JPH06188908A - Packet transfer system - Google Patents

Abstract

PURPOSE:To satisfy a desired delay time by referring to preserved delay times to determine a route corresponding to a designated delay time at the time of a request of packet transfer which designates this delay time. CONSTITUTION:Delay times required to transfer packets from each packet switchboard 100 to destinations through designated routes are periodically collected to this switchboard 100 and are preserved in a delay time collecting means 101 correspondingly to respective routes. When packet transfer designating a desired delay time is requested from a packet terminal PT 200, a line attribute determining part 125 receives and analyzes it through a line correspondence part 1141. A route attribute table 123213 is referred to extract delay time values corresponding to routes, and they are compared with the desired transfer delay time. As the result of comparison, a determining part 102 refers to the collecting means 101 to determine a route corresponding to the desired delay time value and reports it to a line selecting part 121. Thus, the transfer route satisfying the desired transfer delay time is set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packet transfer system in a packet switching network having a plurality of packet switches.

[0002]

2. Description of the Related Art FIG. 6 is a diagram showing an example of a conventional packet switching network, and FIG. 7 is a diagram showing an example of a packet switching device in FIG.

The packet switching network shown in FIG. 6 has a plurality of (four in FIG. 6) packet switches (1) (individual packet switches are referred to as (1 ₁ ) to (1 ₄ )).
And a trunk line (2) for connecting the packet switches (1) to each other (the trunk line connecting the packet switches (1 ₁ ) and (1 ₂ ) is referred to as (2 ₁₂ ), and so on). Has been done.

Each packet switch (1) is shown in FIG.
, Each relay line (2) connecting to another packet switch (1) and the packet terminal (PT) (3)
It is composed of a line corresponding part (11) provided corresponding to each subscriber line (4) accommodating each line and a common part (12) provided commonly to each line corresponding part (11). The line interface (11) performs a communication control function with the corresponding packet terminal (PT) (3) or the packet switch (1 _A ), and the common unit (12) performs the packet switch control function and maintenance operation. Perform a function.

Further, in the common unit (12), a common route selection unit (121) and each packet terminal (PT) are provided.
A route attribute table (122) provided corresponding to (3) is provided.

In each path attribute table (122), the packet transfer paths that can be set when transferring a packet to each of the other packet switches (1) have a short packet transfer delay time, that is, the packet switch (1). The routes are shown in order from the one with the smallest number of relay stages, and when the call setting request is generated from the accommodated packet terminal (PT) (3), the route selection unit (121) is the packet terminal (call source of the call setting request source). PT)
By referring to the route attribute table (122) corresponding to (3), the packet transfer route shown in the route attribute table (122) is set as the packet transfer route.

For example, a packet terminal (PT) (3 _1X ) accommodated in the packet switch (1 ₁ ) transfers a packet to a packet terminal (PT) (3 _3Y ) accommodated in the packet switch (1 ₃ ). for, when sending a call request packet CR to the packet switch (1 ₁₎ via a subscriber line (4 _1X), in the packet switch (1 _1), the common unit (12) is a subscriber line (4 a call request packet CR which is transferred via the _1X), receives and analyzes via the line interface (11 _41X), when identifying the Chakukyoku packet switch (1 _3), packet terminal (PT) ( Route attribute table (122 _41X ) provided in the common part (12) corresponding to 3 _1X )
, The packet transfer route to the packet switch (1 ₃ ) is extracted and notified to the route selection unit (121).

Thereafter, the route selection unit (121) follows the notified packet transfer route to the originating packet terminal (PT).
When the call setup process between the (3 _1X ) and the incoming packet terminal (PT) (3 _3Y ) is executed and the call setup process is completed, the data packet DT transferred from the outgoing packet terminal (PT) (3 _1X ) Is transferred to the incoming packet terminal (PT) ( _33Y ) via the set packet transfer path.

[0009]

As is clear from the above description, in the conventional packet switching network, each packet terminal (PT) accommodated in each packet switching device (1) is accommodated.
A route attribute table (122) is provided corresponding to (3), and a packet transfer route to another packet switch (1) is stored in advance in the route attribute table (122), and a packet terminal (PT) ( Every time a packet transfer request is generated from 3), the packet transfer path extracted from the path attribute table (122) is set and the packet is transferred. Therefore, the packet transferred from the packet terminal (PT) (3) The transfer route was constant.

However, one packet terminal (PT)
The packet transfer set to the same route from (3 _1X ) does not always require the same transfer delay time, and even if the packet transfer delay time is not so short, the same is the same. There was a problem that the packet transfer route of was set.

Since the transfer delay time of each packet transfer route varies depending on the degree of congestion of the route, the route attribute table (1
Even if the packet transfer route specified in 22) is used, there is a problem that the expected transfer delay time is not always provided depending on the degree of congestion.

An object of the present invention is to make it possible to set a packet transfer route which satisfies a desired transfer delay time for each packet transfer request.

[0013]

FIG. 1 is a diagram showing the principle of the present invention. In FIG. 1, reference numeral 100 denotes a plurality of packet switches constituting a packet switching network to which the present invention is applied.
A packet terminal (PT) 00 is accommodated in the packet switch (100).

Reference numeral 101 is a delay time collecting means provided in the packet switch (100) according to the present invention. 10
2 is a route determining means provided in the packet switch (100) according to the present invention.

[0015]

The delay time collecting means (101) periodically collects the delay time required to transfer a packet from the own packet switch (100) to each destination packet switch (100) via each designated route. , Each destination packet switch (100) and each route are stored.

The route determining means (102) is a packet terminal (PT) (2) accommodated in its own packet switch (100).
00) requesting packet transfer with a desired transfer delay time specified, the delay time collection means (101) refers to the delay time being saved and determines the delay time being saved that satisfies the desired transfer delay time. The corresponding route is determined as the packet transfer route.

The route determining means (102) is closest to the desired transfer delay time when the delay time being stored by the delay time collecting means (101) does not satisfy the desired transfer delay time. The route corresponding to the time is determined as the packet transfer route, and the delay time during storage corresponding to the determined packet transfer route is set to the requesting packet terminal (PT) (20).
0) is considered.

The route determining means (102) periodically refers to the delay time being stored in the delay time collecting means (101) even after the packet transfer route is determined, and the delay time corresponding to the packet transfer route is transferred. When the delay time is no longer satisfied, it is considered to redetermine the packet transfer route.

Further, the route determining means (102) sets in advance a maximum number of calls that allows packet transfer simultaneously via each route, and sets the maximum number of calls to a route corresponding to a delay time satisfying a desired transfer delay time. When the call is already set, it is considered to determine the route corresponding to the forwarding delay time being stored, which exceeds the desired forwarding delay time and is as close to the desired forwarding delay time as the packet forwarding route.

Therefore, when the packet terminal accommodated in the packet switching network specifies a desired transfer delay time when making a packet transfer request, a packet transfer path that satisfies the desired transfer delay time is set as much as possible. Further, the transfer delay time of the set packet transfer route can be notified to the packet terminal, and the service level of the packet switching network is greatly improved.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 2 is a diagram showing a packet switching network according to an embodiment of the present invention, FIG. 3 is a diagram showing an example of a packet with a transfer delay selection / display facility, and FIG. 4 is an example of a packet switching device in FIG. FIG. 5 is a diagram showing an example of the route attribute table in FIG. The same reference numerals denote the same objects throughout the drawings.

2 and 4, a packet switch (1 _A ) is provided as the packet switch (100) in FIG. 1, and a packet terminal (PT) (3) is provided as the packet terminal (PT) (200) in FIG. )
Is provided, and the delay time collecting means (10
1), the delay time collecting unit 124 is a common unit 1
2 _A ) and as the route determining means (102) in FIG. 1, a route attribute determining unit (125), a delay time value notifying unit (126), a call number limiting unit (127) and a decision updating unit (128). Is provided in the common section (12 _A ) and further includes delay time collecting means (101) and route determining means (1
02), a route attribute table (123) is provided in the common unit (12 _A ) corresponding to each destination.

The packet switching network shown in FIG. 2 is also composed of four packet switching devices (1 _A ) as in FIG. 6, but each packet switching device (1 _A ) is shown in FIG. Unlike the conventional packet switch (1), FIG.
It has a structure as shown in FIG.

As shown in FIG. 4, the packet switch (1 _A ) includes a plurality of line corresponding parts (11) respectively accommodating a subscriber line (4) or a trunk line (2) and a common part (1).
2 _A ) and the common unit (12 _A ) includes a route selection unit (121) and a delay time collection unit (12 _A ).
4), a route attribute determining unit (125), a delay time value notifying unit (126), a call number limiting unit (127) and a decision updating unit (128), respectively, and a route attribute table (123). However, one packet switching device is provided for each of the other packet switching devices in the packet switching network [packet switching devices (1 _A2 ), (1 _A3 ) and (1 _A4 ) when viewed from the packet switching device (1 _A1 )].

In FIG. 4, the packet switch (1
_A1 ) is illustrated and the subscriber line (4 _1X ) [where X is 1
To N]], the line interface corresponding to (1
1 _41X ), trunk lines (2 ₁₂ ), (2 ₁₃ ), and (2 ₁₄ ) are referred to as (11 ₂₁₂ ), (11 ₂₁₃ ), and (11 ₂₁₄ ), and the packet switch (1 _A2 ), Each route attribute table provided corresponding to
3 ₂₁₂ ), the route attribute tables provided for the packet switch (1 _A3 ) (123 ₂₁₃ ), and the route attribute tables provided for the packet switch (1 _A4 ) (1 ₂₁₃ ).
23 ₂₁₄ ).

The route attribute table (123 ₂₁₂ ) stores (A ₂ ) indicating the packet switch (1 _A2 ) as the destination,
In addition, the packet switch (1 _A1 ) to the packet switch (1 _A1 )
Five types of routes (D ₁₂₁ ) to (D ₁₂₅ ) are stored as routes to _A2 ).

The route (D ₁₂₁ ) is a route from the packet switch (1 _A1 ) to the packet switch (1 _A2 ) directly via the trunk line (2 ₁₂ ), and the route (D ₁₂₂ ) is the packet switch ( 1 _A1 ) to the packet switch (1 _A2 ) via the trunk line (2 ₁₄ ), the packet switch (1 _A4 ) and the trunk line (2 ₂₄ ), and the route (D ₁₂₃ ) is
Packet switch (1 _A1) from the trunk line _(213), a route to the packet switch (1 _A3) and trunk (2 ₂₃₎ via a packet switch (1 _A2), the path (D ₁₂₄₎
From the packet switch (1 _A1 ) to the packet switch (1 ₁₄ ) via the trunk line (2 ₁₄ ), the packet switch (1 _A4 ), the trunk line (2 ₃₄ ), the packet switch (1 _A3 ) and the trunk line (2 ₂₃ ). 1 _A2 ), and the route (D ₁₂₅ ) is from the packet switch (1 _A1 ) to the trunk line (2 ₁₃ ), the packet switch (1 _A2 ), the trunk line (2 ₃₄ ), and the packet switch (1 _A4 ).
And the route to the packet switch (1 _A2 ) via the trunk line (2 ₂₄ ).

Further, in the route attribute table (123 ₂₁₂ ), the delay time values (C ₁₂₁ ) to (C ₁₂₁ ) measured by the delay time collecting unit (124) are associated with the routes (D ₁₂₁ ) to (D ₁₂₅ ). C ₁₂₅ ) and the priority (E) [details undecided] defined corresponding to each of the routes (D ₁₂₁ ) to (D ₁₂₅ ) are stored.

The route attributes (B ₁₂₁ ) to (B ₁₂₅ )
Are the paths (D ₁₂₁ ) to (D ₁₂₅ ) and the delay time value (C
₁₂₁ ) to (C ₁₂₅ ) and priorities (E). A route attribute table (123 ₂₁₃ ) with the packet switch (1 _A3 ) as the destination (A ₃ ) and the packet switch (1 _A4 )
The route attribute table (123 ₂₁₄ ) for the destination (A ₄ ) is also the route attribute table (123 ₂₁₂ ) as shown in FIG.
It has the same configuration as.

On the other hand, the delay time collecting unit (124) is periodically provided in the common unit (12 _A ) of the other packet switches (1 _A2 ), (1 _A3 ) and (1 _A4 ). For the delay time collection unit (124), the routes ( _D121 ) to ( _D125 ), ( _D131 ) to ( _D135 ), and (D
₁₄₁ ) to (D ₁₄₅ ) are designated, and a delay time measurement packet XY predetermined for measuring the transfer delay time is specified.
Is added with the transmission time and transmitted.

The transmitted delay time measurement packet XY
Are designated routes (D ₁₂₁ ) to (D ₁₂₅ ), (D
₁₃₁ ) to (D ₁₃₅ ) or (D ₁₄₁ ) to (D ₁₄₅ ) respectively, the common part (12 _A ) of the destination packet exchanges (1 _A2 ), (1 _A3 ) and (1 _A4 ).
It is transmitted to the delay time collection unit (124) provided therein.

Each delay time collection unit (124) that has received the delay time measurement packet XY adds the reception time to the received delay time measurement packet XY, and then collects the delay time of the source packet switch (1 _A1 ). The part (124) is returned as the destination.

Packet switch (1_A1) Delay time collection unit
(124) is each packet switch (1_A2), (1_A3) Oh
And (1_A4) Common part (12_A) Returned from
Inter-measuring packet XY is received and analyzed and added
Based on the transmission time and the reception time, the packet switch (1
_A1) To each packet switch (1_A2), (1_A3)and
(1_A4) To each specified route (D₁₂₁) Or
(D₁₂₅), (D₁₃₁) To (D₁₃₅), Or (D
₁₄₁) To (D₁₄₅) If the packet was forwarded via
The transfer delay time is measured and the corresponding route attribute
Table (123₂₁₂), (123₂₁₃) And (12
Three₂₁₄), The delay time value (C₁₂₁) To (C
₁₂₅), (C₁₃₁) To (C₁₃₅), And (C₁₄₁)
Through (C₁₄₅) Is stored (updated).

On the other hand, when the call request packet CR is transmitted to the packet terminal (PT) (3) accommodated in the packet switching network, as shown in FIG. It is possible to add a transfer delay selection / display facility (FY) that specifies the packet transfer delay time up to (3), and the International Telegraph and Telephone Consultative Committee (CCIT)
T25) in X25 (1984 version and later).

In this state, for example, the packet switch (1
A packet terminal (PT) (3 _1X ) accommodated in _A1 ) is a packet terminal (P) accommodated in the packet switch (1 _A3 ).
To T) (3 _3Y), if desired the transfer of packets within transfer delay time (T _13), the call request obtained by adding the forward delay select / display facility the desired forward delay time (T ₁₃₎ (FY) A packet CR is created and transmitted to the packet switch (1 _A1 ) via the subscriber line (4 _1X ).

In the packet switch (1 _A1 ), the route attribute determination unit (125) in the common unit (12 _A ) transfers the call request packet CR transferred via the subscriber line (4 _1X ).
Is received and analyzed through the line _interface (11 _41X ), the transfer delay selection / display facility (FY) = (T ₁₃ ) is recognized, and the incoming packet terminal (P
T) (3 _3Y) address (DN _3Y) from Chakukyoku the packet switch (1 _A3) and upon identifying, packet switch (1 _A3)
The route attribute table (123 ₂₁₃ ) provided in the common part (12 _A ) corresponding to (3 _3Y ) is referred to, and stored corresponding to each route (D ₁₃₁ ) to (D ₁₃₅ ). The delay time values (C ₁₃₁ ) to (C ₁₃₅ ) are extracted and compared with the desired transfer delay time (T ₁₃ ).

As a result of the comparison, the desired transfer delay time (T₁₃)
The longest delay time value [eg (C₁₃₃)]
Is selected, the route attribute determination unit (125) causes the delay time value
(C ₁₃₃) Corresponding route (D₁₃₃), That is, packet exchange
Exchange (1_A1) To the trunk line (2 ₁₄), Packet switch (1
_A4) And trunk lines (2₃₄) Via packet switch
(1_A3) To the originating packet terminal (PT) (3
_1X) From the incoming packet terminal (PT) (3_3Y)
It is determined that the packet DT is to be transferred, and the path selection unit (12
1) and notify the desired transfer delay time (T₁₃)
Notify the route selection unit (121).

The route selection unit (121) is a route attribute determination unit.
Route (D) notified from (125) ₁₃₃) Based on
Ket terminal (PT) (3_1XCall request packet received from
The call setup process for the CR
End (PT) (3_1X), The connection completion packet CC is returned to
At this time, as shown in FIG. 3, from the route attribute determination unit (125)
The desired transfer delay time (T₁₃), Transfer delay selection
/ Display facility (FY) is added.

The originating packet terminal (PT) (3 _1X ) observes the transfer delay selection / display facility (FY) = (T ₁₃ ) added to the connection completion packet CC returned from the packet switch (1 _A1 ). By doing so, it is confirmed by the call request packet CR that packet transfer satisfying the desired transfer delay time (T ₁₃ ) is executed.

When the call setting process between the source packet terminal (PT) (3 _1X ) and the destination packet terminal (PT) (3 _3Y ) is completed, the call is transferred from the source packet terminal (PT) (3 _1X ) thereafter. The data packet DT passes through the set packet transfer path (D ₁₃₃ ) and arrives at the incoming packet terminal (P
T) (3 _3Y ).

The delay time value (C ₁₃₁ ) extracted from the route attribute table (123 ₂₁₃ ) by receiving and analyzing the call request packet CR with the transfer delay selection / display facility (FY) = (T ₁₃ ). or (C ₁₃₅₎ as compared to the packet switch path attribute determination unit (1 _A1) is (125), a delay time value which satisfies within desired forward delay time (T ₁₃₎ (C)
If the route cannot be selected, the route attribute determination unit (12
5) is longer than the desired forward delay time (T _13), the most delay time value close to the desired forward delay time (T ₁₃₎ [for example (C
_The route (D ₁₃₁ ) corresponding to ₁₃₁ ), that is, the shortest route from the packet switch (1 _A1 ) to the packet switch (1 _A3 ) via the trunk line (2 ₁₃ ) is the originating packet terminal (PT).
(3 _1X ) determines the route for transferring the data packet DT to the incoming packet terminal (PT) (3 _3Y ), notifies the route selection unit (121), and notifies the delay time value (C ₁₃₁ ) to the route selection unit ( 121).

The route selection unit (121) is a route attribute determination unit.
Route (D) notified from (125) ₁₃₁) Based on
Ket terminal (PT) (3_1XCall request packet received from
The call setup process for the CR
End (PT) (3_1X), The connection completion packet CC is returned to
At the time of delay notified from the route attribute determination unit (125)
Interval value (C₁₃₁), Transfer delay selection / display facility
It is added as (FY).

The originating packet terminal (PT) (3 _1X ) observes the transfer delay selection / display facility (FY) = (C ₁₃₁ ) added to the connection completion packet CC returned from the packet switch (1 _A1 ). By doing so, it is recognized by the call request packet CR that packet transfer is executed with a delay time value (C ₁₃₁ ) close to the desired transfer delay time (T ₁₃ ).

Furthermore, the packet terminal (PT) (3 _1X )
In particular, when it is desired to transfer a packet without specifying a transfer delay time (T ₁₃ ), a call request packet CR without a transfer delay selection / display facility (FY) is created,
It transmits to the packet switch (1 _A1 ) via the subscriber line (4 _1X ).

In the packet switch (1 _A1 ), the route attribute determining unit (125) in the common unit (12 _A ) receives and analyzes the transferred call request packet CR in the same manner as described above, and delays transfer. Recognizing that the selection / display facility (FY) is not added, and the incoming packet terminal (P
T) (3 _3Y) address (DN _3Y) from Chakukyoku the packet switch (1 _A3) and upon identifying, packet switch (1 _A3)
By referring to the route attribute table (123 ₂₁₃ ) provided in the common part (12 _A ) corresponding to (3 _3Y ), each route attribute (B
₁₃₁ ) to ( _B135 ), the stored delay time values ( _C131 ) to ( _C135 ) are extracted, the longest delay time value [for example ( _C135 )] is selected, and the delay time value is selected. (C
₁₃₅ ) corresponding to the route (D ₁₃₅ ), that is, from the packet switch (1 _A1 ) to the trunk line (2 ₁₄ ), the packet switch (1 _A4 ), the trunk line (2 ₂₄ ), the packet switch (1 _A2 ), and the trunk line ( _{2 A} ). 2 ₂₃ ) via packet switch (1 _A3 )
Data packet D from the source packet terminal (PT) (3 _1X ) to the destination packet terminal (PT) (3 _3Y ).
It is determined that T is the route to be transferred, and the route selection unit (121) is notified.

The route selection unit (121) is a route attribute determination unit.
Route (D) notified from (125) ₁₃₃) Based on
Ket terminal (PT) (3_1XCall request packet received from
The call setup process for the CR
End (PT) (3_1X), The connection completion packet CC is returned to
In this case, transfer delay selection / display facility (FY) is added
do not do.

As is clear from the above description, according to this embodiment, the originating packet terminal (PT) (3 _1X ) selects / displays the desired transfer delay time (T ₁₃ ) in the call request packet CR. When sent to the facility (FY) added to the packet switch (1 _A1) as the packet switch (1 _A1) is the path leading to the incoming packet switch (1 _A3) (D
₁₃₁ ) to ( _D135 ), the desired transfer delay time (T
Path (D ₁₃₃ ) having a delay time value (C ₁₃₃ ) satisfying ₁₃ )
₁₃₃ ) is determined as the packet transfer route by the call request packet CR, and when the delay time value that satisfies the desired transfer delay time (T ₁₃ ) is not obtained, the maximum desired transfer delay time (T ₁₃ ) is set. A route (D ₁₃₁ ) having a close delay time value (C ₁₃₁ ) is determined as a packet transfer route according to the call request packet CR, and the originating packet terminal (PT) is further determined.
To (3 _1X) is a call request packet CR, and send to the transfer delay selection / display facility without adding (FY) packet switch (1 _A1), packet switch (1 _A1) incoming packet switch (1 _A3) in Route (D ₁₃₁ ) to (D
_The route (D ₁₃₅ ) having the longest delay time value (C ₁₃₅ ) out of ₁₃₅ ) is determined as the packet transfer route by the call request packet CR.
T) Packet transfer satisfying the desired transfer delay time of (3 _1X ) or packet transfer satisfying the desired transfer delay time can be realized.

It is to be noted that FIGS. 2 to 5 are merely examples of the present invention until now. For example, for packet transfer, a packet terminal (PT) (3 _1X ) accommodated in the packet switch (1 _A1 ).
And the packet terminal (PT) (3 _3Y ) accommodated in the packet switch (1 _A3 ) are not limited to these, and many other modifications are considered. In this case, the effect of the present invention does not change. Further, the packet switch (100) to which the present invention is applied is not limited to the illustrated packet switch (1 _A ), and various modifications can be considered. In any case, the effect of the present invention Does not change. Further, the configuration of the packet switching network which is the object of the present invention is not limited to that shown in the figure, and many other modifications can be considered, but in any case, the effect of the present invention does not change.

The packet switching network to which the present invention is applied is not limited to the one for transferring the packets between the packet terminals (PT) (3) shown in the figure, but the packet transfer between the packet switching networks. A number of other modifications such as a packet switching network for realizing the above are considered, but in any case, the effect of the present invention does not change.

Further, the route attribute determining section (125) only compares the desired transfer delay time (T) designated by the transfer delay selection / display facility (FY) with the delay time value (C), and the route (D). The reference call number (F) is set and set corresponding to each route (D), and the call number limiting unit (1) is set in the route attribute determining unit (125).
27) is added, and if the number of calls less than the reference number of calls (F) has been set, the corresponding route (D) can be determined for packet transfer. When the setting has been completed, by selecting the path (D) having the delay time value (C) longer than the corresponding path (D) to the set number of calls less than the reference number of calls (F), Many other modifications, such as distributing the load on each path (D), are considered, but the effect of the present invention does not change in any case.

Further, the route attribute determining section (125) determines the packet transfer route by referring to the route attribute table (123) only at the call setting stage when the call request packet CR is received, and the set call is released thereafter. The packet transfer is not limited to the one in which the packet transfer is executed on the same route (D) until the end of the call, and the desired transfer delay time (T) is held for each call during the packet transfer after the call is set, and the route attribute is set. The decision updating unit (128) is added to the decision unit (125), and the desired transfer delay time (T) and each delay time value (C) of the corresponding route attribute table (123) are cyclically set even after call setup. And when the delay time value (C) corresponding to the route (D) being set cannot satisfy the desired transfer delay time (T), a route (newly satisfying the desired transfer delay time (T) ( The procedure to re-determine D) is established,
A number of other modifications such as allowing the packet transfer route to be updated even during call setup by this procedure are considered, but the effect of the present invention does not change in any case.

[0052]

As described above, according to the present invention, in the packet switching network, when the packet terminal accommodated in the packet switching network specifies the desired transfer delay time when making a packet transfer request, the desired transfer delay time is set. Will be set as much as possible, and the transfer delay time of the set packet transfer path can be notified to the packet terminal, and the service level of the packet switching network will be greatly improved.

[Brief description of drawings]

FIG. 1 is a diagram showing the principle of the present invention.

FIG. 2 is a diagram showing a packet switching network according to an embodiment of the present invention.

FIG. 3 is a diagram showing an example of a packet with transfer delay selection / display facility.

FIG. 4 is a diagram showing an example of a packet switch in FIG.

5 is a diagram showing an example of a route attribute table in FIG.

FIG. 6 is a diagram showing an example of a conventional packet switching network.

7 is a diagram showing an example of the packet switch in FIG.

[Explanation of symbols]

1, 1 _A , 100 Packet Switch 2 Relay Line 3, 200 Packet Terminal (PT) 4 Subscriber Line 11 Line Corresponding Part 12, 12 _A Common Part 101 Delay Time Collecting Means 102 Route Determining Means 121 Route Selectors 122, 123 Routes Attribute table 124 Delay time collection unit 125 Route attribute determination unit 126 Delay time value notification unit 127 Call number restriction unit 128 Decision update unit

Claims (4)

[Claims] 1. In a packet switching network comprising a plurality of packet switching devices (100), each destination packet switching device (100) is sent to each packet switching device (100) via each route designated by the own packet switching device (100). A delay time collecting means (101) for periodically collecting the delay time required to transfer a packet to the destination packet switch (100) and storing the delay time corresponding to each destination packet switch (100) and each route; and its own packet switch (100). When the packet terminal (PT) (200) accommodated in the server requests a packet transfer with a desired transfer delay time specified, the delay time collecting means (101) refers to the delay time being stored, Route determining means (102) for determining a route corresponding to the delay time during storage satisfying a desired transfer delay time as a packet transfer route. Packet transfer method according to claim. 2. The route determining means (102) is configured to store the delay time in the delay time collecting means (101).
If the desired transfer delay time is not satisfied, the path corresponding to the delay time being stored that is closest to the desired transfer delay time is determined as the packet transfer path, and the storage corresponding to the determined packet transfer path is determined. 2. The packet transfer system according to claim 1, wherein the requesting packet terminal (PT) (200) is notified of the intermediate delay time. 3. The route determining means (102) further comprises the delay time collecting means (10) even after determining the packet transfer route.
The delay time being stored in 1) is periodically referred to, and when the delay time corresponding to the packet transfer path does not satisfy the desired transfer delay time, the packet transfer path is determined again. The packet transfer method according to claim 1. 4. The route determining means (102) sets in advance a maximum number of calls for which packet transfer is permitted via each of the routes, and corresponds to the delay time satisfying the desired transfer delay time. When the maximum number of calls has already been set in the route, the route corresponding to the stored transfer delay time that exceeds the desired transfer delay time and is as close as possible to the desired transfer delay time is determined as the packet transfer route. The packet transfer system according to claim 1, wherein