Internet DRAFT - draft-murakami-dmm-udp-checksum-impact-gtpu
draft-murakami-dmm-udp-checksum-impact-gtpu
DMM T. Murakami
Internet-Draft Arrcus, Inc.
Intended status: Informational S. Matsushima
Expires: 11 January 2024 L. Fujita
SoftBank
10 July 2023
Impact analysis from IPv6 GTP-U checksum calculation
draft-murakami-dmm-udp-checksum-impact-gtpu-01
Abstract
This document describes about the impact on the performance when
calculating the checksum for IPv6 GTP-U packet upon encapsulating the
packet into IPv6 GTP-U.
Status of This Memo
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This Internet-Draft will expire on 11 January 2024.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Notation . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Impact analysis from UDP checksum calculation . . . . . . . . 3
3.1. Vector Packet Processing . . . . . . . . . . . . . . . . 3
3.2. Software base checksum calculation . . . . . . . . . . . 3
3.3. Checksum calculation offload . . . . . . . . . . . . . . 5
4. Security Considerations . . . . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative References . . . . . . . . . . . . . . . . . . 6
7.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
[RFC6935] allows to use zero checksum for IPv6 UDP when using IPv6
UDP for encapsulating a packet. Eliminating the checksum calculation
contributes huge performance improvement in terms of forwarding
packets.
3GPP also allows UDP checksum zero for GTP-U over IPv6 UDP
encapsulation since Release-16 onward[TS.29281]. However, UDP
checksum seem still remained in GTP-U over IPv6/UDP encapsulation
implementations. This can be causing non-negligible performance
impact on nodes, especially in NFV environment, which nodes are
encapsulating the packet into IPv6 GTP-U.
This document describes an analysis of network performance impact
caused by IPv6 UDP checksum calculation. To do the analysis, we
measured latency variation on three environments, (1) UDP checksum
zero, (2) UDP checksum calculated by software, (3) offloading UDP
checksum calculation.
These latencies were measured on a VPP (Vector Packet Processing)
instance when a packet encapsulated with an IPv6, a UDP and a GTP-U
headers.
1.1. Requirements Notation
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.
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2. Terminology
GTP-U: GPRS Tunneling Protocol for User Plane
VPP: Vector Packet Processing
NIC: Network Interface Card
3. Impact analysis from UDP checksum calculation
3.1. Vector Packet Processing
VPP is doing the batching process on the received packets. VPP
stores some received packets and process these packets at once.
Hence, it causes some small degration on latency to send out the
packets to the network.
INPUT: +--+ +--+ +--+ +--+
|P1| |P2| |P3| ... |Pn|
+--+ +--+ +--+ +--+ Batching Process
| (n packets)
| |<------------------->|
OUTPUT: | +--+ +--+ +--+ +--+
| |P1| |P2| |P3| ... |Pn|
| +--+ +--+ +--+ +--+
| |
|<------------ batching time ------------>
Based on VPP, the impact on the latency is measured when
encapsulating the packets into IPv6 GTP-U with software base checksum
calculation and with checksum calculation offload in order to figure
out the impact on the network performance.
In order to simplify the impact analysis, only 1 CPU core is assigned
to the packet processing in VPP and the packets are arrived at one
interface and sent out to another interface. The traffic generator
outside of VPP is sending out the packets and receives IPv6 GTP-U
encapsulated packets. Based on this, the impact on the latency is
measured in each case.
3.2. Software base checksum calculation
This section describes the performance impact analysis when using
software base checksum calculation.
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No checksum calculation: No packet loss
+----------------------+----------------------+--------------------+
| Store-Forward | Store-Forward | Store-Forward |
| Avg Latency (ns) | Min Latency (ns) | Max Letency (ns) |
+----------------------+----------------------+--------------------+
| 15,336 | 14,535 | 124,397 |
+----------------------+----------------------+--------------------+
Software checksum calculation: No packet loss
+----------------------+----------------------+--------------------+
| Store-Forward | Store-Forward | Store-Forward |
| Avg Latency (ns) | Min Latency (ns) | Max Letency (ns) |
+----------------------+----------------------+--------------------+
| 15,477 | 14,592 | 123,337 |
+----------------------+----------------------+--------------------+
INPUT: 100 pps, 1492 byte packet
In this case, there is no impact on the network performance. Since
the incoming packet rate is enough small, the software checksum
calculation can be done within the batching time to process the
packets.
No checksum calculation: No packet loss
+----------------------+----------------------+--------------------+
| Store-Forward | Store-Forward | Store-Forward |
| Avg Latency (ns) | Min Latency (ns) | Max Letency (ns) |
+----------------------+----------------------+--------------------+
| 120,005 | 62,650 | 1,300,217 |
+----------------------+----------------------+--------------------+
Software checksum calculation: 3.676% packet loss
+----------------------+----------------------+--------------------+
| Store-Forward | Store-Forward | Store-Forward |
| Avg Latency (ns) | Min Latency (ns) | Max Letency (ns) |
+----------------------+----------------------+--------------------+
| 8,167,461 | 52,467 | 9,341,807 |
+----------------------+----------------------+--------------------+
INPUT: 275k pps, 1492 byte packet
In this case, there is huge impact on the network performance. If
the total CPU time required for calculating UDP checksum is exceeding
the batching time to process the packets, it causes huge impact on
the latency. In addition, since the checksum calculation steals CPU
times and the software can not acquire enough CPU times to process
the packets, it causes the huge packet loss.
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3.3. Checksum calculation offload
Some of NIC can support UDP checksum calculation offload. When
enabling this function on NIC, UDP checksum is calculated by NIC. In
this case, CPU time is not consumed for calculating UDP checksum.
This section describes the performance impact analysis when enabling
UDP checksum offload on NIC.
No checksum calculation: No packet loss
+----------------------+----------------------+--------------------+
| Store-Forward | Store-Forward | Store-Forward |
| Avg Latency (ns) | Min Latency (ns) | Max Letency (ns) |
+----------------------+----------------------+--------------------+
| 15,336 | 14,535 | 124,397 |
+----------------------+----------------------+--------------------+
UDP checksum offload: No packet loss
+----------------------+----------------------+--------------------+
| Store-Forward | Store-Forward | Store-Forward |
| Avg Latency (ns) | Min Latency (ns) | Max Letency (ns) |
+----------------------+----------------------+--------------------+
| 15,349 | 14,537 | 63,742 |
+----------------------+----------------------+--------------------+
INPUT: 100 pps, 1492 byte packet
In this case, there is no impact on the network performance. Since
the incoming packet rate is enough small, all received packet can be
processed within the batching time.
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No checksum calculation: No packet loss
+----------------------+----------------------+--------------------+
| Store-Forward | Store-Forward | Store-Forward |
| Avg Latency (ns) | Min Latency (ns) | Max Letency (ns) |
+----------------------+----------------------+--------------------+
| 120,005 | 62,650 | 1,380,217 |
+----------------------+----------------------+--------------------+
Software checksum calculation: No packet loss
+----------------------+----------------------+--------------------+
| Store-Forward | Store-Forward | Store-Forward |
| Avg Latency (ns) | Min Latency (ns) | Max Letency (ns) |
+----------------------+----------------------+--------------------+
| 134,126 | 74,090 | 2,443,992 |
+----------------------+----------------------+--------------------+
INPUT: 275k pps, 1492 byte packet
In this case, there is small impact on the network performance. The
time required to calculate UDP checksum by NIC can not be done within
the batching time and hence it causes small degrade on the latency.
However, even though there are huge packet loss when using software
base checksum calculation with same condition, there is no packet
loss when using UDP checksum offload.
4. Security Considerations
No secturity consideration.
5. IANA Considerations
No IANA consideration.
6. Contributors
In addition to the authors listed on the front page, the following
individuals have also made significant contributions to the draft:
(Artwork only available as : No external link available, see draft-
murakami-dmm-udp-checksum-impact-gtpu-01.html for artwork.)
7. References
7.1. Normative References
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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>.
[RFC6935] Eubanks, M., Chimento, P., and M. Westerlund, "IPv6 and
UDP Checksums for Tunneled Packets", RFC 6935,
DOI 10.17487/RFC6935, April 2013,
<https://www.rfc-editor.org/info/rfc6935>.
[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
[TS.23501] 3GPP, "System architecture for the 5G System (5GS)", 3GPP
TS 23.501 17.2.0, 24 September 2021,
<http://www.3gpp.org/ftp/Specs/html-info/23501.htm>.
[TS.29281] 3GPP, "General Packet Radio System (GPRS) Tunnelling
Protocol User Plane (GTPv1-U)", 3GPP TS 29.281 16.1.0,
September 2020.
Authors' Addresses
Tetsuya Murakami
Arrcus, Inc.
2077 Gateway Place, Suite 400
San Jose, CA 95110
United States of America
Email: tetsuya@arrcus.com
Satoru Matsushima
SoftBank
Japan
Email: satoru.matsushima@g.softbank.co.jp
Leo Fujita
SoftBank
Japan
Email: leo.fujita@g.softbank.co.jp
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