Comprehensive Analysis of MPLS routing protocols

MPLS routing protocol is one of the most common protocols in the process of using a router. Many people may not understand the basic concepts of MPLS routing protocol. It doesn't matter. After reading this article, you will certainly have a lot of GAINS, I hope this article will teach you more things. MPLS routing protocol (Multiprotocol Label Switch) was initially proposed to speed up the forwarding of the router, but because MPLS is used in the 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 routing 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, the MPLS routing protocol 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 routing protocol network, the label is separated by the edge router.

MPLS route 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 routing protocols:

1) 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.

2) 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 ).

(3) Aggregate Route-based IP Switch ARIS) is a label exchange solution of IBM. 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.

Obviously, the label exchange-based solutions of different manufacturers cannot be accepted by other manufacturers, and unified standards must be formed. Therefore, in 1997, IETF set up a working group, which has been discussed many times. The term MPLS (Multiprotocol Label Switching) is indeed used as a series of standard names independent of the vendor. The purpose of MPLS routing protocol is to integrate the high performance of Label Switching forwarding and the scalability of Network-layer routing. It is suitable for IPV4 and IPV6. Currently, all MPLS routing protocols are in the draft phase, but many vendors have begun to implement MPLS3. Some products have already been launched. It can also be said that the establishment of a large-scale MPLS-Based IP network and the operators benefiting from it will surely become the leader in the next expansion of the interconnection network.

Advantages of MPLS Routing Protocol

How is IP + ATM different from simply running IP addresses on the ATM backbone? The answer is MPLS. MPLS routing protocol 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. Because the MPLS routing protocol provides flexible IP connection and scalability, as well as the privacy and QOS of FR and ATM, it 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.

The MPLS routing protocol-based solution makes it possible for services in the new online world, such as VPN with QOS. 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 routing protocol 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,