CN101001113B - A burst packet channel reservation method and device - Google Patents

Abstract

The burst packet channel reservation method and device of the present invention, when a burst packet arrives, obtain the offset time, the length of the packet, and the QoS level, perform parallel searches on multiple channels at the same time, and judge whether there is a burst packet according to the state of each channel The channel satisfies the requirements of the burst packet on the sending start time and sending end time, and if there is, the channel that meets the requirements is reserved. The application of the present invention can improve the efficiency of channel reservation and save channel resources.

Description

A burst packet channel reservation method and device

technical field

The invention relates to the technical field of optical burst switching, in particular to a burst packet channel reservation method and device.

Background technique

With the continuous expansion of the scale of the Internet and the emergence of emerging services, the Internet network business has entered a period of rapid growth. Due to the diversity and variability of services, the traditional core switching network has been difficult to adapt to the needs of Internet development. In order to solve such problems, Optical networking technology was born. At present, the optical network adopts static or dynamic wavelength routing, that is, the Optical Circuit Switching (OCS) mechanism. The OCS mechanism protocol is relatively simple, the technology is mature, and it is easy to implement. But this mechanism is similar to the traditional circuit switching mechanism. It takes a certain amount of time to establish and tear down a channel, and this time has nothing to do with the hold time of its connection, but mainly depends on the end-to-end signaling time. When the connection is kept for a short time, the utilization rate of the inevitable channel will drop, so it is not completely suitable for the Internet with volatile traffic.

For the above problems, Optical Burst Switching (OBS) is a solution. In the OBS network, the basic switching unit is a burst packet (burst), and the burst packet is composed of many IP packets. These IP packets Have the same egress edge router address and the same quality of service (Quality of Service, QoS). The OBS node includes a core node and an edge node. As shown in FIG. 1, it is a schematic diagram of the packet sending process of the edge node of the OBS network in the prior art, including the following steps: Step 101, the edge node enters all kinds of service interfaces with the same The IP grouping of egress edge router address and the same QoS requirements is aggregated into a burst packet; step 102, when the length of the burst packet reaches the data length threshold required by the network, or when the survival time of the burst packet reaches the required time threshold, The edge node will no longer add IP data to the burst packet, and send a burst packet assembly completion signal to the scheduler at the same time, so that the burst packet enters the scheduling queue and caches the burst data packets; step 103, the scheduler sends The control packet corresponding to the burst data packet goes to the core node to reserve a network link, and the core node reserves a link for the corresponding burst packet after receiving the control packet; step 104, the burst data packet in the cache does not need to be The optical/electrical/optical conversion process is directly transmitted from the source node to the destination node in the form of an optical signal through the link reserved in advance by the control packet.

On the physical channel, IP data packets can be transmitted by different wavelengths in the same optical fiber, and in terms of time, the control packet must be sent ahead of the burst data packet for a period of time (this time is called offset time). In the preceding steps, if the reservation of the control packet fails, its corresponding burst data packet will be discarded or sent to other nodes through reflective routing. Therefore, how to find a transmittable channel at the edge node of the OBS to reserve resources is a key issue in the implementation of the OBS network.

In the prior art, the ingress node searches each channel in a certain order until it finds a channel that meets the offset time requirement, and then performs data transmission on this channel. However, after in-depth research, the inventors found that since the first searched channel can not be guaranteed to be used to transmit burst packets, the search period is often longer by sequentially searching for available channels by this method.

Contents of the invention

The method and device for channel reservation of burst packets provided by the present invention can be used to search channels in parallel, shorten the average search time, and improve the efficiency of channel reservation.

In an embodiment of the present invention, a method for reserving a burst packet channel is used for reserving a channel for a burst packet to be transmitted in an optical network. The method includes:

Obtain the offset time reference value and the description information of the burst packet;

calculating the sending start time and sending end time of the burst packet according to the offset time reference value and the description information;

According to the sending start time and the sending end time of the burst packet, all available channels are searched in parallel, and whether there is a channel that can be used to transmit the burst packet;

Send a reservation permission signal to the searched channel that can be used to transmit the burst packet, and reserve the channel.

At the same time, the embodiment of the present invention also provides a burst packet channel reservation device, which includes: an information acquisition module, a channel availability detection module, a channel search module and a reservation module. in:

An information acquisition module, configured to acquire an offset time reference value and description information of burst packets to be transmitted;

A description information processing module, configured to generate a sending start time and a sending end time of the burst packet according to the description information;

A channel search module, configured to perform a parallel search on available channels according to the sending start time and sending end time of the burst packet, and search for a channel that can be used to transmit the burst packet;

A reservation module, configured to reserve a channel searched by the channel search module that can be used to transmit the burst packet.

It can be seen from the above that the application of the technical solution of the present invention can reduce the time of channel search and improve the efficiency of channel reservation

Description of drawings

FIG. 1 is a schematic diagram of a packet scheduling process of an edge node of an OBS network in the prior art;

Fig. 2 is the flowchart of the first embodiment of the burst packet channel reservation method of the present invention;

FIG. 3-A is a schematic diagram of time slot overlap in the second embodiment of the burst packet channel reservation method of the present invention;

FIG. 3-B is a schematic diagram of time slot overlap in the second embodiment of the burst packet channel reservation method of the present invention;

Fig. 3-C is a schematic diagram of channel reservation according to the method of the second embodiment of burst packet channel reservation according to the present invention;

Fig. 4 is a schematic diagram of an embodiment of a burst packet channel reservation device according to the present invention.

Detailed ways

The technical solutions of the optical burst packet channel reservation method and system of the present invention will be further described in detail with reference to the accompanying drawings and embodiments.

The invention provides a channel reservation method for a burst packet, which is used for reserving an optical channel when transmitting a burst packet.

first embodiment

In the embodiment of the present invention, when a burst packet needs to reserve a channel to be sent from the edge router to the center router, multiple channels are searched in parallel at the same time according to the length and offset time of the burst packet, and according to the state of the optical channel, it is judged Whether there is a channel that satisfies the sending requirements of the burst packet, and if so, reserve the channel that meets the requirements to transmit the burst packet.

Please refer to Figure 2, specifically, the steps in this embodiment are:

First proceed to step S11, the edge router receives the burst packet to be transmitted, obtains the offset time reference value and the description information of the burst packet, the description information includes the packet length and quality of service level of the burst packet, and then proceeds Step S12.

In this step S12, it is detected whether there is an available channel in the optical channel between the edge router and the central router. If it is detected as not being an available channel, proceed to step S13.

In this step S13, according to the offset time reference value, the packet length of the burst, and the quality of service level information, the sending start time and the sending end time of the burst packet are obtained, and the method for calculating the sending start time and the sending end time of the burst packet It is a prior art and will not be described in detail here. According to the burst packet sending start time and sending end time, all available channels are searched in parallel to determine whether there is a channel with an available time slot to transmit the burst packet, and then proceed to step S14.

In the step S14, according to the result of the search, a reservation permission signal is sent to the first searched channel available for transmitting the burst packet in the step S13, and the channel is reserved for the transmission of the burst packet. In this embodiment, it also includes and sends a reservation rejection signal to other channels judged to be available for transmitting the burst packet, so as to avoid channel occupation. Obviously, if only one channel is searched or if one channel is found and then the search is stopped, no reservation rejection signal is sent.

Wherein, in this embodiment, the step S14 reserves the first determined channel that can be used to transmit the burst packet. In other embodiments, the step S14 may also be: wait for part or all of the channel judgments to be completed, and select a channel according to a certain selection method for reservation. There are many ways to select a channel for reservation, for example: (1) pre-set the priority of each channel, select a channel with a higher priority to reserve, and the priority can be determined according to the physical performance of the channel, such as physical The channel with the best performance is set as the highest priority. How to judge the physical performance of the channel is a common technology in the field, and will not be described in detail here; (2) the minimum gap selection method, which detects the previous burst packet to be sent in each channel. The end time of sending the burst packet, judge the time gap between the two, and select the channel with the smallest time gap for transmission, so as to save channel resources.

In practical applications, the resource reservation status of each optical channel is represented by a resource link list. In each resource linked list, a node is used to record the sending start time and sending end time of each burst packet data frame sent on the channel. When a new burst packet arrives, search for the time slot that matches the burst packet data frame transmission, and then form a node with the sending start time and sending end time of the new burst packet, and insert it into the optical channel in the resource linked list to complete the resource reservation.

second embodiment

This embodiment is basically the same as the first embodiment. When a burst packet arrives, multiple channels are searched in parallel according to the sending start time and sending end time of the packet to determine whether there is an available time slot for the channel to transmit The burst packet. The difference is that in this embodiment, the offset time margin is set. If a channel is judged and found not to meet the transmission requirements of the burst packet, that is, if the channel is reserved, the burst packet to be sent needs to occupy If the time slot overlaps with the time slot occupied by the existing burst packet, the channel is searched again according to the offset time margin. The specific steps to search again are:

S21: judging the situation of burst packet time slot overlap, in the present embodiment, there may be two kinds of overlapping situations: (1) overlap with the burst packet that needs to be sent before the burst packet to be sent on the time slot; 3-A; the time slot overlaps with the burst packet that needs to be sent after the burst packet to be sent, as shown in FIG. 3-B. Then proceed to step S22.

In this step S22, calculate the overlapping range of time slot, judge whether there are enough time slots and the overlapping range is within the offset time margin range, take 3-B as an example, that is, (T1-T0)<(T2 -T3) and (T2-T3)<offset time margin, if these two conditions are met, the channel becomes a reservable channel.

Then can use the same method of step S14 of embodiment one to carry out channel reservation, the difference is: if the channel reserved at last in S14 is the channel that is considered to be available for transmitting the burst packet in the first search, then the The sending start and sending end time of the burst packet remain unchanged; if the channel reserved by S14 is the second search for the channel that is considered to be available for transmitting the burst packet, the sending start and sending end time of the burst packet need to be based on The bias time margin is changed accordingly, as shown in 3-C. .

It can be seen from the above that, through the method of this embodiment, the reservation success rate can be greatly improved, and optical channel resources can be used more flexibly and effectively.

In this embodiment, it is assumed that n kinds of burst packet quality _of service levels are _QoS1 , _QoS2 , and _QoSn respectively. T _f2 , T _fn . Then the formula for calculating the offset time is: T _f2 ＝T _f1 +L ₁ , T _f3 ＝T _f2 +L ₂ ,

The formula for calculating the offset time reference value in this embodiment: T _fn =T _f(n-1) +L _n-1 , wherein n is an integer greater than 1, and is a burst packet whose quality of service is n-1 The packet length.

In this system, the quality of service level information and packet length information of burst packets can be configured by the control plane, and the offset time of burst packets is calculated according to the above formula. Considering the arbitrariness of traffic in the network, in order to minimize the failure of reservations, we use the offset time margin to adjust the offset time, record the offset time margin as T _m , then the range interval of the offset time is (T _f , T _f ±T _m ). In this embodiment, different offset time margins of burst packets can be set for different QoS, and longer offset time offset time margins can be set for burst packets with high QoS levels to improve the possibility of successful reservation, thereby Make it better quality assurance.

After applying the implementation mode of the optical burst packet channel reservation method of the present invention to reserve a successful channel, the burst packet to be transmitted can be inserted into the linked list and the information of the previous nodes can be updated to complete the effective connection of the entire linked list and wait for the actual burst packet to be transmitted. transmission.

An embodiment of the present invention also provides a burst packet channel reservation device. As shown in FIG. 4 , the system includes an information acquisition module, a channel availability detection module, a channel search module and a reservation module.

Wherein, when the edge router receives the burst packet to be transmitted, the information acquisition module obtains the offset time reference value and the description information of the burst packet, and the description information includes the length and QoS level information of the burst packet.

An information processing module, configured to generate a sending start time and a sending end time of the burst packet according to the offset time reference value and description information.

The channel search module searches all channels in parallel according to the sending start time and sending end time of the burst packet, and searches whether there is an available channel for transmitting the burst packet. It should be pointed out that, in order to realize parallel search, the channel search module can also be composed of a plurality of channel search sub-modules, and each channel search sub-module corresponds to a channel and is used to search its corresponding channel; in other embodiments In the above, the channel search module can also be a single module, but it can support parallel search for different channels.

The reservation module is used for reserving the channel searched by the channel search module and available for transmitting the burst packet. In the actual processing, the sending start time and sending end time of the burst packet to be transmitted are formed into a node, inserted into the resource list of the optical channel, and waited to be sent. In this embodiment, since the channel search module is to perform a parallel search, there may be multiple channels to meet the needs, and the reservation module sends a reservation permission signal to the first searched channel to make a reservation, and then stops the search or makes a reservation to the subsequent channel. The searched channel sends a reservation rejection signal. In other embodiments, when the channel search module searches for at least 2 channels that can be used to transmit the burst packet, the reservation module selects one of the channels for reservation, for example, selects the channel with the highest pre-set QoS level Or the channel with the best physical condition, and send reservation rejection information to other channels to reject the reservation.

The embodiment of the present invention may also include a channel availability detection module, which is used to detect and judge whether there is an available channel. In this embodiment, an optical channel that has a physical failure or is prohibited by the user will be detected by the channel availability detection module as Not an available channel. The channel search module only searches available channels.

In addition, the embodiment of the burst packet channel reservation device of the present invention may also include an offset time setting module, which is used to set the offset time margin of the burst packet. When the channel search module finds that an available channel cannot be When making a reservation, the channel can be searched again according to the offset time margin, so that more channels can be searched. The value of the deflection degree can be set according to conditions such as the QoS level of the burst packet, for example, a larger value of the deflection degree is set for a burst packet with a higher QoS level.

To sum up, through at least one embodiment of the burst packet channel reservation method or system provided by the present invention, the channel is searched in parallel when the channel is reserved, which can improve the efficiency of channel search, reduce the time of channel search, and can also select Permanently reserve the best channel for burst packet transmission. In addition, through at least one embodiment of the present invention, after an available channel is searched as unreservable, a second search can be started for it according to the offset time margin, so as to reduce the reservation failure rate, make full and reasonable use of channel resources, and reduce Probability of burst packet collision.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: the present invention can still be Modifications to the specific implementation of the invention or equivalent replacement of some technical features; without departing from the spirit of the technical solution of the present invention, should be included in the scope of the technical solution claimed in the present invention.

Claims (11)

1. a burst packet channel reservation method, for the burst packet reservation channel to be transmitted in optical network, it is characterized in that, the method comprises: A. Obtain the offset time and the description information of the burst packet; B. Calculate the sending start time and sending end time of the burst packet according to the offset time and the description information; C. Perform a parallel search on all available channels according to the start time and end time of sending the burst packet, and search whether there is a channel that can be used to transmit the burst packet; D. Send a reservation permission signal to the searched channel that can be used to transmit the burst packet, and reserve the channel. 2. the burst packet channel reservation method as claimed in claim 1, is characterized in that: In the step D, reserve the first searched channel that can be used to transmit the burst packet. 3. the burst packet channel reservation method as claimed in claim 1, is characterized in that: A priority is set for each channel, and the step D reserves the channel with the highest priority. 4. burst packet channel reservation method as claimed in claim 1, is characterized in that: In the step D, the sending end time of the burst packet sent before the burst packet to be sent in the channel is detected, the time gap between the two is judged, and the channel with the smallest time gap is reserved. 5. the burst packet channel reservation method as claimed in claim 2 or 3 or 4, is characterized in that, further comprises in the described step D: Send reservation rejection messages to unreserved channels among the searched channels. 6. The burst packet channel reservation method according to claim 1, wherein the description information includes: packet length information and service quality level information of the burst packet. 7. burst packet channel reservation method as claimed in claim 1, is characterized in that, the method further comprises: The offset time margin of the preset burst packet, in the step C, if there is a channel that does not meet the transmission requirements of the burst packet, then recalculate the sending start time and time of the burst packet according to the offset time margin Send end time, search the channel again. 8. the burst packet channel reservation method as claimed in claim 1, is characterized in that: The formula for calculating the offset time is: T _fn = T _f(n-1) + L _n-1 , wherein n is an integer greater than 1, and L _n-1 is a burst packet whose quality of service is n-1 The packet length. 9. A burst packet channel reservation device, characterized in that the device comprises: An information acquisition module, configured to acquire offset time and description information of burst packets to be transmitted; A description information processing module, configured to generate a sending start time and a sending end time of the burst packet according to the description information; A channel search module, configured to perform a parallel search on available channels according to the sending start time and sending end time of the burst packet, and search for a channel that can be used to transmit the burst packet; A reservation module, configured to reserve a channel searched by the channel search module that can be used to transmit the burst packet. 10. burst packet channel reservation device as claimed in claim 9, is characterized in that, this device further comprises: The offset time setting module is used to set the offset time margin of the burst packet, and the channel search module is also used to search again for channels that cannot be used to transmit the burst packet according to the offset time margin. 11. The burst packet channel reservation device according to claim 9, wherein the channel search module includes a plurality of channel search sub-modules, and each information search sub-module corresponds to a channel.

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