Application of SRv6 Technology in Home Network

1. SRv6 Concept

Segment Routing (SR) is a source routing technology that assigns a Segment ID to each node or link. The head node combines these Segment IDs to form a Segment List and directs packets to be forwarded according to the Segment List, thereby realizing the programmability of the network.

Currently, Segment Routing technology mainly has two implementations: SR-MPLS and SRv6. Among them, SR-MPLS is a Segment Routing implementation based on the MPLS data plane, and its SID is the MPLS label (Label); SRv6 (Segment Routing over IPv6, segment routing based on IPv6) is a Segment Routing implementation based on the IPv6 data plane, and its SID is the IPv6 address.

SRv6 combines the source routing advantages of Segment Routing with all the characteristics of IPv6, and has multiple network programming spaces, which is in line with the SDN (Software Defined Network) concept.

2. SRv6 Implementation Principle

2.1 SRH package

SRv6 implements segment routing by inserting a routing extension header SRH (Segment Routing Header) into the IPv6 packet header to carry segment transmission information. SRH contains a Segment List represented by a SID list with IPv6 address characteristics. The destination address of the packet will be updated segment by segment according to the Segment List, thereby completing segment-by-segment forwarding.

The SRv6 message format is shown in Figure 1.

Figure 1 SRv6 message format

The fields contained in SRH are explained as follows:

Figure 2 Meaning of SRH extension header fields

2.2 SID Definition

The routable 128-bit SID is usually divided into three parts: Locator, Function, and Arguments. The length of each part is flexibly defined according to actual needs.

• Locator is a network location identifier assigned to a network node and is used to route and forward data packets.
• Function is used to express the forwarding behavior to be performed by the SID. In SRv6 network programming, different forwarding behaviors are expressed by different Functions.
• Arguments are optional parameters that can carry parameters required for command execution, such as user ID, application type, quality requirements, and any other relevant information.

Figure 3 Segment Id format

2.3 Segment Type

SRH directly uses IPv6 addresses to represent segments, which can flexibly support a wide range of types and combine different types of segments to complete specific functions. Generally speaking, segments can be divided into two categories: segments that represent path information and segments that represent service information.

Figure 4 Segment types

3. SRv6 forwarding process

Figure 5 SRv6 forwarding topology

P1 and P2 simulate backbone network devices, PE1 and PE2 simulate backbone network edge devices, and CE1 and CE2 customer access devices Host1 and Host2 act as clients and servers. During the forwarding process, the changes in the destination IP, Segment list encapsulation, SL, Last Entry and other fields can be seen in the pcap package.

3.1 Client access server uplink path

Host1->CE1->PE1->P1->CE2->Host2

CE1:

PE1:

P1:

PE2:

CE2:

3.2 Client access server downstream path

Host2>CE2->PE2->P2->CE1->Host1

CE2:

PE2:

P2:

PE1:

CE1:

4. SRv6 Advantages

• Simple deployment: Only SRv6 policies need to be deployed end-to-end without operating intermediate transmission nodes.
• Intelligence: By interacting with the SDN controller through the MP-BGP protocol, the entire network can be automatically scheduled intelligently.
• Programmable: Segments can be programmed according to business needs.
• Application awareness: Bring application information into the network so that the network can perceive application types and requirements in a timely manner to provide intelligent and customized services.
• Multiple tunnel capabilities: support SRv6 BE, L2VPN, L3VPN

5. SRv6 application scenarios

5.1 Main Application Scenarios of SRv6

5.2 SRv6 Home Application Scenario

The traffic is encapsulated in APN6 through the cloud gateway, and the customized service traffic is imported into the SRv6 acceleration network through the diversion strategy to realize the intelligent scheduling of home broadband services.

6. Summary and Outlook

IPv6 has always been a highly concerned issue in various countries. It is also the foundation for the development of the next generation of the Internet and an important new technology application of the new generation of information technology in my country's strategic emerging industries. With the maturity of SRv6 technology, the application and deployment of IPv6 in the existing network will be accelerated.

As a new generation of IP bearer protocol, SRv6 can simplify and unify traditional complex network protocols, and will be widely used in home broadband business scenarios in computing power networks, network intelligent scheduling, service orchestration, and other aspects.