Design Of Embedded Protocol Stack For Lans Based On LLC

More and more tasks needed to be done by the network cooperation of the embedded systems that had already play key roles in many facts of our daily life. Since cooperation involved, a set of appropriate communication protocol is needed which generally can be classified in two kinds:protocols mostly based on TCP/IP with the ability of connecting to Internet which make the data exchange on Application Layer possible like LWIP, uIP and many stacks provided by commercial OS like Windows CE,VxWorks and Palm OS.The others are relating with industry measure and device control that we referred as Field bus like ProfiBus of Siemens,MODBus of PeterHans,FF and so on.Although they were both designed to serve the data transmission, but because the distinct difference of situation they are intended for,none of the protocols above is befitting in some occasions like the application data communication within a LAN. Since it need neither the capability of transmission through the Internet brought by IP nor the need to read or control the registers,so they are not suitable either as the encapsulation and hierarchy are too complex that leading in an inefficiency or too particular to use.Thus,an appropriate protocol which can fulfill this and besides the restrict resources of embedded system like compute,memory, energy is in dire needed.Besides, many fruits have been acquired in the research of the trusted communication,but most of them still rest on the theory.Weighted computation,direct/indirect trust transfer model were usually used or worked at the application layer use the Key Exchange,Digital Signature and so on.Although generally they can worked effectively in theory, but they are hardly acceptable cause the difficulty to implement and the time consumption.Few trust code can be founded in either open source stacks like Linux 2.4,LWIP or stacks attaching with the commercial OS.In this paper a smart mechanism is put forward and used in E-LLC.So, in order to solve the questions mentioned above while considering stability and safety, a novel efficient communication stack was proposed in this paper and dedicated to the following subjects:Firstly, based on the similarity of data transmission between 802.2 and TCP/IP, make the encapsulation length only one third of TCP/IP while introducing the extra ability of flow control.Secondly, package oriented acknowledgement is designed to solve the problem of Tear-drop attack along with the mass computation wasted in the out-sequence package management brought by the byte oriented acknowledgement.Then,internal gateway mechanism is put forward to avoid the uncertainty as well as the inefficient brought by the process scheduling and the interprocess communication.Finally,considering the trust value of all nodes within the network we introduce the preestimate data filtration mechanism to keep the network efficiency still acceptable under the mass attack from the malicious nodes.