6 PDUs and parameters specific to the present document

24.1933GPPAccess Traffic Steering, Switching and SplittingStage 3TS

6.1 ATSSS parameters

6.1.1 General

The ATSSS parameters are the contents of the ATSSS container as defined in clause 9.11.4.22 of 3GPP TS 24.501 [6].

The purpose of the ATSSS parameters is to indicate the parameters associated with ATSSS (e.g. ATSSS rules).

6.1.2 Encoding of ATSSS parameters

The ATSSS container contents include one or more ATSSS parameters and they are coded as shown in figure 6.1.2-1, figure 6.1.2-2 and table 6.1.2-1.

8

7

6

5

4

3

2

1

ATSSS parameter 1

octet 1

octet a

ATSSS parameter 2

octet a+1*

octet b*

octet b+1*

octet c*

ATSSS parameter N

octet c+1*

octet d*

Figure 6.1.2-1: ATSSS container contents

8

7

6

5

4

3

2

1

ATSSS parameter identifier

octet f

ATSSS parameter contents length

octet f+1

octet f+2

ATSSS parameter contents

octet f+3

octet g

Figure 6.1.2-2: ATSSS parameter

Table 6.1.2-1: ATSSS parameter

The ATSSS parameter identifier is encoded as follows:

Bits

8

7

6

5

4

3

2

1

0

0

0

0

0

0

0

1

ATSSS rules

0

0

0

0

0

0

1

0

Network steering functionalities information

0

0

0

0

0

0

1

1

Measurement assistance information

All other values are spare.

The ATSSS parameter contents for the ATSSS rules are specified according to clause 6.1.3.

The ATSSS parameter contents for the network steering functionalities information are specified according to clause 6.1.4.

The ATSSS parameter contents for the measurement assistance information are specified according to clause 6.1.5.

6.1.3 ATSSS rules

6.1.3.1 Definition of ATSSS rules

The ATSSS rules are defined in 3GPP TS 23.501 [2] and is set of one or more ATSSS rules, where a rule is composed of:

a) a precedence value of the ATSSS rule identifying the precedence of the ATSSS rule;

b) a traffic descriptor matching a service data flow (SDF); and

c) an access selection descriptor including:

1) a steering functionality:

A) MPTCP, the UE steers the SDF by using the MPTCP functionality; or

B) ATSSS-LL functionality, the UE steers the SDF by using the ATSSS-LL functionality; and

NOTE: If the included steering functionality is not supported by the UE, the UE ignores the received ATSSS rule.

2) a steering mode:

A) active-standby, the UE steers the SDF by using the active access if the active access is available. If the active access is not available and the standby access is available, the UE steers the SDF by using the standby access;

B) smallest delay, the UE steers the SDF by using the access network with the smallest RTT;

C) load balancing, the UE steers the SDF across both the 3GPP access and the non-3GPP access with a given precentage; or

D) priority based, the UE steers the SDF over the access with high priority unless the access with high priority is congested, when the UE steers the SDF over both the access with high priority and the access with low priority.

6.1.3.2 Encoding of ATSSS rules

The ATSSS rules are encoded as shown in figure 6.1.3.2-1, figure 6.1.3.2-2 and figure 6.1.3.2-3 and table 6.1.3.2-1.

8

7

6

5

4

3

2

1

ATSSS rule 1

octet a+1

octet s

ATSSS rule 2

octet s+1

octet t

octet t+1

octet u

ATSSS rule n

octet u+1

octet b

Figure 6.1.3.2-1: ATSSS parameter contents including one or more ATSSS rules

8

7

6

5

4

3

2

1

Length of ATSSS rule

octet a+1

octet a+2

Precedence value of ATSSS rule

octet a+3

Length of traffic descriptor

octet a+4

octet a+5

Traffic descriptor

octet a+6

octet s-4

Access selection descriptor

octet s-3

octet s*

Figure 6.1.3.2-2: ATSSS rule

8

7

6

5

4

3

2

1

Length of access selection descriptor

octet s-3

Steering functionality

octet s-2

Steering mode

octet s-1

Steering mode information

octet s*

Figure 6.1.3.2-3: Access selection descriptor

Table 6.1.3.2-1: ATSSS parameter contents including an ATSSS rule

Precedence value of an ATSSS rule (octet a+3)

The precedence value of an ATSSS rule field shall be used to specify the precedence of the ATSSS rule among all ATSSS rules. This field shall include the binary encoded value of the precedence value in the range from 0 to 255 (decimal). The higher the value of the precedence value field, the lower the precedence of the ATSSS rule is.

Traffic descriptor (octets a+6 to s-4)

The traffic descriptor field is, as defined in table 5.2.1 in 3GPP TS 24.526 [5], of variable size and contains a variable number (at least one) of traffic descriptor components. Each traffic descriptor component shall be encoded as a sequence of one octet traffic descriptor component type identifier and a traffic descriptor component value field. The traffic descriptor component type identifier shall be transmitted first.

Traffic descriptor component type identifier

Bits

8

7

6

5

4

3

2

1

0

0

0

0

0

0

0

1

Match-all type

0

0

0

0

1

0

0

0

OS Id + OS App Id type (NOTE 1)

0

0

0

1

0

0

0

0

IPv4 remote address type

0

0

1

0

0

0

0

1

IPv6 remote address/prefix length type

0

0

1

1

0

0

0

0

Protocol identifier/next header type

0

1

0

1

0

0

0

0

Single remote port type

0

1

0

1

0

0

0

1

Remote port range type

0

1

1

0

0

0

0

0

Security parameter index type

0

1

1

1

0

0

0

0

Type of service/traffic class type

1

0

0

0

0

0

0

0

Flow label type

1

0

0

0

0

0

0

1

Destination MAC address type

1

0

0

0

0

0

1

1

802.1Q C-TAG VID type

1

0

0

0

0

1

0

0

802.1Q S-TAG VID type

1

0

0

0

0

1

0

1

802.1Q C-TAG PCP/DEI type

1

0

0

0

0

1

1

0

802.1Q S-TAG PCP/DEI type

1

0

0

0

0

1

1

1

Ethertype type

1

0

0

0

1

0

0

0

DNN type

1

0

0

1

0

0

0

1

Destination FQDN

1

0

1

0

0

0

0

0

OS App Id type

All other values are spare. If received they shall be interpreted as unknown.

Length of access selection descriptor (octet s-3)

Bits

8

7

6

5

4

3

2

1

0

0

0

0

0

0

1

1

If the steering mode is smallest delay

0

0

0

0

0

1

0

0

If the steering mode is not smallest delay

All other values are spare.

Steering functionality (octet s-2)

The steering functionality field shall be encoded by one octet (octet s-2) as follows

Bits

8

7

6

5

4

3

2

1

0

0

0

0

0

0

0

1

UE’s supported steering functionality (NOTE 2)

0

0

0

0

0

0

1

0

MPTCP functionality

0

0

0

0

0

0

1

1

ATSSS-LL functionality

All other values are spare.

If the UE does not support the received encoded steering functionality in the ATSSS rule, the UE shall ignore the ATSSS rule.

Steering mode (octet s-1)

The steering mode descriptor field shall be encoded by one octet (octet s-1) as follows:

Bits

8

7

6

5

4

3

2

1

0

0

0

0

0

0

0

1

Active-standby

0

0

0

0

0

0

1

0

Smallest delay

0

0

0

0

0

0

1

1

Load balancing

0

0

0

0

0

1

0

0

Priority based

All other values are spare.

Steering mode information (octet s)

If the steering mode is defined as active-standby, octet s shall be defined as follows:

Bits

8

7

6

5

4

3

2

1

0

0

0

0

0

0

0

1

Active 3GPP and no standby

0

0

0

0

0

0

1

0

Active 3GPP and non-3GPP standby

0

0

0

0

0

0

1

1

Active non-3GPP and no standby

0

0

0

0

0

1

0

0

Active non-3GPP and 3GPP standby

All other values are spare.

If the steering mode is defined as smallest delay, octet s shall not be encoded.

If the steering mode is defined as load balancing, octet s shall be encoded to show the percentage of the SDF traffic transmitted over 3GPP access and non-3GPP access as follows:

Bits

8

7

6

5

4

3

2

1

0

0

0

0

0

0

0

1

100% over 3GPP and 0% over non-3GPP

0

0

0

0

0

0

1

0

90% over 3GPP and 10% over non-3GPP

0

0

0

0

0

0

1

1

80% over 3GPP and 20% over non-3GPP

0

0

0

0

0

1

0

0

70% over 3GPP and 30% over non-3GPP

0

0

0

0

0

1

0

1

60% over 3GPP and 40% over non-3GPP

0

0

0

0

0

1

1

0

50% over 3GPP and 50% over non-3GPP

0

0

0

0

0

1

1

1

40% over 3GPP and 60% over non-3GPP

0

0

0

0

1

0

0

0

30% over 3GPP and 70% over non-3GPP

0

0

0

0

1

0

0

1

20% over 3GPP and 80% over non-3GPP

0

0

0

0

1

0

1

0

10% over 3GPP and 90% over non-3GPP

0

0

0

0

1

0

1

1

0% over 3GPP and 100% over non-3GPP

All other values are spare

If the steering mode is defined as priority-based, octet s shall be encoded as:

Bits

8

7

6

5

4

3

2

1

0

0

0

0

0

0

0

1

3GPP is high priority access

0

0

0

0

0

0

1

0

non-3GPP is high priority access

All other values are spare.

NOTE 1: For "OS Id + OS App Id type", the traffic descriptor component value field does not specify the OS version number or the version number of the application.

NOTE 2: This value shall be set by the SMF if the UE supports only one steering functionality. The SMF knows the UE’s supported steering functionality during the MA PDU session establishment procedure.

6.1.4 Network steering functionalities information

6.1.4.1 Definition of network steering functionalities information

6.1.4.1.1 MPTCP Functionality

In order for the UE to support the MPTCP functionality, the UE shall support the TCP extensions for multipath operation specified in IETF draft-ietf-mptcp-rfc6824bis [8].

When the UE indicates support for MPTCP functionality and the network accepts to enable the MPTCP functionality for a MA PDU Session of IP type, then the network provides the following information to the UE:

a) two "link-specific multipath" IP addresses/prefixes used only by the MPTCP functionality in the UE, one associated with the 3GPP access and another associated with the non-3GPP access; and

b) the IP address, port number and the type of one or more MPTCP proxies in the UPF.

In this release of the specification, the UPF shall support the Transport Converter as specified in IETF draft-ietf-tcpm-converters [9].

In this release of the specification, the UE shall support the client extensions specified in IETF draft-ietf-tcpm-converters [9].

The UE shall use the "link-specific multipath" addresses/prefixes to establish subflows over non-3GPP access and over 3GPP access.

When the MA PDU session is Ethernet type, the network shall not enable the MPTCP functionality.

6.1.4.1.2 ATSSS-LL Functionality

When the UE indicates ATSSS-LL capability and the network accepts to enable the ATSSS-LL functionality for an MA PDU Session of any supported type, then the network enables ATSSS-LL functionality in the UPF.

In an ATSSS capable UE, the following ATSSS-LL requirements apply:

a) for an MA PDU session of Ethernet PDU session type, the ATSSS-LL functionality is mandatory; and

b) for an MA PDU session of IPv4, IPv6, or IPv4v6 PDU session type,

1) if the UE does not support the MPTCP functionality, the ATSSS-LL functionality is mandatory; and

2) if the UE supports the MPTCP functionality, only ATSSS-LL with active-standby steering mode is mandatory. All other steering modes are optional.

6.1.4.2 Encoding of network steering functionalities information

The network steering functionalities information contains:

a) addressing information for the ATSSS capable UE supporting MPTCP fiunctionality; and

b) addressing information and type for the MPTCP proxy;

and is encoded as shown in figure 6.1.4.2-1, figure 6.1.4.2-2 and table 6.1.4.2-1:

8

7

6

5

4

3

2

1

UE 3GPP IP address type

octet a+1

UE 3GPP IP address

octet a+2

octet k-1

UE non-3GPP IP address type

octet k

UE non-3GPP IP address

octet k+1

octet l-1

Length of MPTCP proxy information

octet l

MPTCP proxy information value 1

octet l+1

octet m+2

MPTCP proxy information value 2

octet n

octet o

MPTCP proxy information value n

octet p

octet s

Figure 6.1.4.2-1: Network steering functionalities information including UE IP addresses and MPTCP proxy information

MPTCP proxy IP address type

octet l+1

MPTCP proxy IP address

octet l+2

octet m-1

MPTCP proxy port

octet m

octet m+1

MPTCP proxy type

octet m+2

Figure 6.1.4.2-2: MPTCP proxy information

Table 6.1.4.2-1: UE IP addresses and MPTCP proxy information

UE 3GPP IP address type (octet a+1) is set as follows:

Bits

8

7

6

5

4

3

2

1

0

0

0

0

0

0

0

1

IPv4

0

0

0

0

0

0

1

0

IPv6

0

0

0

0

0

0

1

1

IPv4v6

If the UE 3GPP IP address type indicates IPv4, then the UE 3GPP IP address field contains an IPv4 address in 4 octets.

If the UE 3GPP IP address type indicates IPv6, then the UE 3GPP IP address field contains an IPv6 address in 16 octets field and 1 octet prefix length field. The IPv6 address field shall be transmitted first.

If the UE 3GPP IP address type indicates IPv4v6, then the UE 3GPP IP address field contains two IP addresses. The first UE 3GPP IP address is an IPv4 address in 4 octets and the second UE 3GPP IP address is an IPv6 address field in 16 octets followed by 1 octet prefix length field.

UE non-3GPP IP address type (octet k) is set as follows:

Bits

8

7

6

5

4

3

2

1

0

0

0

0

0

0

0

1

IPv4

0

0

0

0

0

0

1

0

IPv6

0

0

0

0

0

0

1

1

IPv4v6

If the UE non-3GPP IP address type indicates IPv4, then the UE non-3GPP IP address field contains an IPv4 address in 4 octets.

If the UE non-3GPP IP address type indicates IPv6, then the UE non-3GPP IP address field contains an IPv6 address in 16 octets field and 1 octet prefix length field. The IPv6 address field shall be transmitted first.

If the UE non-3GPP IP address type indicates IPv4v6, then the UE non-3GPP IP address field contains two IP addresses. The first UE non-3GPP IP address is an IPv4 address in 4 octets and the second UE non-3GPP IP address is an IPv6 address field in 16 octets followed by 1 octet prefix length field.

MPTCP proxy IP address type (octet l+1) is set as follows:

Bits

8

7

6

5

4

3

2

1

0

0

0

0

0

0

0

1

IPv4

0

0

0

0

0

0

1

0

IPv6

0

0

0

0

0

0

1

1

IPv4v6

If the MPTCP proxy IP address type indicates IPv4, then the MPTCP proxy IP address field contains an IPv4 address in 4 octets.

If the MPTCP proxy IP address type indicates IPv6, then the MPTCP proxy IP address field contains an IPv6 address in 16 octets.

If the MPTCP proxy IP address type indicates IPv4v6, then the MPTCP proxy IP address field contains two IP addresses. The first MPTCP proxy IP address is an IPv4 address in 4 octets and the second MPTCP proxy IP address is an IPv6 address in 16 octets.

MPTCP proxy type (octet m+2) is set as follows:

Bits

8

7

6

5

4

3

2

1

0

0

0

0

0

0

0

1

Transport converter

All other values are spare.

6.1.5 Measurement assistance information

6.1.5.1 Definition of measurement assistance information

The measurement assistance information is transmitted by the network to the UE.

NOTE: If the UE is only capable of supporting MPTCP functionality, the UE uses the RTT measurements available at the MPTCP layer.

The measurement assistance information is defined in 3GPP TS 23.501 [2] and it contains:

a) addressing for the PMF in the UPF according to:

1) if the PDU session is IP type, the measurement assistance information contains IP address for the PMF with an allocated port number associated with the 3GPP access network and another allocated port number associated with non-3GPP access network; and

2) if the PDU session is Ethernet type, the measurement assistance information contains a MAC address associated with the 3GPP access network and another MAC address associated with the non-3GPP address network for the PMF; and

b) an indicator to report the availability and unavailability of an access network.

6.1.5.2 Encoding of measurement assistance information

The measurement assistance information contains addressing information for the PMF in the UPF and is encoded as shown in figure 6.1.5.2-1 and figure 6.1.5.2-2 and table 6.1.5.2-1 and table 6.1.5.2-2.

8

7

6

5

4

3

2

1

PMF IP address type

octet a+1

PMF IP address

octet a+2

octet b-5

PMF 3GPP port

octet b-4

octet b-3

PMF non-3GPP port

octet b-2

octet b-1

0

Spare

0

Spare

0

Spare

0

Spare

0

Spare

0

Spare

0

Spare

AARI

octet b

Figure 6.1.5.2-1: ATSSS parameter contents including one PMF IP address information

Table 6.1.5.2-1: PMF IP address type

PMF IP address type (octet a+1) is set as follows:

Bits

8

7

6

5

4

3

2

1

0

0

0

0

0

0

0

1

IPv4

0

0

0

0

0

0

1

0

IPv6

0

0

0

0

0

0

1

1

IPv4IPv6

All other values are spare.

If the PMF IP address type indicates IPv4, then the PMF IP address field contains an IPv4 address in 4 octets.

If the PMF IP address type indicates IPv6, then the PMF IP address field contains an IPv6 address in 16 octets.

If the PMF IP address type indicates IPv4IPv6, then the PMF IP address field contains two IP addresses. The first PMF IP address is an IPv4 address in 4 octets and the second PMF IP address is an IPv6 address in 16 octets.

PMF 3GPP port (octets b-4 – b-3) is allocated port number associated with the 3GPP access network.

PMF non-3GPP port (octets b-2 – b-1) is allocated port number associated with the non-3GPP access network.

AARI (access availability reporting indicator) (octet b, bit 1) is set as follows:

Bit

1

0

Do not report the access availability

1

Report the access availability

8

7

6

5

4

3

2

1

PMF 3GPP MAC address

octet a+1

octet a+6

PMF non-3GPP MAC address

octet a+7

octet a+12

0

Spare

0

Spare

0

Spare

0

Spare

0

Spare

0

Spare

0

Spare

AARI

octet a+13

Figure 6.1.5.2-2: ATSSS parameter contents including one PMF MAC address information

Table 6.1.5.2-2: PMF MAC address type

PMF 3GPP MAC address contains a 6 octets MAC address associated with the 3GPP access network.

PMF non-3GPP MAC address contains a 6 octets MAC address associated with the non-3GPP access network.

AARI (access availability reporting indicator) (octet a+13, bit 1) is set as follows:

Bit

1

0

Do not report the access availability

1

Report the access availability

6.2 Encoding of PMF protocol

6.2.1 Message functional definitions and format

Editor’s note: This clause will define the PMF protocol messages exchanged between the UE and the PMF.

6.2.2 Encoding of information element

Editor’s note: This clause will define the encoding of the information element in the PMF protocol messages.

Annex A (informative):
Change history

Change history

Date

Meeting

TDoc

CR

Rev

Cat

Subject/Comment

New version

2019-02

CT1#115

TS skeleton and scope are provided by C1-191625 and C1-191704 respectively.

0.0.0

2019-04

CT1#116

Includes the following contributions agreed by CT1 at CT1#116: C1-192468, C1-192471, C1-192472.

0.1.0

2019-05

CT1#117

Includes the following contributions agreed by CT1 at CT1#117: C1-193488, C1-193489, C1-193769, C1-193770.

0.2.0

2019-09

CT1#119

Includes the following contributions agreed by CT1 at CT1#119: C1-194735, C1-194736, C1-194738, C1-194740, C1-194934, C1-194938, C1-194941, C1-194975, C1-195119, C1-195123, C1-195161, C1-195162.

0.3.0

2019-10

CT1#120

Includes the following contributions agreed by CT1 at CT1#120: C1-196191, C1-196712, C1-196746, C1-196748, C1-196749, C1-196750, C1-196751, C1-196752, C1-196753, C1-196947.

0.4.0

2019-11

CT1#121

Includes the following contributions agreed by CT1 at CT1#121: C1-198239, C1-198709, C1-198712, C1-198713, C1-198714, C1-199036.

0.5.0

2019-12

CT#86

CP-193150

Presentation for information at TSG CT

1.0.0

2019-12

CT#86

CP-192387

A title updated

1.0.1