IDR L. Zhang, Ed.
Internet-Draft T. Zhou
Intended status: Standards Track J. Dong
Expires: 25 April 2024 Huawei
23 October 2023
BGP Flow Specification Extensions for Path Scheduling
draft-zzd-idr-flowspec-path-scheduling-00
Abstract
Path scheduling is required in many network scenarios. For example,
some links or nodes will be shut down in the tidal network when the
traffic decreases, which may lead to the expiration of some routing
paths.
This document defines a new type of component for BGP Flow
Specification to identify the packets arrived at different time slot.
Based on that, the headend can steer packets into different paths at
different time.
Status of This Memo
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This Internet-Draft will expire on 25 April 2024.
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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. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Scheduling time information in FlowSpec . . . . . . . . . . . 3
3.1. Aperiodic Scheduling Time Information . . . . . . . . . . 4
3.2. Periodic Scheduling Time Information . . . . . . . . . . 5
4. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative References . . . . . . . . . . . . . . . . . . 6
7.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
[RFC8955] and [RFC8956] define the BGP [RFC4271] Flow Specification
(FlowSpec) that allows conveying flow specifications and traffic
Action/Rules associated. BGP Flow specifications are encoded within
the MP_REACH_NLRI and MP_UNREACH_NLRI attributes [RFC4760]. Rules
(Actions associated) are encoded in Extended Community attribute
[RFC4360]. The BGP Flow Specification function allows BGP Flow
Specification routes that carry traffic policies to be transmitted to
BGP Flow Specification peers to steer traffic.
[I-D.ietf-idr-ts-flowspec-srv6-policy] describes BGP flow
specification usage that are used to steer data flow into an SR
Policy which can steer traffic into a specific path.
The existing traffic filter rules and actions in FlowSpec are always
effective and will steer specific traffic into one Policy once been
delivered to the headend. However, there are many scenarios that
need to schedule routing paths in the network.
[I-D.zzd-tvr-use-case-tidal-network] introduces the tidal network, in
which the topology of the network will change periodically over time.
The topology change may cause some of the paths invalid, and lead to
path reselection or even recalculation. However, the reselection or
recalculation takes a period of time, which will affect packet
forwarding and cause problems such as packet disorder and packet
loss. On a network with predictable topology changes, the controller
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knows future topology changes, it can deliver several policies for
different topology to the headend in advance. Then the headend
steers traffic to different policies based on time to prevent packet
forwarding from being affected by topology changes.
This document defines a new type of component for BGP Flow
Specification to identify the packets arrived at different time slot.
Based on that, the headend can steer packets into different paths at
different time.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Motivation
[I-D.zzd-tvr-use-case-tidal-network] introduces the time variant
routing scenario in the tidal network, in which the traffic volume
varies greatly at different time. In order to reduce the power
consumption, some of the links and nodes may be shut down when the
traffic is at a low level.
In this scenario, the SR policy originator can generate several
policies for different topologies. The headend doesn’t need to wait
for the advertisement of topology change and just steer traffic in to
different policies based on the flowSpec with scheduling time
information, the affection of topology change is minimized.
3. Scheduling time information in FlowSpec
[RFC8955] defines 12 Components to identify different traffics.
Based on [RFC8955], this document defines a new Component to identify
the arrival time of packets, so as to enable Policies scheduling.
Encoding: <type (1 octet), length (1 octet), scheduling time
information (variabile)]+>
Defines the time information that matches the arrival time of
packets. This component matches if either the arrival time of an IP
packet in the scope of scheduling time information.
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The Scheduling time information has two formats according to the
change regularity of network topology. They are Aperiodic Scheduling
Time Information (ASTI) and Periodic Scheduling Time Information
(PSTI).
3.1. Aperiodic Scheduling Time Information
The ASTI indicates one or more group of matching time slot (each
includes the enable time and disable time) for the packets. The
format of ASTI is shown as follows:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Enable Time |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Disable Time |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ Variable /
| |
Figure 1: Format of ASTI
Type: used to identify the type of scheduling time information. The
value and corresponding types are shown as follows:
+=======+=======================================+
| Value | Type |
+=======+=======================================+
| 0x01 | Aperiodic Scheduling Time Information |
+-------+---------------------------------------+
| 0x02 | Periodic Scheduling Time Information |
+-------+---------------------------------------+
Table 1
Enable Time: the time in seconds indicates the start time when the
packets matching.
Disable Time: the time in seconds indicates the end time when the
packets matching.
Variable: one or more groups of time information (A information group
is composed of Enable Time and Disable time) may be included in one
ASTI.
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3.2. Periodic Scheduling Time Information
The PSTI indicates one or more group of periodic matching time slot
(each includes period, enable time and disable time) for the packets.
The format of PSTI is shown as follows:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Period |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Enable Time |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Disable Time |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
/ Variable /
| |
Figure 2: Format of PSTI
Type: as defined in clause “Aperiodic Scheduling Time Informationâ€
Length: the size of the value field in octets.
Period: the time in seconds between the enable time of one repetition
and the enable time of the next repetition.
Enable Time: the time in seconds indicates when the path(s) is(are)
enabled.
Disable Time: the time in seconds indicates when the path(s) is(are)
disabled
Variable: one or more groups of time information(A information group
is composed of Period, Enable Time and Disable time) may be included
in one PSTI.
4. Procedures
When the headend device (as a FlowSpec client) receives a instruction
with scheduling time information from a BGP FlowSpec Controller, it
will steer the traffic packets matching the time slot and other
conditions in the Flowspec instruction into a specific Policy.
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And the packets will be encapsulated with an SR List <S1, S2, S3> in
the headend device, then send the packets to the TailEnd device along
the path indicated by the SR list.
5. Security Considerations
These extensions to BGP FlowSpec do not add any new security issues
to the existing protocol.
6. IANA Considerations
This document defines a new Component in the registry " Flow Spec
Component Types" to be assigned by IANA:
+=======+=============================+===============+
| Value | Description | Reference |
+=======+=============================+===============+
| TBD1 | Scheduling Time Information | This document |
+-------+-----------------------------+---------------+
Table 2
7. References
7.1. Normative References
[RFC8955] Loibl, C., Hares, S., Raszuk, R., McPherson, D., and M.
Bacher, "Dissemination of Flow Specification Rules",
RFC 8955, DOI 10.17487/RFC8955, December 2020,
<https://www.rfc-editor.org/info/rfc8955>.
[RFC8956] Loibl, C., Ed., Raszuk, R., Ed., and S. Hares, Ed.,
"Dissemination of Flow Specification Rules for IPv6",
RFC 8956, DOI 10.17487/RFC8956, December 2020,
<https://www.rfc-editor.org/info/rfc8956>.
[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760,
DOI 10.17487/RFC4760, January 2007,
<https://www.rfc-editor.org/info/rfc4760>.
[I-D.ietf-idr-ts-flowspec-srv6-policy]
Wenying, J., Liu, Y., Zhuang, S., Mishra, G. S., and S.
Chen, "Traffic Steering using BGP FlowSpec with SR
Policy", Work in Progress, Internet-Draft, draft-ietf-idr-
ts-flowspec-srv6-policy-03, 16 June 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-idr-ts-
flowspec-srv6-policy-03>.
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[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>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
7.2. Informative References
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/info/rfc4271>.
[RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
Communities Attribute", RFC 4360, DOI 10.17487/RFC4360,
February 2006, <https://www.rfc-editor.org/info/rfc4360>.
[I-D.zzd-tvr-use-case-tidal-network]
Zhang, L., Zhou, T., Dong, J., and N. Nzima, "Use Case of
Tidal Network", Work in Progress, Internet-Draft, draft-
zzd-tvr-use-case-tidal-network-02, 28 July 2023,
<https://datatracker.ietf.org/doc/html/draft-zzd-tvr-use-
case-tidal-network-02>.
Authors' Addresses
Li Zhang (editor)
Huawei
Beiqing Road
Beijing
China
Email: zhangli344@huawei.com
Tianran Zhou
Huawei
Email: zhoutianran@huawei.com
Jie Dong
Huawei
Email: jie.dong@huawei.com
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