In modern enterprises, when building the infrastructure of a corporate network , MPLS technology can be used. What are its features? What advantages does it have over traditional routing technologies?
Technology Overview
What is the specifics of MPLS? What is this technology? MPLS is the concept that packets are forwarded to computer networks. Its main feature is in the proposal of an alternative to analyzing by routers such as IPLP headers for all packets, which is carried out in order to determine the direction for their forwarding to the next infrastructure component. If the technology in question is involved, then the header analysis is performed once upon entering the MPLS network, and then the correspondence between the packet parameters and the flow properties is initiated.
MPLS Development Features
MPLS technology was developed by specialists interested in implementing a universal data exchange protocol that would be suitable both for circuit-switched infrastructure and for applications where packets are transmitted. In MPLS networks, a variety of types of traffic can be transmitted - IP, ATM, Ethernet, SONET, SDH. The development of the concept was carried out taking into account the advantages and disadvantages of earlier protocols of a similar purpose. At the same time, in some aspects, MPLS involves the implementation of simpler algorithms in comparison with the approaches used in traditional solutions. According to experts, network equipment that supports MPLS technology is able to oust traditional solutions from the market, which indicates that MPLS developers have done good work to optimize and universalize this concept.
MPLS and IP
So, we know the basic principles of the MPLS concept, what kind of technology it is. In ordinary networks that use the TCP-IP protocol, packet routing is implemented using the IP address of the computer to which the packet is transmitted. In this case, all routers on the network have information about which interface is used for data transfer, as well as which computer needs to redirect the current packet to.
In the case of MPLS, a different approach is taken. He, as we already know, involves the implementation of switching using labels. They are tied to a specific package that is transmitted on the network. Having received it, routers at the same time have information on how to transmit data further - based on the specific value that the MPLS tag has. It can be noted that it is located within the MPLS header, placed between the frame and the packet, in accordance with the accepted format. It is noteworthy that on one package several labels can be placed. In order to indicate that this or that label is the last in the group, special flags are used.
It will be useful to consider in more detail the advantages of the technology in question over traditional solutions.
Key Benefits of MPLS: Data Processing Efficiency
A major advantage of MPLS is that it takes less time to process data than when mapping IP addresses. Moreover, MPLS technology reduces the time it takes to redirect a packet using basic routers. In fact, switching can be carried out using several protocols, in which special tags are used as part of packets of transmitted network data. Due to this, separate switched flows are formed.
MPLS Benefits: Versatility
Another important feature of the concept is universality. In virtually any IP MPLS network can be implemented. The technology in question is well supported at the hardware level. In principle, it is possible to use affordable solutions for the implementation of MPLS - Mikrotik, for example. The principles of bringing the infrastructure to a healthy state are universal. However, when designing an MPLS network, equipment setup must be done by experienced professionals. First of all, they are competent in understanding the features of the network architecture, the characteristics of its hardware components.
MPLS Benefits: Scalability
The MPLS infrastructure is characterized by scalability and a high degree of autonomy with respect to the various protocols through which data is transmitted. The specificity of specific standards implemented at the data link level does not matter. When implementing the MPLS network, there is no need to ensure the functioning of networks at the second level, which are optimized for the transmission of various traffic types. From the point of view of network classification by type of switching, MPLS can rightfully be attributed to the infrastructure in which packet switching is performed.
MPLS Architecture: Basic Devices
Let us examine what devices are supposed to be used in networks where the MPLS concept is applied, what kind of infrastructure is this in terms of using hardware resources. The main devices that are involved in the framework of the corresponding technology include:
- a router compatible with the MPLS concept, as well as with conventional data transfer protocols;
- a router that interacts with devices on which label switching is not performed (including due to the lack of support for MPLS);
- a group of network devices that are used for switching using tags within the framework of a common administration and routing system.
In fact, devices of the first type form a corresponding group, which, in turn, forms a domain. MPLS routers of the second type form the border region of this domain.
Basic principles of MPLS switching
We will study on the basis of what principles switching is carried out in the framework of the technology in question. As we already know, the key component of MPLS is the label. Their exchange is the basis of the corresponding technology. All packets that are transmitted on the network are associated with a particular type of network layer. Each of them is identified with a specific tag. Its value is unique only when considering within a specific section of the path that runs between network nodes located in the neighborhood, that is, routers of the first type (according to the classification considered by us above). Any package will thus include a label. However, the way it is associated with the package will depend on what technology is used as part of the network channel infrastructure .
Communication between routers
A particular router can request network information using some algorithm compatible with MPLS - BGP, for example. The main function of the device in this case is to ensure the exchange of data with neighboring devices through the distribution of labels, subsequently used for switching purposes. Direct exchange of them can be carried out in various ways. For example, the LDP protocol may be involved, or modified versions of other routing standards used by the network administrator.
Component table
In the process of label distribution during the communication of different devices, separate data transmission paths are formed. Each of the routers used has a table that matches the components associated with the input interface and the sections that reflect the characteristics of the output infrastructure. Having received this or that packet in accordance with the interface number, as well as having read the label value, the router sets a specific output interface for the transmitted data. In this case, the old value within the label is corrected and replaced by a new one, which is reflected in that part of the table where the output labels are fixed, after which the packet is sent to another element of the network infrastructure.
The MPLS protocol assumes a one-time identification of individual field values located on one row of the table used. This is due to the fact that the concept under consideration allows for more efficient data transfer in comparison with the methods used in conventional routing, when the IP address of the source device has the longest prefix in the routing table.
MPLS structure
Let us consider in more detail the structural features of the network concept in question. MPLS consists of two main components:
- kernels;
- border area.
The kernel structure contains devices that necessarily support MPLS. They are used as infrastructure components for routing traffic within a dial-up protocol. Thus, the main function of devices present in the kernel is switching.
In turn, the border region is responsible for: classification of packets according to established criteria, for the implementation of related services - for example, related to filtering during data transfer, for managing network traffic. The specified distribution of functions between the core and the border region allows you to configure the MPLS network taking into account the specific location of specific devices within the network.
Labeling Methods
Let us examine in more detail how labeling of data transfer packets using MPLS tags is carried out. First of all, it is worth noting that the label has the following main characteristics: fixed length, uniqueness in the context of a separate connection between neighboring routers.
In fact, a label with the same value can be applied on different parts of the network, but only within the framework of communication between separate pairs of routers. True, in this case, the devices must determine where the data packet, marked with the corresponding labels, came from. In practice, in the simplest network connections, the same set of MPLS tags can be used within an interface.
In more complex infrastructures, it is proposed to use a separate set of labels within a separate module or device. Immediately before being included in the package, the MPLS tag is encoded in accordance with the established algorithm. If the network uses the IP protocol, then the label is placed as part of the packet header. In other cases, it is reflected in the header of the protocol at the channel level. It can also be encoded in a specific value.
Applying Label Groups
In the process of data transfer using the network concept in question, the packet structure may contain, as we noted above, groups of labels - stacks. Each of them may reflect the operation of adding or removing certain tags. At the same time, only at the very top a specific switching result is set. This feature of data transmission in MPLS networks allows tunneling communications to be implemented. The stack contains components that are 32 bits long. In this case, 20 is allocated to the label, 8 - to the counter of the packet lifetime, 1 - reflects the lower limit in the group of labels, 3 - are not used in practice. In general, any label value is possible - excluding a certain number of reserved ones.
Switched Path Structure
In order to understand in detail the principles by which the MPLS network works, what kind of technology it is, it will be useful to study the features of the structure of the dial-up path that is built within the framework of the network infrastructure. Its main feature is that it consists of a set of plots - on the same level. They are switched using tags at a specific level.
In the structure of one or another level, the use of input and output routers is assumed. We noted above that MPLS networks may use the LDP protocol. Let's explore how the dial-up path can line up when LDP is enabled.
First of all, when sending UDP packets, which can involve a large number of addresses, routers establish their own location on the network - using LDP. It can also determine the connection between routers that do not belong to the same channel. This feature of the network structure is important from the point of view of implementing data transmission in the tunnel format.
Once the location of the routers is established, the LDP protocol starts a connection outside TCP, that is, on top of it. As part of it, requests are generated to initiate the binding, as well as information about it. Also, test messages can be sent between different devices in order to verify the network's operability.