draft-ietf-quic-manageability-01.txt   draft-ietf-quic-manageability-02.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 28, 2018 October 25, 2017 Expires: January 3, 2019 July 02, 2018
Manageability of the QUIC Transport Protocol Manageability of the QUIC Transport Protocol
draft-ietf-quic-manageability-01 draft-ietf-quic-manageability-02
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 http://datatracker.ietf.org/drafts/current/. Drafts is at http://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 28, 2018. This Internet-Draft will expire on January 3, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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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. Integrity Protection of the Wire Image . . . . . . . . . 5 2.2. Coalesced Packets . . . . . . . . . . . . . . . . . . . . 5
2.3. Connection ID and Rebinding . . . . . . . . . . . . . . . 5 2.3. Integrity Protection of the Wire Image . . . . . . . . . 5
2.4. Packet Numbers . . . . . . . . . . . . . . . . . . . . . 6 2.4. Connection ID and Rebinding . . . . . . . . . . . . . . . 5
2.5. Initial Handshake and PMTUD . . . . . . . . . . . . . . . 6 2.5. Packet Numbers . . . . . . . . . . . . . . . . . . . . . 6
2.6. Version Negotiation and Greasing . . . . . . . . . . . . 6 2.6. Version Negotiation and Greasing . . . . . . . . . . . . 6
3. Network-visible information about QUIC flows . . . . . . . . 6 3. Network-visible information about QUIC flows . . . . . . . . 6
3.1. Identifying QUIC traffic . . . . . . . . . . . . . . . . 7 3.1. Identifying QUIC traffic . . . . . . . . . . . . . . . . 6
3.1.1. Identifying Negotiated Version . . . . . . . . . . . 7 3.1.1. Identifying Negotiated Version . . . . . . . . . . . 7
3.1.2. Rejection of Garbage Traffic . . . . . . . . . . . . 7 3.1.2. Rejection of Garbage Traffic . . . . . . . . . . . . 7
3.2. Connection confirmation . . . . . . . . . . . . . . . . . 7 3.2. Connection confirmation . . . . . . . . . . . . . . . . . 7
3.3. Flow association . . . . . . . . . . . . . . . . . . . . 8 3.3. Application Identification . . . . . . . . . . . . . . . 7
3.4. Flow teardown . . . . . . . . . . . . . . . . . . . . . . 8 3.4. Flow association . . . . . . . . . . . . . . . . . . . . 8
3.5. Round-trip time measurement . . . . . . . . . . . . . . . 8 3.5. Flow teardown . . . . . . . . . . . . . . . . . . . . . . 8
3.6. Packet loss measurement . . . . . . . . . . . . . . . . . 9 3.6. Round-trip time measurement . . . . . . . . . . . . . . . 8
3.7. Flow symmetry measurement . . . . . . . . . . . . . . . . 9 3.7. Flow symmetry measurement . . . . . . . . . . . . . . . . 10
4. Specific Network Management Tasks . . . . . . . . . . . . . . 9 4. Specific Network Management Tasks . . . . . . . . . . . . . . 10
4.1. Stateful treatment of QUIC traffic . . . . . . . . . . . 9 4.1. Stateful treatment of QUIC traffic . . . . . . . . . . . 10
4.2. Passive network performance measurement and 4.2. Passive network performance measurement and
troubleshooting . . . . . . . . . . . . . . . . . . . . . 9 troubleshooting . . . . . . . . . . . . . . . . . . . . . 10
4.3. Server cooperation with load balancers . . . . . . . . . 10 4.3. Server cooperation with load balancers . . . . . . . . . 10
4.4. DDoS Detection and Mitigation . . . . . . . . . . . . . . 10 4.4. DDoS Detection and Mitigation . . . . . . . . . . . . . . 11
4.5. QoS support and ECMP . . . . . . . . . . . . . . . . . . 11 4.5. QoS support and ECMP . . . . . . . . . . . . . . . . . . 11
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
6. Security Considerations . . . . . . . . . . . . . . . . . . . 11 6. Security Considerations . . . . . . . . . . . . . . . . . . . 12
7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 12 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 12
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
9.1. Normative References . . . . . . . . . . . . . . . . . . 12 9.1. Normative References . . . . . . . . . . . . . . . . . . 13
9.2. Informative References . . . . . . . . . . . . . . . . . 12 9.2. Informative References . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction 1. Introduction
QUIC [QUIC] is a new transport protocol currently under development QUIC [QUIC-TRANSPORT] is a new transport protocol currently under
in the IETF quic working group, focusing on support of semantics as development in the IETF quic working group, focusing on support of
needed for HTTP/2 [QUIC-HTTP]. Based on current deployment semantics as needed for HTTP/2 [QUIC-HTTP]. Based on current
practices, QUIC is encapsulated in UDP and encrypted by default. The deployment practices, QUIC is encapsulated in UDP and encrypted by
current version of QUIC integrates TLS [QUIC-TLS] to encrypt all default. The current version of QUIC integrates TLS [QUIC-TLS] to
payload data and most control information. Given QUIC is an end-to- encrypt all payload data and most control information. Given QUIC is
end transport protocol, all information in the protocol header, even an end-to-end transport protocol, all information in the protocol
that which can be inspected, is is not meant to be mutable by the header, even that which can be inspected, is is not meant to be
network, and will therefore be integrity-protected to the extent mutable by the network, and is therefore integrity-protected to the
possible. extent possible.
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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The words "MUST", "MUST NOT", "SHOULD", and "MAY" are used in this The words "MUST", "MUST NOT", "SHOULD", and "MAY" are used in this
document. It's not shouting; when these words are capitalized, they document. It's not shouting; when these words are capitalized, they
have a special meaning as defined in [RFC2119]. have a special meaning as defined in [RFC2119].
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, which we define as the information QUIC's unencrypted wire image [WIRE-IMAGE], which we define as the
available in the packet header in each QUIC packet, and the dynamics information available in the packet header in each QUIC packet, and
of that information. Since QUIC is a versioned protocol, also the the dynamics of that information. Since QUIC is a versioned
wire image of the header format can change. However, at least the protocol, the wire image of the header format can also change from
mechanism by which a receiver can determine which version is used and version to version. However, at least the mechanism by which a
the meaning and location of fields used in the version negotiation receiver can determine which version is used and the meaning and
process need to be fixed. location of fields used in the version negotiation process is
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] and [QUIC-TLS], and will change to track those documents. [QUIC-TRANSPORT] and [QUIC-TLS], and will change to track those
documents.
2.1. QUIC Packet Header Structure 2.1. QUIC Packet Header Structure
The QUIC packet header is under active development; see section 5 of QUIC packets may have either a long header, or a short header. The
[QUIC] for the present header structure. first bit of the QUIC header indicates which type of header is
present.
The first bit of the QUIC header indicates the present of a long The long header exposes more information. It is used during
header that exposes more information than the short header. The long connection establishment, including version negotiation, server
header is used during connection start including version negotiation, retry, and 0-RTT data. It contains a version number, as well as
server retry, and 0-RTT data while the short header is used after the source and destination connection IDs for grouping packets belonging
handshake and therefore on most data packets to limited unnecessary to the same flow. The definition and location of these fields in the
header overhead. The fields and location of these fields as defined QUIC long header are invariant for future versions of QUIC, although
by the current version of QUIC for the long header are fixed for all future versions of QUIC may provide additional fields in the long
future version as well. However, note that future versions of QUIC header [QUIC-INVARIANTS].
may provide additional fields. In the current version of quic the
long header for all header types has a fixed length, containing,
besides the Header Form bit, a 7-bit header Type, a 64-bit Connection
ID, a 32-bit Packet Number, and a 32-bit Version. The short header
is variable length where bits after the Header Form bit indicate the
present on the Connection ID, and the length of the packet number.
The following information may be exposed in the packet header: Short headers are used after connection establishment. The only
information they contain for inspection on the path is an optional,
variable-length destination connection ID.
o header type: the long header has a 7-bit header type field As of draft version 13 of the QUIC transport document, the following
following the Header Form bit. The current version of QUIC information may be exposed in QUIC packet headers:
defines 6 header types, namely Version Negotiation, Client
Initial, Server Stateless Retry, Server Cleartext, Client
Cleartext, 0-RTT Protected.
o connection ID: The connection ID is always present on the long and o header type: the long header has a 7-bit packet type field
optionally present on the short header indicated by the Connection following the Header Form bit. Header types correspond to stages
ID Flag. If present at the short header it at the same position of the handshake; see Section 4.1 of [QUIC-TRANSPORT].
then for the long header. The position and length pf the
congestion ID itself as well as the Connection ID flag in the o version number: The version number is present in the long header,
short header is fixed for all versions of QUIC. The connection ID and identifies the version used for that packet. Note that during
identifies the connection associated with a QUIC packet, for load- Version Negotiation (see Section 2.6, and Section 4.3 of
[QUIC-TRANSPORT], the version number field has a special value
(0x00000000) that identifies the packet as a Version Negotiation
packet.
o source and destination connection ID: The source and destination
connection IDs are variable-length fields that can be used to
identify the connection associated with a QUIC packet, for load-
balancing and NAT rebinding purposes; see Section 4.3 and balancing and NAT rebinding purposes; see Section 4.3 and
Section 2.3. Therefore it is also expected that the Connection ID Section 2.4. The source connection ID corresponds to the
will either be present on all packets of a flow or none of the destination connection ID the source would like to have on packets
short header packets. However, this field is under endpoint sent to it, and is only present on long packet headers. The
control and there is no protocol mechanism that hinders the destination connection ID, if present, is present on both long and
sending endpoint to revise its decision about exposing the short header packets. On long header packets, the length of the
Connection ID at any time during the connection. connection IDs is also present; on short header packets, the
length of the destination connection ID is implicit.
o packet number: Every packet has an associated packet number. The o length: the length of the remaining quic packet after the length
packet number increases with each packet, and the least- field, present on long headers. This field is used to implement
significant bits of the packet number are present on each packet. coalesced packets during the handshake (see Section 2.2).
In the short header the length of the exposed packet number field
is defined by the (short) header type and can either be 8, 16, or
32 bits. See Section 2.4.
o version number: The version number is present on the long headers o packet number: Every packet has an associated packet number;
and identifies the version used for that packet, expect for the however, this packet number is encrypted, and therefore not of use
Version negotiation packet. The version negotiation packet is to on-path observers. This packet number has a fixed location and
fixed for all version of QUIC and contains a list of versions that length in long headers, and an implicit location and encrypted
is supported by the sender. The version in the version field of variable length in short headers.
the Version Negotiation packet is the reflected version of the
Client Initial packet and is therefore explicitly n ot supported
by the sender.
o key phase: The short header further has a Key Phase flag that is o key phase: The Key Phase bit, present in short headers identifies
used by the endpoint identify the right key that was used to the key used to encrypt the packet during key rotation.
encrypt the packet.
2.2. Integrity Protection of the Wire Image 2.2. Coalesced Packets
Multiple QUIC packets may be coalesced into a UDP datagram, with a
datagram carrying one or more long header packets followed by zero or
one short header packets. When packets are coalesced, the Length
fields in the long headers are used to separate QUIC packets. The
length header field is variable length and its position in the header
is also variable depending on the length of the source and
destionation connection ID. See Section 4.6 of [QUIC-TRANSPORT].
2.3. Integrity Protection of the Wire Image
As soon as the cryptographic context is established, all information As soon as the cryptographic context is established, all information
in the QUIC header, including those exposed in the packet header, is in the QUIC header, including those exposed in the packet header, is
integrity protected. Further, information that were sent and exposed integrity protected. Further, information that were sent and exposed
in previous packets when the cryptographic context was established in previous packets when the cryptographic context was established
yet, e.g. for the cryptographic initial handshake itself, will be yet, e.g. for the cryptographic initial handshake itself, will be
validated later during the cryptographic handshake, such as the validated later during the cryptographic handshake. Therefore,
version number. Therefore, devices on path MUST NOT change any devices on path MUST NOT change any information or bits in QUIC
information or bits in QUIC packet headers. As alteration of header packet headers, since alteration of header information will lead to a
information would cause packet drop due to a failed integrity check failed integrity check at the receiver, and can even lead to
at the receiver, or can even lead to connection termination. connection termination.
2.3. Connection ID and Rebinding
The connection ID in the QUIC packer header is used to allow routing
of QUIC packets at load balancers on other than five-tuple
information, ensuring that related flows are appropriately balanced
together; and to allow rebinding of a connection after one of the
endpoint's addresses changes - usually the client's, in the case of
the HTTP binding. The client set a Connection ID in the Initial
Client packet that will be used during the handshake. A new
connection ID is then provided by the server during connection
establishment, that will be used in the short header after the
handshake. Further a server might provide additional connection IDs
that can the used by the client at any time during the connection.
Therefore if a flow changes one of its IP addresses it may keep the
same connection ID, or the connection ID may also change together
with the IP address migration, avoiding linkability; see Section 7.6
of [QUIC].
2.4. Packet Numbers
The packet number field is always present in the QUIC packet header.
The packet number exposes the least significant 32, 16, or 8 bits of
an internal packet counter per flow direction that increments with
each packet sent. This packet counter is initialized with a random
31-bit initial value at the start of a connection.
Unlike TCP sequence numbers, this packet number increases with every 2.4. Connection ID and Rebinding
packet, including those containing only acknowledgment or other
control information. Indeed, whether a packet contains user data or
only control information is intentionally left unexposed to the
network. The packet number increases with every packet but they
sender may skip packet numbers.
While loss detection in QUIC is based on packet numbers, congestion The connection ID in the QUIC packet headers allows routing of QUIC
control by default provides richer information than vanilla TCP does. packets at load balancers on other than five-tuple information,
Especially, QUIC does not rely on duplicated ACKs, making it more ensuring that related flows are appropriately balanced together; and
tolerant of packet re-ordering. to allow rebinding of a connection after one of the endpoint's
addresses changes - usually the client's, in the case of the HTTP
binding. Client and server negotiate connection IDs during the
handshake; typically, however, only the server will request a
connection ID for the lifetime of the connection. Connection IDs for
either endpoint may change during the lifetime of a connection, with
the new connection ID being negotiated via encrypted frames. See
Section 6.1 of [QUIC-TRANSPORT].
2.5. Initial Handshake and PMTUD 2.5. Packet Numbers
[Editor's note: text needed.] The packet number field is always present in the QUIC packet header;
however, it is always encrypted. The encryption key for packet
number protection on handshake packets sent before cryptographic
context establishment is specific to the QUIC version, while packet
number protection on subsequent packets uses secrets derived from the
end-to-end cryptographic context. Packet numbers are therefore not
part of the wire image that is useful to on-path observers.
2.6. Version Negotiation and Greasing 2.6. 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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[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.
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: a Client Initial with a given version followed by Server handshake: an Initial packet with a given version from a client to
Cleartext packet with the same version implies acceptance of that which a server responds with an Initial packet with the same version
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;
however, these flows can be associated with flows for which a version however, these flows can be associated with flows for which a version
has been identified; see Section 3.3. 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
backscatter). While heuristics based on the first byte of the packet backscatter). While heuristics based on the first byte of the packet
(packet type) could be used to separate valid from invalid first (packet type) could be used to separate valid from invalid first
packet types, the deployment of such heuristics is not recommended, packet types, the deployment of such heuristics is not recommended,
as packet types may have different meanings in future versions of the as packet types may have different meanings in future versions of the
protocol. protocol.
3.2. Connection confirmation 3.2. Connection confirmation
Connection establishment requires cleartext packets and is using a Connection establishment uses Initial, Handshake, and Retry packets
TLS handshake on stream 0. Therefore it is detectable using containing a TLS handshake on Stream 0. Connection establishment can
heuristics similar to those used to detect TLS over TCP. 0-RTT therefore be detected using heuristics similar to those used to
connection may additional also send data packets, right after the detect TLS over TCP. A client using 0-RTT connection may also send
Client Initial with the TLS client hello. These data may be data packets in 0-RTT Protected packets directly after the Initial
reordered in the network, therefore it may be possible that 0-RTT packet containing the TLS Client Hello. Since these packets may be
Protected data packets are seen before the Client Initial packet. reordered in the network, note that 0-RTT Protected data packets may
be seen before the Initial packet. Note that only clients send
Initial packets, so the sides of a connection can be distinguished by
QUIC packet type in the handshake.
3.3. Flow association 3.3. Application Identification
The QUIC Connection ID (see Section 2.3) is designed to allow an on- The cleartext TLS handshake may contain Server Name Indication (SNI)
[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
certificate based on that name. It may also contain information from
Application-Layer Protocol Negotiation (ALPN) [RFC7301], by which the
client exposes the names of application-layer protocols it supports;
an observer can deduce that one of those protocols will be used if
the connection continues.
Work is currently underway in the TLS working group to encrypt the
SNI in TLS 1.3 [TLS-ENCRYPT-SNI], reducing the information available
in the SNI to the name of a fronting service, which can generally be
identified by the IP address of the server anyway. If used with
QUIC, this would make SNI-based application identification impossible
through passive measurement.
3.4. Flow association
The QUIC Connection ID (see Section 2.4) 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 The connection ID to be used for a long-running flow is chosen by the
server (see [QUIC] section 5.6) during the handshake. This value server (see [QUIC-TRANSPORT] section 5.6) during the handshake. This
should be treated as opaque; see Section 4.3 for caveats regarding value should be treated as opaque; see Section 4.3 for caveats
connection ID selection at servers. regarding connection ID selection at servers.
3.4. 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 are currently under discussion: see Changes to this behavior have been discussed in the working group,
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.
3.5. Round-trip time measurement 3.6. Round-trip time 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. The delay flow, during the handshake, as in passive TCP measurement; this
between the Client Initial packet and the Server Cleartext packet requires parsing of the QUIC packet header and the cleartext TLS
sent back to the client represents the RTT component on the path handshake on stream 0.
between the observer and the server, and the delay between this
packet and the Client Cleartext packet in reply represents the RTT
component on the path between the observer and the client. This
measurement necessarily includes any application delay at both sides.
Note that the Server's reply mayalso be a Version Negotiation or
Server Stateless Retry packet. In this case the Client will send
another Client Initial or the connection will fail.
The lack of any acknowledgement information or timestamping In the common case, the delay between the Initial packet containing
information in the QUIC wire image makes running passive RTT the TLS Client Hello and the Handshake packet containing the TLS
estimation impossible. Server Hello represents the RTT component on the path between the
observer and the server. The delay between the TLS Server Hello and
the Handshake packet containing the TLS Finished message sent by the
client represents the RTT component on the path between the observer
and the client. While the client may send 0-RTT Protected packets
after the Initial packet during 0-RTT connection re-establishment,
these can be ignored for RTT measurement purposes.
Changes to this behavior are currently under discussion: see Handshake RTT can be measured by adding the client-to-observer and
https://github.com/quicwg/base-drafts/issues/631. observer-to-server RTT components together. This measurement
necessarily includes any transport and application layer delay at
both sides.
3.6. Packet loss measurement The spin bit experiment, detailed in [QUIC-SPIN], provides an
additional method to measure intraflow per-flow RTT. When a QUIC
flow is sending at full rate (i.e., neither application nor flow
control limited), the latency spin bit described in that document
changes value once per round-trip time (RTT). An on-path observer
can observe the time difference between edges 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
acknowledgements) and/or application layer delay (e.g., waiting for a
request to complete). It therefore provides devices on path a good
instantaneous estimate of the RTT as experienced by the application.
A simple linear smoothing or moving minimum filter can be applied to
the stream of RTT information to get a more stable estimate.
All QUIC packets carry packet numbers in cleartext, and while the An on-path observer that can see traffic in both directions (from
protocol allows packet numbers to be skipped, skipping is not client to server and from server to client) can also use the spin bit
recommended in the general case. This allows the trivial one-sided to measure "upstream" and "downstream" component RTT; i.e, the
estimation of packet loss and reordering between the sender and a component of the end-to-end RTT attributable to the paths between the
given observation point ("upstream loss"). However, since observer and the server and the observer and the client,
retransmissions are not identifiable as such, loss between an respectively. It does this by measuring the delay between a spin
observation point and the receiver ("downstream loss") cannot be edge observed in the upstream direction and that observed in the
reliably estimated. 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 3.7. 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 symmerty 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.
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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 3.4) 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
Extremely limited loss and RTT measurement are possible by passive Limited RTT measurement is possible by passive observation of QUIC
observation of QUIC traffic; see Section 3.5 and Section 3.6. traffic; see Section 3.6. No passive measurement of loss is possible
with the present wire image. Extremely limited observation of
upstream congestion may be possible via the observation of CE
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. the load balancers.
Server-generated Connection IDs must not encode any information other Server-generated Connection IDs must not encode any information other
that that needed to route packets to the appropriate backend that that needed to route packets to the appropriate backend
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Current practices in detection and mitigation of Distributed Denial Current practices in detection and mitigation of Distributed Denial
of Service (DDoS) attacks generally involve passive measurement using of Service (DDoS) attacks generally involve passive measurement using
network flow data [RFC7011], classification of traffic into "good" network flow data [RFC7011], classification of traffic into "good"
(productive) and "bad" (DoS) flows, and filtering of these bad flows (productive) and "bad" (DoS) flows, and filtering of these bad flows
in a "scrubbing" environment. Key to successful DDoS mitigation is in a "scrubbing" environment. Key to successful DDoS mitigation is
efficient classification of this traffic. efficient classification of this traffic.
Limited first-packet garbage detection as in Section 3.1.2 and Limited first-packet garbage detection as in Section 3.1.2 and
stateful tracking of QUIC traffic as in Section 4.1 above can be used stateful tracking of QUIC traffic as in Section 4.1 above can be used
in this classification step. For traffic where the classification in this classification step.
step did not observe a QUIC handshake, the presence of packets
carrying the same Connection ID in both directions is a further
indication of legitimate traffic. Note that these classification
techniques help only against floods of garbage traffic, not against
DDoS attacks using legitimate QUIC clients.
Note that the use of a connection ID to support connection migration Note that the use of a connection ID to support connection migration
renders 5-tuple based filtering insufficient, and requires more state renders 5-tuple based filtering insufficient, and requires more state
to be maintained by DDoS defense systems. However, it is to be maintained by DDoS defense systems, and linkability resistance
questionable if connection migrations needs to be supported in a DDOS in connection ID update mechanisms means that a connection ID aware
attack. If the connection migration is not visible to the network DDoS defense system must have the same information about flows as the
that performs the DDoS detection, an active, migrated QUIC connection load balancer.
may be blocked by such a system under attack. However, a defense
system might simply rely on the fast resumption mechanism provided by However, it is questionable if connection migrations needs to be
QUIC. See also https://github.com/quicwg/base-drafts/issues/203 supported in a DDOS attack. If the connection migration is not
visible to the network that performs the DDoS detection, an active,
migrated QUIC connection may be blocked by such a system under
attack. However, a defense system might simply rely on the fast
resumption mechanism provided by QUIC.
4.5. QoS support and ECMP 4.5. 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
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desired, multiple QUIC connections to the same server might be used, desired, multiple QUIC connections to the same server might be used,
given that establishing a new connection using 0-RTT support is cheap given that establishing a new connection using 0-RTT support is cheap
and fast. and fast.
QoS mechanisms in the network MAY also use the connection ID for QoS mechanisms in the network MAY also use the connection ID for
service differentiation, as a change of connection ID is bound to a service differentiation, as a change of connection ID is bound to a
change of address which anyway is likely to lead to a re-route on a change of address which anyway is likely to lead to a re-route on a
different path with different network characteristics. different path with different network characteristics.
Given that QUIC is more tolerant of packet re-ordering than TCP (see Given that QUIC is more tolerant of packet re-ordering than TCP (see
Section 2.4), Equal-cost multi-path routing (ECMP) does not Section 2.5), Equal-cost multi-path routing (ECMP) does not
necessarily need to be flow based. However, 5-tuple (plus eventually necessarily need to be flow based. However, 5-tuple (plus eventually
connection ID if present) matching is still beneficial for QoS given connection ID if present) matching is still beneficial for QoS given
all packets are handled by the same congestion controller. all packets are handled by the same congestion controller.
5. IANA Considerations 5. IANA Considerations
This document has no actions for IANA. This document has no actions for IANA.
6. Security Considerations 6. Security Considerations
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At the other extreme, supporting current traffic classification At the other extreme, supporting current traffic classification
methods that operate through the deep packet inspection (DPI) of methods that operate through the deep packet inspection (DPI) of
application-layer headers are directly antithetical to QUIC's goal to application-layer headers are directly antithetical to QUIC's goal to
provide confidentiality to its application-layer protocol(s); in provide confidentiality to its application-layer protocol(s); in
these cases, alternatives must be found. these cases, alternatives must be found.
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. balancing. Marcus Ilhar contributed text to Section 3.6 on the use
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.
9. References 9. References
skipping to change at page 12, line 41 skipping to change at page 13, line 35
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] Iyengar, J. and M. Thomson, "QUIC: A UDP-Based Multiplexed
and Secure Transport", draft-ietf-quic-transport-07 (work
in progress), October 2017.
[QUIC-HTTP] [QUIC-HTTP]
Bishop, M., "Hypertext Transfer Protocol (HTTP) over Bishop, M., "Hypertext Transfer Protocol (HTTP) over
QUIC", draft-ietf-quic-http-07 (work in progress), October QUIC", draft-ietf-quic-http-13 (work in progress), June
2017. 2018.
[QUIC-INVARIANTS]
Thomson, M., "Version-Independent Properties of QUIC",
draft-ietf-quic-invariants-01 (work in progress), March
2018.
[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 Transport Layer Security
(TLS) to Secure QUIC", draft-ietf-quic-tls-07 (work in (TLS) to Secure QUIC", draft-ietf-quic-tls-13 (work in
progress), October 2017. progress), June 2018.
[QUIC-TRANSPORT]
Iyengar, J. and M. Thomson, "QUIC: A UDP-Based Multiplexed
and Secure Transport", draft-ietf-quic-transport-13 (work
in progress), June 2018.
[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)
Extensions: Extension Definitions", RFC 6066, DOI
10.17487/RFC6066, January 2011, <https://www.rfc-
editor.org/info/rfc6066>.
[RFC7011] Claise, B., Ed., Trammell, B., Ed., and P. Aitken, [RFC7011] Claise, B., Ed., Trammell, B., Ed., and P. Aitken,
"Specification of the IP Flow Information Export (IPFIX) "Specification of the IP Flow Information Export (IPFIX)
Protocol for the Exchange of Flow Information", STD 77, Protocol for the Exchange of Flow Information", STD 77,
RFC 7011, DOI 10.17487/RFC7011, September 2013, RFC 7011, DOI 10.17487/RFC7011, September 2013,
<https://www.rfc-editor.org/info/rfc7011>. <https://www.rfc-editor.org/info/rfc7011>.
[RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan,
"Transport Layer Security (TLS) Application-Layer Protocol
Negotiation Extension", RFC 7301, DOI 10.17487/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]
Huitema, C. and E. Rescorla, "Issues and Requirements for
SNI Encryption in TLS", draft-ietf-tls-sni-encryption-03
(work in progress), May 2018.
[WIRE-IMAGE]
Trammell, B. and M. Kuehlewind, "The Wire Image of a
Network Protocol", draft-trammell-wire-image-04 (work in
progress), April 2018.
Authors' Addresses Authors' Addresses
Mirja Kuehlewind Mirja Kuehlewind
ETH Zurich ETH Zurich
Gloriastrasse 35 Gloriastrasse 35
8092 Zurich 8092 Zurich
Switzerland Switzerland
Email: mirja.kuehlewind@tik.ee.ethz.ch Email: mirja.kuehlewind@tik.ee.ethz.ch
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