第九章快速、稳定、安全和共享上网——业务通道

2023-09-18 10:12 作者:5G漫话 0人读过 | 我要投稿

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第八章 5G上网的先决条件——信令通道

第九章快速、稳定、安全和共享上网——业务通道

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第九章快速、稳定、安全和共享上网——业务通道

本章相应视频第一部分

接上一章节的话题，第八章 5G上网的先决条件——信令通道

当某个终端用户的第一个PDU Session已经建立完成之后，就意味着该用户就具有了上传或下载网络数据的资格和机会。下面的事情就自然而然地时去发起数据的传送了。

但是，必须明确一点的是，PDU Session建立完成，手机获得了一个IP地址，但并不表示从UE到UPF的所有接口或信道都是已经开通，而事实上应该是通过PDU session的建立，AMF/SMF已经为这个用户设置好了数据传输的相关接口以及每一个相关协议栈的属性参数。而具体的这些属性参数的真正实施，要在该用户有了数据要发送或接收时候进行。

这就相当于作为一个经常收寄快件的老客户，比如在淘宝上长期卖充电宝的商家，于某快递公司签定好了一个长期寄送快件的协议，对于自己发送充电宝的通用的要求做好了协商，比如包装大小、保价额度、每天及时取货、包装上写的内容的固定格式等等。

等这些全部准备好之后，真正这个商家有客人买了充电宝之后，就按照与快递公司的约定在某个时间、某个地点去取件并办理自动登记手续。

9.1 快递公司收到了一个包裹，先做优先级评估 - QoS Flow

欢迎Mr. ChatGPT发言：

Quality of Service (QoS) flow attributes are conveyed in packets forwarded to the gNB (5G base station). In 5G networks, packets are typically carried over an IP-based transport, and QoS information is usually conveyed using the Differentiated Services Code Point (DSCP) field in the IP header. Here's a breakdown of the relevant packet structure and attributes:

1. Ethernet Frame Header:

• Destination MAC Address: Specifies the MAC address of the destination device (e.g., gNB).

• Source MAC Address: Specifies the MAC address of the sender.

• EtherType: Identifies the type of payload. In IP networks, it typically indicates the presence of an IP packet.

2. IP Header:

• Version: Indicates the IP version being used (IPv4 or IPv6).

• DSCP (Differentiated Services Code Point): This is a 6-bit field in the IP header that is used to mark packets with QoS information. It is sometimes referred to as the Differentiated Services (DS) field. The DSCP value is set to indicate the desired QoS treatment for the packet.

• Total Length: Specifies the total length of the IP packet, including the header and payload.

• Identification, Flags, Fragment Offset: Used for fragmentation and reassembly of IP packets (not directly related to QoS).

• Time To Live (TTL): Indicates how many hops the packet can traverse before being discarded.

• Protocol: Specifies the transport layer protocol (e.g., TCP, UDP) used in the packet.

• Source IP Address: The IP address of the sender.

• Destination IP Address: The IP address of the destination (gNB).

3. Transport Layer Header (e.g., TCP/UDP):

• Source Port: Specifies the source port number.

• Destination Port: Specifies the destination port number.

• Sequence Number, Acknowledgment Number, Flags, Window Size: These fields are specific to the transport layer protocol (TCP, UDP) and are used for flow control and error detection but do not directly carry QoS information.

4. Payload:

• The payload contains the actual data being transmitted, which could be application data, voice packets, video packets, etc. QoS-related information is typically not found in the payload itself but rather in the IP header's DSCP field.

5. DSCP Field:

• The DSCP field in the IP header is crucial for conveying QoS information. It consists of 6 bits that are used to mark packets with a specific QoS value. These markings are used by network devices (routers, switches) to determine how to prioritize and treat the packets.

参考网络用户数据的转发过程（4G网络）：

https://www.bilibili.com/video/BV1fZ4y1M7jR/?vd_source=2b72fcc3835291472da2743d71001857

9.1.1 评估本次包裹内容是在快件协议定义的范围内 - PDU Session约定

9.1.2 快件寄送约定范围中可以有多种寄送模板 - TFT

本章相应视频第二部分

TFT、QFI、SDF的关系

• TFT to QFI: TFT is responsible for packet classification and filtering based on various attributes. When a packet matches the criteria defined in a TFT, it is associated with a specific QFI. TFT acts as a bridge between the characteristics of incoming traffic and the identification of the corresponding QoS flow (QFI).

• QFI to SDF: QFIs are components used within SDFs to define and enforce QoS at a granular level. An SDF may include multiple QFIs, each with its own unique QoS rules, as part of the end-to-end QoS management for a specific service or application.

TFT and QFI for SDF: When defining an SDF for a particular service, the operator specifies the QFIs associated with that service and the TFTs that will be used to classify incoming traffic into those QFIs. The combination of TFTs and QFIs within an SDF allows for comprehensive QoS management for that service, ensuring that the right packets are mapped to the appropriate QoS flows.

9.1.3 快件的寄送模板仅仅适用于物流总站向分站传递包裹

9.2 本地递送需要把通用的快件优先级转化成具体的运送方式 - QFI和DRB的转换

本章相应视频第三部分