IS-IS and OSPF extensions for TVR (Time-Variant Routing)
draft-zw-lsr-tvr-extensions-01
| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Zheng Zhang , Haisheng Wu , Jing Wang | ||
| Last updated | 2024-03-03 | ||
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| Intended RFC status | (None) | ||
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| Stream | Stream state | (No stream defined) | |
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draft-zw-lsr-tvr-extensions-01
TVR Z. Zhang
Internet-Draft H. Wu
Intended status: Standards Track ZTE Corporation
Expires: 4 September 2024 J. Wang
China Mobile
3 March 2024
IS-IS and OSPF extensions for TVR (Time-Variant Routing)
draft-zw-lsr-tvr-extensions-01
Abstract
TVR needs IGP to calculate different results depending on the time,
without convergence after the detection of link or nodes. IGP nodes
need to learn the predictable and scheduled changes in advance. This
document defines the IGP extensions for predictable and scheduled
changes of TVR.
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
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and may be updated, replaced, or obsoleted by other documents at any
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 4 September 2024.
Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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 carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Time Variant Algorithm . . . . . . . . . . . . . . . . . . . 4
4. Time Variant sub-TLVs of IS-IS and OSPF FAD Sub-TLV . . . . . 4
5. Handling of the time variant sub-TLV . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6.1. IGP Metric-type Registry . . . . . . . . . . . . . . . . 5
6.2. IS-IS Registry . . . . . . . . . . . . . . . . . . . . . 5
6.3. OSPF Registry . . . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . 6
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
9.1. Normative References . . . . . . . . . . . . . . . . . . 6
9.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
This draft was submitted as [I-D.zw-tvr-igp-extensions].
[I-D.ietf-tvr-use-cases] and [I-D.ietf-tvr-requirements] describe a
new challenge for non-terrestrial networks. In these networks, there
are predictable and scheduled changes of link or nodes. The affected
nodes which connected the changing link or node advertise the changes
after finding the changes. After convergence all the nodes calculate
a new routing table. But for the predictable and scheduled changes,
the nodes can advertise the changes and do the calculation in advance
to reduce the convergence time.
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-----------------------------------------------------
| Satellite Network |
| |
| ---------------- ---------------- |
----| Satellite R1 |------------| Satellite R2 |-----
---------------- ----------------
| |
| |
| |
------------------- -------------------
----| Ground Station1 |---------| Ground Station2 |----
| ------------------- ------------------- |
| |
| |
| Ground Network |
-------------------------------------------------------
Figure 1
For example, in Figure 1, The groud station 1/2 connects the
Satellite. Because of the satellite movement, the metric between
satellite and ground station changes over time. Because the movement
is periodic, the metric is changed periodically. Regardless the
unexpected situation like bad weather, the metric variation is
predicable and scheduled. The groud station 1/2 advertises the
predicable and scheduled metric variation to the ground network.
Then the nodes in the ground network can learn the scheduled metric
and calculate the routing table in advance.
This document defines the a set of extensions to IS-IS, OSPFv2 and
OSPFv3 for predictable and scheduled changes of TVR. These
extensions can be advertised by the node self which has predictable
and scheduled changes, or by the node which connected or adjacenct to
the node which has predictable and scheduled changes.
This document helps the implementation of Intrinsic schedule defined
in section 3.1.1 in [I-D.ietf-tvr-requirements]. And the schedule
based on Flex Algorithm can solve the time overlap mentioned in
section 3.2.7 in [I-D.ietf-tvr-requirements]. The schedule in
different FA may be overlapped, but the constrain-based routing
calculation will not be affected.
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 [RFC2119].
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2. Terminology
TBD.
3. Time Variant Algorithm
The predictable and scheduled changes can be looked as a set of new
constrains which defined in [RFC9350]. The new constrains are
advertised as new sub-tlvs.
4. Time Variant sub-TLVs of IS-IS and OSPF FAD Sub-TLV
A new type of Metric-Type is defined for time variant in IS-IS FAD
sub-TLV which defined in section 5.1 [RFC9350] and OSPF FAD sub-TLV
which defined in section 5.2 [RFC9350].
A new Time Variant sub-TLV is advertised as a sub-TLV of IS-IS FAD
sub-TLV and OSPF FAD sub-TLV. The Time Variant sub-TLV has following
formats:
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 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Recurrence-type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metric1 |
| Time-slot1-begin |
| Time-slot1-end |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metric2 |
| Time-slot2-begin |
| Time-slot2-end |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| . |
. . .
| . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metric[m] |
| Time-slot[m]-begin |
| Time-slot[m]-end |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2
Type: 1-octet. TBD (To be assigned by IANA).
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Length: 1-octet. The number of the set of metric and time-slot.
Recurrence-type: 4-octet. The schedule repetitiveness.
Metric: 4-octet. The metric value of specific time slot. The
value of 0xffffffff indicates unreachable.
Time-slot-begin: 4-octet. The begin time of this time-slot.
Time-slot-end: 4-octet. The end time of this time-slot.
5. Handling of the time variant sub-TLV
The handling follows the definition in [RFC9350], except one or more
timers are scheduled for different time-slot carried in time variant
sub-tlv. When a scheduled time-slot is coming, the associated
routing table needs to be calculated with the associated metric.
When the Recurrence-type in the time variant sub-TLV is set, the
routing table needs to be calculated repeatedly. During the time
which is not covered by the time-slot, the default metric is
suggested to be used for routing calculation.
6. IANA Considerations
The document requests new allocations from the IANA registries as
follows:
6.1. IGP Metric-type Registry
IANA is requested to allocate a new code points from the "IGP Metric-
Type" registry.
+======+=====================+===============+
| Type | Description | Reference |
+======+=====================+===============+
| TBD1 | Time Variant metric | This Document |
+------+---------------------+---------------+
Table 1: IGP Metric-Type
6.2. IS-IS Registry
IANA is requested to allocate a new code points from the "IS-IS Sub-
Sub-TLVs for Flexible Algorithm Definition Sub-TLV" registry.
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+======+==============+===============+
| Type | Description | Reference |
+======+==============+===============+
| TBD2 | Time Variant | This Document |
+------+--------------+---------------+
Table 2: IS-IS TVR sub-TLV
6.3. OSPF Registry
IANA is requested to allocate a new code points from the "OSPF
Flexible Algorithm Definition TLV Sub-TLVs" registry.
+======+==============+===============+
| Type | Description | Reference |
+======+==============+===============+
| TBD3 | Time Variant | This Document |
+------+--------------+---------------+
Table 3: OSPF TVR sub-TLV
7. Security Considerations
This document does not introduce more security consideration than
[RFC9350].
8. Acknowledgements
TBD.
9. References
9.1. Normative References
[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>.
[RFC9350] Psenak, P., Ed., Hegde, S., Filsfils, C., Talaulikar, K.,
and A. Gulko, "IGP Flexible Algorithm", RFC 9350,
DOI 10.17487/RFC9350, February 2023,
<https://www.rfc-editor.org/info/rfc9350>.
9.2. Informative References
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[I-D.ietf-tvr-requirements]
King, D., Contreras, L. M., and B. Sipos, "TVR (Time-
Variant Routing) Requirements", Work in Progress,
Internet-Draft, draft-ietf-tvr-requirements-01, 23 October
2023, <https://datatracker.ietf.org/doc/html/draft-ietf-
tvr-requirements-01>.
[I-D.ietf-tvr-use-cases]
Birrane, E. J., Kuhn, N., Qu, Y., Taylor, R., and L.
Zhang, "TVR (Time-Variant Routing) Use Cases", Work in
Progress, Internet-Draft, draft-ietf-tvr-use-cases-09, 29
February 2024, <https://datatracker.ietf.org/doc/html/
draft-ietf-tvr-use-cases-09>.
[I-D.zw-tvr-igp-extensions]
Zhang, Z. and H. Wu, "IS-IS and OSPF extensions for TVR
(Time-Variant Routing)", Work in Progress, Internet-Draft,
draft-zw-tvr-igp-extensions-02, 17 October 2023,
<https://datatracker.ietf.org/doc/html/draft-zw-tvr-igp-
extensions-02>.
Authors' Addresses
Zheng Zhang
ZTE Corporation
China
Email: zhang.zheng@zte.com.cn
Haisheng Wu
ZTE Corporation
China
Email: wu.haisheng@zte.com.cn
Jing Wang
China Mobile
No.32 XuanWuMen West Street
Beijing
100053
China
Email: wangjingjc@chinamobile.com
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