Introduction
- Currently, the traffic is directed to the corresponding SFC via the VLAN tag.
- The former SFC static (SFS adjacent constituent SFC), with SDN after the dynamic. (SFS does not need to be adjacent to each other.) Dynamically directs traffic to the desired SFS. ）
- The classification of traffic steering methods is divided into three categories:
- Based on package headers
- Based on package tagging
- SDN switches based on personalization.
SFC Introduction
- SFC is defined as a three-tier architecture, a data plane, an SFC overlay, and a control plane.
- The first layer: interconnected network devices. Hardware
- Second layer: SFC elements, such as business classifier (CL), service function forwarder (SFF), and SFS. It should be implemented by software and configured on common hardware. The flexibility is achieved. Can be deployed on any hardware, arbitrary composition of SFC.
- The third layer: responsible for the management of the first layer and two layers.
- SFC Work Flow:
The control plane configures the traffic classifier, calculates the Service function Paths (SFP), the configured traffic classifier filters the traffic and identifies the corresponding SFC, forwards it to the SFF (Service Function forwarder), and sends it to SFS via SFF.
- The SFS is connected by tunneling technology.
About NFV
- The NFV framework consists of three core components:
- Virtual network capabilities (VNF)
- Network function Virtualization Infrastructure (NFVI)
- Management and development of the architecture Framework (Nfv-mano)
- VNFS is a network-enabled software device that will be deployed in NFVI. The NFVI is comprised of vnfs built-in environments, including hardware and software systems. This environment is managed and arranged by Nfv-mano.
Traffic-oriented problems in SFC
- As the name implies, traffic commanders are generally placed in CL and SFF.
- The classification of traffic steering methods is divided into three categories:
- Based on package headers
- Based on package tagging
- SDN Switch based on personalization
The first is based on packet headers for traffic steering,
The second is based in specific tags or re-interpreting some packet fields,
The third is based on personalized switching functionalities and daemons
- SFC's forwarding or traffic guidance includes the following operations: classification, identification, routing, and sometimes encapsulation.
- Classification: The classification process allows traffic to be filtered according to the policy profile.
- Identification: Avoid repeating the classification of the execution, other SFC elements according to the classification results to identify.
- Routing: The tunneling technique between SFS. The route operation is to select the next SFC element in the SFP.
- Two types of packages:
- Transport encapsulation: Used for tunneling between SFS.
- SFC Encapsulation: The path information about the SFP is encapsulated in the packet.
Traffic-oriented method based on Baotou
- A forwarding protocol in NSH:SFC that CL adds a NSH header to the packet to identify the traffic path and share the metadata.
- Sch: Similar to Nsh, Sch contains two types of fields, a mandatory field and an optional field. For mandatory fields, the identifier that represents the traffic, SFF and SF use it for traffic guidance. Optional fields are used to differentiate between different metadata.
- IPV6 extension: Extends the IPv6 head for traffic orientation.
- SRH: Encode the SFP. The IPV6 address of the SFC element is written in the header. As a result, CL inserts the appropriate header, and sffs controls traffic based on the IP address encoded in the header.
- IP protocol extension: The IP header represents the path with an identifier.
Cons: With so many methods, it is difficult to be universal. And how to add Baotou will also increase the cost.
A traffic-oriented approach based on packet tagging
- The principle is to use existing fields.
- Based on MAC address
- VLAN-based tagging
- MPLS-based label
Disadvantage: The original field may be used for other policies, and if what is modified may lead to incorrect guidance.
Based on the programmable switch method
- With the SDN switch acting as CL and SFF, there is a flow table mechanism that provides more flexible traffic guidance.
Cons: An increase in the number of rules affects the memory, processing, and overall switch performance of the switch, increasing the delivery time of the package.
Never forget your original intention
Traffic steering for Service Function Chaining
