Re: [quicwg/multipath] separate Path IDs from Connection IDs (Issue #214)

[Bill Gage <[e-mail]>]

This document is in response to discussions of issue 214 in the QUIC 
multipath GitHub: https://github.com/quicwg/multipath/issues/214

The current MPQUIC draft (-06) binds a connection identifier to a path 
by using the sequence number of a connection identifier as an implicit 
path identifier. To simplify implementation, the current MPQUIC draft 
introduces the concept of multiple application data packet number spaces 
with a different number space for each connection (path). This is in 
contrast to RFC9000 where there is a single application data packet 
number space.

Issue 214 proposed separating path IDs from connection IDs. This 
document uses that separation of identifiers to propose a different path 
model for Multipath QUIC using explicit path identifiers, enabling a 
multipath management framework that retains the principles and 
operations of RFC9000.

The multipath operations described in this document do not change the 
basic operations described in RFC9000. In particular, none of the 
following procedures described in RFC9000 are affected by the use of 
multiple paths:

+ connection management (e.g. the use of NEW_CONNECTION_ID frames and 
subsequent rotation of connection identifiers);

+ key management (e.g. use of key phase bit) and derivation of AEAD 
parameters;

+ packet loss detection and loss recovery (e.g. using type 0x02 ACK 
frames without ECN counts).

However, changes to RFC9002 procedures are required to deal with 
path-dependent characteristics such as path MTU size, RTT and congestion.

Cheers ...

/bill


On 2023-11-11 5:49 p.m., [e-mail] wrote:
 > A new version of Internet-Draft draft-gage-quicmp-pathmodel-00.txt 
has been
 > successfully submitted by Bill Gage and posted to the
 > IETF repository.
 >
 > Name:     draft-gage-quicmp-pathmodel
 > Revision: 00
 > Title:    An Alternate Path Model for Multipath QUIC
 > Date:     2023-11-11
 > Group:    Individual Submission
 > Pages:    14
 > URL: 
https://www.ietf.org/archive/id/draft-gage-quicmp-pathmodel-00.txt
 > Status:   https://datatracker.ietf.org/doc/draft-gage-quicmp-pathmodel/
 > HTML: 
https://www.ietf.org/archive/id/draft-gage-quicmp-pathmodel-00.html
 > HTMLized: 
https://datatracker.ietf.org/doc/html/draft-gage-quicmp-pathmodel
 >
 >
 > Abstract:
 >
 >     The path model used in the current MPQUIC draft binds a connection
 >     identifier to a path.  In fact, the sequence number of a connection
 >     identifier is used as an implicit path identifier.  This has a number
 >     of consequences that may cause MPQUIC to diverge from the principles
 >     of RFC9000.  One of these consequences, for example, is to associate
 >     each connection with a different application data packet number space
 >     rather than maintaining a single application data packet number space
 >     across all connections as defined in RFC9000.
 >
 >     This document proposes a different path model for Multipath QUIC
 >     using explicit path identifiers, enabling a multipath management
 >     framework that retains the principles and operations of RFC9000.
 >
 >
 >
 > The IETF Secretariat
 >
 >