Course Introduction basic network architectures and functions General requirements on the security and reliability Network architectures from the point of secure PA197 Secure Network Design 1. Introduction Eva Hladká, Luděk Matýska Fakulty of Informatics February 18, 2019 Eva Hladká, Luděk Matýska PA197 Secure Network Design 1. Introduction Course Introduction basic network architectures and functions General requirements on the security and reliability Network architectures from the point of secure Q Course Introduction • Course Organization • Course overview Q basic network architectures and functions • data transmission o end to end argument o routing switching Q General requirements on the security and reliability • implication towards the architecture design Q Network architectures from the point of secure • reliable design also in ad-hoc/sensor networks 9 reliable design also in vehicular and/or mobile networks Eva Hladká, Luděk Matýska PA197 Secure Network Design 1. Introduction Course Introduction basic network architectures and functions General requirements on the security and reliability Network architectures from the point of secure Course Organization Course overview LOI u rse u r; gai n izai CI lor i • attending the lectures 9 the knowledge acquired course materials will be published on the course webpage • assessment methodology: <* course literature: * slides, RFCs, ... • literature being announced in relevant course parts Eva Hladká, Luděk Matýska PA197 Secure Network Design 1. Introduction Course Introduction basic network architectures and functions General requirements on the security and reliability Network architectures from the point of secure Course Organization Course overview • the course goal: to provide basic network architectures and functions • data transmission • end to end argument • routing • switching • ... • general requirements on the security and reliability o implication towards the architecture design • Network architectures from the point of secure • reliable design also in • ad-hoc/sensor networks • vehicular and/or mobile networks Eva Hladká, Luděk Matýska PA197 Secure Network Design 1. Introduction Course Introduction basic network architectures and functions General requirements on the security and reliability Network architectures from the point of secure data transmission end to end argument routing switching • the main goal: to ensure a transmission of bits (= the content of passed frames) between sender and receiver o several standards (RS-232-C, CCITT V.24, CCITT X.21, IEEE 802.x) defining electrical, mechanical, functional, and procedural characteristics of interfaces used for connecting various transmission media and devices, e.g.: • parameters of the transmitted signals, their meaning and timing o mutual relationships of control and state signals • connectors' wiring • and many many others Eva Hladká, Luděk Matýska PA197 Secure Network Design 1. Introduction Course Introduction basic network architectures and functions General requirements on the security and reliability Network architectures from the point of secure data transmission end to end argument routing switching - i—v —i— ■ ■ services - uata Iransmission S • Bit-to-Signal Transformation • representing the bits by a signal - electromagnetic energy that can propagate through medium • Bit-Rate Control • the number of bits sent per second • Bit Synchronization • the timing of the bit transfer (synchronization of the bits by providing clocking mechanisms that control both sender and receiver) • Multiplexing • the process of dividing a link (physical medium) into logical channels for better efficiency • Circuit Switching • circuit switching is usually a function of the physical layer • (packet switching is an issue of the data link layer) Eva Hladká, Luděk Matýska PA197 Secure Network Design 1. Introduction Course Introduction data transmission basic network architectures and functions General requirements on the security and reliability routing • data is transferred (via transmission media) in the form of (electromagnetic) signals • the data have to be converted into the signals • signal = a function of time representing changes of physical (electromagnetic) characteristics of the transmission media • data that have to be transferred (Os and Is) - digital (binary) • signals spread through the transmission media - analog or digital 9 some media suitable for both analog and digital transmission -wired media (coaxial cable, twisted pair), optical fibre • some media suitable just for analog transmission - ether (air) Eva Hladká, Luděk Matýska PA197 Secure Network Design 1. Introduction Course Introduction basic network architectures and functions General requirements on the security and reliability Network architectures from the point of secure data transmission end to end argument routing switching • provide an environment for the functionality of physical layer 9 basic distinction: • guided (wired) media 9 provide a conduit from one device to another • twisted pair (LANs, up to lOGbps), coaxial cable, optical fibre (backbones, hundreds of Gbps), etc. • unguided (wire-less) media o transfer an electromagnetic wave without the use of physical conductor • the signals are broadcasted (spread) via ether (air, vacuum, water, etc.) • radio signals, microwave signals, infrared signals, etc. Eva Hladká, Luděk Matýska PA197 Secure Network Design 1. Introduction Course Introduction basic network architectures and functions General requirements on the security and reliability Network architectures from the point of secure data transmission end to end argument routing switching • multiplexing - a technique of sharing an available bandwidth by concurrent communication channels • the goal is to maximize the utilization of the media • applied especially for optical fibres and non-wired media • for analog signals: • Frequency-Division Multiplexing (FDM) • Wave-Division Multiplexing (WDM) 9 for digital signals: • Time-Division Multiplexing (TDM) Eva Hladká, Luděk Matýska PA197 Secure Network Design 1. Introduction Course Introduction basic network architectures and functions General requirements on the security and reliability Network architectures from the point of secure data transmission end to end argument routing switching How to provide demanded functionality in computer networks? • End-to-End (E2E) argument • application demanded functionality is possible to provide wit knowledge and by application if it is possible, communication protocol operations have to be defined by realization only in communication system end nodes or in the closest distance • in lower system levels protocol function should be implemented only if performance increases. • suitable for applications demanding higher degree fidelity transported data and some latency is tolerated. Hop-by-Hop (HbH) • repeating specific functionality on the each two-point connection is possible to obtain increasing performance • it requires storing state informations on inside network nodes =^> limited scalability • useful for applications,where minimize latency is more important then transported data fidelity, (e.g. real-time applications) Eva Hladká, Luděk Matýska PA197 Secure Network Design 1. Introduction Course Introduction basic network architectures and functions General requirements on the security and reliability Network architectures from the point of secure data transmission end to end argument routing switching • the main goal of routing is: • to find optimal paths • the optimality criterion is a metric - a cost assigned for passing through a network • to deliver a data packet to its receiver 9 the routing usually does not deal with the whole packet path • the router deals with just a single step - to whom should be the particular packet forwarded • somebody "closer" to the recipient • so-called hop-by-hop principle • the next router then decides, what to further do with the received packet Eva Hladká, Luděk Matýska PA197 Secure Network Design 1. Introduction Course Introduction basic network architectures and functions General requirements on the security and reliability Network architectures from the point of secure data transmission end to end argument routing switching The basic approaches divide based on the routing table creation / maintenance: 9 static (non-adaptive) • manually (by hand) edited records • suitable for a static topology and smaller networks • dynamic (adaptive) - these respond to network changes • complex (usually distributed) algorithms • e.g.: • centralized - a centre controls the whole routing • isolated - every node on its own • distributed - nodes' cooperation Eva Hladká, Luděk Matýska PA197 Secure Network Design 1. Introduction Course Introduction basic network architectures and functions General requirements on the security and reliability Network architectures from the point of secure data transmission end to end argument routing switching • the routing can be seen as a problem of graph theory • a network can be represented by a graph, where: o nodes represent routers (identified by their IP addresses) • edges represent routers' interconnection (a data link) edges' value = the communication cost • the goal: to find paths having minimal costs between any two nodes in the network Eva Hladká, Luděk Matýska PA197 Secure Network Design 1. Introduction Course Introduction data transmission basic network architectures and functions General requirements on the security and reliability routing Network architectures from the point of secure switching Routing - routing algorithms' required features Required features of any routing algorithm: • accuracy • simplicity 9 effectivness and scalability • to minimize an amount of control information 5% of the whole traffic!) • to minimize routing tables' sizes • robustness and stability 9 a distributed algorithm is necessary • fairness • optimality • "What should be treated as the best path?" Eva Hladká, Luděk Matýska PA197 Secure Network Design 1. Introduction Course Introduction basic network architectures and functions General requirements on the security and reliability Network architectures from the point of secure data transmission end to end argument routing switching IMS Sl»]»]OlSM ÍUMO distributed routing Basic approaches to distributed routing: • Distance Vector (DV) - Bel I man-Ford algorithm • the neighboring routers periodically (or when the topology changes) exchange complete copies of their routing tables • based on the content of received updates, a router updates its information and increments its distance vector number 9 a metric indicating the number of hops in the network • i.e., "all pieces of information about the network just to my neighbors" • Link State (LS) • the routers periodically exchange information about states of the links, to which they are directly connected • they maintain complete information about the network topology - every router is aware of all the other routers in the network • once acquired, the Dijkstra algorithm is used for shortest paths computation Eva Hladká, Luděk Matýska PA197 Secure Network Design 1. Introduction Course Introduction data transmission basic network architectures and functions General requirements on the security and reliability routing Network architectures from the point of secure switching • Packet switching refers to protocols in which messages are divided into packets before sending and each packet is transmitted individually. Once all packets forming a message arrive at the destination, they are recompiled into the original message. • Packet switching operation • Data are transmitted in short packets, typically an upper bound on packet size is 1000 bytes. • Each packet contains part of the user's data and some control information. • The control information should at least contain • destination address • source address • Store and forward - Packets are received, stored briefly and past on the next node. 9 Advantages _ i :___ _rc:_:_____. -:___i_____i _ j______i _ __.. i___i______i i_. ._ Eva Hladká, Luděk Matýska PA197 Secure Network Design 1. Introduction Course Introduction basic network architectures and functions General requirements on the security and reliability Network architectures from the point of secure data transmission end to end argument routing switching Virtual Circuits 9 9 9 9 Pre-planned route is established before any packets sent Call setup before the exchange (handshake) all packets follow the same route and arrive in sequence each packet contains a virtual circuit identifier instead of destination address no routing decision required for each packet clear request to drop circuit Datagrams 9 9 9 9 9 Each packet is treated independently with no reference to packets that have gone before. Packets may arrive out of order Packets may go missing Up to receiver to re-order packets and recover from missing packets More processing time per packet node Robust in the face of link or node failures. Eva Hladká, Luděk Matýska PA197 Secure Network Design 1. Introduction Course Introduction basic network architectures and functions General requirements on the security and reliability Network architectures from the point of secure data transmission end to end argument routing switching • Performance • propagation delay • transmission time • node delay o Packet switching evolution • X.25 packet-switched network • router-based networking • switching vs. routing • frame relay network • ATM network Eva Hladká, Luděk Matýska PA197 Secure Network Design 1. Introduction Course Introduction basic network architectures and functions General requirements on the security and reliability Network architectures from the point of secure data transmission end to end argument routing switching Switching 9 9 9 9 9 path set up at connection time simple table look up table maintenance via signaling no out of sequence delivery lost path may lost connection • much faster than pure routing • link decision made ahead of time, and resources allocate then • Routing can work as connectionless complex routing algorithm table maintenance via protocol out of sequence delivery likely robust: no connections lost significant processing delay output link decision based on packet header contents - at every node 9 9 9 9 9 9 9 Eva Hladká, Luděk Matýska PA197 Secure Network Design 1. Introduction Course Introduction basic network architectures and functions implication towards the architecture design General requirements on the security and reliability Network architectures from the point of secure Eva Hladká, Luděk Matýska PA197 Secure Network Design 1. Introduction Course Introduction basic network architectures and functions General requirements on the security and reliability Network architectures from the point of secure reliable design also in ad-hoc/sensor networks reliable design also in vehicular and/or mobile networks Eva Hladká, Luděk Matýska PA197 Secure Network Design 1. Introduction Course Introduction basic network architectures and functions General requirements on the security and reliability Network architectures from the point of secure reliable design also in ad-hoc/sensor networks reliable design also in vehicular and/or mobile networks Eva Hladká, Luděk Matýska PA197 Secure Network Design 1. Introduction