CN102202106A

CN102202106A - Maintenance method of address compression control table in 6LoWPAN protocol

Info

Publication number: CN102202106A
Application number: CN2011101305075A
Authority: CN
Inventors: 华贵斌; 江勇; 赵倩; 吴双桥; 吴俊华
Original assignee: Shenzhen Graduate School Tsinghua University
Current assignee: Shenzhen Graduate School Tsinghua University
Priority date: 2011-05-19
Filing date: 2011-05-19
Publication date: 2011-09-28
Anticipated expiration: 2031-05-19
Also published as: CN102202106B

Abstract

The invention discloses a maintenance method of an address compression control table in a 6LoWPAN protocol. The method comprises the following steps of: generating a control table and an address cache table in a coordinator node; subtracting N1 and N2 from numerical values of weight items corresponding to valid effect items in the address cache table and the control table respectively, and setting the corresponding effect items to be invalid respectively if the numerical values of the weight items in the address cache table and the control table are not greater than threshold values M1 and M2 respectively; judging whether the control table has invalid effect items, if so, finding the weight items with maximum numerical values in the valid effect items of the address cache table, and setting the effect items to be invalid; and filling IPV6 address prefixes corresponding to the weight items with maximum numerical values into IPV6 address prefix items corresponding to the invalid effect items in the control table, setting the corresponding effect items in the control table to be valid, and sending message containing the IPV6 address prefixes and corresponding index numbers CID to the adjacent sub node by the coordinator node.

Description

The maintaining method of address compression control table in a kind of 6LoWPAN agreement

Technical field

The invention belongs to a low-speed wireless network technology field, territory, relate in particular to the maintaining method of address compression control table in a kind of 6LoWPAN agreement based on IPv6.

Background technology

Background technology for a better understanding of the present invention, can be with reference to following technical data:

[1]?RFC?4944,?Transimission?of?IPv6?Packets?over?IEEE802.15.4?Networks

[2]?draft-ietf-6lowpan-hc-07,?Compression?Format?for?IPv6?Datagrams?in?6LoWPAN?Networks

[3]?draft-ietf-6lowpan-nd-09,?Neighbor?Discovery?Optimization?for?Low-power?and?Lossy?Networks

Wireless personal local area network (WPAN) is the connectionless PAN (Personal Area Network) of a kind of employing.In July, 2003, IEEE is that LR-WPAN has released the IEEE802.15.4 technical standard, and this agreement has mainly defined the agreement of physical layer (PHY) and MAC layer (MAC), and main application scenario is automation meter reading, automation control and sensor network.The short-distance wireless that IEEE802.15.4 is absorbed in low rate, low-power consumption connects, and flank speed only is 250kbps, and battery life can reach 6 months to 2 years, is a kind of economical and efficient, low complex degree, low-power consumption, low data rate and radio network technique cheaply.

What propose network layer protocol on IEEE802.15.4 is ZigBee alliance, they have defined the data frame format and the interactive mode of network layer and application layer, yet the ZigBee agreement can't with the present networks direct communication, therefore people have proposed the 6LoWPAN agreement again, 6LoWPAN is an agreement that designs in order to make wireless sensor network and IPv6 network interconnection intercommunication, and can be described as IPv6 is to be applied to the simplification version that wireless sensor network environment designs.The potentiality of the low power run that 6LoWPAN had make it be well suited for being applied in the equipment from the hand-held set to the instrument, and the support that AES-128 is encrypted simultaneously also provides strong fail safe for wireless network.

In order to transmit the message of IPv6 efficiently on the 802.15.4 link, 6lowpan has introduced adaptation layer between link layer and network layer, reduce the transport overhead of IPv6 message in a large number by adaptation layer.The header compression method of this " pay as you go " formula has been removed the redundant or unnecessary network information in the IP packet header, and IP packet header obtains these network level information from the domain of dependence in link level 802.15.4 packet header when receiving.

The physical layer MTU value of IEEE802.15.4 is 127 bytes, and Frame control expense will consume 25 bytes at most, so data link layer has only 102 bytes to use; The data link layer security algorithm will consume 21 bytes (AES-CCM-128 takies 21 bytes, and AES-CCM-64 takies 13 bytes, and AES-CCM-32 takies 9 bytes), and load has only 81 bytes to use for network layer; Consider 40 byte IPv6 packet header and 8 byte UDP packet header again, remain 33 bytes and use to application layer; Therefore it is imperative to simplify IPv6 packet header.

The basic principle of 6lowpan adaptation layer header-compressed is the field in the ipv6 packet header to be extracted form new packet header, uses which kind of mode to simplify with follow-up which field of the dispatch field identification of a byte.Under the best circumstances, the packed field that the IPv6 address of 40 bytes can a byte of boil down to and the hop limit field of 1 byte.6lowpan adaptation layer data packet head form as shown in Figures 1 to 3.

In order to realize the compression function in IPv6 packet header, RFC4944 has defined LOWPAN_HC1 header and LOWPAN_BC0 header, the LOWPAN_HC1 header-compressed be the IPv6 message, LOWPAN_BC0 packet header compression be broadcasting packet.LOWPAN_HC1 data packet head form as shown in Figure 4, wherein,

SA:IPv6 source address compression control

DA:IPv6 destination address compression control

TF: traffic classes and flow label field control

NH: next header field control

HC2:HC2 compression control (UDP, ICMP, TCP)

IPv6 address, source and purpose IPv6 address have taken 32 bytes altogether in the IPv6 packet header of 40 bytes, be maximum a part of expense.LOWPAN_HC1 packet header allows to generate the IPv6 address from link layer address, and concrete grammar is to use the mac address of 48bits to generate the EUI-64 address, uses the EUI-64 of home link network prefix and generation then

Address combination becomes the IPv6 address of link-local.Because LOWPAN_HC1 only is applicable to the IPv6 address of compression link-local, and can't be suitable for for global address, can only comprise 32 complete byte IPv6 addresses in follow-up packet header.Therefore there is the people to propose the LOWPAN_IPHC header, it depends on the CONTEXT table that a whole network is shared, with the index CID of 4bits, to 16 list items being arranged, 64 prefixes of each IPv6 address of list item storage (adopting 64 IPv6 address prefixs of fixed length scheme) as list item; We just can have 16 indexed networks like this, and the 64bits prefix of each network can replace the space, packet header of an IPv6 address just having been saved 60bits with the index CID of 4bits.As shown in Figure 5,6LOWPAN_IPHC header compression form, the code field of LOWPAN_IPHC is as follows: TF: traffic classes and flow label field control; NH: next field control; HLIM: hop count field restriction; The control of CID:CONTEXT index field; SAC:IPv6 source address compression control; SAM:IPv6 source address compact model; M: multicast compression control; DAC:IPv6 destination address compression control; DAM:IPv6 destination address compact model.

When CONTEXT table maintenance algorithm draws certain address prefix and is used by the packet high-frequency, need that this prefix is put into CONTEXT and show, coordinator node is upgraded operation with the CONTEXT list item, need carry out synchronously whole network; Wherein coordinator node will be upgraded list item to each node broadcasting CONTEXT, and its message adopts the CONTEXT choice format in the 6lowpan Neighbor Discovery Protocol, message format as shown in Figure 6, wherein the CID item accounts for the space of 4 bits.

Wireless sensor network based on IPv6 uses the 6lowpan agreement to carry out communication in network internal, for the short frame length Frame that adapts to IEEE802.15.4 and the low power characteristic of wireless sensor network, the 6lowpan agreement has increased an adaptation layer between data link layer and network layer, its main purpose is that the IPv6 packet header of network layer and the header part more than the network layer are compressed, remove redundant data, reach the optimization effect of network traffics.Up-to-date 6LoWPAN agreement adopts makes IPHC packet header compression algorithm, and the core concept of this algorithm makes safeguards a CONTEXT table that the whole network is synchronous, uses this table to compress as packet header and provides support.

The LOWPAN_IPHC header compression adopts CONTEXT to show to assist compressed IP v6 address, yet any node of whole network that makes can both correctly be discerned the 6lowpan packet after the compression, then the CONTEXT table must be synchronized in the whole network, tend to cause bigger time delay.And the original intention that LOWPAN_IPHC adopts CONTEXT to show is in order to replace the IPv6 address prefix with CID, to reduce packet header to reach, reducing the purpose of flow in the network.But the introducing of CONTEXT table itself needs administration overhead again, and giving in the whole network has so again increased the management data flow.The particularly renewal of CONTEXT list item, each more need guarantee CONTEXT to upgrade in the node that item can be synchronized to whole network and go in new capital, has therefore caused increasing of network traffics objectively.On the other hand,, in the network burst flow, may cause the frequent updating of list item if CONTEXT entry updating algorithm design is bad, thus the emphasis network load.

Summary of the invention

In order to solve the bigger technical problem of above-mentioned offered load, the invention provides the maintaining method of address compression control table in a kind of 6LoWPAN agreement, comprise the steps:

A, in coordinator node, generate control table and address caching table, described control table is made up of a plurality of list items, each list item comprises IPV6 address prefix item, effectiveness item and the weight term of manipulative indexing CID, described address caching table is made up of a plurality of list items, and each list item comprises IPV6 address prefix item, renders a service item and weight term; Wherein, rendeing a service item has effectively and invalid two states;

B, in described address caching table, will subtract N1 with an effective numerical value of corresponding weight term of rendeing a service, be less than or equal to threshold value M1 as if the numerical value of weight term, then the effectiveness item of correspondence be set to invalid;

C, in described control table, will subtract N2 with an effective numerical value of corresponding weight term of rendeing a service, be less than or equal to threshold value M2 as if the numerical value of weight term, then the effectiveness item of correspondence be set to invalid;

D, judge whether there is invalid effectiveness item in the described control table,, find out the weight term of numerical value maximum if having then in effective effectivenesss of described address caching table, should render a service be changed to invalid;

E, the IPV6 address prefix of the weight term correspondence of described numerical value maximum is inserted in the IPV6 address prefix item of effectiveness item correspondence invalid in the described control table, and effectiveness item corresponding in the described control table is changed to effectively, the message that coordinator node will comprise the call number CID of described IPV6 address prefix and correspondence sends on the adjacent child node;

Wherein, N1, N2, M1 and M2 are positive integers.

Preferably, in step D,, then carry out following steps if there is not invalid effectiveness item:

The numerical value of weight limit item during G, described address caching table effective renderd a service, if the numerical value of minimal weight item during doubly described control table effective renderd a service greater than K is execution in step H then;

H, the IPV6 address prefix item that the IPV6 address prefix item of described weight limit item correspondence is corresponding with described minimal weight item exchange numerical value; The numerical value of described minimal weight item is changed to: the numerical value of a and described weight limit item divided by K and, it is invalid that the effectiveness item of weight limit item correspondence described in the described address caching table is changed to, and the effectiveness item of the correspondence of minimal weight item described in the described control table is changed to effectively;

Wherein a and K are positive integers.

Preferably, described coordinator node is carried out following steps after receiving packet:

Steps A 1, described coordinator node be extraction source IPV6 address prefix and purpose IPV6 address prefix in the packet that receives, if packet includes the 6LoWPAN packet header of call number CID, then execution in step A2; Otherwise execution in step A3;

Steps A 2, in described control table, the numerical value of the weight term corresponding with call number CID described in the steps A 1 is added N3;

Steps A 3, described address caching table is carried out following steps:

Steps A 31, if having described source IPV6 address prefix or a purpose IPV6 address prefix, then the numerical value with the weight term of correspondence adds N4; Whether existence is invalid effectiveness item otherwise search;

Steps A 32, if existence be invalid effectiveness item, then described source IPV6 address prefix or purpose IPV6 address prefix are write in the IPV6 address prefix item corresponding with this effectiveness item, and the state that should render a service is set to effectively, and the numerical value of the weight term of correspondence is set to M3;

Steps A 33, if existence be not invalid effectiveness item, in the IPV6 address prefix item that then will be corresponding, write described source IPV6 address prefix or purpose IPV6 address prefix, and the numerical value of the weight term of correspondence is set to M3 with the weight term of numerical value minimum;

Wherein N3, N4 and M3 are positive integers.

Preferably, in described steps A 2,, then keep this numerical value constant if the numerical value of the weight term of described call number CID correspondence is certain numerical value M4; In described steps A 31,, then keep this numerical value constant if the numerical value of the weight term of described correspondence is certain numerical value M5; Wherein M4 and M5 are positive integers.

Preferably, described call number CID length is 4 bits, and described effectiveness item length is 1 bit, and the weight term length of described control table is 6 bits, and the weight term length of described address caching table is 7 bits; Described N1=N2=N3=N4=1, M1=M2=0, K=2, M3=4, M4=63, M5=127.

Pin of the present invention is that the CONTEXT based on LOWPAN_IPHC shows maintenance algorithm on the 6LOWPAN wireless sensor network.This method has following advantage on the basis of existing LOWPAN_IPHC compressed header packet and CONTEXT design:

1. in CONTEXT table and CONTEXT address caching table, a weight weight term is arranged all, preserve the frequency that this IPv6 address prefix occurs with this field in the 6lowpan network, make us can dispatch out high-frequency IPv6 address prefix therein and be kept in the CONTEXT table.

2. for can make the weight term that accounts for a small amount of several bit space can represent frequency of occurrences value as much as possible, in algorithm, adopted timer regularly whole weights to be carried out decrement operations, and when each IPv6 address prefix occurs, increasing operation in packet, such mode can guarantee that active in the recent period IPv6 address prefix can obtain higher weight.

3. the address prefix that will flow through in the packet of telegon node is added up, and obtains the frequency of occurrences of IPv6 address prefix, and is kept in the CONTEXT address caching table with the form of frequency weight.

4. first line of a couplet CONTEXT table and second line of a couplet CONTEXT table in intermediate node (router node), have been introduced, make the hierarchical synchronization algorithm become possibility, the hierarchical synchronization algorithm makes the only synchronously own child node of each node, and the feasible like this CONTEXT that may occur when large scale network is used based on the 6LowPAN agreement of IPHC shows the updating delay problem and effectively slowed down.

5. when upgrading the CONTEXT list item, introduce anti-shake coefficient, prevented the close IPv6 address prefix of frequency and the CONTEXT list item frequent updating problem that produces.

To sum up, the network bandwidth resources that the present invention has avoided causing owing to frequent updating CONTEXT list item is wasted and energy consumption, guarantees that active in the recent period IPv6 address prefix can obtain higher weight, so that network reaches optimization.Proposed simultaneously the hierarchical synchronization algorithm of CONTEXT table again, the feasible CONTEXT table updating delay problem that may occur when large scale network is used based on the 6LowPAN agreement of IPHC is effectively slowed down.

Description of drawings

Fig. 1 is general IPV6 data message form;

Fig. 2 is a LowPan_HC1 compressed IP V6 data message form;

Fig. 3 is LowPan_HC1 compressed IP V6 data message and passes through L2 layer Mesh mode transformat;

Fig. 4 is a 6LOWPAN_HC1 header compression form;

Fig. 5 is a 6LOWPAN_IPHC header compression form;

Fig. 6 is that the CONTEXT in the 6LOWPAN Neighbor Discovery Protocol upgrades itemization format;

Fig. 7 is a CONTEXT table hierarchical synchronization algorithm schematic diagram;

Fig. 8 is the flow chart of a kind of specific embodiment of the present invention.

Embodiment

Below with reference to accompanying drawing, specific embodiments of the invention are described in further detail.

A kind of specific embodiment of the maintaining method of address compression control table comprises the steps: in the 6LoWPAN agreement of the present invention

Wherein, N1, N2, M1 and M2 are positive integers.

In the 6LoWPAN agreement of the present invention among the more specifically embodiment of the maintaining method of address compression control table, at first in coordinator node, generate control table, perhaps be referred to as the CONTEXT table, be used for CID index IPV6 address prefix, each leaf node and root node all keep a CONTEXT table in the network, intermediate node keeps 2 parts of CONTEXT tables, be respectively first line of a couplet CONTEXT table (perhaps being called first line of a couplet control table) and second line of a couplet CONTEXT table (perhaps being called second line of a couplet control table), wherein coordinator node belongs to root node; End node belongs to leaf node, can not transmit packet; Intermediate node can be transmitted packet between end node and coordinator node; Wherein the CONTEXT sheet format is as follows:

IPv6 Prefix (64bits)	Valid(1bit)	Update(1bit)	CID Weight (6bits)
				?	?	?	?

IPv6 address prefix item IPv6 Prefix: the IPV6 address prefix of the 64bits of corresponding CID accounts for 64 bits;

Render a service a Valid: represent whether this is effective, accounts for 1 bit, 1 expression is effective, and 0 expression is invalid;

Upgrade a Update: represent that this list item whether just in renewal process, accounts for 1 bit, 1 expression is upgraded, and 0 is not upgrading;

Weight term CID Weight: the weights of this list item, account for 6 bits, only effective in the telegon node.

The CONTEXT table has only 16 list items, and each occupies 9 byte of memorys, and total table of opening takies 144 byte of memorys.Call number CID promptly is the item number sequence number of CONTEXT table, and for example, the zero list item represents that its corresponding call number CID then is 0, is expressed as 0000 with binary system.Certainly, can in the CONTEXT table, represent call number CID by extra bit, but can increase the size of CONTEXT table like this, upgrade to get up network is caused bigger burden.In addition, the CONTEXT that The present invention be directed in the 6lowpan Neighbor Discovery Protocol that compresses by the CONTEXT table upgrades the maintenance algorithm that the CID in the itemization format carries out, thereby the number of bits of call number CID can be adjusted according to the number of bits of CID in this form.Because intermediate node and end node are only paid close attention to IPV6 address prefix and its corresponding call number CID, thereby the CONTEXT of intermediate node and end node table can include only IPv6 address prefix item IPv6 Prefix.

The CONTEXT table is safeguarded by the network coordinator node, sends broadcast packet by the telegon node when entry updating being arranged at every turn, and leaf and router node receive the CONTEXT table copy of after the lastest imformation this locality being preserved and upgrade operation.

Next generate CONTEXT address caching table in coordinator node, be used for storing the higher IPv6 address prefix of the packet frequency of occurrences, CONTEXT address caching sheet format is as follows:

IPv6 Prefix（64bits）	Valid(1bit)	Weight（7bits）
			?	?	?

IPv6 address prefix item IPv6 Prefix: the IPV6 address prefix of the 64bits of corresponding CID;

Weight term CID Weight: the weights of this list item, account for 7 bits, only effective in the telegon node.

The list item number of CONTEXT address caching table is set to 256 (can change item number according to actual conditions), and every takies 9 byte of memorys.Item in the CONTEXT table must come from CONTEXT address caching table, and maintenance algorithm is selected the IPv6 address prefix of high frequency appearance and is updated in the CONTEXT table according to dispatching algorithm in CONTEXT address caching table.Upgrade the network traffics that the CONTEXT list item is brought in order to reduce, for the close IPv6 address prefix of the frequency of occurrences, we tend to keep the IPv6 address prefix that has used in the CONTEXT table, promptly reduce its frequent updating by controlling anti-shake coefficient a.

In the another kind of specific embodiment of the maintaining method of address compression control table, the handling process that coordinator node whenever receives an Intranet 6lowpan packet or outer net IPv6 packet is as follows in the 6LoWPAN agreement of the present invention:

Step 1 extracts source IPv6 address prefix and purpose IPv6 address prefix respectively from packet, if the packet that receives comprises 6lowpan packet header and for carrying the CID compressed header packet, then changes step 2; Otherwise (if if not the CID compression is not with in 6lowpan packet header or 6lowpan packet header) then changes step 3.

Step 2 is searched corresponding CID in the CONTEXT table, and CID weight is carried out+1 operation, if do not carry out for 63 of maximums+1 operation, the value of keeping CID weight is constant, and this takes turns processing to finish coordinator node;

Step 3 is searched CONTEXT address caching table;

Step 3.1 has been 127 with this weight term Weight value+1(as if this weight term Weight value then if find this address prefix in CONTEXT address caching table, does not then change)

Step 3.2 is then searched the list item of valid=0 if do not find this address prefix in CONTEXT address caching table.

Step 3.3 is then inserted this list item with this source IPv6 address prefix or purpose IPv6 address prefix, and valid is put 1 if find the list item of valid=0, and weight=4 is set;

Step 3.4 is then inserted this source IPv6 address prefix and purpose IPv6 address prefix in the IPv6 address prefix item of the minimum list item of weight value in the address caching table, and weight=4 is set if do not find the list item of valid=0;

In a kind of specific embodiment of maintaining method of address compression control table in the 6LoWPAN agreement of the present invention, the control of the timer of coordinator node is regularly carried out, and the address prefix whether inspection has high-frequency to occur need be put into the CONTEXT table.

Step 4 (aging mechanism) traversal CONTEXT address caching list item, to weight value-1 operation of the list item of each valid=1, if-1 afterwards the weight value be 0 to put this valid value be 0;

Step 5 traversal CONTEXT list item carries out-1 operation to the CID weight value of the list item of each valid=1, if-1 afterwards CID weight value be 0 to put this valid value be 0;

Step 6 judges in the CONTEXT table whether the list item of valid=0 is arranged, if then execution in step 7 is arranged, otherwise execution in step 8;

Step 7 item is found out the weight value (valid=1) in the max{CONTEXT address caching list item }, promptly in the address caching table, find out the IPv6 address prefix item of the maximum list item of valid=1 and weight value, carry out the operation of CONTEXT entry updating, adopt the hierarchical synchronization flow process of CONTEXT table to upgrade (being step 10-14), and effectiveness item valid corresponding in the CONREXT buffer list entry is changed to 0; In the practice, also can adopt in the prior art, directly upgrade with the IPv6 Prefix of the maximum corresponding address of weight value in the CONTEXT address caching list item to valid=0 correspondence in the CONTEXT list item, send to the node that directly links to each other with it by coordinator node then, and be not the method that adopts the hierarchical synchronization of CONTEXT table; Repeating step 6;

Step 8 is judged the weight value (valid=1) in the max{CONTEXT address caching list item } whether greater than the CID weight value (valid=1) in 2 times the min{CONTEXT list item }; Promptly judge the maximum weight value in the CONTEXT address caching list item of valid=1, whether greater than the minimum CID weight value in the CONTEXT list item of 2 times valid=1, if continue step 9, otherwise finish this wheel operation of coordinator node;

Step 9 is with the weight value in the max{CONTEXT address caching list item } CONTEXT address caching list item and the CID weight value in the min{CONTEXT list item the CONTEXT list item, promptly to the IPv6 address prefix item of the maximum correspondence of the weight value in the CONTEXT address caching list item of valid=1, and the IPv6 address prefix item of the correspondence of the minimum of the CID weight value in the CONTEXT list item of valid=1, carry out CONTEXT entry updating operation (being step 15-17).In the practice, also can adopt in the prior art, directly upgrade with the IPv6 Prefix of the maximum corresponding address of weight value in the CONTEXT address caching list item to valid=0 correspondence in the CONTEXT list item, by coordinator node the CONTEXT list item that upgrades is sent to the node that directly links to each other with it then, and be not the method that adopts the hierarchical synchronization of CONTEXT table; Repeating step 8;

In a kind of specific embodiment of maintaining method of address compression control table in the 6LoWPAN agreement of the present invention, the hierarchical synchronization flow process of CONTEXT table.

When CONTEXT table maintenance algorithm draws certain address prefix and used by the packet high-frequency, need this prefix is put into the CONTEXT table, and this moment, CONTEXT still had the list item of valid=0 in showing; Coordinator node is upgraded operation with the CONTEXT list item, need carry out synchronously whole network, adopt the mode of hierarchical synchronization can reduce the latency issue that massive wireless sensor causes synchronously, this algorithm is applicable to tree-like wireless sensor network topology structure, as shown in Figure 7.T1 is a coordinator node, and T2, T4 and T6 are intermediate nodes, and T3, T5, T7, T8 and T9 are end nodes.T1, T2, T3 and T4 were in same synchronizing cycle 1, and T2, T5, T6 are in synchronizing cycle 2 together, and T4, T7 are in synchronizing cycle 3 together, and T6, T8, T9 are in synchronizing cycle 4 together.

Its concrete steps following (got access to CONTEXT list item to be filled out this moment and need be updated to the CONTEXT address caching list item of this CONTEXT list item to be filled out):

Step 10 will be to be inserted the update item of CONTEXT list item be made as 1, represent that this list item upgrades, do not revise other values in this this moment.

The broadcasting of step 11 telegon node comprises the call number CID and the renewal item message to being somebody's turn to do in requisition for the IPV6 address prefix from CONTEXT address caching list item of inserting this list item of this list item, be that CONTEXT upgrades item, wait for each child node (comprising intermediate node that is connected with coordinator node and the end node that is connected with coordinator node) response; During this step, child node still is that the telegon node does not use this CID as 6lowpan adaptation layer address compression parameter; If during this step, receive the 6lowpan packet that carries this CID, still handle by original C ONTEXT contents in table;

After step 12 treats that all child nodes return confirmation, coordinator node is inserted the IPv6 prefix of CONTEXT address caching list item in the CONTEXT list item, the valid of CONTEXT list item is made as 1, update is set to 0, CID weight is made as weight/2+a and (is 63 to the maximum, wherein a is anti-shake coefficient, is integer, can choose as the case may be); The telegon node can normally use this CID to communicate after this step;

Step 13 intermediate node (perhaps router node) receives after CONTEXT that father node sends upgrades, use the identical local first line of a couplet CONTEXT list item of call number CID of this entry updating and this renewal, return confirmation to father node, represent first line of a couplet CONTEXT table to be upgraded, the child node broadcasting CONTEXT to oneself upgrades item simultaneously; This moment, the first line of a couplet CONTEXT table and the second line of a couplet CONTEXT list item of this router node were in the imbalance stage, adopt first line of a couplet CONTEXT to resolve 6LowPAN packet header with the father node communication at imbalance stage intermediate node, use second line of a couplet CONTEXT to show to resolve 6LowPAN packet header with the child node communication;

The packet of transmitting for needs, (promptly this CID has just upgraded from father node and has come if this 6LowPAN packet header CID field is inconsistent in first line of a couplet CONTEXT table and second line of a couplet CONTEXT table, be not updated to as yet in the child node of this node and go), after then needing call number CID to initial data packet header to be replaced with in the second line of a couplet CONTEXT table the corresponding call number CID in IPv6 address with this packet, be forwarded to child node again and go.

After step 14 treats that child node returns affirmation, second line of a couplet CONTEXT list item is upgraded, after this this intermediate node can normally use this CID to communicate, and promptly can communicate by the first line of a couplet or second line of a couplet CONTEXT list item.

In a kind of specific embodiment of maintaining method of address compression control table in the 6LoWPAN agreement of the present invention,

When CONTEXT table maintenance algorithm draws certain address prefix and used by the packet high-frequency, need this prefix is put into the CONTEXT table, and this moment, CONTEXT did not have the list item of valid=0 in showing; Coordinator node is upgraded operation with the CONTEXT list item, need carry out synchronously its concrete steps following (the IPv6 address prefix item of the CONTEXT address caching list item of the IPv6 address prefix item that has remained the CONTEXT list item filled out this moment and need be updated to this CONTEXT list item to be filled out) to whole network:

Step 15 repeating step 10-11;

After step 16 treats that all child nodes return affirmation, the value of the IPv6 prefix of the IPv6 prefix of CONTEXT address caching list item and CONTEXT list item correspondence is exchanged, the valid of CONTEXT list item is made as 1, corresponding valid is made as 0 with CONTEXT address caching list item, update is set to 0, CID weight is made as weight/2+a (be 63 to the maximum, wherein a is anti-shake coefficient); Can normally use this CID to communicate after this step;

Step 17 repeating step 13-14;

The present invention has used for reference the thought of the cache management in the operating system, comprise access frequency weights, address caching, more newer field, anti-shake coefficient, LFU dispatching algorithm etc., the network bandwidth resources of having avoided causing owing to frequent updating CONTEXT list item is wasted and energy consumption, guarantee that active in the recent period IPv6 address prefix can obtain higher weight, so that network reaches optimization.Proposed simultaneously the hierarchical synchronization algorithm of CONTEXT table again, the feasible CONTEXT table updating delay problem that may occur when large scale network is used based on the 6LowPAN agreement of IPHC is effectively slowed down.Taken into full account the burden of maintenance algorithm to network, and the update mechanism of CONTEXT table during burst flow, made list item stable, characteristics such as extensibility is better impel network to reach the optimization of flow.

Claims

1. the maintaining method of address compression control table in the 6LoWPAN agreement is characterized in that, comprises the steps:

Wherein, N1, N2, M1 and M2 are positive integers.

2. the maintaining method of address compression control table in the 6LoWPAN agreement as claimed in claim 1 is characterized in that:

In step D,, then carry out following steps if there is not invalid effectiveness item:

Wherein a and K are positive integers.

3. the maintaining method of address compression control table is characterized in that in the 6LoWPAN agreement as claimed in claim 1, and described coordinator node is carried out following steps after receiving packet:

Steps A 3, described address caching table is carried out following steps:

Wherein N3, N4 and M3 are positive integers.

4. the maintaining method of address compression control table in the 6LoWPAN agreement as claimed in claim 3 is characterized in that: in described steps A 2, if the numerical value of the weight term of described call number CID correspondence is certain numerical value M4, then keep this numerical value constant; In described steps A 31,, then keep this numerical value constant if the numerical value of the weight term of described correspondence is certain numerical value M5; Wherein M4 and M5 are positive integers.

5. the maintaining method of address compression control table in the 6LoWPAN agreement as claimed in claim 4, it is characterized in that: described call number CID length is 4 bits, a described effectiveness length is 1 bit, and the weight term length of described control table is 6 bits, and the weight term length of described address caching table is 7 bits; Described N1=N2=N3=N4=1, M1=M2=0, K=2, M3=4, M4=63, M5=127.