Additional addresses for QUIC

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Table of Contents

1. Introduction

The QUIC protocol specifies several techniques for network path migration. The client can migrate from one of its local addresses to another at any time after the handshake using connection migration. The server can transfer a connection to one of its other addresses shortly after the handshake by using the preferred_address transport parameter. However, it cannot advertise additional addresses that a client may use.¶

This limitation impacts several scenarios. For instance, a multihomed server that has access to several subnets cannot advertise all its addresses. In entreprise deployments where provider-assigned IPv6 Addresses are used to solve the multihoming problem [RFC8678], announcing several server addresses enables applications using QUIC to recover from provider failures. Also, a dual-stack server cannot advertise its other address so that a client losing the address family used to establish the connection can migrate to the other address family.¶

This document proposes a QUIC Transport Parameter enabling a QUIC server to advertise additional addresses that can be used for a QUIC connection.¶

2. Conventions and Definitions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.¶

3. Overview

The additional_addresses transport parameter proposed in this document enables a QUIC server to securely advertise additional addresses. These addresses can be used by the client to migrate to a new server address at any time after the handshake. When [MULTIPATH-QUIC] is used over a QUIC connection, the client can use these addresses to establish additional network paths.¶

When sending packets to a new server address, the client validates the address using Path Validation as described in Section 8.2 of [QUIC-TRANSPORT]. When Preferred Adress and Additional Addresses are used together, the client SHOULD NOT migrate to an additional address before acting on the preferred address indicated by the server.¶

Client            Load-balancer         Server @ IP a   Server @ IP b
|                      |                      |               |
|       Initial[0]: CRYPTO(CH)                |               |
|---------------------/F/-------------------->|               |
                             ....
| Handshake[0]: CRYPTO(EE(Pr.Addr=a,A.Addr=b)]|               |
|<--------------------/F/---------------------|               |
                             ....
|       Handshake[0]: CRYPTO(Fin)             |               |
|---------------------/F/-------------------->|               |
|    /* Migration to Preferred Address a */   |               |
|-------------------------------------------->|               |
                             ....
|                      |                      |
|                      |                      .               |
| 1-RTT[1]: PATH_CHALLENGE  /* Migration to Add. Address b */ |
|------------------------------------------------------------>|
|                                   1-RTT[1]: PATH_RESPONSE   |
|<------------------------------------------------------------|
|                                                             |
                                                Legend
                                                  /F/ Forwarded by LB

4. Additional Addresses Transport Parameter

The following transport parameter is defined:¶

additional_addresses (TBD - experiments use 0xadda):

A list of server addresses that the client can migrate the connection to. This transport parameter MUST NOT be sent by a client.¶

Additional Addresses {
  Additional Address (..) ...,
}

Additional Address {
  Address Version (8),
  IP Address (..),
  IP Port (16),
}

Address Version:

A 8-bit value identifying the Internet address version of this address. The value 4 indicates IPv4 while 6 indicates IPv6.¶

IP Address:

The address value. Its size depends on its version. IPv4 addresses are 32-bit long while IPv6 addresses are 128-bit long.¶

IP Port:

A 16-bit value representing the port to use with this IP Address.¶

5. Security Considerations

This document specifies a mechanism allowing servers to influence the IP addresses towards which clients send QUIC packets. In this case, a malicious server could cause a client to send packets to a victim. A countermeasure similar to Section 21.5.3 of [QUIC-TRANSPORT] is to limit the packets that are sent to a non-validated additional addresses.¶

A client MUST NOT send non-probing frames to an additional address prior to validating that address. The generic measures described in Section 21.5.6 of [QUIC-TRANSPORT] also remain applicable for further mitigation.¶

6. IANA Considerations

This document defines a new transport parameter for advertising additional addresses. The draft defines a provisional identifier for experiments. IANA will allocate the final identifier.¶

The following entry in Table 1 should be added to the "QUIC Transport Parameters" registry under the "QUIC Protocol" heading.¶

Acknowledgments

We thank Quentin De Coninck and Francois Michel for their feedback and comments on the first version of this document.¶

Authors' Addresses