KR20100105086A - Method for compressing the header of an ip packet and a node in a network based on multiple addresses therefor - Google Patents

Abstract

PURPOSE: A method for compressing a header of an ip packet and a node configuring a network based on a plurality of addresses for the method are provided to compress an IPv6 multicast packet in an IEEE 802.15.4 network to transmit the packet, thereby minimizing a network load. CONSTITUTION: A MAC(Medium Access Control) layer(610) controls communication with another node. An IPv6(Internet Protocol version6) layer(630) performs mapping between an IPv6 address and a MAC address of a destination multicast group or a destination node. The IPv6 layer generates an IP packet. A 6LoWPAN(IPv6 over Low power Wireless Personal Area Network) adaptation layer(620) compresses/decompresses or fragments/defragments an IPv6 header to transmit an IPv6 data packet in an IEEE 802.15.4 network. The 6LoWPAN adaptation layer selects a routing path from a node to the destination multicast group or the destination node.

Description

TECHNICAL FOR COMPRESSING THE HEADER OF AN IP PACKET AND A NODE IN A NETWORK BASED ON MULTIPLE ADDRESSES THEREFOR}

The present invention relates to a method for transmitting a data packet having a destination upper layer address between nodes in a network composed of a plurality of nodes each having an upper layer address and a lower layer address. The present invention relates to a header compression method for transmitting an IPv6 data packet in an IEEE 802.15.4 network, which is a wireless network.

The Institute of Electrical and Electronics Engineers (IEEE) 802.15.4 network is a media access control (MAC) address-based network aimed at low power consumption. The maximum length of a MAC frame is 127 bytes and 6LoWPAN (IPv6 over low power). Wireless personal area network is a technology for transmitting IPv6 data packets in an IEEE 802.15.4 network.

IPv6 is a protocol with an address system of 128bits. When applied to a sensor network, IP6 can be assigned to each sensor node. 6LoWPAN is an upper layer of IEEE 802.15.4 MAC / PHY. It provides an environment that can use the communication protocol used on the Internet.

The sensor network is called the USN (Ubiquitous Sensor Network) in Korea, and the name is called the Wireless Sensor Network (WSN) in overseas. These sensor networks are spreading worldwide. In recent years, ZigBee has standardized higher network technologies based on IEEE 802.15.4 technology. In particular, IETF (Internet Engineering Task Force) has a header of 40 bytes of IPv6, IEEE 802.15.4 WPAN (Wireless Personal Area Network) section. Header compression techniques have been researched to reduce.

The IEEE 802.15.4 MAC header can be variably up to 25 bytes, and the payload length of the MAC frame can be 102-118 bytes. Since the minimum transmission unit (MTU) of an IPv6 packet is 1280 bytes, in order to deliver an IPv6 packet in IEEE 802.15.4, an IPv6 header is compressed or an IPv6 packet is fragmented.

A method of compressing and forwarding headers of IPv6 unicast packets in RFC 4944, which is currently a 6LoWPAN standard, is presented. The header compression method of 6LoWPAN can be applied only to unicast packets. In the case of IPv6 multicast packets, the destination address is not configured as a "prefix + interface ID", but has a separate address scheme. The problem is that the destination address of the packet cannot be compressed.

Accordingly, there is a need for a method of efficiently transmitting IPv6 multicast packets while minimizing network load by compressing and transmitting IPv6 multicast packets in an IEEE 802.15.4 network.

According to an aspect of the present invention, a node configuring a multi-address based network includes: an IP layer having an IP address and configured to generate an IP packet inserted into a payload field of a MAC frame; An adaptation layer configured to compress the header of the IP packet; A MAC layer having a MAC address and configured to control communication with other nodes based on the MAC address, wherein the adaptation layer compresses the multicast address of the IP packet, and the compressed multicast address is a multicast group Contains an ID.

According to another aspect of the present invention, in a node constituting a plurality of address-based networks, and including an IP layer, an adaptation layer, and a MAC layer, the method of compressing a header of an IP packet by the adaptation layer may include: IP from the IP layer; Receiving a packet; Extracting a header of the IP packet; Checking whether an address of the IP packet is a multicast address; Compressing the multicast address of the IP packet.

According to the present invention, a method of compressing headers of nodes and IP packets constituting a multi-address based network compresses and transmits IPv6 multicast packets in an IEEE 802.15.4 network, thereby efficiently minimizing network load and efficiently The advantage is that it can be transmitted.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention; In describing the present invention, detailed descriptions of related well-known functions and configurations are omitted in order not to obscure the subject matter of the present invention.

FIG. 1 is a diagram illustrating a MAC frame structure of IEEE 802.15.4, and FIG. 2 is a diagram showing a frame structure of an IPv6 packet inserted into a payload field of the MAC frame. The MAC frame 100 has a length of 127 bytes, and includes a frame control field 110, a sequence number field 120, an address information field 130, and a payload field ( 140 and a frame check sequence (FCS) field 150. The frame control field 110 has a length of 2 bytes, and information such as a frame type, a protocol version, and a neighbor discovery option is inserted (or described). The sequence number field 120 has a length of 1 byte and has a value of increasing by 1 in order of transmission. The FCS field 150 has a length of 2 bytes and has error detection information.

The address information field 130 has a length of 4-20 bytes, and is assigned a destination personal area network (PAN) field 132 and a MAC address for a next hop (ie, a node to receive the frame). A destination address field 134, a source PAN field 136, and a source address field 138 to which the MAC address for the node that delivered the frame is assigned.

The payload field 140 has a length of 102 to 118 bytes and includes an IPv6 packet 200 having an IPv6 header field 205 and an IPv6 payload field 290.

The IPv6 header field 205 is a 2-bit VER (version) field 210 indicating an IP version, a 1 byte TC (traffic class) field 220 indicating a service type, and a flow for distinguishing an IPv6 packet flow. 20-bits long FL (flow label) field 230, 2-bytes length PL (payload length) field 240 representing the length of the IPv6 payload field 290, and 1-byte length NH for indicating the extension header (next header) field 250, a 1 byte hop limit (HL) field 260 similar to the time to live (TTL) field of IPv4, a 16-byte source IPv6 address field 270, and a 16-byte length Destination IPv6 address field 280.

In the worst case, the IPv6 payload field 290 has a length of 62 bytes or less, and 6LoWPAN compresses the header of the IPv6 packet to solve this problem.

3 is a diagram illustrating a compressed IPv6 packet. The compressed IPv6 packet 300 includes an 8-bits long IPv6 dispatch field 310 indicating the header type, an HC1 header field 305 and an IPv6 payload field 290, which header field 305 It includes a 1-byte HC1 encoding field 320 representing the compressed information, and the uncompressed fields 330.

In a typical IPv6 dispatch field, a value indicating that a 6LoWPAN frame is not included or a value indicating an uncompressed IPv6 address may be inserted, and the LOWPAN_HC1 (0100 0010) indicating a compressed IPv6 packet may be inserted in the IPv6 dispatch field 310. The value of is inserted.

Table 1 below describes the meaning represented by each component bit of the HC1 encoding value.

Bit field Compressed field meaning bit 0 and 1 IPv6 Source Address 00: PI *, II *
01: PI *, IC *
10: PC, II
11: PC, IC bit 2 and 3 IPv6 Destination Address 00: PI, II
01: PI, IC
10: PC, II
11: PC, IC bit 4 Traffic Class and
Flow label 0: not compressed; full 8 bits for Traffic Class and 20 bits for Flow Label are sent
1: Traffic Class and Flow Label are zero bit 5 and 6 Next Header 00: not compressed; full 8 bits are sent
01: UDP
10: ICMP
11: TCP bit 7 HC2 encodings 0: No more header compression bits
1: HC1 encoding immediately followed by more header compression bits per HC2 encoding format. Bits 5 and 6 determine which of the possible HC2 encodings apply (eg, UDP, ICMP, or TCP encodings)

* PI: Prefix carried in-line (prefix information is included without omission)

* PC: Prefix compressed (link-local prefix assumed) (prefix information is omitted)

* II: Interface identifier carried in-line (interface ID information is not omitted but included)

* IC: Interface identifier elided (derivable from the corresponding link-layer address) (interface ID information is omitted)

Configuration of IPv6 address for 6LoWPAN is as follows.

1. If configured with a long address of 64bits: "64bits prefix + 64bits long address"

2. In case of short address of 16bits: "64bits prefix + 16bits_PAN: 00ff: fe00: 16bits_short_address"

4 is a diagram illustrating a scheme of an IPv6 multicast address.

The IPv6 multicast address 400 has a group ID with a value of 0xFF inserted in the start field 410 of the highest 8 bits, a flag field 420 of 4 bits, a scope field 430 of 4 bits, and a prefix of 112 bits. Field 440.

Table 2 below describes the meanings of flags configuring the IPv6 multicast address 400.

0 reserved R Embedding the Rendezvous Point (RP) Address in an IPv6 Multicast Address P Unicast-Prefix-based IPv6 Multicast Addresses T T = 0 indicates a permanently-assigned ("well-known") multicast address, assigned by the Internet Assigned Numbers Authority (IANA).
T = 1 indicates a non-permanently-assigned ("transient" or "dynamically" assigned) multicast address.

In the case of an IPv6 multicast packet, the lowest 1-bit T value of the flag has a value of 0 indicating that it is a permanently assigned multicast address or a value of 1 indicating that it is a temporarily assigned multicast address.

Table 3 below describes the meaning of the scope constituting the IPv6 multicast address 400.

value meaning value meaning 0 reserved 8 Organization-Local scope One Interface-Local scope 9 (unassigned) 2 Link-Local scope A (unassigned) 3 reserved B (unassigned) 4 Admin-Local scope C (unassigned) 5 Site-Local scope D (unassigned) 6 (unassigned) E Global scope 7 (unassigned) F reserved

The group ID specifies a permanent or temporary multicast group within a given scope. The term "permanent" means that the assigned multicast address is independent of scope, and the term "transient" means that the assigned multicast address is only meaningful within a given scope.

For a brief introduction to multicast, unicast and anycast, multicast refers to one source node sending IPv6 packets to multiple nodes belonging to a particular group, where unicast refers to one source node. Refers to sending an IPv6 packet to a destination node in which anycast node transmits an IPv6 packet to multiple nodes belonging to a particular group, but only one of the plurality of nodes (e.g., Closely located) is selected to receive IPv6 packets.

Without considering the R value of the flag, the types of IPv6 multicast addresses are as follows.

1. Known or predefined multicast address (P = 0, T = 0)

When the scope value is 0 to F and the T value of the flag is 0, the reserved multicast address is shown in Table 4 below.

Reserved Multicast Address FF00: 0: 0: 0: 0: 0: 0: 0
FF01: 0: 0: 0: 0: 0: 0: 0
FF02: 0: 0: 0: 0: 0: 0: 0
FF03: 0: 0: 0: 0: 0: 0: 0
FF04: 0: 0: 0: 0: 0: 0: 0
FF05: 0: 0: 0: 0: 0: 0: 0
FF06: 0: 0: 0: 0: 0: 0: 0
FF07: 0: 0: 0: 0: 0: 0: 0
FF08: 0: 0: 0: 0: 0: 0: 0
FF09: 0: 0: 0: 0: 0: 0: 0
FF0A: 0: 0: 0: 0: 0: 0: 0
FF0B: 0: 0: 0: 0: 0: 0: 0
FF0C: 0: 0: 0: 0: 0: 0: 0
FF0D: 0: 0: 0: 0: 0: 0: 0
FF0E: 0: 0: 0: 0: 0: 0: 0
FF0F: 0: 0: 0: 0: 0: 0: 0

According to RFC 3307, the group ID has a value of 0x00000001 to 0xFFFFFFFF and is mapped to the lower 32 bits of the multicast address.

The group ID predefined in IANA can be found in RFC 2375, and specific examples are shown in Table 5 below.

All Nodes Addresses FF01: 0: 0: 0: 0: 0: 0: 1
FF02: 0: 0: 0: 0: 0: 0: 1 All Routers Addresses FF01: 0: 0: 0: 0: 0: 0: 2
FF02: 0: 0: 0: 0: 0: 0: 2
FF05: 0: 0: 0: 0: 0: 0: 2

IANA also pre-defined the solicited multicast address. The requested multicast address is an address calculated from a node's unicast address or anycast address. That is, the requested multicast address is calculated using the lower 24 bits of the IPv6 unicast / anycast address.

To illustrate a predefined requested multicast address is shown in Table 6.

Solicited Multicast Address FF02: 0: 0: 0: 0: 1: FFXX: XXXX

In the illustrated requested multicast address, XX: XXXX corresponds to the lower 24 bits of the unicast / anycast address.

2. Dynamically assigned multicast address (P = 0, T = 1)

According to RFC 3307, dynamic allocation methods include an allocation method by a server and an allocation method by a host. The group ID has a value of 0x80000000 ~ 0xFFFFFFFF.

3. Multicast address based on unicast prefix (P = 1, T = 1)

5 is a diagram illustrating a unicast prefix based multicast addressing scheme. The unicast prefix based multicast address allocation method refers to allocating a multicast address based on a network prefix belonging to a corresponding unicast domain.

The unicast prefix based multicast address 500 has a start field 510 of the highest 8 bits having a value of 0xFF, a flag field 520 of 4 bits, a scope field 530 of 4 bits, and a value of 0xFF. An 8-bit reserved field 540, an 8-bit length field (plen, 550) that indicates the length of the network prefix, and a 64-bit network prefix field (560) that indicates the global unicast prefix used by the unicast domain. And a 32-bit group ID field 570 having a value of 0x40000000 to 0x7FFFFFFF according to RFC 3307. For example, a unicast prefix based multicast address of a unicast domain using 3ffe: ffff: 1 :: / 48 is ff3x: 0030: 3ffe: ffff: 0001 :: / 96, and x is a scope value.

6 is a diagram illustrating a main configuration of nodes constituting a multi-address-based network according to a preferred embodiment of the present invention.

The node 600 includes an IEEE 802.15.4 MAC layer 610, which is a lower layer (second layer or data link layer), a 6LoWPAN adaptation layer 620, which is an intermediate layer, and an upper layer (third layer). Or an IPv6 layer 630, which is a network layer.

The MAC layer 610 has a unique MAC address and controls communication with other nodes based on the MAC address.

The IPv6 layer 630 has a unique IPv6 address, performs a mapping between the IPv6 address and the MAC address of the destination multicast group or destination node, and based on the mapping, determines the MAC address of the destination multicast group or destination node. Decide In addition, the IPv6 layer 630 generates an IP packet inserted into the payload field of the MAC frame.

The 6LoWPAN adaptation layer 620 performs an IPv6 header compression / decompression or fragmentation / defragmentation function for transmitting an IPv6 data packet in an IEEE 802.15.4 network, and the node Select a routing path from 210 to the destination multicast group or destination node.

7 illustrates a summary of types of IPv6 multicast addresses.

As described above, among the types of IPv6 multicast addresses, a known or predefined multicast address (P = 0, T = 0) and a unicast prefix based multicast address (P = 1, T = 1) are described above. Compression is possible at the 6LoWPAN adaptation layer 620. That is, the 6LoWPAN adaptation layer 620 omits the prefix of the group ID field 440 to which the start field 410 and the prefix are added in the IPv6 multicast address 400.

8 illustrates a compressed IPv6 packet according to a preferred embodiment of the present invention.

The compressed IPv6 packet 700 includes an 8-bit length IPv6 dispatch field 710 representing a header type, a BC1 header field 705, and an IPv6 payload field 770. The header field 705 includes an 8-bits BC1 encoding field 720 representing compression information, an 8-bits length hop limit field 730 for limiting the number of hops, a 4-bits length flag field 740, and a 4-bits length. Scope field 750, and multicast group ID field 760 of 16 bits or 32 bits in length. The flag indicates whether the multicast address of the compressed IPv6 packet 700 is a known or predefined multicast address (P = 0, T = 0) and the length of the group ID. Scope indicates the transmission range of the compressed IPv6 packet 700.

In order to compress an IPv6 multicast packet in the 6LoWPAN adaptation layer, it is necessary to define a new IPv6 dispatch value. To this end, a value of LOWPAN_BC1 (0100 0011) indicating a compressed IPv6 multicast packet is inserted into the IPv6 dispatch field 710. do.

Table 7 below describes the meaning represented by each component bit of the BC1 encoding value.

BC1 encoding (8bits) meaning bits 0 and 1 IPv6 Source Address, as defined in RFC 4944. bits 2 and 3 00: Well-Known Address (P = 0, T = 0)
01: Dynamically Assigned Address, not compressed (P = 0, T = 1)
10: Not Compressed
11: Unicast-mapped Address (P = 1, T = 1) bits 4 Traffic Class and Flow Label, per RFC 4944. bits 5 and 6 Next Header, as defined in RFC 4944. bit 7 HC2 encoding

Table 8 below describes the meaning represented by each configuration bit of the flag value.

flag meaning bit 0 and 1 00: All Nodes Addresses
01: All Router Addresses
10: Solicited Multicast Address
11: Well-known Addreess bits 2 and 3 00: Group ID does not exist.
01: 16bits Group ID
10: 32bits Group ID
11: Reserved

The scope value is used by copying the scope value of the multicast address before compression.

The 6LoWPAN adaptation layer 620 performs the following steps to compress the header of the IPv6 multicast packet.

1. Receive an uncompressed IPv6 multicast packet from the IP layer.

2. Extract the header of the IPv6 multicast packet.

3. Confirm that the destination address of the IPv6 multicast packet is a compressible multicast address. The 6LoWPAN adaptation layer 620 may determine whether compression is possible through the flag field of the destination multicast address.

4. If the destination multicast address is a known or predefined multicast address (P = 0, T = 0) and a unicast prefix based multicast address (P = 1, T = 1), then the destination multicast address In step 8, the prefix of the group ID field added with the start field and the prefix is omitted, and the IPv6 dispatch field and the BC1 encoding field are added.

According to the present invention, the IPv6 multicast packet can be compressed more efficiently than the conventional compression method, and the compression method of the present invention is compared with the conventional compression method as shown in Table 9 below.

Conventional Do not compress multicast addresses. 40 bytes IPv6 Header => compressed to 19 bytes LOWPAN_HC1 (1byte) + HC1 encoding (1byte) + hop limit (1byte) + 16bytes (destination address) Invention Also compresses multicast addresses. 40 bytes IPv6 Header => compressed to 6 bytes LOWPAN_BC1 (1byte) + BC1 encoding (1byte) + hop limit (1byte) + flag and scope (1byte) + group ID (2bytes)

On the other hand, in the detailed description of the present invention has been described with respect to specific embodiments, it will be apparent to those skilled in the art that various modifications are possible without departing from the scope of the present invention.

In the foregoing description, the term hierarchical may be changed to a hierarchical device including a device for a network such as a switch, a router, a gateway, a server computer, or a combination thereof, or may be a functional module implemented in software or hardware, or You can change it to a block. For example, the IPv6 layer, the 6LoWPAN adaptation layer and the MAC layer may be changed in terms of IPv6 layer device, 6LoWPAN adaptation layer device and MAC layer device, respectively.

It is apparent that the method of compressing a header of an IP packet of the present invention may be implemented in the form of hardware, software (ie, a program), or a combination thereof. Such a program may be stored in a machine-readable volatile or nonvolatile recording medium such as a computer, and the recording medium may be a storage device such as a ROM, a memory such as a RAM, a memory chip, an integrated circuit, a CD, a DVD, a magnetic disk, or the like. , Magnetic tape or the like. That is, the compression method of the header of the IP packet of the present invention can be embodied in the form of a program including codes for realizing this. Further, such a program may be electrically transmitted through any medium, such as a communication signal propagating by wire or wirelessly, and the present invention includes equivalents thereof.

1 is a diagram illustrating a MAC frame structure of IEEE 802.15.4;

2 is a diagram illustrating a frame structure of an IPv6 packet inserted into a payload field of a MAC frame;

3 is a diagram illustrating a compressed IPv6 packet,

4 is a diagram illustrating a scheme of an IPv6 multicast address;

6 is a view showing the main configuration of a node constituting a multi-address based network according to a preferred embodiment of the present invention;

7 illustrates a summary of types of IPv6 multicast addresses;

8 illustrates a compressed IPv6 packet according to a preferred embodiment of the present invention.

Claims (11)

In a node configuring a multi-address based network, An IP layer having an IP address and configured to generate an IP packet inserted into a payload field of a MAC frame; An adaptation layer configured to compress the header of the IP packet; A MAC layer having a MAC address and configured to control communication with other nodes based on the MAC address, The adaptation layer compresses the multicast address of the IP packet, and the compressed multicast address comprises a multicast group ID. The method of claim 1, The IP packet received from the IP layer by the adaptation layer includes a multicast group ID to which a prefix is added, and the adaptation layer omits the prefix. The method of claim 2, And the adaptation layer adds a dispatch field indicating a compressed multicast packet and an encoding field indicating compression information to the compressed IP packet. The method of claim 2, The adaptation layer configures a multiple address-based network, adding a flag field indicating a length of the multicast group ID and a scope field indicating a transmission range of the compressed IP packet to the compressed IP packet. Node. In a node constituting a plurality of address-based network, including a IP layer, an adaptation layer and a MAC layer, in the compression method of the header of the IP packet by the adaptation layer, Receiving an IP packet from the IP layer; Extracting a header of the IP packet; Checking whether an address of the IP packet is a multicast address; And compressing a multicast address of the IP packet. The method of claim 5, And the compressed multicast address includes a multicast group ID. The method of claim 6, The compressing method includes compressing the prefix from the multicast group ID to which the prefix included in the IP packet is added. The method of claim 7, wherein The compression process further comprises adding a dispatch field indicating a compressed multicast packet and an encoding field indicating compression information to the compressed IP packet. The method of claim 7, wherein The compression process may further include adding a flag field indicating a length of the multicast group ID and a scope field indicating a transmission range of the compressed IP packet to the compressed IP packet. Compression method of the header. A computer-readable recording medium having recorded thereon a program for executing the method for compressing a header of an IP packet according to any one of claims 5 to 9. A node provided with a recording medium on which a program for executing the method for compressing a header of an IP packet according to any one of claims 5 to 9 is recorded.

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