Brief history of MPLS Development

MPLSMultiprotocol Label Switch (MPLSMultiprotocol Label Switch) was originally proposed to speed up router forwarding, but because MPLS is used in Traffic engineering Traffic Engeering) and VPN are two key technologies in the current IP network. MPLS has become an important standard for expanding the IP network scale.

The key to MPLS protocol is to introduce the Label Concept. It is a short and easy-to-process information that does not contain topology information and only has local meaning. Label is short for ease of processing, and can usually be referenced directly using indexes. It only has a local significance to facilitate allocation. People familiar with ATM may naturally think of VPI/VCI in the ATM. In this case, the VPI/VCI in the ATM is a tag, so the ATM is actually a tag exchange.
In an MPLS network, when an IP packet enters the first MPLS device, the MPLS edge router is encapsulated with a label. The MPLS edge router analyzes the content of the IP packet and selects appropriate labels for these IP packets. Compared with the traditional IP routing analysis, MPLS not only analyzes the destination address information in the IP packet header. It also analyzes other information in the IP header, such as TOS. Then, all nodes in the MPLS network use this short label as the basis for forwarding decision. When the IP packet finally leaves the MPLS network, the label is separated by the edge router.
MPLS protocol development process
In 1996, Ipsilon launched the IP Switching protocol, which immediately caused a big shock in the data communication industry. Ipsilon, a small obscure company, became a well-known company in the data communication industry. As a result, it caused a great revolution in router technology. Various companies have successively launched their own layer-3 Exchange solutions, the following protocols play a key role in the development of MPLS protocols:

IP Exchange Technology
IP Switching. Proposed by Ipsilon in 1996, and launched commercial products that support this agreement. This Protocol makes an ATM switch a router, so it has the high performance of an ATM switch, thus breaking through the performance restrictions of traditional routers. The basic purpose of IP exchange is to efficiently integrate the IP router of an ATM switch using the method of discarding the ATM control plane. The creation of IP Switching labels is driven by data streams. Ipsilon defines a set of protocols, including the tag binding Protocol Ipsilon Flow Management Protocol or IFMP, RFC) and the Switch Management Protocol is called General Switch Management Protocol or GSMP, RFC ). GSMP is only used to control a single ATM switch and virtual connections that span the switch.

Tag Switching)
Shortly after Ipsilon announced their IP exchange, Cisco announced its Tag exchange technology, but it was called "Tag exchange Tag Switching )". Tag Switching is a Tag method developed by CISCO. Unlike IP Switching, Tag Switching does not rely on the data stream driver to create a Tag forwarding table. It relies on a control plane equivalent to the ATM protocol ), the Tag Switching network consists of Tag Edge Routers and Tag Switching Routers. The IP packet is tagged and encapsulated on the Tag Edge Routers. The next hop route is determined based on standard routing algorithms such as OSPF and BGP ). Tag binding and Distribution use the Tag Distribution Protocol, TDP ). Compared with IP address exchange and CSR, tag exchange is technically different. For example, on a vswitch, it does not set forward tables based on data traffic. What is different from the ATM network is that for many connection layer technologies, it provides detailed instructions. Like Ipsilon, Cisco also made the RFC for the described technology. However, Cisco is preparing to use IETF to standardize their technology. To achieve this goal, they drafted a large number of Internet files to illustrate all aspects of tag exchange technology. It is through the continuous efforts of Cisco that we finally have the MPLS Working Group we now know, And now MPLS has become a general term for tag switching.
IBM ARIS
Also shortly after Cisco announced their tag exchange technology and made efforts to standardize it in IETF, IBM drafted documents to describe another new tag exchange technology, they call it a centralized routing-Based IP address exchange technology (ARIS ). Compared with other tag exchange technologies, ARIS is more similar to Cisco's tag exchange technology. Both use traffic control instead of data traffic to set forward tables. However, ARIS is significantly different from label exchange in some aspects. Many ARIS ideas have entered the MPLS standard. Similar to Tag Switching and ARIS, tags are associated with the same Aggregation Router. Different from IP Switching, tags are bound to the same stream. The control flow such as route update is used to establish the label Switching path). The egress router is the initiator. ARIS is designed to use ATM as its data link layer. It is a point-to-point protocol. It runs directly on the IP address of the adjacent router, and provides methods to establish and exchange labels between the adjacent routers. The key concept of ARIS is "Egress Identifier ). Label Distribution begins with the egress router and is regularly transmitted to the ingress router through the network.
MPLS workgroup
While Cisco announced their label exchange technology, they also announced that they would standardize it. Shortly after they proposed a series of Internet drafts on tag exchange, a BOF meeting was held in May. Cisco, IBM, and toshba attended the meeting. The BOF meeting became an important meeting in the history of IETF.
Since many companies have produced similar products to solve the new problems in the network at that time, standardization of this technology became a major topic at the conference. Although some people were wondering whether these technologies could solve new problems in the network. For example, some people thought that the problem would be even more confusing, without a standardization Working Group, there will be more incompatible tag exchange products, making the market more chaotic. As a result, the drafting of the Working Group's Articles of Association began. By the beginning of 1997, an IETF was finally able to accept the articles of association. The first meeting of the Working Group was held in April 1997.
Significance of MPLS

Improve network usage
Currently, China's backbone network bandwidth usage is less than 10%. Therefore, how to attract more users to use network resources is a concern of operators and service providers. Router manufacturers all see the best use of MPLS is to integrate networks carrying a variety of different types of services into a single network. Most network operators and service providers believe that using MPLS to unify various services is a long-term development direction.
Simplify IPv6 implementation
The IPv4 address is very lacking. It is time to implement IPv6. If MPLS is implemented on IPv4, the implementation difficulty of IPv6 is reduced, Because MPLS completely disconnects packet forwarding. The major capability of IPv6 for IPv4 is the expansion of the address space, so the corresponding routing algorithm has not changed, and the control protocol for forwarding data packets has not changed. Therefore, on a platform that clearly separates forwarding and control, you only need to change the corresponding control protocol, and there is no need to change the forwarding. After doing so, with the development of the current optical transmission technology, the bandwidth of the network is growing almost unlimitedly. For example, a single optical fiber can be uploaded to several TBS, the forwarding equipment (vro) in the network must also adapt to the development of transmission technology and be improved very quickly. The basic method is to use hardware forwarding. The architecture of the dedicated forwarding and control protocols is also more convenient for hardware forwarding. Because the label format of only one package is fixed, and it is very easy to implement in hardware, this trend is that MPLS also has some of its advantages in a very high-speed network. Therefore, the implementation of MPLS simplifies some new IPv6 functions.
Business opportunities for new vendors
In fact, the emergence of MPLS has given new manufacturers and products a lot of opportunities and given them a new living space. The battle for traditional IP networks has ended. In the new battlefield, it is suitable for manufacturers with high starting points to play a role in it. If traditional vendors do not change from a hardware platform, they will not be able to process high-speed forwarding at such a wide network processing speed. Therefore, a new hardware platform must be available on the premise of broadband, which is an opportunity for new vendors.
Advantages of MPLS 
How is IP + ATM different from simply running IP addresses on the ATM backbone? The answer is MPLS. MPLS is a key technology in commercial IP networks. It allows service providers to obtain the combined profit of IP, ATM, and FR on a single network for the first time. MPLS provides flexible IP connection and scalability, as well as the privacy and QOS of FR and ATM, and has become a widely accepted standard.
Using MPLS, the IP service can transmit data over a switched network with optional routes and multiple services through the following processes:
1. The network determines the packet selection and QOS requirements.
2. Mark the packet to be allocated, and tell the vswitch or vro where to send the packet. The specific service attributes of each packet: QOS, private, and so on.
3. packets are exchanged on the network backbone without any additional routing.
MPLS-based solutions make it possible for services in the new online world, such as qos vpn. The main benefit of MPLS labeling is the ability to differentiate services for a single data stream.
MPLS provides high-performance expansion of IP services because service decisions are determined at the edge of the network and are exchanged without intermediate re-processing. MPLS enables the ATM network to achieve end-to-end three-layer intelligence and achieve important high performance. In addition, MPLS eliminates the complex protocols and address resolutions required for IP over ATM. With the value-added extension of MPLS, service providers can quickly and effectively transmit advanced IP services, such:
Connectionless IP VPNs with FR private property but no end-to-end virtual circuit
Implement a wide range of business strategies with multiple IP Service Classes
Low-cost controlled services extend the market share for small and medium-sized businesses

Service providers that Implement MPLS-Based IP + ATM solutions retain all user business and begin to build profitable services from new IP opportunities. Using IP + ATM solutions:
This makes it possible for a service that generates profits.
Revenue and profit growth from value-added IP Services
Reduce the time to enter the market
Reduce the cost of * operations
Increase ROI
Increase market share