KR100572693B1 - How to Look Up Internet Protocol Packets - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to an internet protocol packet lookup method.

2. The technical problem to be solved by the invention

The present invention provides an IPv6 packet using a small sized CAM storing only 128-bit local interface prefix entry information of a node processing an IPv6 packet, and multi-step forwarding tables storing 64-bit or less network prefix entry information. To provide a lookup method for IPv6 Internet Protocol packets required for transmitting IPv6 packets coming in from nodes on all networks that communicate with each other to their destinations in a minimum amount of time.

3. Summary of Solution to Invention

According to an aspect of the present invention, there is provided an Internet protocol packet lookup method, comprising: a CAM lookup step of receiving a packet from a packet receiver, extracting header information, extracting a destination address from the extracted header information, and performing a lookup on a CAM (Content Addressable Memory); A CAM lookup checking step of checking whether a lookup matching has occurred in the CAM lookup step; In the CAM lookup checking step, if a match is found, the packet is delivered to the central controller. If the match is not found, the multibit-tri table is determined by using the index stored in the CAM to determine the location of the multibit-tri table. A multibit-tri table lookup step of performing a lookup by using a lookup step; A multi-bit-tri table lookup checking step of checking whether a matching occurs in the multi-bit-tri table lookup step; And in the multi-bit table lookup checking step, if a match occurs, the packet is transmitted to an external network, so that the packet is transmitted to a packet transmitter, and if a match does not occur, the packet is discarded or a packet is transmitted to a default route. Including.

4. Important uses of the invention

The present invention is used in network systems and the like.

IPv6, Internet Protocol, Prefix, Lookup, Forwarding Information, Local Interface Information, Index, CAM

Description

{Method for Internet Protocol Packet Lookup}             

1 is a diagram illustrating an embodiment of an IPv6 prefix lookup structure using a general multi-bit forwarding table.

Figure 2 is an embodiment explanatory diagram showing a forwarding table to which the present invention is applied.

3 is a flowchart illustrating an embodiment of an Internet protocol lookup method according to the present invention;

4 is a flowchart of another embodiment of an internet protocol lookup method according to the present invention;

* Explanation of symbols for the main parts of the drawings

201: packet receiver 202: local interface information

203: index 204: forwarding information

205: Index 206: N th forwarding table

207: local controller 208: packet transmitter

The present invention relates to an IPv6 Internet Protocol packet lookup method required for transmitting IPv6 packets received from nodes on all networks communicating using IPv6 (Internet Protocol version 6) packets to a corresponding destination within a minimum time. A forwarding entry stored in a local interface IPv6 address CAM (Content Addressable Memory (CAM)) having a 128-bit prefix has an IPv6 packet having a prefix of up to 128 bits variable length introduced into a node that processes an IPv6 packet. Compares first, if there is a matching forwarding entry, it is a local address, so the current node processes this packet, and if it does not exist, it forwards the entry that matches the IPv6 packet prefix entered in the multilevel forwarding table using Multibit-Trie. 128-bit IPv6 free in minimum time It relates to Internet protocol packet lookup how you can look up the bus.

Today's Internet requires a large number of nodes (e.g. routers or switches) that can handle faster packet transfers and process packets faster due to the rapid increase in host and user traffic and data traffic. It requires a high band on the transmission medium. Faster transmission media can be realized by replacing copper wires with optical cables, and research in this area is being actively conducted on the Internet backbone network.

A typical packet processing system, a router, consists mainly of four parts: a routing control processor, an input / output interface, a switch fabric, and a forwarding engine.

The forwarding engine determines the output port of the packet based on a forwarding table that contains the mapping between the packet's destination address and the output port, which is called a packet prefix lookup, and prefix lookup in the form of Longest Prefix Matching (LPM). Should be done. Here, the LPM scheme refers to a method of finding a forwarding entry in which the most significant bit of the IP packet prefix matches the prefix of the incoming IP packet with the prefix of the forwarding entry.

Since the IPv6 protocol is a next-generation protocol that supplements and improves the shortcomings of the IPv4 protocol, which is the current protocol based on the Internet network, most IPv6 prefix lookup methods are based on the IPv4 prefix lookup method. Take a look at

The prefix lookup algorithm for IPv4 packets published to date evaluates the advantages and disadvantages and performance of the algorithm according to the number of memory accesses, memory usage, and forwarding entry update rate.

Conventionally, various IPv4 prefix lookup algorithms have been introduced, but it can be divided into two broadly.

The early software-based retrieval techniques, the "Radix tree" and "PATRICIA tree" techniques, were used in early routers because they did not require fast lookups because of the small amount of memory required, but the large number of forwarding entry updates and the number of memory accesses. Way.

Multi-Tri-Tri is a method of comparing multiple bits at a time when comparing conventional IP prefixes one bit at a time.It requires a large amount of memory and takes a long time for forwarding entry update, but performs a prefix lookup at high speed. This is how you can do it. In addition, it is easy to implement in hardware, there is an advantage that can be fast prefix lookup.

FIG. 1 is an exemplary diagram illustrating an IPv6 prefix lookup structure using a general multibit-triforwarding table, and illustrates a case where a multibit-trilook lookup structure is applied to an IPv6 prefix lookup.

In the figure, "101" represents a packet receiver, "102" represents forwarding information, "103" represents an index, "104" represents a forwarding table, and "105" represents a packet transmitter.

Referring to FIG. 1, when the general multi-bit look-up structure is used for IPv6 prefix lookup, it requires a lot of memory and a considerable number of memory accesses. For example, since the length of the prefix of the IPv6 packet coming from the packet receiver 101 is 128 bits, the forwarding table 104 is generated when divided by 8 by the fixed length. In other words, the Nth forwarding table 104 becomes the 16th table, the maximum number of memory accesses is 16, and the maximum memory size used cannot be calculated accurately. However, when one forwarding entry size is 32 bytes, the worst case is " Primary Table Size (2 ⁸ * 32 Bytes) * Secondary Table Size (2 ⁸ * 32 Bytes) * ... * 16 Primary Table Size (2 ⁸ * 32 Bytes) . Of course, the more you divide by the fixed length, the less memory you use. In this case, the forwarding entry structure divides and compares IPv6 prefixes sequentially entered from the primary table to the Nth table 104 and sends them to the packet transmitter 105 according to the forwarding information 102. If there is no match, the next table to be compared may be found according to the index 103 indicating the next table.

In addition, a hardware implementation method using CAM has been proposed, but there is a costly problem, and an indirect lookup algorithm that can access memory in a pipelined manner to reduce the number of memory accesses is presented. However, there is a problem that is difficult to apply to IPv6 packets.

The present invention has been proposed to solve the above-mentioned problems. The present invention provides a small size CAM that stores only 128-bit local interface prefix entry information of a node processing an IPv6 packet and network prefix entry information of 64 bits or less. To provide a lookup method for IPv6 Internet Protocol packets required to transfer IPv6 packets coming in from nodes on all networks that communicate using IPv6 packets to corresponding destinations using multi-stage forwarding tables. There is this.

In the method of the present invention for achieving the above object, in the Internet protocol packet lookup method, a packet is received from a packet receiver to extract header information, and a destination address is extracted from the extracted header information to a content addressable memory (CAM). A CAM lookup step of performing a lookup; A CAM lookup checking step of checking whether a lookup matching has occurred in the CAM lookup step; In the CAM lookup checking step, if a match is found, the packet is delivered to the central controller. If the match is not found, the multibit-tri table is determined by using the index stored in the CAM to determine the location of the multibit-tri table. A multibit-tri table lookup step of performing a lookup by using a lookup step; A multi-bit-tri table lookup checking step of checking whether a matching occurs in the multi-bit-tri table lookup step; And in the multi-bit table lookup checking step, if a match occurs, the packet is transmitted to an external network, so that the packet is transmitted to a packet transmitter, and if a match does not occur, the packet is discarded or a packet is transmitted to a default route. It includes.

In addition, the method of the present invention, the information receiving and storing step of receiving and storing information on the local interface from the central controller; An index for storing a local controller to transmit a packet when the local interface information is received, or an index having multibit-tri table location information to continue the lookup if the local interface information is not matched, in the CAM (Content Addressable Memory). Storage step; And storing the forwarding information received from the central controller in the multi-bit-tri table.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a diagram illustrating an embodiment of a forwarding table to which the present invention is applied.

In the figure, "201" is a packet receiver, "202" is local interface information, "203" is index, "204" is forwarding information, "205" is index, "206" is Nth order forwarding table, and "207" is Local controller, and "208" represents a packet transmitter.

It is checked whether the IPv6 packet prefix received from the packet receiver 201 is the local interface information 202.

For local interface information, the prefix length is 128 bits, and the prefix of packets to be forwarded is 64 bits or less, so that separate lookups can be used to reduce memory usage and reduce the number of memory accesses.

By comparing the local interface information contained in the CAM with the incoming IPv6 packet prefix, if a match is found, the packet is transmitted to the local controller 207, and if it is not matched, the index is used using the next primary multibit-tri table. Look up. Here, the Nth table 206 may be changed depending on the case in which the IPv6 prefix is divided into fixed lengths. If the partition is divided into 16, the Nth table becomes a 16th table.

An important point of the present invention is that the IPv6 prefix length looking up in the multibit-tri table is 64 bits. The fixed length can be changed depending on the available memory.

The forwarding entry structure of the multi-bit-tri table divides and compares IPv6 prefixes sequentially inserted from the primary table to the N-th table and sends them to the packet transmitter 208 according to the forwarding information 204 when they match. If there is no match, the next table to be compared may be found according to the index 205 indicating the next table. This dramatically reduces memory usage and the number of memory accesses compared to the traditional multibit-try approach. This is because only 64 bits are looked up without 128 bits.

That is, since the IPv6 packet prefix is 128 bits in length, a large amount of memory and the number of memory accesses are required to perform LPM. Thus, it is very difficult to look up an IPv6 prefix using the IPv4 prefix lookup method up to now. That is, an IPv6 prefix lookup method that can look up packets with IPv6 prefix at high speed with LPM, and a forwarding table management method required for this need to be required, and the cost for constructing the packet should be low.

Therefore, the present invention focuses on the fact that when an IPv6 prefix performs LPM and matches 128 bits, the IPv6 packet is a local interface. First, the 128-bit local node of the node processing the IPv6 packet without first looking up the entire IPv6 prefix is considered. A small size CAM that stores only interface prefix entry information is used to first look up whether it is local interface information. The size of the CAM used here is proportional to the number of local interfaces. That is, the size of CAM is obtained by multiplying 128 bits by the size of the local interface. To date, the number of local interfaces of nodes that process IPv6 packets at high speed is not high. Thus, because a small memory size CAM can be used, even if the CAM is used, the additional cost is low and the lookup speed can be determined as the local interface prefix with only one memory access. In addition, an external network prefix of 64 bits or less may solve this problem by performing an IPv6 prefix lookup using a multi-bit-try method using multi-step forwarding tables capable of fast lookup.

3 is a flowchart illustrating an embodiment of an Internet protocol lookup method according to the present invention, and illustrates a process of dividing an IPv6 prefix into fixed lengths to construct a multibit-tri table.

As shown in FIG. 3, in the Internet protocol lookup method according to the present invention, the process of dividing an IPv6 prefix into fixed lengths to construct a multibit-tri table comprises: first, forwarding information and information about a local interface from a central controller. In operation 302, an index having a local controller to transmit a packet when the received interface information is matched or a multi-bit table position information to continue the lookup when the interface information is not matched (302) is received.

Next, IPv6 packet prefix lookup is possible by storing forwarding information rather than a local interface in a multibit-tri table (303).

4 is a flowchart illustrating another embodiment of the Internet protocol lookup method according to the present invention, and illustrates an overall process of looking up an IPv6 prefix using a CAM and a multibit-tri table.

As shown in FIG. 4, the Internet protocol lookup method according to the present invention first receives a packet from a packet receiver, extracts header information, extracts a destination address from the extracted header information, and performs a lookup in the CAM. In operation 402, it is checked whether lookup matching has occurred (403).

As a result of the check, if a match is found, the packet is forwarded to the central controller (405) and the IPv6 packet lookup is terminated. If there is no match, the index stored in the CAM is used to determine the location of the multibit-tri table, and the lookup is continued using the multibit-tritable (404).

The multibit-tri table can be configured in multiple stages. When the multi-bit-tri table is sequentially looked up, it is checked whether a matching occurs (406), and if so, the packet is transmitted to an external network, so the packet is forwarded to the packet transmitter (408). If it does not occur, the CAM is inconsistent with the local interface information and also with the multibit-tri table forwarding information, so there is no matching forwarding information. Therefore, the packet is discarded or the packet is transmitted to the default route (407).

As described above, the method of the present invention may be implemented as a program and stored in a recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.) in a computer-readable form.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible in the art without departing from the technical spirit of the present invention. It will be apparent to those of ordinary skill.

As described above, since the CAM having a small memory size can be used, even though the CAM is used, the additional cost is low and the lookup speed can be determined as a local interface prefix with only one memory access, and also less than 64 bits. External network prefix performs IPv6 prefix lookup using multi-bit forwarding table using multi-level forwarding table which enables high-speed lookup. Therefore, it is possible to perform 128-bit IPv6 prefix lookup at high speed. It works.

Claims (6)

In the Internet protocol packet lookup method, A CAM lookup step of receiving a packet from a packet receiver, extracting header information, extracting a destination address from the extracted header information, and performing a lookup in a CAM (Content Addressable Memory); A CAM lookup checking step of checking whether a lookup matching has occurred in the CAM lookup step; In the CAM lookup checking step, if a match is found, the packet is delivered to the central controller. If the match is not found, the multibit-tri table is determined by using the index stored in the CAM to determine the location of the multibit-tri table. A multibit-tri table lookup step of performing a lookup by using a lookup step; A multi-bit-tri table lookup checking step of checking whether a matching occurs in the multi-bit-tri table lookup step; And In the multi-bit table lookup check step, if a match occurs, the packet is to be transmitted to an external network, so the packet is transmitted to a packet transmitter, and if a match does not occur, a packet processing step of discarding the packet or transmitting the packet to a default route. Internet protocol packet lookup method comprising a. The method of claim 1, An information receiving and storing step of receiving and storing information on a local interface from the central controller; An index for storing a local controller to transmit a packet when the local interface information is received, or an index having multibit-tri table location information to continue the lookup if the local interface information is not matched, in the CAM (Content Addressable Memory). Storage step; And Forwarding information storage step of storing the forwarding information received from the central controller in the multi-bit-tri table Internet protocol packet lookup method further comprising. The method according to claim 1 or 2, The CAM, And an index to an area having forwarding information according to the lookup result. The method of claim 3, wherein The multibit-tri table is, An internet protocol packet lookup method comprising an index to an area having forwarding information according to a lookup result and comprising two or more tables. The method of claim 4, wherein The multibit-tri table is, The Internet protocol packet lookup method of claim 2, wherein each multibit-tri table includes an index that can point to the next table according to the lookup result. The method of claim 3, wherein The packet processing step, If no matching occurs, the CAM is inconsistent with local interface information and also with the multibit-tri table forwarding information. Therefore, there is no matching forwarding information. Therefore, the Internet discards the packet or transmits the packet to the default route. Protocol packet lookup method.

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