Internet DRAFT - draft-detnet-jitter-bandwidth-misordering
draft-detnet-jitter-bandwidth-misordering
DeNet WG L. Chen
Internet-Draft S. Qian
Intended status: Standards Track SEU
Expires: November 7, 2019 T. Ao
ZTE
May 6, 2019
DetNet Packet Jitter, Bandwidth and Misordering Passive Performance
Measurement
draft-detnet-jitter-bandwidth-misordering-00
Abstract
Deterministic Networking (DetNet) can provide data transmission with
end-to-end bounded latency and extremely low packet loss for user's
services. In order to better control and manage deterministic
network services. It is necessary to measure and monitor DetNet QoS
information. As introduced in [I-D.chen-detnet-loss-delay], packet
loss rates and end-to-end delay can be measured by using passive
Performance Measurement (PM) in MPLS-based DetNet encapsulation.
This document implement three new QoS related attribute to support
passive Performance Measurement for DetNet service.
Status of This Memo
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This Internet-Draft will expire on November 7, 2019.
Copyright Notice
Copyright (c) 2019 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. DetNet Control Word based PM . . . . . . . . . . . . . . . . 3
2.1. Jitter . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Used Bandwidth . . . . . . . . . . . . . . . . . . . . . 5
2.3. Misordering packets . . . . . . . . . . . . . . . . . . . 6
3. Security Considerations . . . . . . . . . . . . . . . . . . . 7
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
6.1. Informative References . . . . . . . . . . . . . . . . . 7
6.2. Normative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
As defined in [I-D.ietf-detnet-architecture], DetNet can provide data
transmission with end-to-end bounded latency and extremely low packet
loss for user's services. In order to ensure the efficiency and
accuracy of information collection and management, it is necessary to
measure and monitor DetNet QoS information.
DetNet QoS information includes minimum and maximum delay, bounded
jitter, packet loss ratio and an upper bound on misordering packet in
general. Apart from this, link bandwidth information also play an
important role in resource allocation.
As introduced in [I-D.chen-detnet-loss-delay], packet loss rates and
end-to-end delay can be measured by using passive Performance
Measurement (PM) in MPLS-based DetNet encapsulation. Which defines
two new flags in the d-CW(control word) and three new TLVs to LM and
DM messages.
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Inspird by that, we implement protocol mechanisms to support passive
Performance Measurement for bounded jitter, misordering packet and
used bandwidth.
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].
1.2. Terminology
The terminology is defined as [I-D.ietf-detnet-architecture],
[RFC3270], [RFC6374], [RFC2475] and [RFC2474].
2. DetNet Control Word based PM
MPLS-based DetNet encapsulation introduces an S-Lable and a d-CW.
Meanwhile [I-D.chen-detnet-loss-delay] document defines two new flags
in the d-CW. Here this document defines a new flag in the d-CW(as
shown in Figure 1). The B bit is defined to indicate whether the
bandwidth measurement is enabled.
+-----------------+
~ IP/MPLS Tunnel ~
+-----------------+ <--\
| Service Label | |
+-----------------+ +-- Service Layer Header
+----| Control Word | |
| +-----------------+ <--/
| | Payload |
| +-----------------+
|
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+--->|0 0 0 0|L|D|B| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: DetNet Control Word
where:
o L bit: Loss measurement indicator; 1 means the loss measurement is
enabled, otherwise the loss measurement is not enabled.
o D bit: Delay measurement indicator; 1 means the delay measurement
is enabled, otherwise the delay measurement is not enabled. When
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a node receive a packet with D bit set, it will timestamp the
packet and copy it for further PM processing.
o B bit: Bandwidth measurement indicator; 1 means the bandwidth
measurement is enabled, otherwise the bandwidth measurement is not
enabled.
Assume a DetNet service path between node A and node B, where node A
is the ingress node, and node B is the egress node. The packets with
same interval number belong to the same measurement interval.
[Editor notes: The detail of measurement interval and flags in DetNet
Control Word can be found in [I-D.chen-detnet-loss-delay]]
2.1. Jitter
In brief, jitter can be calculated by delay.To measure the delay of a
packet, the D bit of the d-CW MUST be set.
If the D bit of the d-CW is set, recording both the flow-id of DetNet
flow and the node-id of node.
At the ingress node, record the time when sending the packet, with
the timestamp indexed by the sequence number. At the egress node,
when receiving a packet with D bit set, record the time when the
packet was received, with the timestamp indexed by the sequence
number.
When the measurement interval comes, all the information of node-id,
flow-id, sequence number and timestamps need to be sent to the
centralized controller.
The mechanism for sending information to a centralized controller is
out side the scope of this document.
After that, the centralized controller can find the sequence number
and timestamps between adjacent nodes such as AB by flow-id and node-
id.
Then, with the timestamps from the ingress and egress nodes, and the
sequence number, the packet delay can be calculated as below.
Delay[n] = B_RxT[n] - A_TxT[n], where:
o B_RxT[n] identifies the timestamp at node B when receiving the No.
"n" packet;
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o A_TxT[n] identifies the timestamp at node A when sending the No.
"n" packet;
After getting multiple sets of Delay[n] informatin, the packet jitter
in the No. "t" measurement interval can be calculated as below.
Jitter[t] = Max(Delay[i] - Delay[j]), where:
o Delay[i] identifies the No. "i" packet's delay between A and B;
o Delay[j] identifies the No. "j" packet's delay between A and B;
2.2. Used Bandwidth
To measure the used bandwidth of DetNet flows between A and B, both
of the D bit and B bit of the d-CW MUST be set.
If the B and D bit of the d-CW are set, recording both the flow-id of
DetNet flow and the node-id of node.
At the ingress node, record the time and accumulate the packet bytes
when sending the packet, with the timestamp indexed by the sequence
number. At the egress node, when receiving a packet with B and D bit
set, record the time and accumulate the packet bytes when the packet
was received, with the timestamp indexed by the sequence number.
When the measurement interval comes, all the information of node-id,
flow-id, sequence number, timestamps and packet bytes need to be sent
to the centralized controller. Then the packet bytes need to be
reset to zero for next measurement interval.
After that, the centralized controller can find the sequence number,
timestamps and packet bytes between adjacent nodes such as AB by
flow-id and node-id.
Then, with the timestamps and packet bytes from the ingress and
egress nodes, and the sequence number, the used bandwidth in No. "t"
measurement interval can be calculated as below.
Bandwidth[t] = Max(A_TxB[t], B_RxB[t])*8/Delay [t], where:
o Delay [i] identifies the No. "i" packet's delay between A and B,
the measurement method has been introduced in section 2.1;
o B_RxB[n] identifies the total bytes received at node B in the No.
"n" measurement interval with the same flow-id;
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o A_TxB[n] identifies the total bytes sended at node A in the No.
"n" measurement interval with the same flow-id;
2.3. Misordering packets
Since the measurement of the maximum misordering packets only
requires the sequence number of the DetNet flows, there is no need to
additionally add a flag bit to the MPLS control word. The D bit of
the d-CW can re reused.
To measure the maximum misordering packets, the D bit of the d-CW
MUST be set.
At the ingress node, record the time when sending the packet, with
the timestamp indexed by the sequence number. At the egress node,
when receiving a packet with D bit set, record the time when the
packet was received, with the timestamp indexed by the sequence
number.
When the measurement interval comes, all the information of node-id,
flow-id, sequence number and timestamps need to be sent to the
centralized controller.
After that, the centralized controller can find the sequence number
and timestamps between adjacent nodes such as AB by flow-id and node-
id.
A packet can be classified as a misordering packet if it has a
sequence number smaller than its predecessors.
Specifically, let M DetNet flows, denoted as (S1, . . . ,Sm), be the
total number of flows sent from node A to B.
In each flow Si consisting of K packets, we assign to each packet j a
sequence number aj which is a successive integer from 1 to K in the
order of the packet emission and so we create the source sequence as
(a1, . . . ,aK). Assume an output sequence (b1, . . . , bP) of Si
observed at the receiving node B, where P <= K be the total number of
packets received out of the K packets sent. Due to loss, the amount
K may less than P.
The sequence is said to be in order if for any index k (1 <= k <= P)
holds bk <= bq (0 <= q <= k), else the flow is said to reached at the
destination midordering, and the packet k is a reordered packet in
the reordered flow. The total number of reordered packets in flow Si
is written as Li.
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For example, for the sequence of an arrived reordered flow
(1,2,3,5,4,7,6,8), there are 2 reordered packets (packet 4 and packet
6), which leads to L = 2. Note that in this document reordering does
not correlate with loss (same as [2][8][9]). For example, a received
flow (1,2,3,4,5,6,8) is considered as in order.
3. Security Considerations
TBD.
4. IANA Considerations
TBD.
5. Acknowledgements
TBD.
6. References
6.1. Informative References
[RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
and W. Weiss, "An Architecture for Differentiated
Services", RFC 2475, DOI 10.17487/RFC2475, December 1998,
<https://www.rfc-editor.org/info/rfc2475>.
6.2. Normative References
[I-D.chen-detnet-loss-delay]
Chen, M. and A. Malis, "DetNet Packet Loss and Delay
Performance Measurement", draft-chen-detnet-loss-delay-01
(work in progress), October 2018.
[I-D.ietf-detnet-architecture]
Finn, N., Thubert, P., Varga, B., and J. Farkas,
"Deterministic Networking Architecture", draft-ietf-
detnet-architecture-12 (work in progress), March 2019.
[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>.
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[RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black,
"Definition of the Differentiated Services Field (DS
Field) in the IPv4 and IPv6 Headers", RFC 2474,
DOI 10.17487/RFC2474, December 1998,
<https://www.rfc-editor.org/info/rfc2474>.
[RFC3270] Le Faucheur, F., Wu, L., Davie, B., Davari, S., Vaananen,
P., Krishnan, R., Cheval, P., and J. Heinanen, "Multi-
Protocol Label Switching (MPLS) Support of Differentiated
Services", RFC 3270, DOI 10.17487/RFC3270, May 2002,
<https://www.rfc-editor.org/info/rfc3270>.
[RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay
Measurement for MPLS Networks", RFC 6374,
DOI 10.17487/RFC6374, September 2011,
<https://www.rfc-editor.org/info/rfc6374>.
Authors' Addresses
Liquan Chen
South-east University
No.2 Sipailou
Nanjing, Jiangsu 210096
PR China
Email: lqchen@seu.edu.cn
Sijie Qian
South-east University
No.2 Sipailou
Nanjing, Jiangsu 210096
PR China
Email: sijieqian@foxmail.com
Ting Ao
ZTE corporation
No.50 Software Avenue
Nanjing, Jiangsu 210012
PR China
Email: ao.ting@zte.com.cn
URI: http://www.zte.com.cn
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