> {
auto_fr_v6prefixcidsid2loopback(&auto_fr_v6pref(cid), cid, sid)
}
Figure 11: RIFT Auto-FR: auto_fr_cidsidv6loopback
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/// Function sorts vector of system IDs first,
/// Followed by a shuffle taking largest/smallest/2nd largest/2nd smallest.
/// Preference is used to take the according subsets to run this algorithm
/// sequentially.
pub(crate) fn auto_fr_sids2frs(mut v: Vec<(FloodReflectionPreferenceType,
UnsignedSystemID)>)
-> Vec<UnsignedSystemID> {
v.par_sort_by(|(p1, s1),
(p2, s2)|
match p2.cmp(p1) {
Ordering::Equal => s2.cmp(s1),
e @ _ => e
});
let mut elected = vec![];
while elected.len() < MAX_AUTO_FR_FRS && !v.is_empty() {
let pref = (&v[0]).0;
let mut splitat = 0;
while splitat < v.len() && (&v[splitat]).0 == pref {
splitat += 1;
}
let mut so = v.split_off(splitat);
std::mem::swap(&mut v, &mut so);
let mut mixed = if so.len() > 2 {
let mut s = so.split_off(so.len() / 2);
s.reverse();
interleave(so.into_iter(), s.into_iter())
.collect::<Vec<_>>()
} else {
so
};
elected.extend(mixed.drain(..))
}
elected.drain(..).map(|(_, sid)| sid).collect()
}
Figure 12: RIFT Auto-FR: auto_fr_sids2frs
pub(crate) fn auto_fr_v62octets(a: Ipv6Addr) -> Vec<u8> {
a.octets().iter().cloned().collect()
}
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Figure 13: RIFT Auto-FR: auto_fr_v62octets
/// generic bytes derivation used for different purposes
pub fn auto_fr_v6hash(cid: FloodReflectionClusterIDType, sid: UnsignedSystemID)
-> [u8; 8] {
let sub = (cid as UnsignedSystemID) ^ sid.rotate_right(8);
sub.to_ne_bytes()
}
Figure 14: RIFT Auto-FR: auto_fr_v6hash
/// local address with encoded cluster ID and system ID for collision free identifiers. Basis
/// for several different prefixes.
pub fn auto_fr_v6prefixcidsid2loopback(v6pref: &str, cid: FloodReflectionClusterIDType,
sid: UnsignedSystemID) -> Result<Ipv6Addr, ServiceErrorType> {
assert!(cid != ILLEGAL_CLUSTER_I_D);
let a = format!("{}00::{}",
v6pref,
sid.to_ne_bytes()
.iter()
.chunks(2)
.into_iter()
.map(|chunk|
chunk.fold(0u16, |v, n| (v << 8) | *n as u16))
.map(|v| format!("{:04X}", v))
.collect::<Vec<_>>()
.into_iter()
.join(":")
);
Ipv6Addr::from_str(&a)
.map_err(|_| ServiceErrorType::INTERNALRIFTERROR)
}
Figure 15: RIFT Auto-FR: auto_fr_v6prefixcidsid2loopback
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/// cluster prefixes derived instead of advertising default on the cluster to allow
/// for default route on ToF or leaves
pub fn auto_fr_cid2cluster_prefixes(cid: FloodReflectionClusterIDType) -> Result<Vec<IPPrefixType>, ServiceErrorType> {
vec![
(auto_fr_cidsidv6loopback(cid, ILLEGAL_SYSTEM_I_D as _), AUTO_FR_V6PREFLEN),
(auto_fr_cidfrpref2frloopback(cid, 0 as _), AUTO_FR_V6PREFLEN),
]
.into_iter()
.map(|(p, _)|
match p {
Ok(_) => Ok(
IPPrefixType::Ipv6prefix(
IPv6PrefixType {
address: auto_fr_v62octets(p?),
prefixlen: AUTO_FR_V6PREFLEN as _,
})),
Err(e) => Err(e),
}
)
.collect::<Result<Vec<_>, _>>()
}
Figure 16: RIFT Auto-FR: auto_fr_cid2cluster_prefixes
Authors' Addresses
Jordan Head (editor)
Juniper Networks
1133 Innovation Way
Sunnyvale, CA
United States of America
Email: jhead@juniper.net
Tony Przygienda
Juniper Networks
1133 Innovation Way
Sunnyvale, CA
United States of America
Email: prz@juniper.net
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Colby Barth
Juniper Networks
1133 Innovation Way
Sunnyvale, CA
United States of America
Email: cbarth@juniper.net
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