< draft-ietf-quic-manageability-04.txt   draft-ietf-quic-manageability-05.txt >
Network Working Group M. Kuehlewind Network Working Group M. Kuehlewind
Internet-Draft B. Trammell Internet-Draft Ericsson
Intended status: Informational ETH Zurich Intended status: Informational B. Trammell
Expires: October 26, 2019 April 24, 2019 Expires: January 6, 2020 Google
July 05, 2019
Manageability of the QUIC Transport Protocol Manageability of the QUIC Transport Protocol
draft-ietf-quic-manageability-04 draft-ietf-quic-manageability-05
Abstract Abstract
This document discusses manageability of the QUIC transport protocol, This document discusses manageability of the QUIC transport protocol,
focusing on caveats impacting network operations involving QUIC focusing on caveats impacting network operations involving QUIC
traffic. Its intended audience is network operators, as well as traffic. Its intended audience is network operators, as well as
content providers that rely on the use of QUIC-aware middleboxes, content providers that rely on the use of QUIC-aware middleboxes,
e.g. for load balancing. e.g. for load balancing.
Status of This Memo Status of This Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 26, 2019. This Internet-Draft will expire on January 6, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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publication of this document. Please review these documents publication of this document. Please review these documents
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to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Notational Conventions . . . . . . . . . . . . . . . . . 3 1.1. Notational Conventions . . . . . . . . . . . . . . . . . 4
2. Features of the QUIC Wire Image . . . . . . . . . . . . . . . 3 2. Features of the QUIC Wire Image . . . . . . . . . . . . . . . 4
2.1. QUIC Packet Header Structure . . . . . . . . . . . . . . 4 2.1. QUIC Packet Header Structure . . . . . . . . . . . . . . 4
2.2. Coalesced Packets . . . . . . . . . . . . . . . . . . . . 6 2.2. Coalesced Packets . . . . . . . . . . . . . . . . . . . . 6
2.3. Use of Port Numbers . . . . . . . . . . . . . . . . . . . 6 2.3. Use of Port Numbers . . . . . . . . . . . . . . . . . . . 6
2.4. The QUIC handshake . . . . . . . . . . . . . . . . . . . 6 2.4. The QUIC handshake . . . . . . . . . . . . . . . . . . . 6
2.5. Integrity Protection of the Wire Image . . . . . . . . . 10 2.5. Integrity Protection of the Wire Image . . . . . . . . . 11
2.6. Connection ID and Rebinding . . . . . . . . . . . . . . . 10 2.6. Connection ID and Rebinding . . . . . . . . . . . . . . . 11
2.7. Packet Numbers . . . . . . . . . . . . . . . . . . . . . 11 2.7. Packet Numbers . . . . . . . . . . . . . . . . . . . . . 11
2.8. Version Negotiation and Greasing . . . . . . . . . . . . 11 2.8. Version Negotiation and Greasing . . . . . . . . . . . . 11
3. Network-visible information about QUIC flows . . . . . . . . 11 3. Network-visible information about QUIC flows . . . . . . . . 12
3.1. Identifying QUIC traffic . . . . . . . . . . . . . . . . 11 3.1. Identifying QUIC traffic . . . . . . . . . . . . . . . . 12
3.1.1. Identifying Negotiated Version . . . . . . . . . . . 12 3.1.1. Identifying Negotiated Version . . . . . . . . . . . 12
3.1.2. Rejection of Garbage Traffic . . . . . . . . . . . . 12 3.1.2. Rejection of Garbage Traffic . . . . . . . . . . . . 13
3.2. Connection confirmation . . . . . . . . . . . . . . . . . 12 3.2. Connection confirmation . . . . . . . . . . . . . . . . . 13
3.3. Application Identification . . . . . . . . . . . . . . . 13 3.3. Application Identification . . . . . . . . . . . . . . . 13
3.4. Flow association . . . . . . . . . . . . . . . . . . . . 13 3.4. Flow association . . . . . . . . . . . . . . . . . . . . 14
3.5. Flow teardown . . . . . . . . . . . . . . . . . . . . . . 14 3.5. Flow teardown . . . . . . . . . . . . . . . . . . . . . . 14
3.6. Flow symmetry measurement . . . . . . . . . . . . . . . . 14 3.6. Flow symmetry measurement . . . . . . . . . . . . . . . . 14
3.7. Round-Trip Time (RTT) Measurement . . . . . . . . . . . . 14 3.7. Round-Trip Time (RTT) Measurement . . . . . . . . . . . . 14
3.7.1. Measuring initial RTT . . . . . . . . . . . . . . . . 14 3.7.1. Measuring initial RTT . . . . . . . . . . . . . . . . 15
3.7.2. Using the Spin Bit for Passive RTT Measurement . . . 15 3.7.2. Using the Spin Bit for Passive RTT Measurement . . . 15
4. Specific Network Management Tasks . . . . . . . . . . . . . . 16 4. Specific Network Management Tasks . . . . . . . . . . . . . . 16
4.1. Stateful treatment of QUIC traffic . . . . . . . . . . . 16 4.1. Stateful treatment of QUIC traffic . . . . . . . . . . . 17
4.2. Passive network performance measurement and 4.2. Passive network performance measurement and
troubleshooting . . . . . . . . . . . . . . . . . . . . . 16 troubleshooting . . . . . . . . . . . . . . . . . . . . . 17
4.3. Server cooperation with load balancers . . . . . . . . . 16 4.3. Server cooperation with load balancers . . . . . . . . . 17
4.4. DDoS Detection and Mitigation . . . . . . . . . . . . . . 17 4.4. DDoS Detection and Mitigation . . . . . . . . . . . . . . 17
4.5. Distinguishing acknowledgment traffic . . . . . . . . . . 17 4.5. Distinguishing acknowledgment traffic . . . . . . . . . . 18
4.6. QoS support and ECMP . . . . . . . . . . . . . . . . . . 17 4.6. QoS support and ECMP . . . . . . . . . . . . . . . . . . 18
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
6. Security Considerations . . . . . . . . . . . . . . . . . . . 18 6. Security Considerations . . . . . . . . . . . . . . . . . . . 19
7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 18 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 19
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 19
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 18 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
9.1. Normative References . . . . . . . . . . . . . . . . . . 19 9.1. Normative References . . . . . . . . . . . . . . . . . . 19
9.2. Informative References . . . . . . . . . . . . . . . . . 19 9.2. Informative References . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
1. Introduction 1. Introduction
QUIC [QUIC-TRANSPORT] is a new transport protocol currently under QUIC [QUIC-TRANSPORT] is a new transport protocol currently under
development in the IETF quic working group, focusing on support of development in the IETF QUIC working group, focusing on support of
semantics as needed for HTTP/2 [QUIC-HTTP]. Based on current semantics as needed for HTTP/2 [QUIC-HTTP]. Based on current
deployment practices, QUIC is encapsulated in UDP and encrypted by deployment practices, QUIC is encapsulated in UDP and encrypted by
default. The current version of QUIC integrates TLS [QUIC-TLS] to default. The current version of QUIC integrates TLS [QUIC-TLS] to
encrypt all payload data and most control information. encrypt all payload data and most control information.
Given that QUIC is an end-to-end transport protocol, all information Given that QUIC is an end-to-end transport protocol, all information
in the protocol header, even that which can be inspected, is not in the protocol header, even that which can be inspected, is not
meant to be mutable by the network, and is therefore integrity- meant to be mutable by the network, and is therefore integrity-
protected. While less information is visible to the network than for protected. While less information is visible to the network than for
TCP, integrity protection can also simplify troubleshooting because TCP, integrity protection can also simplify troubleshooting because
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information. information.
This document provides guidance for network operation on the This document provides guidance for network operation on the
management of QUIC traffic. This includes guidance on how to management of QUIC traffic. This includes guidance on how to
interpret and utilize information that is exposed by QUIC to the interpret and utilize information that is exposed by QUIC to the
network as well as explaining requirement and assumptions that the network as well as explaining requirement and assumptions that the
QUIC protocol design takes toward the expected network treatment. It QUIC protocol design takes toward the expected network treatment. It
also discusses how common network management practices will be also discusses how common network management practices will be
impacted by QUIC. impacted by QUIC.
Of course, network management is not a one-size-fits-all endeavour: Since QUIC's wire image [WIRE-IMAGE] is integrity protected and not
practices considered necessary or even mandatory within enterprise modifiable on path, in-network operations are not possible without
networks with certain compliance requirements, for example, would be terminating the QUIC connection, for instance using a back-to-back
proxy. Proxy operations are not in scope for this document. QUIC
proxies must be fully-fledged QUIC endpoints, implementing the
transport as defined in [QUIC-TRANSPORT] and [QUIC-TLS] as well as
proxy-relevant semantics for the application(s) running over QUIC
(e.g. HTTP/3 as defined in [QUIC-HTTP]).
Network management is not a one-size-fits-all endeavour: practices
considered necessary or even mandatory within enterprise networks
with certain compliance requirements, for example, would be
impermissible on other networks without those requirements. This impermissible on other networks without those requirements. This
document therefore does not make any specific recommendations as to document therefore does not make any specific recommendations as to
which practices should or should not be applied; for each practice, which practices should or should not be applied; for each practice,
it describes what is and is not possible with the QUIC transport it describes what is and is not possible with the QUIC transport
protocol as defined. protocol as defined.
QUIC is at the moment very much a moving target. This document QUIC is at the moment very much a moving target. This document
refers the state of the QUIC working group drafts as well as to refers the state of the QUIC working group drafts as well as to
changes under discussion, via issues and pull requests in GitHub changes under discussion, via issues and pull requests in GitHub
current as of the time of writing. current as of the time of writing.
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The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
2. Features of the QUIC Wire Image 2. Features of the QUIC Wire Image
In this section, we discusses those aspects of the QUIC transport In this section, we discusses those aspects of the QUIC transport
protocol that have an impact on the design and operation of devices protocol that have an impact on the design and operation of devices
that forward QUIC packets. Here, we are concerned primarily with that forward QUIC packets. Here, we are concerned primarily with the
QUIC's unencrypted wire image [WIRE-IMAGE], which we define as the unencrypted part of QUIC's wire image [WIRE-IMAGE], which we define
information available in the packet header in each QUIC packet, and as the information available in the packet header in each QUIC
the dynamics of that information. Since QUIC is a versioned packet, and the dynamics of that information. Since QUIC is a
protocol, the wire image of the header format can also change from versioned protocol, the wire image of the header format can also
version to version. However, at least the mechanism by which a change from version to version. However, at least the mechanism by
receiver can determine which version is used and the meaning and which a receiver can determine which version is used and the meaning
location of fields used in the version negotiation process is and location of fields used in the version negotiation process is
invariant [QUIC-INVARIANTS]. invariant [QUIC-INVARIANTS].
This document is focused on the protocol as presently defined in This document is focused on the protocol as presently defined in
[QUIC-TRANSPORT] and [QUIC-TLS], and will change to track those [QUIC-TRANSPORT] and [QUIC-TLS], and will change to track those
documents. documents.
2.1. QUIC Packet Header Structure 2.1. QUIC Packet Header Structure
QUIC packets may have either a long header, or a short header. The QUIC packets may have either a long header, or a short header. The
first bit of the QUIC header indicates which type of header is first bit of the QUIC header indicates which type of header is
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that can be used to identify the connection associated with a QUIC that can be used to identify the connection associated with a QUIC
packet, for load-balancing and NAT rebinding purposes; see packet, for load-balancing and NAT rebinding purposes; see
Section 4.3 and Section 2.6. Long packet headers additionally Section 4.3 and Section 2.6. Long packet headers additionally
carry a source connection ID. The source connection ID carry a source connection ID. The source connection ID
corresponds to the destination connection ID the source would like corresponds to the destination connection ID the source would like
to have on packets sent to it, and is only present on long packet to have on packets sent to it, and is only present on long packet
headers. On long header packets, the length of the connection IDs headers. On long header packets, the length of the connection IDs
is also present; on short header packets, the length of the is also present; on short header packets, the length of the
destination connection ID is implicit. destination connection ID is implicit.
o length: the length of the remaining quic packet after the length o length: the length of the remaining QUIC packet after the length
field, present on long headers. This field is used to implement field, present on long headers. This field is used to implement
coalesced packets during the handshake (see Section 2.2). coalesced packets during the handshake (see Section 2.2).
o token: Initial packets may contain a token, a variable-length o token: Initial packets may contain a token, a variable-length
opaque value optionally sent from client to server, used for opaque value optionally sent from client to server, used for
validating the client's address. Retry packets also contain a validating the client's address. Retry packets also contain a
token, which can be used by the client in an Initial packet on a token, which can be used by the client in an Initial packet on a
subsequent connection attempt. The length of the token is subsequent connection attempt. The length of the token is
explicit in both cases. explicit in both cases.
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Key Phase bit is cryptographically obfuscated. Key Phase bit is cryptographically obfuscated.
2.2. Coalesced Packets 2.2. Coalesced Packets
Multiple QUIC packets may be coalesced into a UDP datagram, with a Multiple QUIC packets may be coalesced into a UDP datagram, with a
datagram carrying one or more long header packets followed by zero or datagram carrying one or more long header packets followed by zero or
one short header packets. When packets are coalesced, the Length one short header packets. When packets are coalesced, the Length
fields in the long headers are used to separate QUIC packets. The fields in the long headers are used to separate QUIC packets. The
length header field is variable length and its position in the header length header field is variable length and its position in the header
is also variable depending on the length of the source and is also variable depending on the length of the source and
destionation connection ID. See Section 4.6 of [QUIC-TRANSPORT]. destination connection ID. See Section 4.6 of [QUIC-TRANSPORT].
2.3. Use of Port Numbers 2.3. Use of Port Numbers
Applications that have a mapping for TCP as well as QUIC are expected Applications that have a mapping for TCP as well as QUIC are expected
to use the same port number for both services. However, as with TCP- to use the same port number for both services. However, as with TCP-
based services, especially when application layer information is based services, especially when application layer information is
encrypted, there is no guarantee that a specific application will use encrypted, there is no guarantee that a specific application will use
the registered port, or the used port is carrying traffic belonging the registered port, or the used port is carrying traffic belonging
to the respective registered service. For example, [QUIC-TRANSPORT] to the respective registered service. For example, [QUIC-TRANSPORT]
specifies the use of Alt-Svc for discovery of QUIC/HTTP services on specifies the use of Alt-Svc for discovery of QUIC/HTTP services on
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5-tuple belong to the same QUIC connection. 5-tuple belong to the same QUIC connection.
2.4. The QUIC handshake 2.4. The QUIC handshake
New QUIC connections are established using a handshake, which is New QUIC connections are established using a handshake, which is
distinguishable on the wire and contains some information that can be distinguishable on the wire and contains some information that can be
passively observed. passively observed.
To illustrate the information visible in the QUIC wire image during To illustrate the information visible in the QUIC wire image during
the handshake, we first show the general communication pattern the handshake, we first show the general communication pattern
visible in the UDP datagams containing the QUIC handshake, then visible in the UDP datagrams containing the QUIC handshake, then
examine each of the datagrams in detail. examine each of the datagrams in detail.
In the nominal case, the QUIC handshake can be recognized on the wire In the nominal case, the QUIC handshake can be recognized on the wire
through at least four datagrams we'll call "QUIC Client Hello", "QUIC through at least four datagrams we'll call "QUIC Client Hello", "QUIC
Server Hello", and "Initial Completion", and "Handshake Completion", Server Hello", and "Initial Completion", and "Handshake Completion",
for purposes of this illustration, as shown in Figure 1. for purposes of this illustration, as shown in Figure 1.
Packets in the handshake belong to three separate cryptographic and Packets in the handshake belong to three separate cryptographic and
transport contexts ("Initial", which contains observable payload, and transport contexts ("Initial", which contains observable payload, and
"Handshake" and "1-RTT", which do not). QUIC packets in separate "Handshake" and "1-RTT", which do not). QUIC packets in separate
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+----------------------------------------------------------+ | +----------------------------------------------------------+ |
| QUIC PADDING frame | | | QUIC PADDING frame | |
+----------------------------------------------------------+<-+ +----------------------------------------------------------+<-+
Figure 2: Typical 1-RTT QUIC Client Hello datagram pattern Figure 2: Typical 1-RTT QUIC Client Hello datagram pattern
The Client Hello datagram exposes version number, source and The Client Hello datagram exposes version number, source and
destination connection IDs, and information in the TLS Client Hello destination connection IDs, and information in the TLS Client Hello
message, including any TLS Server Name Indication (SNI) present, in message, including any TLS Server Name Indication (SNI) present, in
the clear. The QUIC PADDING frame shown here may be present to the clear. The QUIC PADDING frame shown here may be present to
ensure the Client Hello datagram has a minumum size of 1200 octets, ensure the Client Hello datagram has a minimum size of 1200 octets,
to mitigate the possibility of handshake amplification. Note that to mitigate the possibility of handshake amplification. Note that
the location of PADDING is implementation-dependent, and PADDING the location of PADDING is implementation-dependent, and PADDING
frames may not appear in the Initial packet in a coalesced packet. frames may not appear in the Initial packet in a coalesced packet.
+------------------------------------------------------------+ +------------------------------------------------------------+
| UDP header (source and destination UDP ports) | | UDP header (source and destination UDP ports) |
+------------------------------------------------------------+ +------------------------------------------------------------+
| QUIC long header (type = Initial, Version, DCID, SCID) (Length) | QUIC long header (type = Initial, Version, DCID, SCID) (Length)
+------------------------------------------------------------+ | +------------------------------------------------------------+ |
| QUIC CRYPTO frame header | | | QUIC CRYPTO frame header | |
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+------------------------------------------------------------+ | +------------------------------------------------------------+ |
| encrypted payload (presumably ACK frame) | | | encrypted payload (presumably ACK frame) | |
+------------------------------------------------------------+<-+ +------------------------------------------------------------+<-+
| QUIC short header | | QUIC short header |
+------------------------------------------------------------+ +------------------------------------------------------------+
| 1-RTT encrypted payload | | 1-RTT encrypted payload |
+------------------------------------------------------------+ +------------------------------------------------------------+
Figure 5: Typical QUIC Handshake Completion datagram pattern Figure 5: Typical QUIC Handshake Completion datagram pattern
Similar to Initial Competion, Handshake Completion also exposes no Similar to Initial Completion, Handshake Completion also exposes no
additional information; observing it serves only to determine that additional information; observing it serves only to determine that
the handshake has completed. the handshake has completed.
When the client uses 0-RTT connection resumption, 0-RTT data may also When the client uses 0-RTT connection resumption, 0-RTT data may also
be seen in the QUIC Client Hello datagram, as shown in Figure 6. be seen in the QUIC Client Hello datagram, as shown in Figure 6.
+----------------------------------------------------------+ +----------------------------------------------------------+
| UDP header (source and destination UDP ports) | | UDP header (source and destination UDP ports) |
+----------------------------------------------------------+ +----------------------------------------------------------+
| QUIC long header (type = Initial, Version, DCID, SCID) (Length) | QUIC long header (type = Initial, Version, DCID, SCID) (Length)
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Section 5.1 of [QUIC-TRANSPORT]. Section 5.1 of [QUIC-TRANSPORT].
2.7. Packet Numbers 2.7. Packet Numbers
The packet number field is always present in the QUIC packet header; The packet number field is always present in the QUIC packet header;
however, it is always encrypted. The encryption key for packet however, it is always encrypted. The encryption key for packet
number protection on handshake packets sent before cryptographic number protection on handshake packets sent before cryptographic
context establishment is specific to the QUIC version, while packet context establishment is specific to the QUIC version, while packet
number protection on subsequent packets uses secrets derived from the number protection on subsequent packets uses secrets derived from the
end-to-end cryptographic context. Packet numbers are therefore not end-to-end cryptographic context. Packet numbers are therefore not
part of the wire image that is useful to on-path observers. part of the wire image that is visible to on-path observers.
2.8. Version Negotiation and Greasing 2.8. Version Negotiation and Greasing
Version negotiation is not protected, given the used protection Version negotiation is not protected, given the used protection
mechanism can change with the version. However, the choices provided mechanism can change with the version. However, the choices provided
in the list of version in the Version Negotiation packet will be in the list of version in the Version Negotiation packet will be
validated as soon as the cryptographic context has been established. validated as soon as the cryptographic context has been established.
Therefore any manipulation of this list will be detected and will Therefore any manipulation of this list will be detected and will
cause the endpoints to terminate the connection. cause the endpoints to terminate the connection.
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3.1.1. Identifying Negotiated Version 3.1.1. Identifying Negotiated Version
An in-network observer assuming that a set of packets belongs to a An in-network observer assuming that a set of packets belongs to a
QUIC flow can infer the version number in use by observing the QUIC flow can infer the version number in use by observing the
handshake: an Initial packet with a given version from a client to handshake: an Initial packet with a given version from a client to
which a server responds with an Initial packet with the same version which a server responds with an Initial packet with the same version
implies acceptance of that version. implies acceptance of that version.
Negotiated version cannot be identified for flows for which a Negotiated version cannot be identified for flows for which a
handshake is not observed, such as in the case of NAT rebinding; handshake is not observed, such as in the case of connection
however, these flows can be associated with flows for which a version migration; however, these flows can be associated with flows for
has been identified; see Section 3.4. which a version has been identified; see Section 3.4.
In the rest of this section, we discuss only packets belonging to In the rest of this section, we discuss only packets belonging to
Version 1 QUIC flows, and assume that these packets have been Version 1 QUIC flows, and assume that these packets have been
identified as such through the observation of a version negotiation. identified as such through the observation of a version negotiation.
3.1.2. Rejection of Garbage Traffic 3.1.2. Rejection of Garbage Traffic
A related question is whether a first packet of a given flow on known A related question is whether a first packet of a given flow on known
QUIC-associated port is a valid QUIC packet, in order to support in- QUIC-associated port is a valid QUIC packet, in order to support in-
network filtering of garbage UDP packets (reflection attacks, random network filtering of garbage UDP packets (reflection attacks, random
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The cleartext TLS handshake may contain Server Name Indication (SNI) The cleartext TLS handshake may contain Server Name Indication (SNI)
[RFC6066], by which the client reveals the name of the server it [RFC6066], by which the client reveals the name of the server it
intends to connect to, in order to allow the server to present a intends to connect to, in order to allow the server to present a
certificate based on that name. It may also contain information from certificate based on that name. It may also contain information from
Application-Layer Protocol Negotiation (ALPN) [RFC7301], by which the Application-Layer Protocol Negotiation (ALPN) [RFC7301], by which the
client exposes the names of application-layer protocols it supports; client exposes the names of application-layer protocols it supports;
an observer can deduce that one of those protocols will be used if an observer can deduce that one of those protocols will be used if
the connection continues. the connection continues.
Work is currently underway in the TLS working group to encrypt the Work is currently underway in the TLS working group to encrypt the
SNI in TLS 1.3 [TLS-ENCRYPT-SNI], reducing the information available SNI in TLS 1.3 [TLS-ESNI]. If used with QUIC, this would make SNI-
in the SNI to the name of a fronting service, which can generally be based application identification impossible through passive
identified by the IP address of the server anyway. If used with measurement.
QUIC, this would make SNI-based application identification impossible
through passive measurement.
3.4. Flow association 3.4. Flow association
The QUIC Connection ID (see Section 2.6) is designed to allow an on- The QUIC Connection ID (see Section 2.6) is designed to allow an on-
path device such as a load-balancer to associate two flows as path device such as a load-balancer to associate two flows as
identified by five-tuple when the address and port of one of the identified by five-tuple when the address and port of one of the
endpoints changes; e.g. due to NAT rebinding or server IP address endpoints changes; e.g. due to NAT rebinding or server IP address
migration. An observer keeping flow state can associate a connection migration. An observer keeping flow state can associate a connection
ID with a given flow, and can associate a known flow with a new flow ID with a given flow, and can associate a known flow with a new flow
when when observing a packet sharing a connection ID and one endpoint when when observing a packet sharing a connection ID and one endpoint
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However, since the connection ID may change multiple times during the However, since the connection ID may change multiple times during the
lifetime of a flow, and the negotiation of connection ID changes is lifetime of a flow, and the negotiation of connection ID changes is
encrypted, packets with the same 5-tuple but different connection IDs encrypted, packets with the same 5-tuple but different connection IDs
may or may not belong to the same connection. may or may not belong to the same connection.
The connection ID value should be treated as opaque; see Section 4.3 The connection ID value should be treated as opaque; see Section 4.3
for caveats regarding connection ID selection at servers. for caveats regarding connection ID selection at servers.
3.5. Flow teardown 3.5. Flow teardown
The QUIC does not expose the end of a connection; the only indication QUIC does not expose the end of a connection; the only indication to
to on-path devices that a flow has ended is that packets are no on-path devices that a flow has ended is that packets are no longer
longer observed. Stateful devices on path such as NATs and firewalls observed. Stateful devices on path such as NATs and firewalls must
must therefore use idle timeouts to determine when to drop state for therefore use idle timeouts to determine when to drop state for QUIC
QUIC flows. flows.
Changes to this behavior have been discussed in the working group, Changes to this behavior have been discussed in the working group,
but there is no current proposal to implement these changes: see but there is no current proposal to implement these changes: see
https://github.com/quicwg/base-drafts/issues/602. https://github.com/quicwg/base-drafts/issues/602.
3.6. Flow symmetry measurement 3.6. Flow symmetry measurement
QUIC explicitly exposes which side of a connection is a client and QUIC explicitly exposes which side of a connection is a client and
which side is a server during the handshake. In addition, the which side is a server during the handshake. In addition, the
symmerty of a flow (whether primarily client-to-server, primarily symmetry of a flow (whether primarily client-to-server, primarily
server-to-client, or roughly bidirectional, as input to basic traffic server-to-client, or roughly bidirectional, as input to basic traffic
classification techniques) can be inferred through the measurement of classification techniques) can be inferred through the measurement of
data rate in each direction. While QUIC traffic is protected and data rate in each direction. While QUIC traffic is protected and
ACKS may be padded, padding is not required. ACKs may be padded, padding is not required.
3.7. Round-Trip Time (RTT) Measurement 3.7. Round-Trip Time (RTT) Measurement
Round-trip time of QUIC flows can be inferred by observation once per Round-trip time of QUIC flows can be inferred by observation once per
flow, during the handshake, as in passive TCP measurement; this flow, during the handshake, as in passive TCP measurement; this
requires parsing of the QUIC packet header and recognition of the requires parsing of the QUIC packet header and recognition of the
handshake, as illustrated in Section 2.4. It can also be inferred handshake, as illustrated in Section 2.4. It can also be inferred
during the flow's lifetime, if the endpoints use the spin bit during the flow's lifetime, if the endpoints use the spin bit
facility described below and in [QUIC-TRANSPORT], section 17.3.1. facility described below and in [QUIC-TRANSPORT], section 17.3.1.
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Server Hello represents the RTT component on the path between the Server Hello represents the RTT component on the path between the
observer and the server. The delay between the TLS Server Hello and observer and the server. The delay between the TLS Server Hello and
the Handshake packet containing the TLS Finished message sent by the the Handshake packet containing the TLS Finished message sent by the
client represents the RTT component on the path between the observer client represents the RTT component on the path between the observer
and the client. While the client may send 0-RTT Protected packets and the client. While the client may send 0-RTT Protected packets
after the Initial packet during 0-RTT connection re-establishment, after the Initial packet during 0-RTT connection re-establishment,
these can be ignored for RTT measurement purposes. these can be ignored for RTT measurement purposes.
Handshake RTT can be measured by adding the client-to-observer and Handshake RTT can be measured by adding the client-to-observer and
observer-to-server RTT components together. This measurement observer-to-server RTT components together. This measurement
necessarily includes any transport and application layer delay at necessarily includes any transport and application layer delay (the
both sides. latter mainly caused by the asymmetric crypto operations associated
with the TLS handshake) at both sides.
3.7.2. Using the Spin Bit for Passive RTT Measurement 3.7.2. Using the Spin Bit for Passive RTT Measurement
The spin bit provides an additional method to measure per-flow RTT The spin bit provides an additional method to measure per-flow RTT
from observation points on the network path throughout the duration from observation points on the network path throughout the duration
of a connection. Endpoint participation in spin bit signaling is of a connection. Endpoint participation in spin bit signaling is
optional in QUIC. That is, while its location is fixed in this optional in QUIC. That is, while its location is fixed in this
version of QUIC, an endpoint can unilaterally choose to not support version of QUIC, an endpoint can unilaterally choose to not support
"spinning" the bit. Use of the spin bit for RTT measurement by "spinning" the bit. Use of the spin bit for RTT measurement by
devices on path is only possible when both endpoints enable it. Some devices on path is only possible when both endpoints enable it. Some
endpoints may disable use of the the spin bit by default, others only endpoints may disable use of the spin bit by default, others only in
in specific deployment scenarios, e.g. for servers and clients where specific deployment scenarios, e.g. for servers and clients where the
the RTT would reveal the presence of a VPN or proxy. In order to not RTT would reveal the presence of a VPN or proxy. To avoid making
make these connections identifiable based on the usage of the spin these connections identifiable based on the usage of the spin bit, it
bit, it is recommended that all endpoints disable "spinning" randomly is recommended that all endpoints randomly disable "spinning" for at
for at least one eighth of connections, even if otherwise enabled by least one eighth of connections, even if otherwise enabled by
default. An endpoint not participating in spin bit signaling for a default. An endpoint not participating in spin bit signaling for a
given connection can use a fixed spin value for the duration of the given connection can use a fixed spin value for the duration of the
connection, or can set the bit randomly on each packet sent. connection, or can set the bit randomly on each packet sent.
When in use and a QUIC flow sends data continuously, the latency spin When in use and a QUIC flow sends data continuously, the latency spin
bit in each direction changes value once per round-trip time (RTT). bit in each direction changes value once per round-trip time (RTT).
An on-path observer can observe the time difference between edges An on-path observer can observe the time difference between edges
(changes from 1 to 0 or 0 to 1) in the spin bit signal in a single (changes from 1 to 0 or 0 to 1) in the spin bit signal in a single
direction to measure one sample of end-to-end RTT. direction to measure one sample of end-to-end RTT.
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much greater than network RTT. When the sender is application- much greater than network RTT. When the sender is application-
limited and e.g. only sends small amount of periodic application limited and e.g. only sends small amount of periodic application
traffic, where that period is longer than the RTT, measuring the spin traffic, where that period is longer than the RTT, measuring the spin
bit provides information about the application period, not the bit provides information about the application period, not the
network RTT. network RTT.
Since the spin bit logic at each endpoint considers only samples from Since the spin bit logic at each endpoint considers only samples from
packets that advance the largest packet number, signal generation packets that advance the largest packet number, signal generation
itself is resistant to reordering. However, reordering can cause itself is resistant to reordering. However, reordering can cause
problems at an observer by causing spurious edge detection and problems at an observer by causing spurious edge detection and
therefore low RTT estimates, if reordering occurs across a spin-bit therefore inaccurate (i.e., lower) RTT estimates, if reordering
flip in the stream. occurs across a spin-bit flip in the stream.
Simple heuristics based on the observed data rate per flow or changes Simple heuristics based on the observed data rate per flow or changes
in the RTT series can be used to reject bad RTT samples due to lost in the RTT series can be used to reject bad RTT samples due to lost
or reordered edges in the spin signal, as well as application or flow or reordered edges in the spin signal, as well as application or flow
control limitation; for example, QoF [TMA-QOF] rejects component RTTs control limitation; for example, QoF [TMA-QOF] rejects component RTTs
significantly higher than RTTs over the history of the flow. These significantly higher than RTTs over the history of the flow. These
heuristics may use the handshake RTT as an initial RTT estimate for a heuristics may use the handshake RTT as an initial RTT estimate for a
given flow. Usually such heuristics would also detect if the spin is given flow. Usually such heuristics would also detect if the spin is
either constant or randomly set for a connection. either constant or randomly set for a connection.
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client to server and from server to client) can also use the spin bit client to server and from server to client) can also use the spin bit
to measure "upstream" and "downstream" component RTT; i.e, the to measure "upstream" and "downstream" component RTT; i.e, the
component of the end-to-end RTT attributable to the paths between the component of the end-to-end RTT attributable to the paths between the
observer and the server and the observer and the client, observer and the server and the observer and the client,
respectively. It does this by measuring the delay between a spin respectively. It does this by measuring the delay between a spin
edge observed in the upstream direction and that observed in the edge observed in the upstream direction and that observed in the
downstream direction, and vice versa. downstream direction, and vice versa.
4. Specific Network Management Tasks 4. Specific Network Management Tasks
In this section, we address specific network management and In this section, we review specific network management and
measurement techniques and how QUIC's design impacts them. measurement techniques and how QUIC's design impacts them.
4.1. Stateful treatment of QUIC traffic 4.1. Stateful treatment of QUIC traffic
Stateful treatment of QUIC traffic is possible through QUIC traffic Stateful treatment of QUIC traffic (e.g., at a firewall or NAT
and version identification (Section 3.1) and observation of the middlebox) is possible through QUIC traffic and version
handshake for connection confirmation (Section 3.2). The lack of any identification (Section 3.1) and observation of the handshake for
visible end-of-flow signal (Section 3.5) means that this state must connection confirmation (Section 3.2). The lack of any visible end-
be purged either through timers or through least-recently-used of-flow signal (Section 3.5) means that this state must be purged
eviction, depending on application requirements. either through timers or through least-recently-used eviction,
depending on application requirements.
The QUIC header optionally contains a Connection ID which can be used
as additional entropy beyond the 5-tuple, if needed. The QUIC
handshake needs to be observed in order to understand whether the
Connection ID is present and what length it has.
4.2. Passive network performance measurement and troubleshooting 4.2. Passive network performance measurement and troubleshooting
Limited RTT measurement is possible by passive observation of QUIC Limited RTT measurement is possible by passive observation of QUIC
traffic; see Section 3.7. No passive measurement of loss is possible traffic; see Section 3.7. No passive measurement of loss is possible
with the present wire image. Extremely limited observation of with the present wire image. Extremely limited observation of
upstream congestion may be possible via the observation of CE upstream congestion may be possible via the observation of CE
markings on ECN-enabled QUIC traffic. markings on ECN-enabled QUIC traffic.
4.3. Server cooperation with load balancers 4.3. Server cooperation with load balancers
skipping to change at page 19, line 30 skipping to change at page 20, line 11
RTT Measurement (ACM Computer Communication Review)", July RTT Measurement (ACM Computer Communication Review)", July
2015, <http://www.sigcomm.org/sites/default/files/ccr/ 2015, <http://www.sigcomm.org/sites/default/files/ccr/
papers/2015/July/0000000-0000002.pdf>. papers/2015/July/0000000-0000002.pdf>.
[IPIM] Allman, M., Beverly, R., and B. Trammell, "In-Protocol [IPIM] Allman, M., Beverly, R., and B. Trammell, "In-Protocol
Internet Measurement (arXiv preprint 1612.02902)", Internet Measurement (arXiv preprint 1612.02902)",
December 2016, <https://arxiv.org/abs/1612.02902>. December 2016, <https://arxiv.org/abs/1612.02902>.
[QUIC-APPLICABILITY] [QUIC-APPLICABILITY]
Kuehlewind, M. and B. Trammell, "Applicability of the QUIC Kuehlewind, M. and B. Trammell, "Applicability of the QUIC
Transport Protocol", draft-ietf-quic-applicability-03 Transport Protocol", draft-ietf-quic-applicability-04
(work in progress), October 2018. (work in progress), April 2019.
[QUIC-HTTP] [QUIC-HTTP]
Bishop, M., "Hypertext Transfer Protocol Version 3 Bishop, M., "Hypertext Transfer Protocol Version 3
(HTTP/3)", draft-ietf-quic-http-20 (work in progress), (HTTP/3)", draft-ietf-quic-http-20 (work in progress),
April 2019. April 2019.
[QUIC-INVARIANTS] [QUIC-INVARIANTS]
Thomson, M., "Version-Independent Properties of QUIC", Thomson, M., "Version-Independent Properties of QUIC",
draft-ietf-quic-invariants-04 (work in progress), April draft-ietf-quic-invariants-04 (work in progress), April
2019. 2019.
skipping to change at page 20, line 30 skipping to change at page 21, line 9
[RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan, [RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan,
"Transport Layer Security (TLS) Application-Layer Protocol "Transport Layer Security (TLS) Application-Layer Protocol
Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301, Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301,
July 2014, <https://www.rfc-editor.org/info/rfc7301>. July 2014, <https://www.rfc-editor.org/info/rfc7301>.
[RFC7605] Touch, J., "Recommendations on Using Assigned Transport [RFC7605] Touch, J., "Recommendations on Using Assigned Transport
Port Numbers", BCP 165, RFC 7605, DOI 10.17487/RFC7605, Port Numbers", BCP 165, RFC 7605, DOI 10.17487/RFC7605,
August 2015, <https://www.rfc-editor.org/info/rfc7605>. August 2015, <https://www.rfc-editor.org/info/rfc7605>.
[TLS-ENCRYPT-SNI] [TLS-ESNI]
Huitema, C. and E. Rescorla, "Issues and Requirements for Rescorla, E., Oku, K., Sullivan, N., and C. Wood,
SNI Encryption in TLS", draft-ietf-tls-sni-encryption-04 "Encrypted Server Name Indication for TLS 1.3", draft-
(work in progress), November 2018. ietf-tls-esni-03 (work in progress), March 2019.
[TMA-QOF] Trammell, B., Gugelmann, D., and N. Brownlee, "Inline Data [TMA-QOF] Trammell, B., Gugelmann, D., and N. Brownlee, "Inline Data
Integrity Signals for Passive Measurement (in Proc. TMA Integrity Signals for Passive Measurement (in Proc. TMA
2014)", April 2014. 2014)", April 2014.
[WIRE-IMAGE] [WIRE-IMAGE]
Trammell, B. and M. Kuehlewind, "The Wire Image of a Trammell, B. and M. Kuehlewind, "The Wire Image of a
Network Protocol", draft-trammell-wire-image-04 (work in Network Protocol", RFC 8546, DOI 10.17487/RFC8546, April
progress), April 2018. 2019, <https://www.rfc-editor.org/info/rfc8546>.
Authors' Addresses Authors' Addresses
Mirja Kuehlewind Mirja Kuehlewind
ETH Zurich Ericsson
Gloriastrasse 35
8092 Zurich Email: mirja.kuehlewind@ericsson.com
Switzerland
Email: mirja.kuehlewind@tik.ee.ethz.ch
Brian Trammell Brian Trammell
ETH Zurich Google
Gloriastrasse 35 Gustav-Gull-Platz 1
8092 Zurich 8004 Zurich
Switzerland Switzerland
Email: ietf@trammell.ch Email: ietf@trammell.ch
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