draft-ietf-quic-manageability-03.txt   draft-ietf-quic-manageability-04.txt 
Network Working Group M. Kuehlewind Network Working Group M. Kuehlewind
Internet-Draft B. Trammell Internet-Draft B. Trammell
Intended status: Informational ETH Zurich Intended status: Informational ETH Zurich
Expires: April 25, 2019 October 22, 2018 Expires: October 26, 2019 April 24, 2019
Manageability of the QUIC Transport Protocol Manageability of the QUIC Transport Protocol
draft-ietf-quic-manageability-03 draft-ietf-quic-manageability-04
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 April 25, 2019. This Internet-Draft will expire on October 26, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 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.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Notational Conventions . . . . . . . . . . . . . . . . . 3 1.1. Notational Conventions . . . . . . . . . . . . . . . . . 3
2. Features of the QUIC Wire Image . . . . . . . . . . . . . . . 3 2. Features of the QUIC Wire Image . . . . . . . . . . . . . . . 3
2.1. QUIC Packet Header Structure . . . . . . . . . . . . . . 4 2.1. QUIC Packet Header Structure . . . . . . . . . . . . . . 4
2.2. Coalesced Packets . . . . . . . . . . . . . . . . . . . . 5 2.2. Coalesced Packets . . . . . . . . . . . . . . . . . . . . 6
2.3. Use of Port Numbers . . . . . . . . . . . . . . . . . . . 5 2.3. Use of Port Numbers . . . . . . . . . . . . . . . . . . . 6
2.4. The QUIC handshake . . . . . . . . . . . . . . . . . . . 5 2.4. The QUIC handshake . . . . . . . . . . . . . . . . . . . 6
2.5. Integrity Protection of the Wire Image . . . . . . . . . 10 2.5. Integrity Protection of the Wire Image . . . . . . . . . 10
2.6. Connection ID and Rebinding . . . . . . . . . . . . . . . 10 2.6. Connection ID and Rebinding . . . . . . . . . . . . . . . 10
2.7. Packet Numbers . . . . . . . . . . . . . . . . . . . . . 10 2.7. Packet Numbers . . . . . . . . . . . . . . . . . . . . . 11
2.8. Version Negotiation and Greasing . . . . . . . . . . . . 10 2.8. Version Negotiation and Greasing . . . . . . . . . . . . 11
3. Network-visible information about QUIC flows . . . . . . . . 11 3. Network-visible information about QUIC flows . . . . . . . . 11
3.1. Identifying QUIC traffic . . . . . . . . . . . . . . . . 11 3.1. Identifying QUIC traffic . . . . . . . . . . . . . . . . 11
3.1.1. Identifying Negotiated Version . . . . . . . . . . . 11 3.1.1. Identifying Negotiated Version . . . . . . . . . . . 12
3.1.2. Rejection of Garbage Traffic . . . . . . . . . . . . 12 3.1.2. Rejection of Garbage Traffic . . . . . . . . . . . . 12
3.2. Connection confirmation . . . . . . . . . . . . . . . . . 12 3.2. Connection confirmation . . . . . . . . . . . . . . . . . 12
3.3. Application Identification . . . . . . . . . . . . . . . 12 3.3. Application Identification . . . . . . . . . . . . . . . 13
3.4. Flow association . . . . . . . . . . . . . . . . . . . . 12 3.4. Flow association . . . . . . . . . . . . . . . . . . . . 13
3.5. Flow teardown . . . . . . . . . . . . . . . . . . . . . . 13 3.5. Flow teardown . . . . . . . . . . . . . . . . . . . . . . 14
3.6. Round-trip time measurement . . . . . . . . . . . . . . . 13 3.6. Flow symmetry measurement . . . . . . . . . . . . . . . . 14
3.7. Flow symmetry measurement . . . . . . . . . . . . . . . . 14 3.7. Round-Trip Time (RTT) Measurement . . . . . . . . . . . . 14
4. Specific Network Management Tasks . . . . . . . . . . . . . . 15 3.7.1. Measuring initial RTT . . . . . . . . . . . . . . . . 14
4.1. Stateful treatment of QUIC traffic . . . . . . . . . . . 15 3.7.2. Using the Spin Bit for Passive RTT Measurement . . . 15
4. Specific Network Management Tasks . . . . . . . . . . . . . . 16
4.1. Stateful treatment of QUIC traffic . . . . . . . . . . . 16
4.2. Passive network performance measurement and 4.2. Passive network performance measurement and
troubleshooting . . . . . . . . . . . . . . . . . . . . . 15 troubleshooting . . . . . . . . . . . . . . . . . . . . . 16
4.3. Server cooperation with load balancers . . . . . . . . . 15 4.3. Server cooperation with load balancers . . . . . . . . . 16
4.4. DDoS Detection and Mitigation . . . . . . . . . . . . . . 15 4.4. DDoS Detection and Mitigation . . . . . . . . . . . . . . 17
4.5. QoS support and ECMP . . . . . . . . . . . . . . . . . . 16 4.5. Distinguishing acknowledgment traffic . . . . . . . . . . 17
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 4.6. QoS support and ECMP . . . . . . . . . . . . . . . . . . 17
6. Security Considerations . . . . . . . . . . . . . . . . . . . 16 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 17 6. Security Considerations . . . . . . . . . . . . . . . . . . . 18
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 18
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 17 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18
9.1. Normative References . . . . . . . . . . . . . . . . . . 17 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 18
9.2. Informative References . . . . . . . . . . . . . . . . . 17 9.1. Normative References . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19 9.2. Informative References . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20
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. Given QUIC is encrypt all payload data and most control information.
an end-to-end transport protocol, all information in the protocol
header, even that which can be inspected, is is not meant to be Given that QUIC is an end-to-end transport protocol, all information
mutable by the network, and is therefore integrity-protected to the in the protocol header, even that which can be inspected, is not
extent possible. meant to be mutable by the network, and is therefore integrity-
protected. While less information is visible to the network than for
TCP, integrity protection can also simplify troubleshooting because
none of the nodes on the network path can modify the transport layer
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: Of course, network management is not a one-size-fits-all endeavour:
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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.
1.1. Notational Conventions 1.1. Notational Conventions
The words "MUST", "MUST NOT", "SHOULD", and "MAY" are used in this The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
document. It's not shouting; when these words are capitalized, they "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
have a special meaning as defined in [RFC2119]. "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. 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
QUIC's unencrypted wire image [WIRE-IMAGE], which we define as the QUIC's unencrypted wire image [WIRE-IMAGE], which we define as the
information available in the packet header in each QUIC packet, and information available in the packet header in each QUIC packet, and
the dynamics of that information. Since QUIC is a versioned the dynamics of that information. Since QUIC is a versioned
protocol, the wire image of the header format can also change from protocol, the wire image of the header format can also change from
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[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
present. present.
The long header exposes more information. It is used during The long header exposes more information. It is used during
connection establishment, including version negotiation, server connection establishment, including version negotiation, retry, and
retry, and 0-RTT data. It contains a version number, as well as 0-RTT data. It contains a version number, as well as source and
source and destination connection IDs for grouping packets belonging destination connection IDs for grouping packets belonging to the same
to the same flow. The definition and location of these fields in the flow. The definition and location of these fields in the QUIC long
QUIC long header are invariant for future versions of QUIC, although header are invariant for future versions of QUIC, although future
future versions of QUIC may provide additional fields in the long versions of QUIC may provide additional fields in the long header
header [QUIC-INVARIANTS]. [QUIC-INVARIANTS].
Short headers are used after connection establishment. The only Short headers are used after connection establishment, and contain
information they contain for inspection on the path is an optional, only an optional destination connection ID and the spin bit for RTT
variable-length destination connection ID. measurement.
As of draft version 13 of the QUIC transport document, the following The following information is exposed in QUIC packet headers:
information may be exposed in QUIC packet headers:
o header type: the long header has a 7-bit packet type field o demux bit: the second most significant bit of the first octet
every QUIC packet of the current version is set to 1, for
demultiplexing with other UDP-encapsulated protocols.
o latency spin bit: the third most significant bit of first octet in
the short packet header. The spin bit is set by endpoints such
that tracking edge transitions can be used to passively observe
end-to-end RTT. See Section 3.7.2 for further details.
o header type: the long header has a 2 bit packet type field
following the Header Form bit. Header types correspond to stages following the Header Form bit. Header types correspond to stages
of the handshake; see Section 4.1 of [QUIC-TRANSPORT]. of the handshake; see Section 17.2 of [QUIC-TRANSPORT].
o version number: the version number present in the long header, and
identifies the version used for that packet. Note that during
Version Negotiation (see Section 2.8, and Section 17.2.1 of
o version number: The version number is present in the long header,
and identifies the version used for that packet. Note that during
Version Negotiation (see Section 2.8, and Section 4.3 of
[QUIC-TRANSPORT], the version number field has a special value [QUIC-TRANSPORT], the version number field has a special value
(0x00000000) that identifies the packet as a Version Negotiation (0x00000000) that identifies the packet as a Version Negotiation
packet. packet.
o source and destination connection ID: The source and destination o source and destination connection ID: short and long packet
connection IDs are variable-length fields that can be used to headers carry a destination connection ID, a variable-length field
identify the connection associated with a QUIC packet, for load- that can be used to identify the connection associated with a QUIC
balancing and NAT rebinding purposes; see Section 4.3 and packet, for load-balancing and NAT rebinding purposes; see
Section 2.6. The source connection ID corresponds to the Section 4.3 and Section 2.6. Long packet headers additionally
destination connection ID the source would like to have on packets carry a source connection ID. The source connection ID
sent to it, and is only present on long packet headers. The corresponds to the destination connection ID the source would like
destination connection ID, if present, is present on both long and to have on packets sent to it, and is only present on long packet
short header packets. On long header packets, the length of the headers. On long header packets, the length of the connection IDs
connection IDs is also present; on short header packets, the is also present; on short header packets, the length of 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 packet number: Every packet has an associated packet number; o token: Initial packets may contain a token, a variable-length
opaque value optionally sent from client to server, used for
validating the client's address. Retry packets also contain a
token, which can be used by the client in an Initial packet on a
subsequent connection attempt. The length of the token is
explicit in both cases.
Retry and Version Negotiation packets are not encrypted or obfuscated
in any way. For other kinds of packets, other information in the
packet headers is cryptographically obfuscated:
o packet number: Most packets (with the exception of Version
Negotiation and Retry packets) have an associated packet number;
however, this packet number is encrypted, and therefore not of use however, this packet number is encrypted, and therefore not of use
to on-path observers. This packet number has a fixed location and to on-path observers. The offset of the packet number is encoded
length in long headers, and an implicit location and encrypted in the header for packets with long headers, while it is implicit
variable length in short headers. (depending on Destination Connection ID length) in short header
packets. The length of the packet number is cryptographically
obfuscated.
o key phase: The Key Phase bit, present in short headers identifies o key phase: The Key Phase bit, present in short headers, specifies
the key used to encrypt the packet during key rotation. the keys used to encrypt the packet, supporting key rotation. The
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]. destionation connection ID. See Section 4.6 of [QUIC-TRANSPORT].
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| QUIC short header | | QUIC short header |
+------------------------------------------------------------+ +------------------------------------------------------------+
| 1-RTT encrypted payload | | 1-RTT encrypted payload |
+------------------------------------------------------------+ +------------------------------------------------------------+
Figure 4: Typical QUIC Initial Completion datagram pattern Figure 4: Typical QUIC Initial Completion datagram pattern
The Initial Completion datagram does not expose any additional The Initial Completion datagram does not expose any additional
information; however, recognizing it can be used to determine that a information; however, recognizing it can be used to determine that a
handshake has completed (see Section 3.2), and for three-way handshake has completed (see Section 3.2), and for three-way
handshake RTT estimation as in Section 3.6. handshake RTT estimation as in Section 3.7.
+------------------------------------------------------------+ +------------------------------------------------------------+
| UDP header (source and destination UDP ports) | | UDP header (source and destination UDP ports) |
+------------------------------------------------------------+ +------------------------------------------------------------+
| QUIC long header (type = Handshake, Version, DCID, SCID) (Length) | QUIC long header (type = Handshake, Version, DCID, SCID) (Length)
+------------------------------------------------------------+ | +------------------------------------------------------------+ |
| encrypted payload (presumably ACK frame) | | | encrypted payload (presumably ACK frame) | |
+------------------------------------------------------------+<-+ +------------------------------------------------------------+<-+
| QUIC short header | | QUIC short header |
+------------------------------------------------------------+ +------------------------------------------------------------+
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The connection ID in the QUIC packet headers allows routing of QUIC The connection ID in the QUIC packet headers allows routing of QUIC
packets at load balancers on other than five-tuple information, packets at load balancers on other than five-tuple information,
ensuring that related flows are appropriately balanced together; and ensuring that related flows are appropriately balanced together; and
to allow rebinding of a connection after one of the endpoint's to allow rebinding of a connection after one of the endpoint's
addresses changes - usually the client's, in the case of the HTTP addresses changes - usually the client's, in the case of the HTTP
binding. Client and server negotiate connection IDs during the binding. Client and server negotiate connection IDs during the
handshake; typically, however, only the server will request a handshake; typically, however, only the server will request a
connection ID for the lifetime of the connection. Connection IDs for connection ID for the lifetime of the connection. Connection IDs for
either endpoint may change during the lifetime of a connection, with either endpoint may change during the lifetime of a connection, with
the new connection ID being negotiated via encrypted frames. See the new connection ID being negotiated via encrypted frames. See
Section 6.1 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 useful to on-path observers.
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The QUIC wire image is not specifically designed to be The QUIC wire image is not specifically designed to be
distinguishable from other UDP traffic. distinguishable from other UDP traffic.
The only application binding currently defined for QUIC is HTTP The only application binding currently defined for QUIC is HTTP
[QUIC-HTTP]. HTTP over QUIC uses UDP port 443 by default, although [QUIC-HTTP]. HTTP over QUIC uses UDP port 443 by default, although
URLs referring to resources available over HTTP over QUIC may specify URLs referring to resources available over HTTP over QUIC may specify
alternate port numbers. Simple assumptions about whether a given alternate port numbers. Simple assumptions about whether a given
flow is using QUIC based upon a UDP port number may therefore not flow is using QUIC based upon a UDP port number may therefore not
hold; see also [RFC7605] section 5. hold; see also [RFC7605] section 5.
While the second most significant bit (0x40) of the first octet is
always set to 1 in QUIC packets of the current version, this is not a
recommended method of recognizing QUIC traffic, as it only provides
one bit of information and is quite prone to collide with UDP-based
protocols other than those that this static bit is meant to allow
multiplexing with.
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 NAT rebinding;
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3.2. Connection confirmation 3.2. Connection confirmation
Connection establishment uses Initial, Handshake, and Retry packets Connection establishment uses Initial, Handshake, and Retry packets
containing a TLS handshake. Connection establishment can therefore containing a TLS handshake. Connection establishment can therefore
be detected using heuristics similar to those used to detect TLS over be detected using heuristics similar to those used to detect TLS over
TCP. A client using 0-RTT connection may also send data packets in TCP. A client using 0-RTT connection may also send data packets in
0-RTT Protected packets directly after the Initial packet containing 0-RTT Protected packets directly after the Initial packet containing
the TLS Client Hello. Since these packets may be reordered in the the TLS Client Hello. Since these packets may be reordered in the
network, note that 0-RTT Protected data packets may be seen before network, note that 0-RTT Protected data packets may be seen before
the Initial packet. Note that only clients send Initial packets, so the Initial packet.
the sides of a connection can be distinguished by QUIC packet type in
the handshake. Note that clients send Initial packets before servers do, servers
send Handshake packets before clients do, and only clients send
Initial packets with tokens, so the sides of a connection can be
generally be confirmed by an on-path observer. An attempted
connection after Retry can be detected by correlating the token on
the Retry with the token on the subsequent Initial packet.
3.3. Application Identification 3.3. Application Identification
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
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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
address (IP address and port) with the known flow. address (IP address and port) with the known flow.
The connection ID to be used for a long-running flow is chosen by the However, since the connection ID may change multiple times during the
server (see [QUIC-TRANSPORT] section 5.6) during the handshake. This lifetime of a flow, and the negotiation of connection ID changes is
value should be treated as opaque; see Section 4.3 for caveats encrypted, packets with the same 5-tuple but different connection IDs
regarding connection ID selection at servers. may or may not belong to the same connection.
The connection ID value should be treated as opaque; see Section 4.3
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 The QUIC does not expose the end of a connection; the only indication
to on-path devices that a flow has ended is that packets are no to on-path devices that a flow has ended is that packets are no
longer observed. Stateful devices on path such as NATs and firewalls longer observed. Stateful devices on path such as NATs and firewalls
must therefore use idle timeouts to determine when to drop state for must therefore use idle timeouts to determine when to drop state for
QUIC flows. QUIC 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. Round-trip time measurement 3.6. Flow symmetry measurement
QUIC explicitly exposes which side of a connection is a client and
which side is a server during the handshake. In addition, the
symmerty of a flow (whether primarily client-to-server, primarily
server-to-client, or roughly bidirectional, as input to basic traffic
classification techniques) can be inferred through the measurement of
data rate in each direction. While QUIC traffic is protected and
ACKS may be padded, padding is not required.
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. handshake, as illustrated in Section 2.4. It can also be inferred
during the flow's lifetime, if the endpoints use the spin bit
facility described below and in [QUIC-TRANSPORT], section 17.3.1.
3.7.1. Measuring initial RTT
In the common case, the delay between the Initial packet containing In the common case, the delay between the Initial packet containing
the TLS Client Hello and the Handshake packet containing the TLS the TLS Client Hello and the Handshake packet containing the TLS
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 at
both sides. both sides.
The spin bit experiment, detailed in [QUIC-SPIN], provides an 3.7.2. Using the Spin Bit for Passive RTT Measurement
additional method to measure intraflow per-flow RTT. When a QUIC
flow is sending at full rate (i.e., neither application nor flow The spin bit provides an additional method to measure per-flow RTT
control limited), the latency spin bit described in that document from observation points on the network path throughout the duration
changes value once per round-trip time (RTT). An on-path observer of a connection. Endpoint participation in spin bit signaling is
can observe the time difference between edges in the spin bit signal optional in QUIC. That is, while its location is fixed in this
in a single direction to measure one sample of end-to-end RTT. Note version of QUIC, an endpoint can unilaterally choose to not support
that this measurement, as with passive RTT measurement for TCP, "spinning" the bit. Use of the spin bit for RTT measurement by
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
in specific deployment scenarios, e.g. for servers and clients where
the RTT would reveal the presence of a VPN or proxy. In order to not
make these connections identifiable based on the usage of the spin
bit, it is recommended that all endpoints disable "spinning" randomly
for at least one eighth of connections, even if otherwise enabled by
default. An endpoint not participating in spin bit signaling for a
given connection can use a fixed spin value for the duration of the
connection, or can set the bit randomly on each packet sent.
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).
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
direction to measure one sample of end-to-end RTT.
Note that this measurement, as with passive RTT measurement for TCP,
includes any transport protocol delay (e.g., delayed sending of includes any transport protocol delay (e.g., delayed sending of
acknowledgements) and/or application layer delay (e.g., waiting for a acknowledgements) and/or application layer delay (e.g., waiting for a
request to complete). It therefore provides devices on path a good response to be generated). It therefore provides devices on path a
instantaneous estimate of the RTT as experienced by the application. good instantaneous estimate of the RTT as experienced by the
A simple linear smoothing or moving minimum filter can be applied to application. A simple linear smoothing or moving minimum filter can
the stream of RTT information to get a more stable estimate. be applied to the stream of RTT information to get a more stable
estimate.
However, application-limited and flow-control-limited senders can
have application and transport layer delay, respectively, that are
much greater than network RTT. When the sender is application-
limited and e.g. only sends small amount of periodic application
traffic, where that period is longer than the RTT, measuring the spin
bit provides information about the application period, not the
network RTT.
Since the spin bit logic at each endpoint considers only samples from
packets that advance the largest packet number, signal generation
itself is resistant to reordering. However, reordering can cause
problems at an observer by causing spurious edge detection and
therefore low RTT estimates, if reordering occurs across a spin-bit
flip in the stream.
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
or reordered edges in the spin signal, as well as application or flow
control limitation; for example, QoF [TMA-QOF] rejects component RTTs
significantly higher than RTTs over the history of the flow. These
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
either constant or randomly set for a connection.
An on-path observer that can see traffic in both directions (from An on-path observer that can see traffic in both directions (from
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.
Application-limited and flow-control-limited senders can have
application and transport layer delay, respectively, that are much
greater than network RTT. Therefore, the spin bit provides network
latency information only when the sender is neither application nor
flow control limited. When the sender is application-limited by
periodic application traffic, where that period is longer than the
RTT, measuring the spin bit provides information about the
application period, not the RTT. 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 application or flow control
limitation.
Since the spin bit logic at each endpoint considers only samples on
packets that advance the largest packet number seen, signal
generation itself is resistant to reordering. However, reordering
can cause problems at an observer by causing spurious edge detection
and therefore low RTT estimates, if reordering occurs across a spin
bit flip in the stream. This can be probabilistically mitigated by
the observer also tracking the low-order bits of the packet number,
and rejecting edges that appear out-of-order [RFC4737].
3.7. Flow symmetry measurement
QUIC explicitly exposes which side of a connection is a client and
which side is a server during the handshake. In addition, the
symmerty of a flow (whether primarily client-to-server, primarily
server-to-client, or roughly bidirectional, as input to basic traffic
classification techniques) can be inferred through the measurement of
data rate in each direction. While QUIC traffic is protected and
ACKS may be padded, padding is not required.
4. Specific Network Management Tasks 4. Specific Network Management Tasks
In this section, we address specific network management and In this section, we address 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 is possible through QUIC traffic
and version identification (Section 3.1) and observation of the and version identification (Section 3.1) and observation of the
handshake for connection confirmation (Section 3.2). The lack of any handshake for connection confirmation (Section 3.2). The lack of any
visible end-of-flow signal (Section 3.5) means that this state must visible end-of-flow signal (Section 3.5) means that this state must
be purged either through timers or through least-recently-used be purged either through timers or through least-recently-used
eviction, depending on application requirements. eviction, depending on application requirements.
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 3.6. 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
In the case of content distribution networking architectures In the case of content distribution networking architectures
including load balancers, the connection ID provides a way for the including load balancers, the connection ID provides a way for the
server to signal information about the desired treatment of a flow to server to signal information about the desired treatment of a flow to
the load balancers. Guidance on assigning connection IDs is given in the load balancers. Guidance on assigning connection IDs is given in
skipping to change at page 16, line 16 skipping to change at page 17, line 32
DDoS defense system must have the same information about flows as the DDoS defense system must have the same information about flows as the
load balancer. load balancer.
However, it is questionable if connection migrations needs to be However, it is questionable if connection migrations needs to be
supported in a DDOS attack. If the connection migration is not supported in a DDOS attack. If the connection migration is not
visible to the network that performs the DDoS detection, an active, visible to the network that performs the DDoS detection, an active,
migrated QUIC connection may be blocked by such a system under migrated QUIC connection may be blocked by such a system under
attack. However, a defense system might simply rely on the fast attack. However, a defense system might simply rely on the fast
resumption mechanism provided by QUIC. resumption mechanism provided by QUIC.
4.5. QoS support and ECMP 4.5. Distinguishing acknowledgment traffic
Some deployed in-network functions distinguish pure-acknowledgment
(ACK) packets from packets carrying upper-layer data in order to
attempt to enhance performance, for example by queueing ACKs
differently or manipulating ACK signaling. Distinguishing ACK
packets is trivial in TCP, but not supported by QUIC, since
acknowledgment signaling is carried inside QUIC's encrypted payload,
and ACK manipulation is impossible. Specifically, heuristics
attempting to distinguish ACK-only packets from payload-carrying
packets based on packet size are likely to fail, and are emphatically
NOT RECOMMENDED.
4.6. QoS support and ECMP
[EDITOR'S NOTE: this is a bit speculative; keep?] [EDITOR'S NOTE: this is a bit speculative; keep?]
QUIC does not provide any additional information on requirements on QUIC does not provide any additional information on requirements on
Quality of Service (QoS) provided from the network. QUIC assumes Quality of Service (QoS) provided from the network. QUIC assumes
that all packets with the same 5-tuple {dest addr, source addr, that all packets with the same 5-tuple {dest addr, source addr,
protocol, dest port, source port} will receive similar network protocol, dest port, source port} will receive similar network
treatment. That means all stream that are multiplexed over the same treatment. That means all stream that are multiplexed over the same
QUIC connection require the same network treatment and are handled by QUIC connection require the same network treatment and are handled by
the same congestion controller. If differential network treatment is the same congestion controller. If differential network treatment is
skipping to change at page 17, line 9 skipping to change at page 18, line 36
6. Security Considerations 6. Security Considerations
Supporting manageability of QUIC traffic inherently involves Supporting manageability of QUIC traffic inherently involves
tradeoffs with the confidentiality of QUIC's control information; tradeoffs with the confidentiality of QUIC's control information;
this entire document is therefore security-relevant. this entire document is therefore security-relevant.
7. Contributors 7. Contributors
Dan Druta contributed text to Section 4.4. Igor Lubashev contributed Dan Druta contributed text to Section 4.4. Igor Lubashev contributed
text to Section 4.3 on the use of the connection ID for load text to Section 4.3 on the use of the connection ID for load
balancing. Marcus Ilhar contributed text to Section 3.6 on the use balancing. Marcus Ilhar contributed text to Section 3.7 on the use
of the spin bit. of the spin bit.
8. Acknowledgments 8. Acknowledgments
This work is partially supported by the European Commission under This work is partially supported by the European Commission under
Horizon 2020 grant agreement no. 688421 Measurement and Architecture Horizon 2020 grant agreement no. 688421 Measurement and Architecture
for a Middleboxed Internet (MAMI), and by the Swiss State Secretariat for a Middleboxed Internet (MAMI), and by the Swiss State Secretariat
for Education, Research, and Innovation under contract no. 15.0268. for Education, Research, and Innovation under contract no. 15.0268.
This support does not imply endorsement. This support does not imply endorsement.
skipping to change at page 17, line 21 skipping to change at page 19, line 4
8. Acknowledgments 8. Acknowledgments
This work is partially supported by the European Commission under This work is partially supported by the European Commission under
Horizon 2020 grant agreement no. 688421 Measurement and Architecture Horizon 2020 grant agreement no. 688421 Measurement and Architecture
for a Middleboxed Internet (MAMI), and by the Swiss State Secretariat for a Middleboxed Internet (MAMI), and by the Swiss State Secretariat
for Education, Research, and Innovation under contract no. 15.0268. for Education, Research, and Innovation under contract no. 15.0268.
This support does not imply endorsement. This support does not imply endorsement.
9. References 9. References
9.1. Normative References 9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
9.2. Informative References 9.2. Informative References
[Ding2015] [Ding2015]
Ding, H. and M. Rabinovich, "TCP Stretch Acknowledgments Ding, H. and M. Rabinovich, "TCP Stretch Acknowledgments
and Timestamps - Findings and Impliciations for Passive and Timestamps - Findings and Impliciations for Passive
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-02 Transport Protocol", draft-ietf-quic-applicability-03
(work in progress), July 2018. (work in progress), October 2018.
[QUIC-HTTP] [QUIC-HTTP]
Bishop, M., "Hypertext Transfer Protocol (HTTP) over Bishop, M., "Hypertext Transfer Protocol Version 3
QUIC", draft-ietf-quic-http-15 (work in progress), October (HTTP/3)", draft-ietf-quic-http-20 (work in progress),
2018. April 2019.
[QUIC-INVARIANTS] [QUIC-INVARIANTS]
Thomson, M., "Version-Independent Properties of QUIC", Thomson, M., "Version-Independent Properties of QUIC",
draft-ietf-quic-invariants-03 (work in progress), October draft-ietf-quic-invariants-04 (work in progress), April
2018. 2019.
[QUIC-SPIN]
Trammell, B. and M. Kuehlewind, "The QUIC Latency Spin
Bit", draft-ietf-quic-spin-exp-00 (work in progress),
April 2018.
[QUIC-TLS] [QUIC-TLS]
Thomson, M. and S. Turner, "Using Transport Layer Security Thomson, M. and S. Turner, "Using TLS to Secure QUIC",
(TLS) to Secure QUIC", draft-ietf-quic-tls-15 (work in draft-ietf-quic-tls-20 (work in progress), April 2019.
progress), October 2018.
[QUIC-TRANSPORT] [QUIC-TRANSPORT]
Iyengar, J. and M. Thomson, "QUIC: A UDP-Based Multiplexed Iyengar, J. and M. Thomson, "QUIC: A UDP-Based Multiplexed
and Secure Transport", draft-ietf-quic-transport-15 (work and Secure Transport", draft-ietf-quic-transport-20 (work
in progress), October 2018. in progress), April 2019.
[RFC4737] Morton, A., Ciavattone, L., Ramachandran, G., Shalunov,
S., and J. Perser, "Packet Reordering Metrics", RFC 4737,
DOI 10.17487/RFC4737, November 2006,
<https://www.rfc-editor.org/info/rfc4737>.
[RFC6066] Eastlake 3rd, D., "Transport Layer Security (TLS) [RFC6066] Eastlake 3rd, D., "Transport Layer Security (TLS)
Extensions: Extension Definitions", RFC 6066, Extensions: Extension Definitions", RFC 6066,
DOI 10.17487/RFC6066, January 2011, DOI 10.17487/RFC6066, January 2011,
<https://www.rfc-editor.org/info/rfc6066>. <https://www.rfc-editor.org/info/rfc6066>.
[RFC6928] Chu, J., Dukkipati, N., Cheng, Y., and M. Mathis, [RFC6928] Chu, J., Dukkipati, N., Cheng, Y., and M. Mathis,
"Increasing TCP's Initial Window", RFC 6928, "Increasing TCP's Initial Window", RFC 6928,
DOI 10.17487/RFC6928, April 2013, DOI 10.17487/RFC6928, April 2013,
<https://www.rfc-editor.org/info/rfc6928>. <https://www.rfc-editor.org/info/rfc6928>.
skipping to change at page 19, line 11 skipping to change at page 20, line 32
"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-ENCRYPT-SNI]
Huitema, C. and E. Rescorla, "Issues and Requirements for Huitema, C. and E. Rescorla, "Issues and Requirements for
SNI Encryption in TLS", draft-ietf-tls-sni-encryption-03 SNI Encryption in TLS", draft-ietf-tls-sni-encryption-04
(work in progress), May 2018. (work in progress), November 2018.
[TMA-QOF] Trammell, B., Gugelmann, D., and N. Brownlee, "Inline Data
Integrity Signals for Passive Measurement (in Proc. TMA
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", draft-trammell-wire-image-04 (work in
progress), April 2018. progress), April 2018.
Authors' Addresses Authors' Addresses
Mirja Kuehlewind Mirja Kuehlewind
ETH Zurich ETH Zurich
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