MPLS network application

MPLS Multiprotocol Label Switching-Multi-Protocol Label exchange technology is a new technology that uses tags to guide high-speed and efficient data transmission on open communication networks. Its value lies in its ability to introduce the connection mode in a connectionless network. Its main advantage is that it reduces network complexity, is compatible with various mainstream network technologies, and can reduce network costs by 50%, ensure QoS and security when providing IP services, and have traffic engineering capabilities. In addition, MPLS addresses VPN scalability and maintenance costs. MPLS technology is the most competitive communication network technology in the next generation.

The main characteristics of MPLS technology: the packet forwarding mechanism of MPLS in the network is based on fixed-length labels, which simplifies the forwarding mechanism and makes the forwarding router capacity easily extended to a too-bit level; make full use of the original IP route, and improve it on this basis; ensure the flexibility of MPLS network routing; discard the complicated ATM signaling, seamlessly integrates the advantages of IP technology into the efficient hardware forwarding of ATM. MPLS is a connection-oriented transmission technology that can provide effective QoS Assurance; MPLS is a link layer-independent technology that supports X.25, frame relay, ATM, DWDM ......, Multi-network interconnection is ensured. MPLS supports a large-scale hierarchical network topology with excellent network scalability. MPLS label merging mechanism supports the combined transmission of different data streams; MPLS supports traffic engineering, cos, QoS, and large-scale virtual private network;

Advantages of MPLS: MPLS simplifies the forwarding process under strict matching of fixed-length labels, and the hardware basis of this Forwarding is cheap and mature ATM exchange technology, this greatly reduces the R & D investment of equipment manufacturers. MPLS separates routing and packet forwarding from the IP network, which enables the evolution of Routing Technology in the MPLS network to be promoted by modifying forwarding methods; the new routing technology can be applied directly to the network without interrupting the network operation, without having to change the forwarding technology on the existing router. MPLS simplifies the integration technology between ATM and IP, they are promoted to unify, thereby balancing users' huge investment in ATM and IP networks, thus reducing network maintenance costs and scalability. in MPLS networks, explicit routing can be directly used, it enhances the network traffic control and self-recovery capabilities to support more new businesses. Additionally, MPLS guarantees connection reliability, so that various new services can be implemented on the MPLS-Based IP network. MPLS technology further promotes the division of network functions and pushes complicated transaction processing to the edge of the network, this facilitates maintaining the scalability of the IP protocol in a large network; MPLS network The use of the label stack in the network reduces the size of the route table and greatly improves the routing scalability. MPLS can be used in multiple link layer technologies to maximize the balance between the original technologies, protecting existing investment and network resources, MPLS can provide connection-oriented services in a connectionless or explicit routing mode, which makes MPLS suitable for dynamic tunneling technology, it also guarantees the QoS requirements of data transmission services. tunnel technology is currently an effective means to support VPN services. QoS is the basis for realizing voice and real-time multimedia information transmission over IP networks as a comprehensive platform.

Based on its advantages, MPLS has developed rapidly around the world. In 2001, with the initial maturity of MPLS technology, operators began to use MPLS to create or upgrade their networks. In 2002, China Telecom established its high-density IP/MPLS network in mainland China. China Telecom, the US company, will provide mplsvpn, leased line services to mainland China, and direct IP Access to Chinanet to American companies with business in China. In 2003, MPLS technology was widely used. Sify Ltd., India's largest interner network and E-Commerce provider, has built India's largest MPLS network that provides secure VPN services and serves as an Internet gateway connected to the United States. In early 2004, sprint, a national carrier in the United States, launched the mpls vpn service for enterprise users. In the same year, China tietong IP backbone network fully adopts the MPLS technology for architecture, by deploying a dedicated mpls vpn Router (PE) in major cities across the country ), china tietong IP backbone network can provide mpls vpn services nationwide. In 2004, the global MPLS business volume exceeded 5 billion US dollars, with an annual growth rate of 20%. It is foreseeable that, with business innovation and application promotion, MPLS will show a more rapid development speed in the future.

IP outlet-MPLS 

With the rapid development of the Internet, people have put forward higher demands for applications. Due to the lack of effective traffic and network bandwidth management methods, the network is often congested. The failure to provide QoS guarantees makes many applications, such as voice and video, insufficient for the current IP technology. The emerging Multi-Protocol Label Switching Technology (MPLS) is expected to solve this problem.

How MPLS works

According to the current definition, MPLS is a label-Based IP Route Selection Method. These tags can be used to represent a hop-by-hop or explicit route, and specify the Quality of Service (QoS), virtual private network, and traffic that affects a specific type (or traffic of a special user) other types of information transmitted over the network.

Currently, the routing protocol selects the shortest path between a specified source and destination, regardless of whether the path is overloaded. With explicit routing selection, service providers can select the path through which special traffic passes, enabling the traffic to select a low-latency path.

The MPLS protocol converts a third-level Packet Exchange to a second-level exchange. MPLS can use a variety of layer-2 protocols. The MPLS Working Group has standardized the labels used on Frame Relay, ATM and PPP links, and IEEE 802.3 LAN. One advantage of MPLS running on Frame Relay and ATM is that it brings arbitrary IP connectivity to these connection-oriented technologies. Currently, the main development direction of MPLS is ATM. This is mainly because ATM has a strong traffic management function and can provide QoS services. The combination of ATM and MPLS technology can fully play the role of traffic management and QoS.

A tag is the header used to forward data packets. The Header Format depends on the network characteristics. In a vro network, the label is a separate 32-bit header. In an ATM, tags are placed in the virtual circuit identifier/virtual channel identifier (VCI/VPI) cell header. At the core, only the tag is interpreted, but the packet header is not read. The key to MPLS scalability is to mark that it is meaningful only between two devices that communicate with each other.

When an IP packet enters the core of the network, the edge router assigns a label to it. Since then, the MPLS device will view the tag information from start to end and switch these labeled packages to their destination (see the schematic ). Due to the decrease in route processing, the network wait time is reduced, but the scalability is increased.

The quality of service type of MPLS data packets can be determined by the MPLS Edge Router Based on various parameters of the IP packet, such as the IP Source Address, Destination Address, port number, and TOS value. For an IP packet that arrives at the same destination, different forwarding paths can be created based on its TOS value to meet its transmission quality requirements. At the same time, through the management of special routes, it can effectively solve the load balancing and congestion problems in the network. For example, when there is congestion in the network, MPLS can create a new forwarding route in real time to share its traffic to relieve network congestion.

Currently, there are two types of protocols used by the vendor. One is the restricted routing label Allocation Protocol (crldp ), the other is the Resource Reservation Protocol (RSVP ). The tag Allocation Protocol (LDP) provides communication between edge devices and core devices, and is used with routing selection protocols, such as OSPF, Isis, and OSPF (Enhanced Internal Gateway Routing Protocol) or BGP and so on are combined to allocate tags between the edge and the core device to establish a tag switching path. Currently, the MPLS workgroup uses both methods. Although it is often a positive choice, there are two standards to solve the same problem, which will obviously bring about serious interoperability problems. Many vendors also find themselves shouldering the burden of implementing two sets of protocols.

Vendors expect the market to decide which method will succeed, but past experience has proved that users often postpone adopting new technologies due to instability.

MPLS applications

MPLS will help carriers provide better IP services. Like AT & T, Level 3, MCI WorldCom, and uunet, their MPLS networks have been deployed and marketed. Operators also face a major problem: whether to use MPLS to simplify their existing ATM network or establish an MPLS network without ATM. The answer to the question depends on the type of data to be transmitted. The MPLS architecture is better for packet networks, while ATM is the best choice for voice and Bit Synchronization data.

MPLS brings more bandwidth control, throughput guarantee, and VPC functionality. In MPLS networks, even packet speech services such as IP speech will be improved, because the waiting time is shortened and congestion control is enhanced. All in all, all these results are intended to allow users to enjoy better services from service providers. Therefore, when selecting a supplier or evaluating a contract, pay attention to the situation where the peer party provides MPLS.

Obviously, MPLS is mainly for service providers and carriers. However, it also has many features that will benefit enterprise users, whether they use public or private WAN services.

Virtual Private Network

An application that has great potential benefits to service providers by MPLS is the support for VPN services. Using MPLS for VPN is to establish a VPN by using an ATM or frame relay permanent virtual circuit (PVC) or various forms of tunnel to interconnect the customer's router.

VPN using MPLS can provide many favorable conditions based on the PVC mode. Customers can select their own addressing plans, which may or may not overlap with plans of other customers or service providers. Each customer can believe that the data will only be sent to the site in the customer's VPN. Because of this, encryption is often not required, which is different from many tunneling methods. However, unlike the PVC mode, the mpls vpn mode achieves high scalability with the increasing number of sites and customers. It also supports communication between any two points in a site in a VPN, without the need to install a complete PVC mesh or transmit traffic back on the service provider's network. For each mpls vpn customer, the service provider's network seems to provide a Virtual Private backbone network, through which the customer can contact other sites in the Organization, you cannot contact any other customer's sites.

From the customer's point of view, an important advantage of the mpls vpn mode is that in many cases, compared with the PVC mode, the routing can be greatly simplified. Mpls vpn customers can use service providers as the default route to all sites of the company instead of managing route selection through a technically complex virtual backbone network consisting of many PVCs.

VPN service providers often need to provide customers with a series of QoS ). Mpls vpn uses the new differential service technology to support QoS. These technologies allow customer traffic to be classified when entering the provider's network based on various policies, such as the source site and application type. In this network, the traffic types are identified by titles or by different tags. Routers use them to determine queuing treatment, and thus determine QoS parameters such as latency and loss.

Traffic Engineering

Another benefit MPLS provides to service providers is in the traffic engineering field. Traffic Engineering refers to the ability to control the communication flow in the network. It aims to reduce congestion and make full use of available functions.

For example, in the traffic engineering example shown in, there are two paths from router C to router E. If a router selects one of the shortest paths from C to E, it will send all the network communications that are scheduled to reach through E. Therefore, the traffic on the path may cause congestion, while the load on the other path is insufficient. To maximize the performance of the entire network, it may be desirable to transfer some traffic from one link to another.

Although people in this simple example can set the cost of the C-D-E path to be equal to the cost of the C-F-G-E path, however, this load balancing method will become very troublesome in complex topology networks (although this method is not impossible ). The display path implemented by MPLS can be used as a simpler and more flexible way to solve this problem, so that part of the traffic in a crowded path is transferred to a non-crowded path.

The solution to traffic engineering problems is to establish a tag and tag exchange path through different control modules. For example, the traffic control module can create a path from A to C to D to E, and the other path from B to C to F to g to E. You can manage communication flows on the network by defining policies that select certain information packages to follow these paths.

In the future, MPLS will use the restricted route selection to determine the traffic engineering policy. In this environment, you only need to specify the expected flow load (a traffic matrix) between different network points, and the route selection system will calculate the optimal route to transmit the load, then, determine the explicit path.

Integration of IP and ATM

MPLS enables the ATM switch to perform almost all the functions of the IP router. It has this capability because the MPLS Forwarding mode-tag switching-is identical to the forwarding mode provided by the hardware of the ATM switch. The main difference between a traditional ATM switch and an ATM tag switch is the control software used to create VCI table items on the switch. The ATM tag switch uses the IP Route Selection protocol and the tag Allocation Protocol (LDP) to create such a tag.

An ATM tag switch can be used as a traditional ATM switch at the same time. In such an environment, exchange resources (such as VCI space or bandwidth) are divided between the traditional ATM control plane and the MPLS control plane. The MPLS control plane can be used to provide IP-based services, while the ATM control plane provides atm-oriented services or PVC services such as circuit simulation.

MPLS is a common technology that can implement many new services for service providers. It provides a flexible method to provide virtual private network services by using QoS (including Intranet and external networks), which provides good scalability for service providers and allows the use of various QoS, and reduces the management burden of VPN customers. MPLS Traffic Engineering features are useful as a way to manage the traffic and Link Utilization of a routing network. Finally, as a method that integrates ATM and IP technology, it is advantageous for a provider who wants to use the ATM Backbone Network to establish a Multi-service network.

Cisco

Cisco has released a number of products that provide tag switching technology to service providers and large enterprise networks. The current product has the following two basic functions:

1. Combined with an IGP protocol, such as Open Shortest Path First (OSPF), the label assignment protocol (TDP) is used to implement the destination-based unicast routing capability;
2. The traffic engineering capability balances the traffic load to make better use of all links in the backbone network.

Current MPLS Product

Both the edge and center of the MPLS network can use cisco MPLS products: edge devices, or edge exchange routers (edge LSR), which are a full-featured layer-3 device, the L2 Switch or L3 router can be marked as an LSR.

Cisco will continuously add MPLS functions, such as creating highly scalable Virtual Private Network (VPN) that does not require tunnel and encryption, and providing service-level (COS) functions, service providers can provide priority levels for different types of businesses, even in VPN. The constraint-based routing capability will also enhance the traffic engineering function, so that network administrators can optimize the traffic routing between pop on the backbone network, and automatically set the tunnel and map the traffic to the tunnel.

Lucent

Lucent Technology has launched the product IP navigator Based on MPLS technology. IP navigator and B-stdx, cbx 500, and GX 550 vswitches can build multi-service solutions, in addition to providing ATM, frame relay, and traditional IP services, it can also provide services with Service Quality Assurance Based on IP addresses.

1. Provide voice over IP service with absolute Service Quality

IP navigator has the absolute quality of service (absolute QoS) function, that is, it can establish end-to-end connections that meet the quality of voice service. The multivoice gateway and IP navigator of Lucent technology can be used to build a voice over IP service network with absolute service quality. The multivoice Gateway provides an interface between the PSTN and IP-based networks to enable voice calls to access IP networks. When the voice signal passes through the multivoice gateway, it is converted into a VoIP group voice stream. The multivoice gateway sets the service type (ToS) bytes in the Voice group to a specific value, and instructs the IP navigator that the IP packet is a voice group. After the IP navigator receives the voice group, it checks whether there is an switched virtual circuit (SVC) between the source and the sink. If there is an SVC between the source and the sink, the SVC will automatically send the group. If SVC does not exist, IP navigator uses end-to-end connections that meet the quality requirements of voice transmission to provide low-latency and Low-jitter transmission channels for Voice Groups, this guarantees the quality of speech service. Because ATM is used as the network base, it can provide large-scale voice communication, and is suitable for establishing large-scale voice communication networks.

2. IP-based VPN Service

The VPN technology of IP Navigator can provide multiple VPN networks on an MPLS network at the same time, supporting a variety of applications, such as lan remote access, enterprise network interconnection and Internet applications.

The VPN function of IP navigator assigns a route domain and an ID number to each VPN user. Each VPN user can have its own routing protocol and route table. The IP addresses used by different VPN users can overlap, so that users can use IP navigator to interconnect without changing their IP address planning. IP navigator supports the following routing protocols: BGP-4, OSPF, rip-2, and others. IP navigator takes security measures on the VPN to ensure that IP connections cannot be established between different VPNs, which is equivalent to physically isolating the two networks. IP navigator uses the QoS service mechanism of the ATM network to ensure the bandwidth, transmission quality, latency, and other service quality for VPN users. IP navigator provides VPN management through the user Proxy gateway, allowing you to obtain comprehensive configuration, performance, and fault information in real time.

Marconi

(Formerly fore System Company)

For a long time, Marconi communication (fore System) plays a crucial role in the development of MPLS technology and provides comprehensive support for MPLS technology.

1. In a device (such as a ASX-4000 backbone switch), MPLS provides support for ATM, pos (Packet over SDH), DWDM and Ethernet at the same time to achieve end-to-end IP connection. In addition, the special technologies of Marconi are fully utilized in connection, including Te (Traffic Engineering), Tm (Traffic Management), Cr (Capacity-aware routing selection), and QoS (Service Quality ).
2. Implement connection-oriented link layer (Coll) within a control plane ). In the past, IP and ATM fusion technology needed two sets of control plane protocols. Now, Marconi MPLS technology only needs one control plane to implement a complete Coll (connection oriented Link Layer ).
3. Provides the "Midnight boat" working mode. The Marconi device can provide ATM and IP control plane functions on the same physical port, so that the same physical network supports multiple control mechanisms at the same time to achieve smooth transition between ATM and MPLS.
4. Provides a high-speed and intelligent hardware platform supporting MPLS. The tag switching hardware of Marconi provides queuing, buffering, scheduling, and shaping functions based on connection and connection groups, as well as port and port groups. Ensure optimal matching between MPLS software and hardware.
5. Upgrade flexibly according to user requirements. Marconi provides pure ATM mode, pure IP mode, and MPLS mode, and can coexist and switch between these modes. All of these are implemented through software upgrades.
6. Provides a large tunnel or connection hierarchy. Marconi MPLS provides a flexible tag stack mechanism that supports multi-level virtual connections and multi-level VPN, that is, multi-level virtual connection nesting and VPN nesting.
7. Solve the IP address joining problem of N2. Marconi MPLS uses IGP (interior gateway protocol) to provide direct IP address joining, avoiding time-consuming and labor-consuming route update problems.
8. Simplifies the IP address lookup process. The full-line MPLS product of Marconi ensures that IP address lookup, forwarding, and classification are performed only on connected inbound and outbound devices, greatly improving the network efficiency.
9. Supports merging connection data streams.

   The MPLS of Marconi communication (fore System Company) not only has all the functions required by the IETF standard, but also is flexible, secure, and reliable in implementation.

How multi-protocol tag switching works:

The MPLS specification proposed by the Internet Engineering Task Team places the reliability, delivery mechanism and QoS performance of the ATM on a large IP network. MPLS defines a tag-driven connection for reliable and fast IP packet delivery in a multi-vendor environment.

1. Send an IP packet to an MPLS Device
   
2. The MPLS device defines the optimal route for the package and transmits it over the WAN. It also adds an MPLS label to each package. For each hop on the WAN, The vro or vswitch only displays the MPLS flag and forwards the packet.
   
3. The MPLS device transfers the package to another appropriate destination, or re-attaches the package to a new destination