Internet DRAFT - draft-pce-traffic-prediction
draft-pce-traffic-prediction
PCE Working Group B. Yan, Ed.
Internet-Draft Y. Zhao, Ed.
Intended status: Standards Track W. Wang, Ed.
Expires: July 7, 2018 X. Yu, Ed.
J. Zhang, Ed.
bupt
January 3, 2018
PCEP Extension for Traffic Prediction
draft-pce-traffic-prediction-01
Abstract
The Path Computation Element Communication Protocol (PCEP) provides
mechanisms for Path Computation Elements (PCEs) to perform path
computations in response to Path Computation Clients (PCCs) requests.
It is helpful for PCEs to calculate more reasonable path if PCCs can
provide information of traffic prediction. This memo specifies
extensions to PCEP that allow PCE to request prediction-related
information.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on July 7, 2018.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Overview of Protocol Extensions . . . . . . . . . . . . . . . 4
5.1. Capability Advertisement . . . . . . . . . . . . . . . . 4
5.2. New Messages . . . . . . . . . . . . . . . . . . . . . . 4
5.3. Normal Communication Procedure . . . . . . . . . . . . . 5
5.3.1. Initialization Phase . . . . . . . . . . . . . . . . 5
5.3.2. Traffic Prediction Request Sent by a PCE to a PCC . . 6
5.3.3. Traffic Prediction Reply Sent by a PCC to a PCE . . . 6
5.4. Error Reporting . . . . . . . . . . . . . . . . . . . . . 7
6. PCEP Messages . . . . . . . . . . . . . . . . . . . . . . . . 7
6.1. The TPReq Message . . . . . . . . . . . . . . . . . . . . 8
6.2. The TPRep Message . . . . . . . . . . . . . . . . . . . . 8
6.3. The PAUpd Message . . . . . . . . . . . . . . . . . . . . 8
6.4. The PCErr Message . . . . . . . . . . . . . . . . . . . . 8
7. Object Formats . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. OPEN Object . . . . . . . . . . . . . . . . . . . . . . . 8
7.1.1. Traffic Prediction Capability TLV . . . . . . . . . . 8
7.2. No Prediction Object . . . . . . . . . . . . . . . . . . 9
7.3. Prediction Tracker Object . . . . . . . . . . . . . . . . 9
7.3.1. Traffic Prediction Identifier TLV . . . . . . . . . . 9
7.3.2. Traffic Prediction State TLV . . . . . . . . . . . . 9
7.3.3. Prediction Attribute TLV . . . . . . . . . . . . . . 10
7.4. Prediction Requirement Object . . . . . . . . . . . . . . 10
7.4.1. Prediction Sequence TLV . . . . . . . . . . . . . . . 10
7.4.2. Prediction Expired Time TLV . . . . . . . . . . . . . 10
7.5. Prediction Information Object . . . . . . . . . . . . . . 10
7.5.1. Link Prediction TLV . . . . . . . . . . . . . . . . . 10
7.6. Prediction Area Object . . . . . . . . . . . . . . . . . 11
7.6.1. Link TLV . . . . . . . . . . . . . . . . . . . . . . 11
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
9. Security Considerations . . . . . . . . . . . . . . . . . . . 12
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 12
12. Normative References . . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
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1. Introduction
[RFC5440] provides the Path Computation Element Communication
Protocol (PCEP). PCEP defines the communication between a Path
Computation Client (PCC) and a Path Control Element (PCE), or between
PCE and PCE, enabling computation of Multiprotocol Label Switching
(MPLS) for Traffic Engineering Label Switched Path (TE LSP)
characteristics.
For calculating proper path according to the tendency of traffic
distribution in specific network area, this memo introduce a
mechanism to make PCE able to get predicted information from PCC for
specific path computation request.
2. 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].
3. Terminology
This memo uses the following terms defined in [RFC5440]: PCC, PCE,
PCEP Speaker.
4. Motivation
Along the network scale expansion and incremental diversity of
network equipments, the network complexity increases exponentially,
then the path computation in network becomes harder. Considering
both traffic distribution at present and its trend in future in time
dimension, PCE could make better decision to reduce network
congestion, and optimize network performance. There are many
effective methods which can complete traffic prediction accurately,
however, the key point is where the past data set for prediction to
be saved. In some scenarios, as a requester, PCC holds much more
information than the responser PCE which can be used to do
prediction, and not limited within single informations such as
occupied bandwidth on specific network links.
Another reason for this memo is the tradeoff between PCCs and PCEs on
storage resource and computing resource. If vendor choose
computational resource intensive methods to predict, such as machine
learning, there should be much more computing resource request.
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5. Overview of Protocol Extensions
5.1. Capability Advertisement
During PCEP Initialization Phase, PCEP Speakers (PCC or PCE)
advertise their support of extensions for traffic prediction. A PCEP
Speaker includes the "Traffic Prediction Capability" TLV, described
in Section 7.1.1, in the OPEN Object to advertise its support for
traffic prediction extensions. The Traffic Prediction Capability TLV
includes the 'Prediction Capability' Flag that indicates whether the
PCEP Speaker supports prediction operations, and other Flags
indicates further capabilities.
The PCEP extensions for traffic prediction MUST NOT be used if one or
both PCEP Speakers have not included the Traffic Prediction
Capability TLV in their respective OPEN message. If the PCEP Speaker
on the PCC supports the extensions of this memo but does not set this
flag as 1, then if the PCC receive TPReq message from the PCE, it
MUST generate a PCErr with error-type ..., error-value... and it
SHOULD terminate the PCEP session.
this block should describe the error condition!!!
5.2. New Messages
This memo define the following new PCEP messages:
Traffic Prediction Request Message for Path Computation (TPReq): A
PCEP message sent by a PCE to a PCC to request prediction for subset
of whole network which contains specific network elements and network
links. Each TPReq message MUST contain the predicted time sequence
and expired time, MAY contain the sub-network description to be
predicted and requirement for prediction accuracy, A PCE MAY send
traffic prediction request message to a PCC at any time as long as it
consideres this operation necessary. The details of TPReq message is
described in Section 6.1.
Traffic Prediction Reply Message for Path Computation (TPRep): A PCEP
message sent by a PCC to a PCE to reply specific TPReq message, which
contains prediction results for specific sub-network. Each TPRep
message MUST contain predicted sub-network description, and related
prediction information sequence. A PCC sends traffic prediction
reply message if and only if it received related TPReq message. The
details of TPRep message is described in Section 6.2.
Precdiction Attribute Update Message for Path Computation (PAUpd): A
PCEP message sent by a PCC to a PCE to indicate the scope changes of
prediction attributes. Each PAUpd MAY contain sub-network
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description, prediction time scope, and prediction accuracy scope. A
PCC MUST send prediction attribute update message to a PCE immediatly
after OPEN message defined in [RFC5440], or some attributes has been
changed. The details of PAUpd message is described in Section 6.3.
5.3. Normal Communication Procedure
5.3.1. Initialization Phase
In initialization phase of a PCEP session, the Traffic Prediction
Capability TLV in OPEN message sent by PCC indicates the capability
about traffic prediction that PCC can do, while the TLV sent by PCE
indicates the requests about traffic prediction that PCE MAY make.
If any flag in Traffic Prediction Capability TLV was set to 1 by both
sides, then they reached an agreement about the function advertised
by this flag. However, if P flag was not set to 1 by both sides,
then all other flags SHOULD NOT be parsed; and if not, PCC MUST send
a PAUpd message to PCE to initialize the scope of variable prediction
attributes with TPS-ID (see Section 7.3.2) set to 1. After received
the first PAUpd message from PCC, PCE MUST send a TPReq message to
confirm it with TPS-ID set to 1, too. The Initialization Phase is
shown in Figure 1.
+-+-+ +-+-+
|PCC| |PCE|
+-+-+ +-+-+
| |
| Open msg |
|-------- |
(Exchange Traffic| \ Open msg |
Prediction | \ ---------|
Capability) | \/ |
| /\ |
| / -------->|
| / |
|<------ |
| |
| PAUpd msg |
(Initialize |-------------------->|
Scop of | |
Attributes) | TPReq msg |
|<--------------------|
| |
Figure 1: Initialization Phase
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5.3.2. Traffic Prediction Request Sent by a PCE to a PCC
Once a PCE has sucessfully established a PCEP session with one or
more PCEs, if a traffic prediction event is triggered that requires
the traffic prediction results of a subset of network, the PCE first
selects one or more PCCs which have advertised they can predict
traffic for the subset.
Once the PCE has selected a PCC, it sends a TPReq message to the PCE.
For example, "Predict the traffic in 5 minutes with link=link_id...".
Each request is uniquely identified by a tp-id (See Section 7.3.1)
number and PCC-PCE address pair. The process is shown in Figure 2.
Details about the TPReq message can be found in Section 6.1.
+-+-+ +-+-+
|PCC| |PCE|
+-+-+ +-+-+
| | 1)Traffic Prediction Event
| | 2)PCC Selection
| | 3)Traffic Prediction Request
|<--- TPReq message----| Sent to the Selected PCC
| |
| |
Figure 2: Traffic Prediction Request
5.3.3. Traffic Prediction Reply Sent by a PCC to a PCE
After receiving a traffic prediction request form a PCE, the PCC
triggers a prediction computation, If the PCC manages to predict
traffic in time that satisfies the set of required constraints, the
PCC returns the result to the requesting PCE. The process is shown
in Figure 3.
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+-+-+ +-+-+
|PCC| |PCE|
+-+-+ +-+-+
| |
| |
| |
|<--- TPReq message----|
1) Traffic Prediction | |
Request Received | |
2) Predict Succefully | |
3) Predicted Result | |
Sent to the PCE | |
|---- TPRep message--->|
Figure 3: Traffic Prediction Reply (Success)
However, if the PCC can not predict traffic in time, it SHOULD
provide the reason let to failure by sending a TPRep message with No-
Prediction object (See Section 7.2). Upon receiving a reply like
this, a PCE MAY decide to resend a modified request or take any other
appropriate action.
+-+-+ +-+-+
|PCC| |PCE|
+-+-+ +-+-+
| |
| |
| |
|<--- TPReq message----|
1) Traffic Prediction | |
Request Received | |
2) Predict Unsuccefully| |
3) Cause of Failure | |
Sent to the PCE | |
|---- TPRep message--->|
Figure 4: Traffic Prediction Reply (Failure)
Details about the TPRep message can be found in Section 6.2.
5.4. Error Reporting
6. PCEP Messages
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6.1. The TPReq Message
<TPReq Message> ::= <Common Header>
<PCE-prediction-request>
Where:
<PCE-prediction-request> ::= <prediction-tracker>
[<prediction-area>]
<prediction-requirement>
6.2. The TPRep Message
<TPRep Message> ::= <Common Header>
<PCC-prediction-reply>
Where:
<PCC-prediction-reply> ::= <prediction-tracker>
([<prediction-info-list>] | no-prediction)
<prediction-info-list> ::= <prediction-info>
[<prediction-info-list>]
6.3. The PAUpd Message
<PAUpd Message> ::= <Common Header>
<prediction-tracker>
6.4. The PCErr Message
7. Object Formats
7.1. OPEN Object
7.1.1. Traffic Prediction Capability TLV
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=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |A|S|P|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: The Traffic Prediction Capability TLV format
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The type (16 bits) of the TLV is to be assigned by IANA. The length
field is 16 bit-long and has a fixed value of 4.
The value comprises several field - Flags (32 bits) :
A (PREDICTION-ACCURACY-CAPABILITY - 1 bit): if set to 1 by a PCC, the
A Flag indicates that the PCC can measure the accuracy of prediction
results; if set to 1 by a PCE, the A Flag indicates that the PCE is
capable of requesting prediction results satisfying the lowest
accuracy.
S (PREDICTION-TIME-SEQUENCE-CAPABILITY - 1 bit): if set to 1 by a
PCC, the S Flag indicates that the PCC can provide a sequence of
prediction in time dimension; if set to 1 by a PCE, the S Flag
indicates that the PCE is capable of requesting a sequence prediction
results.
P (PREDICTION-CAPABILITY - 1 bit): if set to 1 by a PCC, the P Flag
indicates that the PCC can provide traffic prediction ability to PCE;
if set to 1 by a PCE, the P Flag indicates that the PCE is capable of
requesting traffic prediction. The PREDICTION-CAPABILITY Flag must
be advertised by both a PCC and a PCE to allow TPReq, TPRep, and
PAUpd messages on a PCEP session. If P Flag is set to 0, other Flags
in this TLV don't make sense.
7.2. No Prediction Object
7.3. Prediction Tracker Object
7.3.1. Traffic Prediction Identifier TLV
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=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TP-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
7.3.2. Traffic Prediction State TLV
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=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TPS-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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7.3.3. Prediction Attribute TLV
7.4. Prediction Requirement Object
7.4.1. Prediction Sequence TLV
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=8N |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Datetime |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Datetime |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// ...... //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Datetime |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
7.4.2. Prediction Expired Time TLV
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=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Datetime |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
7.5. Prediction Information Object
7.5.1. Link Prediction TLV
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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=16 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS-ID |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Datetime |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Predicted Speed (kb/s) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
7.6. Prediction Area Object
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Object-Class | OT |Res|P|I| Object Length (bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flag |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Link TLvs //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: Prediction Area Object Format
7.6.1. Link TLV
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=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS-ID |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: Link TLV Format
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8. IANA Considerations
9. Security Considerations
10. Acknowledgments
11. Contributors
12. 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>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<https://www.rfc-editor.org/info/rfc5440>.
Authors' Addresses
Boyuan Yan (editor)
Beijing University of Posts and Telecommunications
Xitucheng Road
Beijing, Haidian Dist 100876
China
Phone: +86-18810528290
Email: yanboyuan@bupt.edu.cn
Yongli Zhao (editor)
Beijing University of Posts and Telecommunications
Xitucheng Road
Beijing, Haidian Dist 100876
China
Phone: +86-13811761857
Email: yonglizhao@bupt.edu.cn
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Wei Wang (editor)
Beijing University of Posts and Telecommunications
Xitucheng Road
Beijing, Haidian Dist 100876
China
Phone: +86-15210830183
Email: weiw@bupt.edu.cn
Xiaosong Yu (editor)
Beijing University of Posts and Telecommunications
Xitucheng Road
Beijing, Haidian Dist 100876
China
Phone: +86-13811731723
Email: xiaosongyu@bupt.edu.cn
Jie Zhang (editor)
Beijing University of Posts and Telecommunications
Xitucheng Road
Beijing, Haidian Dist 100876
China
Phone: +86-13911060930
Email: lgr24@bupt.edu.cn
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