JP5814830B2 - Destination search apparatus and search method for flow unit packet transfer - Google Patents

Description

  The present invention relates to a destination search apparatus and a search method for searching for a destination on a flow table including a wild card in a destination search of a flow switch.

  In recent years, flow-based networking that enables finer granularity of service quality control by performing communication control in units of flows has been studied. A flow is a series of communication for each application identified by IP and port number. In flow-based networking, QoS control and path control according to users and applications are possible.

  A flow switch, which is a relay node for flow-based networking, refers to an entry registered in the flow table and sends a packet to an appropriate transfer destination. The flow entry is composed of entry priority, fields (matching conditions) corresponding to each information of the reception IF and header, and transfer destination information.

  In order to enable flexible control over flows, studies on software-based flow switches that have been speeded up by GPUs and the like are underway.

  Conventional methods relating to destination search include methods such as routing table search in software routers, exact match search in flow routers, and linear search.

  Non-Patent Document 1 describes an application method of binary tree search called Patricia-Tree. This method is used for searching destinations of OSs such as Linux and FreeBSD as a search method for realizing longest prefix matching in IP route search.

  Non-Patent Document 2 describes a flow search method in a commercial flow router. By making all the flows completely coincident entries, it is possible to perform a high-speed flow search by hash.

In order to solve the above-mentioned problems, the destination search apparatus for flow unit packet transfer according to the present invention includes a flow control information table composed of entries including a wild card for performing a linear search, and a perfect match entry for performing a hash search. The packet forwarding table configured and the field that is not a wild card in the flow control information table perform matching determination with the received packet information in parallel by the GPU to search for matching entries, and hash the packet forwarding table. Search processing control means for searching for a matching entry by performing a search ,
The search processing control means selects a plurality of entries from the flow control information table, and generates a match determination matrix in which 1 is assigned to a field in which a wild card of each entry is set, and 0 is assigned to other fields. A means for executing a match determination with received packet information of a field in which 0 is set in a column unit of the match determination matrix in parallel by the GPU, and substituting 1 into a matrix element of the match determination matrix corresponding to the matched field And means for setting an entry in which all fields are 1 in the match determination matrix as a match entry.

Donald R. Morrison et al. "PATRICIA: Practical Algorithm To Retrieve Information Coded in Alpha numeric" Journal of the ACM, Volume 15 Issue 4 October 1968 L. G. Roberts "The Next Generation of IP-Flow Routing" SSGRR 2003S July 2003 Sangjin Han et al. "PacketShader: a GPU-accelerated Software Router" Proceedings of ACM SIGCOMM 2010 August 2010

  However, the conventional IP route search represented by Non-Patent Document 1 is based on the longest prefix match search and cannot be applied to a flow table search including a plurality of fields as a match condition. To apply the exact match search shown in Non-Patent Document 2, it is necessary to define flow entries for all flows. Considering the operation, setting a large number of flow entries is poor in scale. In Non-Patent Document 3, wild card search is also considered, but when the number of entries increases due to linear search, the effect of performance degradation becomes large.

  Therefore, an object of the present invention is to provide a destination search apparatus and a search method for packet-based packet transfer that speeds up a search process of a flow table including a wild card in a software-based flow switch.

  In order to solve the above problems, a destination search apparatus for flow unit packet transfer according to the present invention includes a flow control information table configured by entries including a wild card for performing a linear search, and a perfect match entry for performing a hash search. The packet forwarding table configured and the field that is not a wild card in the flow control information table perform matching determination with the received packet information in parallel by the GPU to search for matching entries, and hash the packet forwarding table. Search processing control means for searching for a matching entry by performing a search.

  Further, it is preferable that the search processing control means first searches the packet forwarding table and searches the flow control information table when there is no corresponding entry.

  The search processing control means preferably adds an entry corresponding to the received packet information to the packet forwarding table when there is an entry that matches the flow control information table.

  Further, the packet forwarding table includes a deletion flag, and the search processing control unit overwrites the deletion flag of the searched entry with “non-target”, deletes the entry whose deletion flag is “target”, It is also preferable to further include a packet forwarding table management means for overwriting the deletion flag of the entry whose deletion flag is “non-target” with “target”.

In order to solve the above-described problem, a destination search method for transferring a packet in a flow unit according to the present invention performs a linear search on a received packet for a non-wildcard field in a flow control information table including entries including a wildcard. match determination information by parallel implemented in GPU, retrieving the matching entry, by performing a hash search packet constructed forwarding table exact match entry, retrieving a matching entry, the Selecting a plurality of entries from the flow control information table, generating a match determination matrix in which 1 is assigned to a field in which a wild card of each entry is set, and 0 in other cases, and a column unit of the match determination matrix The match judgment with the received packet information of the field set to 0 in G Parallel performed in U, it has a step of substituting one matrix element of the match determination matrix corresponding to the matched field; and all the fields in the match determination matrix and matching entry entry is 1.

  According to the feature that the number of management entries on the flow table is reduced by applying the wild card of the present invention, the flow entries can be set and set in units of applications, destination networks, etc., so that the operational scalability is improved. The effect is obtained.

  Further, according to the feature that the flow table including the wild card is searched at high speed by the GPU, an effect that the processing throughput is improved can be applied to a larger capacity network such as a core network.

1 shows a system configuration diagram of a flow destination search apparatus of the present invention. FIG. 5 is a flowchart showing a destination search procedure. The flow chart of a search of a flow control information table is shown. The flowchart of a packet forwarding table search is shown. In the embodiment of the present invention, the configuration of the flow control information table and the coincidence determination matrix and the update contents at the time of retrieval are shown. 4 shows the structure of a packet forwarding table and the update contents at the time of retrieval in an embodiment of the present invention. The update contents at the time of deleting the unnecessary entry of the packet forwarding table in the embodiment of the present invention are shown.

  The best mode for carrying out the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a system configuration diagram of a flow destination search apparatus of the present invention.

  The flow destination search device 1 of the present invention acquires packet information from the packet transmitting / receiving unit 2, refers to two flow tables (flow control information table 13, packet transfer table 15), searches for matching entries, and Returns destination information for. Further, the flow control information table 13 is managed according to the control policy.

  The flow destination search apparatus 1 includes a search processing control unit 11, a flow control information table management unit 12, a flow control information table 13, a packet transfer table management unit 14, and a packet transfer table 15. The flow destination search apparatus 1 is connected to the packet transmission / reception unit 2 to acquire a received packet and notify a transfer destination. In addition, the flow destination search device 1 is connected to the control policy management unit 3 and receives an update of the flow control information.

  The search processing control unit 11 searches the packet transfer table 15 and the flow control information table 13 to obtain appropriate transfer destination information based on the information of the received packet, and notifies the packet transmission / reception unit 2 of the obtained transfer destination information. To do. If there is no necessary entry in the packet transfer table 15, entry addition processing is performed.

  The flow control information table 13 holds the definition of the flow control information as an entry. Each entry can specify a wild card in an arbitrary field, and an entry priority indicating a matching priority is set for all entries. The search for this table is performed based on a linear search.

  The packet transfer table 15 holds complete match entry information of the current flow. It consists of a complete match entry with a hash value obtained from packet match information as a key and a deletion flag indicating whether or not the flow information can be deleted, and a search by hash is performed.

  The flow control information table management unit 12 updates the flow control information table 13 based on a request from the control policy management unit 3.

  The packet transfer table management unit 14 monitors whether there is flow information that is no longer used on the packet transfer table 15 and deletes unnecessary entries.

  The flow control information table 13 and the packet forwarding table 15 may be developed in a memory on the GPU for high speed data access.

  The control policy management unit 3 requests entry addition and deletion to the flow control information management table 13. The request form is, for example, manual setting from the operator screen, route information update from the routing daemon, and flow information setting from the signaling daemon.

  FIG. 2 is a flowchart showing a destination search procedure. The operation of the flow destination search device 1 will be described below based on this flowchart.

Step 1: Reception of packet information, the packet transmitting / receiving unit 2 receives packet information (reception IF, MAC, VLAN, IP, port number) and transmits it to the search processing control unit 11.
Step 2: Hash value calculation and search processing control unit 11 calculates a hash value for packet transfer table search based on the received packet information received from packet transmission / reception unit 2.
Step 3: Packet transfer table search and search processing control unit 11 searches packet transfer table 15 based on the calculated hash value.
Step 4: Judgment of presence / absence of matching entry. If there is a corresponding entry in the packet forwarding table 15, the process proceeds to Step 5, and if there is no corresponding entry, the process proceeds to Step 6.
Step 5: The transfer destination information of the corresponding entry is notified, and the search processing control unit 11 notifies the packet transmitting / receiving unit 2 of the transfer destination information of the corresponding entry.
Step 6: Search and search processing control unit 11 of flow control information table 11 searches the flow control information table 13 for an entry corresponding to the received packet.
Step 7: Determination of presence / absence of matching entry. If there is a corresponding entry in the flow control information table 13, the process proceeds to Step 8. If there is no corresponding entry, the process proceeds to Step 10.
Step 8: Adding a new entry to the packet transfer table, the search processing control unit 11 adds a new entry to the packet transfer table 15 based on the received packet information and the corresponding transfer destination information.
Step 9: The transfer destination information of the corresponding entry is notified, and the search processing control unit 11 notifies the packet transmitting / receiving unit 2 of the transfer destination information of the corresponding entry.
Step 10: The packet is discarded assuming that there is no mismatch response and transfer destination.

  FIG. 3 shows a search flowchart of the flow control information table 13. Hereinafter, the search of the flow control information table 13 will be described based on this flowchart.

Step 31: Generation of a coincidence determination matrix, a plurality of entries are first selected from the higher priority, and a coincidence determination matrix for these entry groups is generated. The coincidence determination matrix is a matrix for holding the coincidence status of each field. 1 is assigned to the matrix element corresponding to the field in which the wild card of each entry is set, and 0 is assigned to the other elements.
Step 32: Match determination required field selection, In each column on the match determination matrix, a portion where 0 is set is a field that requires a match determination with an entry, and is therefore selected.
Step 33: The field match determination process and the match determination with the received packet information in units of columns that can be executed in the same instruction are performed in parallel on the GPU. When field match determination is completed for all entries in the entry group, 1 is assigned to the matrix element of the match determination matrix corresponding to the matched field.
Step 34: Extract matching entry. If there is an entry in which all the fields match (all entries are 1), the entry with the highest priority among them is set as the matching entry for the packet. If there is no matching entry, the matching determination for the next entry group in the flow control information table 13 is repeated. Note that it is desirable to perform parallel processing by the GPU because the determination of whether the entries match in all fields is performed by performing bitwise AND of the fields on all entries.

  FIG. 4 shows a search flowchart of the packet forwarding table 15. Hereinafter, the search of the packet forwarding table 15 will be described based on this flowchart.

Step 41: Search by hash value, search processing control unit 11 searches packet forwarding table 15 using a hash value for received packet information as a key.
Step 42: Matching condition determination, if there is an entry associated with the corresponding hash value, it is determined whether all the matching conditions are equal. If they are equal, the process proceeds to step 43. If they are not equal, the process proceeds to step 44.
Step 43: Overwrite the deletion flag, if it is equal, the entry is matched and the table deletion flag is overwritten with 0 (non-deletion target).
Step 44: Re-search, if not equal, continue searching for matching entries based on applied hash algorithm. For example, in the case of the open hash method, the hash value is recalculated and searched by rehashing. In the case of the chain hash method, search is performed by sequentially tracing a list including entries associated with the hash value.

  In the packet forwarding table 15, an entry is added based on the information in the flow control information table 13 every time a new flow arrives. Therefore, if an unnecessary entry is not deleted, the capacity limit of the table is reached, and a new entry is added. Can not be. Therefore, unnecessary entries are deleted by the following procedure. The packet forwarding table management unit 14 sequentially checks the deletion flag of each entry separately from the destination search, and deletes information as an unnecessary entry when the deletion flag is 1 (deletion target). If the deletion flag is 0 (non-deletion target), the entry is not deleted, the deletion flag is overwritten with 1, and the process proceeds to the next entry check. Therefore, an entry that has not been referenced until the next check is deleted as an unnecessary entry.

Examples of the present invention are shown below. FIG. 5 shows a flow control information table search in the embodiment of the present invention. FIG. 5A shows an example of a flow control information table, and FIGS. 5B and 5C show examples of a coincidence determination matrix.
Step 31 and FIG. 5B show an entry group of the coincidence determination matrix generated from the flow control information table of FIG. Entry priorities 10 to 40 are shown. In the wild card field of FIG. 5A, 1 is substituted, and 0 is substituted otherwise. In this example, the entry group has only four rows, but actually, more rows are selected, and parallel computation of GPUs is performed with many multiplicity.
In step 32, FIG. 5B, the field enclosed by the square is the selected entry.
Step 33, FIG. 5C shows a match determination matrix in which 1 is assigned to the matched field in the GPU match determination calculation. In FIG. 5C, the field enclosed by a square is an entry to which 1 is substituted.
In step 34, the example of FIG. 5C, the shaded entry is an entry in which all fields match. An entry with a higher priority and a priority of 20 is extracted as a matching entry.

FIG. 6 shows a packet forwarding table search in the embodiment of the present invention.
Step 41, from the received packet information (IF = eth1, D-MAC = D: D: D, S-MAC = E: E: E,...), A hash value H (received packet information) = 0x0001 is obtained. Search for.
Step 42, the hash value 0x0001 is an entry that is dotted in FIG. It is determined whether the received packet information and the matching conditions are all equal. Here, since all are equal, it progresses to step 43.
Step 43, overwrite the deletion flag with 0.

  FIG. 7 shows unnecessary entry deletion in the packet forwarding table in the embodiment of the present invention. The entries having the hash values 0x0001 and 0x0010 are deleted by the cyclic check because the deletion flag is 1. The entries with hash values 0x0000 and 0x0011 are overwritten with 1 because the deletion flag is 0.

  By applying the high-speed flow switch using the destination search apparatus of the present invention to the core network of the communication carrier, end-to-end flow unit control that is impossible with the conventional Internet becomes possible. As a result, communication quality suitable for each application can be provided, and improvement in service quality can be realized. In addition, network resources can be used more efficiently, which leads to a reduction in track facility costs.

  Moreover, all the embodiments described above are illustrative of the present invention and are not intended to limit the present invention, and the present invention can be implemented in other various modifications and changes. Therefore, the scope of the present invention is defined only by the claims and their equivalents.

DESCRIPTION OF SYMBOLS 1 Flow destination search apparatus 2 Packet transmission / reception part 3 Control policy management part 11 Search process control part 12 Flow control information table management part 13 Flow control information table 14 Packet transfer table management part 15 Packet transfer table

Claims (4)

A flow control information table composed of entries including wildcards for performing a linear search;
A packet forwarding table consisting of exact match entries that perform a hash search;
Match the received packet information with the field that is not a wild card in the flow control information table by matching the received packet information in parallel by searching for a matching entry and performing a hash search on the packet forwarding table. Search processing control means for searching for entries;
Equipped with a,
The search processing control means includes
Means for selecting a plurality of entries from the flow control information table, and generating a match determination matrix in which 1 is assigned to a field in which a wild card of each entry is set, and 0 is assigned to other fields;
Means for executing a match determination with received packet information of a field in which 0 is set in a column unit of the match determination matrix in parallel by the GPU, and substituting 1 into a matrix element of the match determination matrix corresponding to the matched field; ,
Means for making an entry in which all fields are 1 in the match determination matrix as a match entry;
A destination retrieval apparatus for flow unit packet transfer characterized by comprising: The search processing control means includes
2. The destination search apparatus according to claim 1 , wherein when there is a matching entry in the flow control information table, an entry corresponding to the received packet information is added to the packet forwarding table. The packet forwarding table includes a deletion flag,
The search processing control means overwrites the deletion flag of the searched entry with “non-target”,
A packet forwarding table management means for deleting an entry whose deletion flag is “target” and overwriting the deletion flag of an entry whose deletion flag is “non-target” with “target”;
The destination search device according to claim 1 , further comprising: Searching for a matching entry by performing a parallel search on a non-wildcard field of a flow control information table composed of entries including a wildcard by performing a linear search in parallel with the received packet information on the GPU; ,
Searching for a matching entry by performing a hash search on a packet forwarding table comprising exact match entries; and
Selecting a plurality of entries from the flow control information table, and generating a match determination matrix in which 1 is assigned to a field in which a wild card of each entry is set, and 0 is assigned to other fields;
A step of performing a match determination with the received packet information of a field in which 0 is set in a column unit of the match determination matrix in parallel by the GPU, and substituting 1 into a matrix element of the match determination matrix corresponding to the matched field; ,
Making an entry in which all fields are 1 in the match determination matrix as a match entry;
A destination search method for packet-based packet transfer.

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