WO2001089158A1

WO2001089158A1 - Method for controlling resources in a communication network

Info

Publication number: WO2001089158A1
Application number: PCT/SE2001/001004
Authority: WO
Inventors: Per Lindgren; Bengt J. Olsson
Original assignee: Net Insight Ab
Priority date: 2000-05-17
Filing date: 2001-05-09
Publication date: 2001-11-22
Also published as: SE0001814L; SE0001814D0; AU2001258967A1

Abstract

The present invention refers to a method for controlling resources in a communication network comprising nodes interconnected by links, each carrying a bitstream that is divided into frames, each frame in turn being divided into time slots that are allocatable to form circuit-switched channels. According to the invention, resources in the form of write access to time slots are associated with administrative entities. Allocation of resources is then done in such a way that allocation of resources to channels pertaining to a subject administrative entity is guaranteed to the extent by which resources have been associated with the subject administrative entity.

Description

METHOD FOR CONTROLLING RESOURCES IN A COMMUNICATION

NETWORK

Technical Field of the Invention

The present invention refers the field of data and telecommunications, and more specifically to a method for controlling resources in a communication network co pri- sing nodes interconnected by links, each carrying a bitstream that is divided into frames, each frame in turn being divided into time slots that are allocatable to form circuit-switched channels.

Background of the Invention

When operating networks of the above mentioned kind, there often exists a need or desire to have the possibility of letting different network operators, service providers, and end users operate over the same network infrastructure in a integrated but still separated manner. For example, there may be situations wherein an operator wants to be able to sell network capacity to another operator or to a service provider, which in turn might want to sell part of that network capacity to an end user. In fact, depending on legal regulatory aspect within different countries, regions and/or contexts, such sharing of the network resources are required to provide for a competitive environment.

A problem in such situations is how to let different operators control/use part of the same network in a simple manner, allowing for as much distributed/delegated control as possible, without risking having one operator affecting the integrity or traffic of another.

One way of addressing this problem is described in the International Patent Application WO99/55036, wherein so-called priority levels are used to provide different service classes. This prior art has the advantage that a service having a higher priority will not be affected by a service having a lower priority. On the other hand, if a service is not assigned the highest available priority, the user/operator thereof will never be certain that the integrity and traffic of the channel will be unaffected by other channels, unless this can be assured by considering the total overview of all priorities that is and will be assigned over the relevant parts of the network, which of course is a complex task to undertake.

Another way of addressing this problem is described in the International Patent Application WO00/21251, wherein so call "virtual links" or "tunnels" are created, optionally in a recursive manner, with the possibility of allowing different operators to control operation within the respective tunnels. This prior art has the advantage that the "tunnel"-approach completely separates one operator's traffic and control from the others, and that it also reduces the amount of control signaling within the network. However, a disadvantage is that dynamic creation of such tunnels typically may require the nodes to be able to handle signaling in relation to both physical and virtual interfaces, including signaling for channel management, topology discovery, resource management, link/traffic monitoring, etc, adding complexity to the node design.

An object of the invention is therefore to provide an alternative approach to how to allow different operators and/or other types of administrative entities to operate over the same network while preserving control and traffic integrity.

Summary of the invention

The object above is achieved by the invention as defined in the accompanying claims.

According to an aspect of the invention, there is provided a method of the kink mentioned in the introduc- tion, wherein resources in the form of write access to time slots are associated with administrative entities, or vice versa, and wherein resources are then allocated in such a way that allocation of resources to channels pertaining to a subject administrative entity is guaranteed to the extent by which resources have been associated with the subject administrative entity. Preferably, resources are allocated in such a way that resources associated with a subject administrative entity are only allocatable to channels that pertain to the subject administrative entity.

The invention is thus based upon the idea of dividing the pool of resources in the form of write access to time slot positions of the frames on different links of the network into different sub-pools, each being reserved to be used for channels that pertains to a respective administrative entity, such as a respective operator, a service provider, and/or and end user.

An advantage of the invention is that a number of time slots can be set aside on a number of links of the network to exclusively service for example an operator A. Operator A will then "own" these slots on the network and will thus be able to use these at his own discretion.

According to a preferred embodiment of the invention, messages pertaining to, for example, channel establishment will be defined to carry information identifying the administrative entity that a subject channel pertains to. Nodes that participate in the channel establishment procedure will receive the channel establishment message and will derive the administrative entity therefrom. The node will then determine if there exists resources that are associated with said administrative entity and that are not already allocated to channels pertaining to said administrative entity and will accordingly, if such resources exists, enable said resources to be allocated to said channel.

An advantage of the invention is thus that there is no need to establish different instances of the control signaling protocols/control functions used in the network (one for each operator) , as the same control signaling protocols/control functions can be used by all operators, while using the administrative entity as a means for the network nodes to sort out which operator/entity that is allowed to use/monitor/control which resources. This consequently not only advantageously addresses the problem of how to implement the multi-operator network, but also makes it possible for a number of administrative entities to have their own virtual network built upon a common infrastructure and still sharing the set of common control functions.

According to yet another preferred embodiment of the invention, the administrative entities are structured in a hierarchical manner. If, for example, a portion of a links total amount of resources is set aside for operator A, a sub-portion thereof may be set aside by operator A to be used for operator A's customer B, and a sub-portion thereof may be set aside by customer B to be used for customer B's subdivision C, etc., the entity A.B.C then being a subentity of the entity A.B, which in turn is a subentity of the entity A.

Consequently, resources are preferably allocated during channel set up in such a way that allocation of resources to channels pertaining to a hierarchical level of an administrative entity shall be guaranteed to the extent that resources are associated with said hierarchical level of said administrative entity.

The hierarchy is advantageously realized using entity identification structured as such in a hierarchical manner, for example in similar to how IP (Internet Protocol) addresses are structured in a hierarchical manner. Similarly, when determining if the entity defined in a channel establishment message have been assigned resources on a subject link, a "longest matching" paradigm similar to the ones used when performing a look- up in a routing table may be used. The longest match then gives the set of slots available for that request. This enables the use of well-known and simply realized mechanism for identifying hierarchical entities.

Preferably each hierarchical level of an administrative entity is provided with control of the association of resources, assigned to the respective hierarchical level of said administrative entity, to lower levels of said administrative entity, thereby allowing, for example, operator A to assign resources to the service provider B, allowing service provider B to assign a portion thereof to its customer C, etc.

As is understood, there are many ways in which resources and administrative entities can be associated with each other, the invention not being limited to any special embodiment thereof. According to an embodiment of the invention, administrative entities are associated with resources in the form of time slots on a link by link basis, enabling configuration of different resource distributions on different links. This embodiment has the advantage of adjusting the amount of resources set aside on different links according to the actual capacity needs that the subject administrative entity has over different parts of the network.

According to another embodiment, administrative entities are associated with resources on an overall network basis, the same amount of resources being associated to said administrative entity on all links of the network. This embodiment has the advantage of suggesting a simple "overall" approach to resource management. According to yet another embodiment, administrative entities are associated with resources on a network path basis, the same amount of resources being associated to said administrative entity on all links following said network path. This embodiment provides a simple means for an operator to identify one or more relevant paths over the network and to get resources reserved on the links following those paths. According to the invention, resources can be assigned on a link by link basis, said links either being actual physical links interconnecting ports of neighbor node, or logical links, each being defined by one or more physical links that are configured in series to form a unidirectional medium forwarding a frame of time slots in the downstream direction.

The invention can advantageously also be used in conjunction with schemes for providing channel priority and/or for building virtual links or "tunnels" as suggested in the prior arts discussed above. The invention can also be accompanied by mechanisms for dynamically redistributing write access to time slots among nodes connected to the same shared medium. Although the use of a more strict division of resources among administrative entities is preferred, not allowing for any allocation of slots over the boundaries set by the division and thereby simplifying implementation, mechanisms for, for example, allowing temporary borrowing of resources can also be added, for example allowing an operator B to use resources associated with operator A as long as A doesn't require those resources.

The above-mentioned aspects, features and advantages of the invention will be more fully understood from the following description of preferred embodiments thereof.

Brief Description of the Drawings

Preferred exemplifying embodiments of the invention will now be described with reference to the accompanying drawings, wherein:

Fig. 1 -exemplifies a network of nodes of the kind referred to by the invention according to an embodiment thereof;

Fig. 2 illustrates the frame structure used in the network of Fig. 1;

Fig 3 shows an embodiment of a resource table used by the nodes in Fig. 1; Fig 4 shows an alternative embodiment of a resource table used by the nodes in Fig. 1;

Fig 5 exemplifies the structure of a channel establishment request message of the kind transmitted among the nodes of the network in Fig. 1; and

Figs. βa-6c illustrate alternative approaches for distributing resource in a network according to different embodiments of the invention.

Detailed Description of the Preferred Embodiment

A network of nodes as referred to by the invention according to an embodiment thereof is schematically shown in Fig. 1. The exemplifying network comprises four nodes 11-14 interconnected via four optical fibers 21-24' together forming a unidirectional single ring link. A bitstream circulating on the single ring link (in the direction illustrated by the semi-circular dashed arrow in the center of Fig. 1, is carried by the fiber 21 from node 11 to node 12, by the fiber 22 from node 12 to node 13, by the fiber 23 from node 13 to node 14, and by the fiber 24 from node 14 to node 11.

The structure of the bitstream propagating on the ring link in Fig. 1 is schematically shown in Fig. 2. As illustrated, the bitstream is divided into recurrent, essentially fixed size (125 μs) frames, each of which in turn being divided into a plurality (N) of fixed size (64 bit) time slots. The start of each frame is defined by a frame start signal, illustrated as a black filled slot in Fig. 2. During normal operation, write access to the time slots (i.e. ■ the time slot positions) of the recurring frame is distributed among the nodes connected to the ring link in such a way that no two nodes shall have write access to the same time slot position, at least not over the same portion of the ring link. Each node is arranged to establish circuit-switched channels over the link by allocating one or more of the time slots that it has write access to to the respective channels. Each such channel will typically have only one sender, but may as such be unicasted, multicasted or broadcasted on the link, i.e. may be established to be received by one node, some of the nodes, or all nodes on the link. When for example establishing a channel over the link, the node setting-up the channel over the link need typically inform the one or more recipients of the channel about, for example, which time slot position that the channel will be defined by on the link, i.e. which' time slot positions of the recurring frame that the recipients shall read data from for the subject channel. To transmit such information to the recipient nodes, each node typically uses a so-called control channel, defined by respective one or more time slots within the recurring frame, to communicate with other nodes. Thus, in this embodiment, control channels are used for control signaling among the nodes connected to the link and are separate from the so-called data channels that are established, using control signaling, to carry so-called payload traffic, such as data traffic or streaming voice or video traffic.

To be noted, the nodes of the network may just as well operate in any other kind of link topology than the one illustrated in Fig. 1, such as point-to-point or bus topologies .

In order for a node to know which time slots of a recurring frame that may be used for channels pertaining to different administrative entities, each node will, according to an exemplifying embodiment, store a resource table of the- kind illustrated as table 100 in Fig. 3. The resource table 100 is provides to identify, for each time slot position of the frame that the resource table refers to, an administrative entity associated with the time slot position (column "ADMINISTRATIVE ENTITY" in Fig. 3) and any current allocation of the time slot to an actual channel (column "CHANNEL" in Fig. 3) . To be noted, the number of time slots included within a frame in Fig. 3 {as well as in Fig. 2) is merely illustrative.

The administrative entity associated with a time slot has the purpose of identifying/controlling which administrative entity, which could be an operator, service provider, customer, end user, or the like, that shall have the right to use to the resource, i.e. the time slot position, for channels to be established.

The administrative entities used in this exemplified embodiment are structured in a hierarchical manner, for example similar to the way that IP (Internet Protocol) addresses are structured in a hierarchical manner. The highest level in the hierarchy of administrative entities is in this embodiment called ROOT and encompasses all sublevel entities. The second level is in this embodiment used to identify different network operators offering services over the subject network, such as operators A and B. The third level is used to identify end users served by the respective operators, such as end users C and D served by operator A. Of course, additional levels could be added as desired. In this manner, the administrative entity is used as a tool to define which operator that shall be allowed to use which slots. In turn each operator may define which end users that shall be allowed to use which slots within the slots that the respective operator has access to, etc.

For example, in the resource table of Fig. 3, it is assumed that time slot positions 1-7 of the frame are reserved to be used for channels in service of operator A (administrative entity A) , whereas time slot positions 8-

12 are to be used for channels in service of operator B

(administrative entity B) . Slots 13-15 have been assigned the administrative entity "ROOT", which means that they may be used for channels in service of any operator/- customer. Also, slot position zero (0) has been assigned the administrative entity "SYSTEM", which means that this slot is reserved for the network as such for control signaling.

Furthermore, of the slots 1-7 to be used in service of operator A, slots 3-5 are reserved to be used for channels in service of operator's A customer C (administrative entity A.C), whereas slots 6-7 are to be used for channels in service operator's A customer D (administrative entity A.D) .

The structure of a channel establishment request message of the kind used by the nodes of the • network in Fig. 1 when establishing channels will now be described with reference to Fig. 5. Each channel establishment request message 50 will typically include a first field 51 defining the message type, i.e. in this case defining that the message is a channel establishment request message, a second field 52 identifying the administrative entity that the message pertains to, a third field 53 identifying the channel that the message refers to, a fourth field 54 identifying the desired bandwidth for the channel, a fifth field 55 identifying the source node being the originating point of the channel, and a sixth field 56 identifying the destination node for the subject channel. Several additional information fields will typically also be included in the message format, however not being shown or described more in detail herein.

According to an embodiment of the invention, when establishing a channel, a channel establishment request of the kind shown in Fig. 5 will be transmitted and forwarded on a hop by hop basis from the source node to the destination node of the subject channel, and the content of the message will be set to identify the administrative entity that the channel pertains to, for example identifying which operator and/or end user that the channel pertains to. A node that participates in the estab- lishment of the channel will receive the channel establishment request message and derive therefrom the administrative entity defined in the second field 52 of the message. The node will then compare the administrative entity defined in the message with the administrative entities in the table 100 of Fig. 3 to derive possible time slot positions to be used for the channel. In doing this, the node will in this embodiment use a "longest match" approach for comparing entities, in some respects similar to the approach used when identifying a longest match next hop route in an IP routing table as is well known to those skilled in the art. Assume for example that a channel establishment request for a channel CHl with a bandwidth corresponding to two slots per frame is received by a node that uses the resource table 100 of in Fig. 3, and that the request identifies the administrative entity A.C (for example meaning operator A, end user C) . The longest matches in table 100 of Fig. 3 will then be the entries (administrative entity A.C) of time slot positions 3-5. The second longest match, forming a higher level in the hierarchy of administrator entities, will be the entries (administra- tive entity A) of time slot positions 1-2, and the third longest match, referring to an even higher level in the hierarchy of administrative entities, will be the entries (ROOT) of time slot positions 13-15. Accordingly, the node will primarily try to allocate slots representing the longest match to accommodate the channel establishment request. If non of those slots are free to be allocated at the moment, it will try to use the slots representing the second longest match, and so on. Thus, in the subject case, it is assumed that slots associated with the longest match entities are in fact available, and that the node accordingly selects to allocate slot positions 3 and 4 to the channel CHI, as shown in the entries of the channel column of the table in Fig. 3.

Similarly, assume that a channel establishment request for a channel CH2 with a bandwidth corresponding to one slot per frame is received by the node, and that the request identifies the administrative entity A.E (meaning operator A, end user E) . As there are no A.E entries in the table 100 of Fig. 3, the longest matches will then be the entries (administrative entity A) of time slot positions 1-2, and the second longest match will be the entries (ROOT) of time slot positions 13-15. Thus, in this case, assuming that slots associated with the longest match entities are in fact available, the node accordingly allocates slot position 1 to the channel CH2, as shown in the entries of the channel column of the table in Fig. 3.

Using the same approach, a channel request message from administrative entity B (or sub-entities thereof) will typically result in allocation of slots 8-12 thereto, as is the case with channel CH3 which is assumed to have a bandwidth corresponding to two slots per frame and to pertain to administrative entity B.

If a channel request refers to neither administrative entity A nor administrative entity B, or if it in fact do refer to, for example, administrative entity A but all time slot positions reserved for administrative entity A are already occupied by other channels, the request can still possibly be accommodated using the slots 13-15 associated with the administrative entity "ROOT", as exemplified by channel CH4 which has been allocated slots 13 and 14.

To be noted, if a node receiving a request does not control or have write access to all relevant slot positions in the subject frame, which may be the case if the node is operating in relation to a bus or ring link that is shared by other nodes, as is the case for the nodes illustrated in Fig. 1, more or less advanced schemes may be added for nodes to borrow/lend or in other ways redistribute write access to slot positions among each other. Such lending/borrowing and redistribution will then typically be made with the purpose of accommodating the channel establishment request in accordance with the distribution of access to time slots among administrative entities as defined in accordance with the invention. However, examples on how such schemes could be designed will not be described more in detail herein. Also, note that in situations wherein a node already controls all the resources that can be put to its disposal, as is the case with a node forming one end of a point-to-point connection or a node sitting on a shared link on which no redistribution of resources is possible, no such added schemes will typically be necessary. Furthermore, different schemes of providing additional priority among channels, either within the boundaries set by the association of resources to administrative entities or overriding the boundaries set by the association of resources to administrative entities, may also be added within the scope of the invention.

To be noted, the content of the table 100 in Fig. 3 of a node can be configured and controlled in many ways. Typically, the content can be manually configured at the node and/or controlled by a management system communica- ting with the nodes using for example SNMP (Simple Network Management Protocol) or the like, either using in-band communication channels or using an external management network. Alternatively, the nodes could use a resource distribution protocol, by which the content of the table in different nodes are defined using control signaling among the nodes.

Whether using SNMP based management or using a specific resouce distribution protocol, authentication/- authorization of messages defining/requestin changes of the association of resources to administrative entities in one or more nodes is in the preferred embodiment performed by including an administrative entity in such a message and by accepting or rejecting the changes suggested in the message only to the extent that an hierarchical level of an administrative entity identified in such a message message is only allowed to control the association of resources, assigned to said hierarchical level of said administrative entity, to lower levels of said administrative entity.

As an alternative embodiment, Fig. 4 shows a resource table 110 in which administrative entities are associated with resources in the form of time slots, but instead of specifically identifying which specific slot positions that shall be available for a specific administrative entity, as is the case in the table 100 in Fig. 3, the resource table 110 of Fig. 4 merely defines the amount of resource to be made available ^'for a specific administrative entity. More specifically, in the exemplifying situation, table 110 states that 300 slots shall be made available to administrative entity A, and that 200 slots shall be made available to administrative entity B. Table 110 furthermore defines that of the 300 slots made available to administrative entity A, 50 thereof shall be made available to administrative sub- entity A.C (for example operator A's customer C) . As is understood, when using a table 110 as illustrated in Fig. 4, additional means are needed to sort out exactly which specific time slot positions that are made available to form the amounts defined by the resource table 110.

Figs. 6a-6c illustrate alternative approaches for assigning resource in a network to administrative enti- ties according to different embodiments of the invention, each simplifying network management in its own way. In the figures, a network 200 is shown comprising eight nodes, shown as circles, interconnected via links, shown as straight lines. In the embodiment illustrated in Fig. 6a, association of resources with administrative entities is performed on an overall network basis. In this context, this means that an administrative entity is associated with the same amount or set of resources on all links of the network, thereby creating a homogenous "reservation" of resources. To exemplify, in Fig. 6a it is assumed that administrative entity A is associated with 50 time slots on all links of the network, as indicated by the numbers shown next to each link.

In the embodiment illustrated in Fig. 6b, association of resources and administrative entities is per- formed on a link by link basis. In this context, this means that an administrative entity may be associated with a different amount or set of resources on different links of the network. To exemplify, in Fig. 6b it is assumed that administrative entity A is associated with time slots only on links forming part of the ■ subnetwork 210, and that entity A furthermore is associated with 150 slots on one of the links, with 50 slots on three of the links, and with 10 slots on the remaining link of the subnetwork 210, as indicated by the numbers shown next to each link.

In the embodiment illustrated in Fig. 6c, association of resources with an administrative entity is performed on a network path basis. In this context, this means that an administrative entity is associated with the same amount or set of resources on all links forming a path through the network. To exemplify, in Fig. 6c it is assumed that administrative entity A is associated with 50 time slots on all links forming part of the network path 220, as indicated by the numbers shown next to each link.

As is understood, other approaches than the ones described above may be used, as well as combinations thereof, to simplify network management in the desired way. Even though exemplifying embodiment of the invention has been described in detail above, modifications, combinations and alterations thereof may be made, as will be clear to those skilled in the art, within the scope of the invention, which is defined by the accompanying claims.

Claims

1. A method for controlling resources in a communication network comprising nodes interconnected by links, each carrying a bitstream that is divided into frames, each frame in turn being divided into time slots that are allocatable to form circuit-switched channels, said method comprising: associating resources in the form of write access to time slots with administrative entities, or vice versa; allocating resources in such a way that allocation of resources to channels pertaining to a subject administrative entity is guaranteed to the extent by which resources have been associated with the subject administrative entity.

2. A method as claimed in claim 1, said allocating step comprising allocating resources in such a way that resources associated with a subject administrative entity are only allocatable to channels that pertain to said subject administrative entity.

3. A method as claimed in claim 1 or 2, said allocating step comprising: determining, when establishing a channel, which administrative entity that said channel pertains to; and determining if there exist resources that are associated with said administrative entity and that are not already allocated to channels pertaining to said administrative entity and, if such resources exist, enabling said resources to be allocated to said channel.

4. A method as claimed in claim 3, wherein said step of determining, when establishing a channel, which administrative entity that said channel pertains to comprises : receiving a channel establishment request; and deriving, from said channel establishment request, information designating which administrative entity that said request pertains to.

5. A method as claimed in claim 1, 2, 3, or 4, said entities being structured in a hierarchical manner.

6. A method as claimed in claim 5, said allocating step comprising allocating resources in such a way that allocation of resources to channels pertaining to a hierarchical level of an administrative entity shall be guaranteed to the extent that resources are associated with said hierarchical level of said administrative entity.

7. A method as claimed in claim 5 or 6, said allocating step comprising allocating resources in such a way that resources associated with a hierarchical level of an administrative entity are only allocatable to chan- nels that pertain to said or hierarchical level, or to sublevels thereof, of said administrative entity.

8. A method as claimed in claim 5, 6, or 7, said allocating step comprising: determining, when establishing a channel, which administrative entity, and which hierarchical level thereof, that said channel pertains to; and determining if there exists resources that are associated with said hierarchical level, or to a supralevel thereof, of said administrative entity and that are not allocated to already established channels pertaining to said hierarchical level, or to a supralevel thereof, of administrative entity and, if such resources exists, enabling said resources to be allocated to said channel.

9. A method as claimed in any one of claims 1-8, said associating step comprises associating each time slot with an administrative entity.

10. A method as claimed in any one of claims 1-8, said associating step comprising associating an administrative entity with a number of non-explicitly identified time slots.

11. A method as claimed in any one of claims 1-8, said associating step comprising associating an administrative entity with a number of explicitly identified time slots.

12. A method as claimed in any one of claims 1-11, wherein said step of associating administrative entities with resources in the form of time slots is performed on a link by link basis, enabling configuration of different resource distributions on different links.

13. A method as claimed in any one of claims 1-11, wherein said step of associating an administrative entity with resources in the form of write access to time slots is performed on an overall network basis, the same amount of resources being associated to said administrative entity on all links of the network.

14. A method as claimed in any one of claims 1-11, wherein said step of associating an administrative entity with resources in the form of write access to time slots is performed on a network path basis, the same amount of resources being associated to said administrative entity on all links following said network path.

15. A method as claimed in any one of claims 1-14, wherein said links are logical links, each being defined by one or more physical links that are configured in series to form a unidirectional medium forwarding a frame of time slots in the downstream direction.

16. A method as claimed in any one of claims 1-14, wherein said links are physical links, each interconnecting neighbor nodes.

17. A method as claimed in any one of claims 1-16, wherein said step of associating resources with admini- strative entities is controlled at each node .based upon instructions received from a network management system communicating with said node.

18. A method as claimed in any one of claims 1-16, wherein said step of associating resources with administrative entities is controlled at each node based messages exchanged between using an in-band resource distribution protocol supported by the nodes.

19. A method as claimed in any one of claims 1-16, wherein an administrative entity refers to a defined entity using the network, such as an operator, a customer, and end user, or an application.

20. A method as claimed in any one of claims 1-19, including providing a hierarchical level of an administrative entity with the possibility of controlling the association of resources, assigned to said hierarchical level of said administrative entity, to lower levels of said administrative entity. AMENDED CLAIMS

[received by the International Bureau on 9 October 2001 (09.10.01); original claims 1-20 replaced by new claims 1-18 (4 pages)]

1. A method for controlling resources in a communication network comprising nodes interconnected by links, each carrying a bitstream that is divided into frames, each frame in turn being divided into time slots- that are allocatable to form circuit-switched channels, said method comprising: associating resources in the form of write access to time slots with administrative entities, or vice versa, said administrative entities being defined network using entities that are structured in a hierarchical manner; and allocating resources in such a way that: allocation of resources to channels pertaining to a subject administrative entity is_ guaranteed to the extent by which resources have been associated with the subject administrative entity, and allocation of resources to channels pertaining to a hierarchical level of an administrative entity shall be guaranteed to the extent that resources are associated with said hierarchical level of said administrative entity.

4. A method as claimed in claim 3, wherein said step of determining, when establishing a channel, which administrative entity that said channel pertains to comprises : receiving a channel establishment request; and deriving, from said channel establishment request, information designating which administrative entity that said request^' pertains to.

5. A method as claimed in claim 1, said allocating step comprising allocating resources in such a way that resources associated with a hierarchical level of an administrative entity are only allocatable to channels that pertain to said or hierarchical level, or to sublevels thereof, of said administrative entity.

6. A method as claimed in claim 1 or 5, said allocating step comprising: determining, when establishing a channel, which administrative entity, and which hierarchical level thereof, that said channel pertains to; and determining if there exists resources that are associated with said hierarchical level, or to a supralevel thereof, of said administrative entity and that are not allocated to already established channels pertaining to said hierarchical level, or to a supralevel thereof, of administrative entity and, if such resources exists, enabling said resources to be allocated to said channel .

7. A method as claimed in any one of claims 1-6, said associating step comprises associating each time slot with an administrative entity.

8. A method as claimed in any one of claims 1-6, said associating step comprising associating an administrative entity with a number of non-explicitly identified time slots.

9. A method as claimed in any one of claims 1-6, said associating step comprising associating an administrative entity with a number of explicitly identified time slots .

10. A method as claimed in any one of claims 1-9, wherein said step of associating administrative entities with resources in the form of time slots is performed on a link by link basis, enabling configuration of different resource distributions on different links.

11. A method as claimed in any one of claims 1-9, wherein said step of associating an administrative entity with resources in the form of write access to time slots is performed on an overall network basis, the same amount of resources being associated to said administrative entity on all links of the network.

12. A method as claimed in any one of claims 1-9, wherein said step of associating an administrative entity with resources in the form of write access to time slots is performed on a network path basis, the same amount of resources being associated to said administrative entity on all links following said network path.

13. A method as claimed in any one of claims 1-12, wherein said links are logical links, each being defined by one or more physical links that are configured in series to form a unidirectional medium forwarding a frame of time slots in the downstream direction.

14. A method as claimed 'in any one of claims 1-12, wherein said links are physical links, each interconnecting neighbor nodes.

15. A method as claimed in any one of claims 1-14, wherein said step of associating resources with administrative entities is controlled at each node;based upon instructions received from a network management system communicating with said node.

16. A method as claimed in any one of claims 1-14, wherein said step of associating resources with administrative entities is controlled at each node based messages exchanged between using an in-band resource distribution protocol supported by the nodes .

17. A method as claimed in any one of claims 1-14, wherein an administrative entity refers to at least one of an operator, a service provider, a customer, and an end user.

18. A method as claimed in any one of claims 1-17, including providing a hierarchical level of an administrative entity with the possibility of controlling the association of resources, assigned to said hierarchical level of said administrative entity, to lower levels of said administrative entity.