【5G核心网】 NAS之5GS session management

深碍√TFBOYSˉ_ 2022-12-05 05:18 582阅读 0赞

5GS session management (5GSM) information elements，本文分析 NAS SM 消息的信息元素， 以及 5GS session management message 消息

# 1. 5GS session management (5GSM) information elements #

###    1.1 5GSM capability ###

5GSM capability 信息元素的目的是指示与 PDU 会话管理有关的 UE 能力。 5GSM capability 是类型4信息元素，其最小长度为 3 个字节，最大长度为15个字节。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70][] Figure 9.11.4.1.1: 5GSM capability information element

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 1][] Table 9.11.4.1.1: 5GSM capability information element

###    1.2 5GSM cause ###

5GSM cause 信息元素的目的是指示拒绝 5GSM 请求的原因。 5GSM cause 是类型2信息元素，长度为2个字节

![20200909142319730.png][] Figure 9.11.4.2.1: 5GSM cause information element

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 2][] Table 9.11.4.2.1: 5GSM cause information element

###    1.3 Always-on PDU session indication ###

Always-on PDU 会话指示信息元素的目的是指示是否将 PDU 会话建立为 Always-on PDU 会话。

###    1.4 Always-on PDU session requested ###

Always-on PDU 会话请求信息元素的目的是指示是否请求将 PDU 会话建立为始终在线的 PDU 会话。

###    1.5 Allowed SSC mode ###

允许的 SSC 模式信息元素的目的是指示允许 UE 用于 PDU 会话的 SSC 模式。

![20200909143045685.png][] Figure 9.11.4.5.1: Allowed SSC mode information element

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 3][] Table 9.11.4.5.1: Allowed SSC mode information element

###    1.6 Extended protocol configuration options ###

参见3GPP TS 24.008中的10.5.6.3A节\[12\]

###    1.7 Integrity protection maximum data rate ###

integrity protection maximum data rate 信息元素完的目的是让 UE 向网络指示用于上行链路的用户面完整性保护的每个 UE 的最大数据速率，和用于下行链路的用户面完整性保护的每个 UE 的最大数据速率

![2020090914355617.png][] Figure 9.11.4.7.1: Integrity protection maximum data rate information element

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 4][] Table 9.11.4.7.2: Integrity protection maximum data rate information element

###    1.8 Mapped EPS bearer contexts ###

映射的 EPS 承载上下文信息元素的目的是指示 PDU 会话的 EPS 上下文，如6.1.4.1节所述。 映射的 EPS 承载上下文信息元素是类型6信息元素，其最小长度为7个字节，最大长度为65538个字节。

###    1.9 Maximum number of supported packet filters ###

“最大支持的包过滤器数量”信息元素的目的是让 UE 向网络指示与信令 QoS 规则关联的包过滤器的最大数量，UE 可以为正在建立的 PDU 会话支持该数量。 PDU 会话类型为“ IPv4”，“ IPv6”，“ IPv4v6”或“以太网”。

支持的最大数据包过滤器数量是类型3信息元素，长度为3个字节。

![20200909144434632.png][] Figure 9.11.4.9.1: Maximum number of supported packet filters information element

###    1.10 PDU address ###

>     PDU 地址信息元素的目的是分配给 UE：
> 
>  -  与 PDU 会话关联的 IPv4 地址
> 
>  -  与 PDU 会话关联的 IPv6 链路本地地址的接口标识符
> 
>  -  与 PDU 会话相关联的 IPv4 地址和 IPv6 链接本地地址的接口标识符

PDU 地址是类型4信息元素，其最小长度为7个字节，最大长度为15个字节。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 5][] Figure 9.11.4.10.1: PDU address information element

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 6][] Table 9.11.4.10.1: PDU address information element

###    1.11 PDU session type ###

PDU 会话类型信息元素的目的是指示 PDU 会话的类型。 PDU 会话类型是类型1信息元素。

![20200909145128877.png][] Figure 9.11.4.11.1: PDU session type information element

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 7][] Table 9.11.4.11.1: PDU session type information element

###    1.12 QoS flow descriptions ###

QoS 流描述信息元素的目的是指示 UE 要使用的一组 QoS 流描述。 QoS 流描述信息元素是类型6信息元素，其最小长度为6个字节。最大场对为65538个字节

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 8][]**Figure 9.11.4.12.1: QoS flow descriptions information element**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 9][] Figure 9.11.4.12.2: QoS flow description

--  QoS flow identifier (QFI) (bits 6 to 1 of octet 4)

> QFI field contains the QoS flow identifier.
> 
> Bits
> 
> **6 5 4 3 2 1**
> 
> **0 0 0 0 0 0 no QoS flow identifier assigned**
> 
> **0 0 0 0 0 1 QFI 1**
> 
> to
> 
> 1 1 1 1 1 1 QFI 63
> 
> The network shall not set the QFI value to 0.

--  Operation code (bits 8 to 6 of octet 5)

> Bits
> 
> 8 7 6
> 
> ***0 0 1 Create new QoS flow description***
> 
> ***0 1 0 Delete existing QoS flow description***
> 
> ***0 1 1 Modify existing QoS flow description***
> 
> All other values are reserved.

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 10][] Figure 9.11.4.12.3: Parameters list

![20200827191822599.png][] Figure 9.11.4.12.4: Parameter

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 11][]

###    1.13 QoS rules ###

QoS 规则信息元素的目的是指示 UE 要使用的一组 QoS 规则

>     -  上行链路用户流量的分类和标记
> 
>     -  识别网络要用于特定下行链路用户业务的 QoS 流

QoS 规则可以包含一组包过滤器，其由零个或多个 UL 方向的分组过滤器，零个或多个 DL 方向的分组过滤器，以及两者组合模式。分组过滤器集确定到 QoS 流的流量映射。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 12][] Figure 9.11.4.13.1: QoS rules information element

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 13][] Figure 9.11.4.13.2: QoS rule (u=m+2)

-- QoS rule identifier (octet 4)

> Bits
> 
> **8 7 6 5 4 3 2 1**
> 
> **0 0 0 0 0 0 0 0 no QoS rule identifier assigned**
> 
> **0 0 0 0 0 0 0 1 QRI 1**
> 
> to
> 
> 1 1 1 1 1 1 1 1 QRI 255
> 
> The network shall not set the QRI value to 0.

>    --  Rule operation code (bits 8 to 6 of octet 7)  
> Bits  
> 8 7 6
> 
> **0 0 0 Reserved  
> 0 0 1 Create new QoS rule**
> 
> **0 1 0 Delete existing QoS rule**
> 
> 0 1 1 Modify existing QoS rule and add packet filters
> 
> 1 0 0 Modify existing QoS rule and replace all packet filters
> 
> 1 0 1 Modify existing QoS rule and delete packet filters
> 
> 1 1 0 Modify existing QoS rule without modifying packet filters
> 
> 1 1 1 Reserved

--  QoS rule precedence (octet m+1)

--  QoS flow identifier (QFI) (bits 6 to 1 of octet m+2)

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 14][] Figure 9.11.4.13.3: Packet filter list when the rule operation is "modify existing QoS rule and delete packet filters" (z=N+7)

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 15][] Figure 9.11.4.13.4: Packet filter list when the rule operation is "create new QoS rule", or "modify existing QoS rule and add packet filters" or "modify existing QoS rule and replace all packet filters"

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 16][]

###    1.14 Session-AMBR ###

Session-AMBR 信息元素的目的是指示， UE 建立 PDU 会话时的初始订阅 PDU 会话总最大比特率，或者指示新的订阅 PDU 会话总最大比特率（如果网络对其进行了更改）。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 17][] Figure 9.11.4.14.1: Session-AMBR information element

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 18][] Table 9.11.4.14.1: Session-AMBR information element

# 2. 5GS session management messages #

###    2.1 PDU session establishment request ###

>     Message type: PDU SESSION ESTABLISHMENT REQUEST
> 
>     Significance: dual
> 
>     Direction: UE to network

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 19][]  Table 8.3.1.1.1: PDU SESSION ESTABLISHMENT REQUEST message content

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 20][]

###    2.2 PDU session modification procedure ###

**     2.2.1 UE-requested PDU session modification procedure**

> Message type: PDU SESSION MODIFICATION REQUEST
> 
> Significance: dual
> 
> Direction: UE to network

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 21][] Table 8.3.7.1.1: PDU SESSION MODIFICATION REQUEST message content

**    2.2.1 PDU session modification complete**

> Message type: PDU SESSION MODIFICATION COMPLETE
> 
> Significance: dual
> 
> Direction: UE to network

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 22][] Table 8.3.10.1.1: PDU SESSION MODIFICATION COMPLETE message content

###    2.3 PDU session release procedure ###

**    2.3.1 PDU session release request**

> Message type: PDU SESSION RELEASE REQUEST
> 
> Significance: dual
> 
> Direction: UE to network

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 23][] Table 8.3.12.1.1: PDU SESSION RELEASE REQUEST message content

**    2.3.2 PDU session release command**

> Message type: PDU SESSION RELEASE COMMAND
> 
> Significance: dual
> 
> Direction: network to UE

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 24][] Table 8.3.14.1.1: PDU SESSION RELEASE COMMAND message content

**   2.3.3 PDU session release complete**

> Message type: PDU SESSION RELEASE COMPLETE
> 
> Significance: dual
> 
> Direction: UE to network

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob25nbGluemhhbmc_size_16_color_FFFFFF_t_70 25][] Table 8.3.15.1.1: PDU SESSION RELEASE COMPLETE message content

TS 23.501

TS 24.008

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[20200827191822599.png]: /images/20221123/0a2259a5b46747e2a7d5bcc6a3cd9512.png
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