WO2000051396A1

WO2000051396A1 - Method for determining a communication path in a communication network between two neighboring network nodes

Info

Publication number: WO2000051396A1
Application number: PCT/DE2000/000315
Authority: WO
Inventors: Clemens Hauber
Original assignee: Siemens Aktiengesellschaft
Priority date: 1999-02-24
Filing date: 2000-02-02
Publication date: 2000-08-31
Also published as: DE19907923C2; DE19907923A1; CA2364707A1; EP1157586A1

Abstract

In order to authorize a connection between two neighboring network nodes (N1, N4) in a connecting line bundle (TG) consisting of several connecting lines, a search algorithm determines on which of the connecting lines (T1,..., Tn) can the connection still be established. To this end, said new connection is initially classified. In accordance with said classification, different search cycles are executed to detect a connection line with sufficient free residual transmission capacity. The connection is rejected in case of an unsuccessful search.

Description

description

Method for determining a connection path in a communication network between two neighboring network nodes.

The invention relates to a method according to the preamble of claim 1.

Contemporary communication networks have a plurality of network nodes which are interlinked via connection paths. These are formed from several connection lines (trunks), which are combined to form connection line bundles (trunk groups).

In modern communication networks, different traffic mixtures are routed via the connection paths arranged between two or more network nodes. For example, information can be transmitted using a synchronous (STM) or asynchronous (ATM) transfer mode. The information can have different bandwidths. As a rule, information that is transmitted as narrowband signals is distinguished from information that is transmitted as wide-band or broadband signals. The connection between two neighboring, i.e. network nodes connected to one another via a bundle of connecting lines are of particular importance.

In general, two decisions have to be made when establishing a connection in order to determine a connection path between two neighboring network nodes. On the one hand, a decision must be made on which of the connecting lines of the connecting line bundle which connects the network nodes in question still has sufficient capacity to be able to establish a connection.

On the other hand, one of the connection paths conceivable with regard to the available capacity should be selected in such a way that optimal traffic quality (grade of service) results. This is necessary because a selected connection path should ensure the lowest possible probability of blocking (blocking probability) and the associated low probability of connection loss (connection loss probability) for subsequent connections.

A procedure with which these two tasks (search and selection) can be carried out is referred to as a search strategy process or search strategy (hunting strategy).

From the publication “Probability of Loss of Data Traffics with different Bit Rates Hunting One Common PCM Channel, Proceedings of 8 ^th International Teletraffic Congress (ITC 8), 1976, pp. 525.1 - 525.8, Lothar Katzschner, and Reinhard Scheller ", such a search strategy method is known.

Accordingly, a sequential search of all connecting lines in question is carried out. An attempt is made to determine the "smallest gap" that the new connection can just take up. The search process is started with the first connection line in the connection line bundle and continues step by step until all connection lines have been checked. The selection criterion is firstly the still available transmission capacity on the connection line is used in relation to the peak bit rate of the connection to be accommodated. It is examined whether the freely available transmission capacity is greater than or equal to the peak bit rate of this connection. In practice, several connection lines can meet this criterion it is then determined on which of these connecting lines the lowest remaining transmission capacity would remain if the new connection was accepted. The new connection is accepted on this connecting line. If sufficient free transmission capacity is not found , the connection in question is rejected. This known method was developed in particular for a homoge ^¬ ne traffic characteristic, where each connection setup s was accompanied kbit having the same capacity requirement of 64 / per connection. However, this homogeneity of traffic when establishing a connection is often no longer present in modern communication networks. In addition to the conventional narrowband connections with 64kbit / s, there are, for example, broadband connections with nx64 kbit / s (in the case of STM-based connection-oriented multiple rate services) or even broadband connections with any bit rate granularity in the case of ATM traffic.

However, this creates completely new requirements for establishing a connection. So the traffic performance for all types of traffic must be as high and as robust as possible with the least possible mutual interference. In the case of ATM traffic, this results in the demand for a load distribution that is as uniform as possible across all connecting lines of a connecting line bundle. Otherwise, connections on heavily used trunk lines would experience a longer delay in the associated queues than on low-capacity trunk lines.

The known search strategy method has the disadvantage that when the trunk group is heavily loaded, in the event that a connection of a high-bit-rate connection is requested, this may be necessary. can no longer be accepted because there are many gaps, but none are large enough. In addition, an uneven load distribution (“unbalanced load”) results, in particular when the connecting line bundle is under low load.

The invention has for its object to show a way how connection paths can be determined in a communication network even with inhomogeneous traffic. The object is achieved on the basis of the features specified in the preamble of patent ^claim 1 by the features specified in the characterizing part.

The provision of a new search strategy is particularly advantageous in the invention. The search to ensure the largest gaps for high bit rate connections leads to excellent results in terms of blocking probability and load distribution. This clearly exceeds the search used in the state of the art to find the smallest suitable gap.

Advantageous developments of the invention are specified in subclaim 2.

The invention is explained in more detail below with reference to an exemplary embodiment shown in the figures.

Show it:

1 shows the configuration on which the method according to the invention is carried out; FIG. 2 shows the search algorithm according to the invention

A communication network is shown in FIG. For the sake of simplicity, only 4 network nodes Nι ... N are shown. Two network nodes, for example the network nodes Ni, N _4, are connected to one another via a connecting line bundle TG. A plurality of connecting lines Tι ... T _n are arranged in the connecting line bundle TG. Each of the connecting lines Tι ... T _n has a specified transmission capacity C _s as the physical transmission parameter. The residual transmission capacity C _r (Ti) (i = l ... n) freely available for further connections results from the physical transmission capacity C _s minus the sum the peak bit rates R _p - of the currently connected m connections (j = 1, 2 ..., m).

In the following it is assumed that a connection V from the network node Ni to the network node N _{4 is} to be established.

The corresponding relationships are shown in Fig. 2.

Accordingly, the connections are first classified into the highest bit rate and not the highest bit rate connections HBR, N-HBR. The criterion for which connections are to be regarded as highest bit rate is e.g. B. specified by the corresponding service. In the following, the connecting lines Tι ... T _{n are} then examined to determine whether the new connection V can be accommodated. Depending on the connection of the connection V to the classes HBR, N-HBR, a different search strategy is used.

In general, the search strategy is started with the first connection line Ti of the connection line bundle TG and always ends with the last connection line T _n for connections with the highest bit rate after a search cycle, for connections with the highest bit rate after one or two search cycles.

A connection V of the highest bit rate belonging to the class HBR is accepted on one of the connection lines T _ι ... T _n when its free residual transmission capacity exceeds the peak bit rate of the connection V the most. The new connection V is thus sorted into the "largest gap". As can be seen from FIG. 2, two criteria are thus required for the sorting. Firstly, the freely available residual transmission capacity of the connection line Ti just examined must be greater than or equal to the peak bit rate of the new connection V. On the other hand, the free residual transmission capacity must exceed the peak bit rate of the new connection V most, for this purpose a variable C _r _Last_ Optimum is introduced, in which the largest value just determined is always entered In the HBR class, the search always ends after a search cycle.

If the new connection V is a connection which is not at the highest bit rate and is assigned to the class N-HBR, then it is accepted on one of the connection lines Tι ... T _n if its free residual transmission capacity after deducting a multiple as large as possible the peak bit rate Rp (HBR) of the highest bit rate connections (“ensuring the largest gaps for high bit rate connections”) at least exceeds the peak bit rate of the connection V. The new connection V is thus in the “smallest gap after deduction of the largest possible reservation budget for connections of the Class HBR "sorted. As can be seen from FIG. 2, two criteria are thus required for the sorting. On the one hand, the remainder from the modulo division of the freely available residual transmission capacity of the connection line T _x just examined by the peak bit rate of connections with the highest bit rate must be greater than or equal to the peak bit rate of the new connection V. On the other hand, the remainder from modulo division of the free residual transmission capacity by the peak bit rate of connections with the highest bit rate must least exceed the peak bit rate of the new connection V. For this purpose, a variable C _r _Last_Optimum is also introduced, in which the smallest value just determined is always entered. If the search is successful according to the criteria mentioned, the search for a search cycle ends for connections of the class N-HBR that are not at the highest bit rate.

If the new connection V cannot be sorted on any of the connection lines, a second search cycle is started. The connection V is then accepted - without taking into account a reservation budget for connections of the HBR class - on one of the connecting lines Tι ... T _n when its free residual transmission capacity least exceeds the peak bit rate of the connection. The new connection V is thus sorted into the "smallest gap". As shown in FIG. Obviously, two criteria for sorting are required. On the one hand, the freely available residual transmission capacity of the connection line Ti just examined must be greater than or equal to the peak bit rate of the new connection V. Second, the remaining free transmission capacity has the Spit ^¬ zenbitrate the new compound V at least exceed. For this purpose, the smallest just determined value is always entered in the variable C _r _Letzt_Optimum. For connections of the N-HBR class with the highest bit rate, the search ends at the latest after this second search cycle.

In the present exemplary embodiment, connections were generally spoken of. This can be any type of connection. Connections that transmit information using a synchronous transfer method (STM) can thus be set up using the method according to the invention, as can connections that transmit information using an asynchronous transfer method (ATM).

Claims

claims

1. A method for determining a connection path in a communication network, with a plurality of compounds, each of K over a wide ^¬ plurality of connection lines (T I ... T _n) between two adjacent network node are routed (N ₁ ... N ₄₎ , and reserve the transmission capacities (R _P j) on these connecting lines (T _ι ... T _n ), and with at least one further connection (V), which are additionally accommodated on one of the connecting lines (T _ι ... T _n ) is to be determined by a search algorithm on which of the connection lines (Tι ... T _n ) this connection (V) can still be accommodated according to an acceptance criterion, characterized in that a classification of the at least one further connection (V) in two classes (HBR, N-HBR) is carried out, that belonging to a class (HBR) checks whether the freely available residual transmission capacity C _r (Ti) of the verb just examined Indication line (Ti) is greater than or equal to the peak bit rate of the at least one further connection (V) and, in this case, one of the connecting lines determined in this way is chosen to be the one whose remaining free transmission capacity exceeds the peak bit rate of this connection (V) the most, and that if it belongs the remaining class (N-HBR) is checked whether the remainder from the modulo division of the freely available residual transmission capacity C _r (Ti) of the connecting line (i) under investigation is larger by the peak bit rate (Rp (HBR)) of connections with the highest bit rate is equal to the peak bit rate of the at least one further connection (V) and in this case the connection lines determined in this way is used to select the one whose remainder from module division of the free residual transmission capacity by the peak bit rate of the highest bit rate connections the peak bit rate of this connection (V) am at least exceeds, or otherwise a further search cycle is started in which it is checked whether the freely available residual transmission capacity (C _r (Ti)) of the connection line (T) currently being examined is greater than or equal to the peak bit rate of the at least one further connection (V) and in this case among the Connection lines determined in this way are selected whose free residual transmission capacity at least exceeds the peak bit rate of this connection (V).

2. The method according to claim 1, characterized in that a search cycle of the search strategy with the first connecting line (Ti) of the connecting line bundle (TG) is started, applied to all connecting lines (Tι ... T _n ) and with the last connecting line (T _n ) ends.