ES2530542B1 - Communications system, network element and procedure to facilitate the routing of data packets - Google Patents

Abstract

Communications system, network element and procedure to facilitate the routing of data packets. # A system, network element and procedure to facilitate the transmission of data from a first data network using a first data transport mechanism to a second data network using a second data transport mechanism, which includes: mapping a data packet from the first data network to the second data network by assigning first and second tags to the data packet; mapping a first portion of quality of service information relating to the data packet of the first network to a field in the first label; and map a second portion of the quality of service information for the first network data packet to a field in the second tag. Preferably, the first data transport mechanism is IP and the second data transport mechanism is MPLS or Ethernet. The quality of service information of the first data network in both first and second labels can be used to apply a corresponding quality of service by network elements of the second data network. Advantageously, when the first portion of quality of service information is 3 bits long, and the second portion of quality of service information is 3 bits long, this allows up to 64 kinds of quality of service to be applied in the second network.

Description

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DESCRIPTION

Communications system, network element and procedure to facilitate the routing of data packets

Field of the Invention

The present invention relates to the transmission of data through networks of different types. Specifically, the present invention relates to the transmission of data through networks of different types, so that the quality of service parameters are maintained. Even more specifically, the present invention relates to the transmission of data from an Internet Protocol (IP) network to a network with a different data transport mechanism, such as Ethernet or tag switching multiprotocol, MPLS ("Multiprotocol Label Switching"), so that they retain all traffic classes, or at least most of them, used by the Internet protocol.

Background

The quality of service requirements for transport networks are important for many products and services that use communications networks, particularly products and services in the fields of M2M (machine to machine), automotive, mHealth (mobile health), which refers to procedures related to medicine and public health supported by mobile communication devices), cloud computing and virtualization of networks.

The Internet Protocol (IP) is a protocol used extensively to transmit data across networks. It is a routing protocol that encapsulates data packets with source and destination addresses in order to route the packets through the network. Typically, a quality of service is provided in the Internet protocol through the differentiated service mechanism (DiffServ). DiffServ classifies data traffic, placing each data packet in a traffic class of a limited number of traffic classes. Each router (also called "router") in the network is configured to differentiate traffic based on the classes designated for each packet, instead of differentiating network traffic based on the requirements of an individual flow. Each kind of traffic can be managed differently, ensuring a

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preferential treatment for high priority traffic.

DiffServ uses a 6-bit field (DS field) in the header of an IP-encapsulated packet for the purpose of classifying service quality. This 6-bit field allows to support up to 64 different classes. In this regard, the code point of differentiated services (DSCP) is an 8-bit field, in which 3 bits are the code selector points of class (CS) Selector ”), another 3 bits are the precedence of discard (DP, of the English“ Drop Precedence ”) and 2 bits designated either as without current use (CU, of the English“ Currently Unused ”) or, for IPv4 and IPv6, as an expKcita congestion notification (ECN).

The applications and use of the 64 different traffic categories of the Internet protocol are defined in standards RFC 2597, RFC 2598 and RFC 2474.

The Internet protocol has been used extensively by telecommunication network providers in their terrestrial networks for data transmission, however, there is currently a transition from the Internet protocol to multi-protocol label switching (MPLS). As the Internet protocol will continue to be used in many concurrent networks, there is a need to be able to effectively transfer data between IP networks and MPLS networks.

In MPLS, a 4-byte tag is appended to the data packets, where a 20-bit unstructured tag value field is provided, as well as 3 bits for experimental use (EXP), a bit to indicate the background of the stack (S) of the English "Stack") and 8 bits for a field of life time (TTL) of the English "Time To Live"). An illustration of this label is provided in Figure 1.

Currently, the 3-bit EXP field is used as a service class field in the MPLS tag. When IP packets are mapped to such an MPLS tag, it is only possible to map a portion of the DSCP, typically the CS class selector code point field. Therefore, while the Internet protocol supports up to 64 different classes of service (that is, the 6-bit DSCP field allows 26 = 64 different classes), MPLS only supports 8 (that is, the 3-bit field only allows 23 = 8 classes). Therefore, MPLS can essentially only map class selector code points directly, but not discard precedence code points. Therefore, service differentiation capacity is lost when mapping IP packets to MPLS, since the 64 different service classes must be reduced to only 8.

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A corresponding problem exists in relation to the effective transfer of data between IP networks and Ethernet networks. The Ethernet standard, as defined in IEEE 802.1p, is similarly capable of only supporting up to 8 different classes of service, because there is only a 3-bit field for quality of service, QoS, service) Therefore, there is a need to improve the quality of service in the mapping between data transport mechanisms, and specifically when mapping IP to a data transport mechanism that provides fewer kinds of service.More specifically, this need It applies to mapping for IP / MPLS networks, and IP / Ethernet networks.

Summary of the invention

According to a first aspect, the present invention provides a method for facilitating the routing of a data packet using a network element located in a second data network, in which the received data packet has been transmitted through a first data network that uses a first data transport mechanism to the second data network that uses a second data transport mechanism, and the received packet has been adapted for use by the second data network, such that the procedure includes the network element: read a first field of a first label associated with the data packet; and if the first field indicates that the data packet is being transmitted according to a given quality of service configuration, read a second field of a second label; and use the data from the first and second fields in combination in order to provide an improved quality of service for the data package.

Preferably the given quality of service configuration is a guaranteed forwarding and the procedure also includes recognizing the first field as defining a guaranteed forwarding class by virtue of a value of the first field, such that the recognition serves as a trigger to read the second field of the second label. Advantageously, the present invention allows an increased number of QoS fields to be associated with a data package in order to provide an improved quality of service for that package. Minimal changes need to be made to the nodes / network elements in order to support this aspect of the invention: the network nodes only need to be programmed to recognize an entry or value in the first field of the first data packet as a defining of a guaranteed forwarding class.

In another aspect, the present invention provides a method to facilitate the

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data transmission from a first data network that uses a first data transport mechanism to a second data network that uses a second data transport mechanism, which includes: mapping a data packet from the first data network to the second data network by assigning first and second labels to the data packet; mapping a first portion of quality of service information relating to the data packet of the first network to a field in the first label; and map a second portion of the quality of service information for the first network data packet to a field in the second tag.

Ideally, the quality of service information of the first data network is combined in both the first and second labels, and consequently is used to apply a corresponding quality of service by network elements of the second data network. Advantageously, when the first portion of the service quality information is 3 bits long, and the second portion of the service quality information is 3 bits long, this allows up to 64 kinds of service quality to be applied in the second network. .

Preferably the first data transport mechanism is IP. The second data transport mechanism is one configured to house fewer classes of service than the first data transport mechanism. When the first data transport mechanism is IP, the second data transport mechanism can be MPLS or Ethernet.

These aspects of the invention advantageously utilize the ability of MPLS and Ethernet to assign multiple headers / labels to packets being transmitted. For example, for Ethernet, this capability is defined in IEEE 802.1ad (sometimes referred to as Q-in-Q), and in MPLS the concept of label stacking is defined in RFC3032 (that is, the use of the value of bit S (see figure 1) to know if a given MPLS tag is the last tag or not).

When two or more tags are used, one is typically defined as an external / service tag and the other is an internal / customer tag. In this configuration, and when the first data transport mechanism is IP, a 3-bit component of the 6-bit DSCP segment is copied to an appropriate 3-bit segment of the internal tag (for example, the first 3 bits) and a different 3-bit component of the DSCP segment is copied into an appropriate 3-bit segment of the external tag (for example, the last 3 bits). The core network is then able to extract all 6 bits and determine which of the 64 possible classes of service is applied to the packet (that is, 26 = 64).

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Therefore, this aspect of the invention advantageously provides a direct way of mapping the quality of service (QoS) parameters of the Internet protocol based on differentiated services, which are capable of supporting up to 64 different traffic categories, over a network. IP / MPLS

This allows enriching the degree of network quality levels, and also increasing the granularity of the service quality mapping. This is a feature that has a particular application in the modernization of transport networks for its evolution towards all IP.

Other aspects of the invention are set forth in the appended claims.

Brief description of the drawings

A detailed description of the embodiments of the invention will be given below with reference to the figures, in which: Figure 1 illustrates an example of an MPLS tag;

Figure 2 illustrates a first embodiment of the invention, in relation to the mapping of

data from an IP network to an MPLS network;

Figure 3 illustrates an example of an Ethernet VLAN tag; Y

Figure 4 illustrates a second embodiment of the invention, in relation to the mapping of data from an IP network to an Ethernet network.

Detailed description

Multi-protocol tag switching (MPLS) is a mechanism used in high-performance telecommunications networks that direct and transport data from one network node to the next. It can encapsulate packets of various network protocols. MPLS is a highly scalable data transport mechanism, indifferent to the protocol.

In an MPLS network, tags are assigned to data packets (see Figure 1). Decisions on packet forwarding are made only based on the contents of this label, without the need to examine the package itself. This allows to create end-to-end circuits along any type of transport means, using any protocol.

Therefore, MPLS essentially creates "virtual links" between distant nodes.

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MPLS is an important advance for telecommunications companies, as it allows voice, data and multimedia traffic to converge into a single secure network. Communications in an MPLS network can be prioritized so that a lower priority can be assigned to activities such as sending an email than to critical business applications or sensitive to delays such as voice over IP.

As indicated above, however, there is a transition problem in relation to the sending of data packets from a network supported by IP to a network supported by MPLS, since MPLS does not support QoS classes at the same level as IP.

According to a first embodiment of the invention, however, MPLS is adapted in order to retain the 64 kinds of service in the transition from a packet of a network supported by IP to a network supported by MPLS. This embodiment of the invention will be described in relation to Figure 2.

In this regard, Figure 2 schematically shows some of the network elements used in a network supported by MPLS. An IP packet that is being routed to its destination, this being an evolved packet core (EPC) server, would be received by an element of the IP network, in this case a B LTE node ( "Long Term Evolution"), and forwarded to the EPC server. The route to this EPC server passes at least partially through a network that supports MPLS. In Figure 2, this entry to the MPLS network is the provider's frontier router (router), and the B LTE node will therefore pass the IP packet to the incoming PE router .

The network element responsible for adapting the package to adapt it to MPLS is, in this case, the incoming PE router. The incoming PE router makes this modification, and then sends the adapted packet through the MPLS network, through one or more routers that play the role of the provider's routers (P), in this case. , the MPLS network exit point for the destination point is the output PE router.

To adapt the packet, the incoming PE router creates two MPLS tags for the data packet, these being an MPLS service tag and an MPLS link tag. The 3 DSCP DP bits of the IP data packet are copied into the EXP field of one of the tags, typically the MPLS service tag. The 3 DSCP CS bits are copied into the

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EXP field of the other tag, typically the MPLS link tag.

These two tags can then be used by each router through the MPLS network. For example, the following is an example of an algorithm that can be used by routers along the MPLS network in order to adapt the 64 different service classes now designated in MPLS packets:

IF “3-bit MPLS EXP Link Tag” EN AFxy Pattern THEN LOOK “3-bit MPLS Label EXP Service Tag”

DETERMINE Discard Precedence

IF NOT

Do nothing END

The AFxy pattern refers to guaranteed forwarding (AF) for jump behavior, as defined in RCF2597 and subsequently updated by RFC3260. Guaranteed forwarding allows the operator to provide shipping security as long as the traffic does not exceed a defined speed. A traffic that exceeds the predefined speed faces a higher probability of being discarded if congestion occurs.

Guaranteed forwarding defines four different AF classes, class 4 being the highest priority. It also defines three discard preference values, so that within each class a high, medium or low discard preference is assigned to the packages. Therefore, the combination of classes and discard preference results in 12 different DSCP encodings from AF11 to AF43 according to Table 1:

 Class 1 Class 2 Class 3 Class 4

 (Minimum maximum)

 Discard under

 AF11 AF21 AF31 AF41

 Medium discard

 AF12 AF22 AF32 AF42

 Discard high

 AF13 AF23 AF33 AF43

TABLE 1

Therefore, from this table it can be seen that the concept of guaranteed forwarding can be

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defined as AFxy, where x (1..4) defines the class, and y (1.3) defines the discard preference.

To implement the guaranteed forwarding, each node extracts and uses the AF data to give different forwarding guarantees when necessary. AF data can be used to decide what kind of service (for example, AF1, AF2, etc.) will be penalized or discarded in case of bandwidth congestion or when the traffic exceeds the allocated intermediate storage space and the agreed link bandwidth (that is, with reference to the service level agreement). This also applies within each AFx class (for example, AF13 packages will be discarded before packages in AF12 and before packages in AF 11).

The present invention implemented in MPLS maps the class encodings in the 3 EXP bits of MPLS link, which is X (1..4). The algorithm of the present invention recognizes these bits in the MPLS tag as relative to guaranteed forwarding by virtue of having a value of 1 to 4. This can be achieved by reference to a comparison table having the recognized guaranteed forwarding values. When a comparison shows that the MPLS tag value is an AF class, this recognition serves as the criterion to trigger the query process (that is, IF "MPLS EXP 3-bit link tag" IS AFxy Pattern THEN LOOK AT " MPLS Label EXP 3-bit Service Tag ”DETERMINE Discard Precedence). That is, the network element / router will then refer to the EXP field of the MPLS service tag and use its value in order to implement the discard preference, if necessary.

Therefore, as a whole, when a router recognizes the value in the link EXP as a defining class of an AF class, the packet will be assigned to a suitable queue (that is, a queue is preferably reserved for each AF class). Because the router determines that the link EXP value is an AF class, the router will know that it can access the service EXP field to obtain a discard precedence value. The router can extract this value for use until a packet is dispensed with (that is, either forwarded or discarded). The discard precedence value is typically stored temporarily in relation to the AF service class, so that the two fields are combined or at least used in combination. Alternatively, the router can access the service EXP field when necessary (for example, when a queue is congested, in order to determine which packet or packets

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discard in order to relieve tail congestion).

The routers in the MPLS network are therefore capable of using both EXP fields by using this algorithm, and therefore basing a quality of service decision on both fields (that is, according to 64 different possible classes of service). A small adaptation to intermediate routers may be necessary in order to allow them to implement this algorithm.

It will be appreciated that this solution is retroactively compatible with the current IP / MPLS QoS implementation, in which only the MPLS link tag is analyzed.

Advantageously, this embodiment of the invention allows 64 different kinds of service to be provided while only one single link is used through the MPLS network from the PE input router to the PE output router. In other words, you only need to use a link to transport different services with different experimental bit values.

Next, a second embodiment of the invention will be described in relation to Figure 4, in which an Ethernet network is adapted in order to retain the 64 kinds of service in the transition of a packet of an IP-supported network. to a network supported by Ethernet.

In this regard, Figure 4 schematically shows some of the network elements used in an Ethernet network. An IP packet that is being routed to its destination, which is that of a service server, would be received by an IP network element, in this case a service client, and forwarded to the service server. The route to this service server passes at least partially through an Ethernet-supported network.

Ethernet is a network standard for local area networks (LANs), and one of the most widely used implementations in relation to virtual local area networks (LANs). IEEE 802.1Q is the network standard that supports virtual LANs (VLANs) over an Ethernet network. This standard defines a VLAN tagging system for Ethernet frames, so that a single link can be used to transport data for various VLANs.

The Ethernet VLAN tag is illustrated in Figure 3. The tag has a 16-bit field,

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which is the Tag Protocol Identifier (TPID), as well as a 16-bit field with Tag Control Information (TCI). The TCI typically consists of 12 bits for a VLAN identifier (VID), 1 bit for a discard eligibility indicator (DEI), and 3 bits for dot field Priority Code Point (PCP). The 3-bit PCP field is used for quality of service: IEEE 802.1p.

In Figure 4, the input to the Ethernet network is the input border (or border) switch, and consequently the service client passes the IP packet to the input border switch. The input border switch is a computer network device located at the entry point of the IP network to connect the end user to the Ethernet network.

The input border switch is responsible for adapting the IP packet to accept Ethernet. The input border switch makes this modification, and then resends the adapted packet through the Ethernet network, by means of one or more intermediate central switches. Central switches are computer network devices located within the Ethernet network. In this example, the output point of the Ethernet network for the destination point is the output border switch (whose function, in the mode of realization illustrated in Figure 4, is not affected).

To adapt the package, this embodiment takes advantage of the fact that IEEE 802.1ad (Q-in-Q) allows stacking multiple headers in a data packet. More specifically, the input border switch creates two Ethernet tags / headers for the data packet, in accordance with IEEE 802.1ad, a client VLAN header and a service VLAN header. The 3 DSCP DP bits of the IP data packet are copied into the 3 bits in one of the headers, typically the client VLAN header (that is, 3 p-bits of the internal header / tag). The 3 DSCP CS bits are copied into 3 bits in the other header, typically the service VLAN header (that is, 3 p-bits of the external header / tag). The 3 p-bits in each header are typically corresponding fields.

For example, the following is an example of an algorithm by the incoming border switching node to perform the operation described in the previous paragraph:

FOR ALL IP Services

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COPY “DSCP DP bits“ A “3 p-bits VLAN client)

COPY “DSCP CS bits“ A “3 p-bits service VLAN)

Y

MAKE THE SERVICE QUALITY DECISION BASED ON PRIOR CRITERIA (p-bits in service VLAN and p-bits in client VLAN)

These two headers can then be used by one or more of the intermediate central switches to route the packet to its destination. For example, the following is an example of an algorithm that can be used by the central switches in order to accept the 64 different service classes now designated in the Ethernet packets:

IF “3 p-bits VLAN service” AFxy Pattern THEN LOOK “3 p-bits VLAN client”

DETERMINE Discard Precedence

IF NOT

Do nothing

FINISH

Therefore this algorithm allows the central switches of the Ethernet network to access the 6 bits for the evaluation of QoS, and therefore base a service quality decision in both fields on the client and service headers (that is, of according to possible 64 different kinds of service). For example, when an Ethernet switch is a blocking switch, it typically has a minimum of eight queues, and uses a queue algorithm, such as weighted random early detection to manage those queues. The additional quality of service information provided in the headers can be used to implement a priority discard functionality in at least four of these queues (that is, in the case of queue congestion, in order to determine which package (s) ) is discarded first.

It should be noted that at least four queues have been mentioned above, since the number of queues required will be at least four when implementing insured forwarding, since each type of insured forwarding x (1..4) is ideally assigned to a QoS queue different to have all the functionality of insured forwarding. Discard precedence classes and (1..3) are then applied within each queue when a queue becomes congested.

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A small adaptation of the central switches may be necessary in order to allow this algorithm to be implemented.

A further improvement could be made to this mode of realization of the invention using external bits to route through a "privileged" network.

It should be appreciated that in both embodiments, if the logical criteria of the DSCP changed in any mode, these embodiments of the invention could be adapted to these changes simply by changing a mapping table associated with the EXP bits of MPLS / CoS bits Ethernet, so that the new DSCP definitions would be reflected in the mapping table of the MPLS EXP bits / Ethernet CoS bits.

The embodiments of the invention have been described with reference in particular to IP networks that are mapped to an MPLS or Ethernet network. The inventive concept can also be applied to other data network migrations in which the final data network configuration has fewer kinds of service than the original data network configuration.

In addition, the inventive concept has been described in relation to accepting 64 different classes of service, using two different MPLS / Ethernet tags. However, if more than 6 bits are needed in the future to accommodate additional data and / or classes of service, additional MPLS / Ethernet tags could be used in a corresponding way.

Likewise, the inventive concept has been described mainly in relation to its use in relation to guaranteed forwarding. Although this is a preferred embodiment, the invention could also be applied to other 6-bit QoS implementations. For example, if a new QoS logic based on 6 bits is defined in the future, the inventive concept could also be adapted to apply the new logic, so that it provides 6-bit QoS values in MPLS and Ethernet. As a specific example, if in the future it was decided to place a precedence of discarding 1, 2 and 3 in a class of Best Try BE service (the English “Best Effort”), the precedence of BE drop (eg, BE1, BE2, BE3) could be adapted in a similar way to the preferred embodiment for AF service classes.

Additionally, the invention has been described primarily in relation to a transfer of an IP network to one that typically supports fewer kinds of service, such as networks

MPLS / Ethernet, however, the solution is backwards compatible.

The embodiments of the invention also apply to newly developed network configurations, as well as improvements made to existing network configurations.

5 The embodiments of the invention have a particular application to data sent at least partially through a mobile network, namely mobile networks that implement long-term evolution, LTE (in English "Long Term Evolution"). Network quality is of particular importance when mobile networks are developed, both in terms of speed and reliability of coverage.

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Claims (14)

5 10 fifteen twenty 25 30 35 1. A procedure to facilitate the routing of a data packet that is transmitted from a first data network that uses a first data transport mechanism to a second data network using a second data transport mechanism, which includes: map the data packet from the first data network to the second data network by assigning first and second tags to the data packet; map a first portion of service quality information related to the package of the first data network to a first field in the first label; Y map a second portion of the quality of service information for the package of data from the first data network to a second field in the second tag; in which the first mechanism of data transport is Internet protocol, IP. 2. A method according to claim 1 which further includes the following steps performed by a network element located in the second data network, in which the received data packet has been transmitted through the first data network up to the second data network: read the first field of the first label associated with the data packet; and if the first field indicates that the data packet is being transmitted according to a given quality of service configuration, read the second field of the second label; Y use the data from the first and second fields in combination in order to provide an improved quality of service for the data package. 3. The procedure of claim 2, wherein the given quality of service configuration is guaranteed forwarding and the procedure further includes recognizing the first field as defining a guaranteed return class by virtue of a value of the first field, such that the recognition serves as a trigger to read the second field of the second label. 4. The procedure of any preceding claim, which also includes applying a quality of service to the packet transmitted through the second network using the quality of service information on both first and second labels. 5. The procedure any preceding claim, in which the information of 5 10 fifteen twenty 25 30 35 Quality of service of the first data network both the first and the second label can be used to apply a corresponding quality of service by network elements of the second data network. 6. The procedure of any preceding claim, wherein the first portion of service quality information is 3 bits long, and the second portion of service quality information is 3 bits long, and the procedure includes using portions. first and second of service quality information of the first and second tags in combination in order to apply up to 64 kinds of service quality for the transmission of data packets through the second network. 7. The procedure of any preceding claim, which also includes incorporating an indicator in the first label in order to indicate that service quality information is also included in the second label. 8. The procedure of any preceding claim, in which the first and second labels have the same format, and the second field in the second label where the second portion of the service quality information is mapped is the field in the second label. corresponding to the first field in the first label where the first portion of the quality of service information is mapped. 9. The procedure of any preceding claim, wherein the first portion of service quality information is mapped from a first portion of a service quality field of the first network data packet and the second portion of quality information of service is mapped to a second portion of the service quality field. 10. The method of any preceding claim, wherein the second data transport mechanism is multi-protocol tag switching, MPLS. 11. The method of any one of claims 1 to 9, wherein the second data transport mechanism is Ethernet. 12. A network element located in a second data network, and adapted to facilitate the routing of a received data packet, in which the received data packet has been transmitted through a first data network using a first data transport mechanism to the second data network that uses a second data mechanism 5 10 fifteen twenty 25 30 35 data transport, and the received package has been adapted for use by the second data network, the element being configured to: read a first field of a first label associated with the data packet; and if the first field indicates that the data packet is being transmitted according to a given quality of service configuration, read a second field from a second label; Y use the data from the first and second fields in combination in order to provide improved quality of service for the data package; in which the first mechanism of data transport is Internet protocol, IP. 13. A communications system that includes at least first and second network elements located in a second data network, which are adapted to facilitate the routing of a received data packet, when the received data packet has been transmitted through a first data network that uses a first data transport mechanism to a second data network that uses a second data transport mechanism, such that: The first network element is configured to adapt the data packet received for use in the second data network by: map the data packet received from the first data network to the second network of data by assigning first and second tags to the data packet; map a first portion of service quality information related to the package of data from the first network to a first field in the first tag; map a second portion of the quality of service information for the package of data from the first network to a second field in the second tag; Y forward the adapted packet to the element of the second data network; The second network element is configured to: read the first field of the first label associated with the adapted data packet; if the first field indicates that the data packet is being transmitted according to a given quality of service configuration, read the second field of the second label; Y use the data from the first and second fields in combination in order to provide an improved quality of service for the data package; in which the first mechanism of data transport is Internet protocol, IP. 14. The communication system of revindication 13 in which the second data network uses a tag-switched data transport mechanism multiprotocol, MPLS or an Ethernet data transport mechanism, and the data packet has been transmitted from the first data network using an Internet protocol data transport mechanism, and adapted for use by the second data network , such that the fields of quality of service first and second correspond to 5 fields of quality of service of the Internet protocol.