01 - ethernet tcpip - v5.1.ppt

Ethernet TCP/IP OverviewBasic Ethernet Technologies

Schneider Electric*- Ethernet TCP/IP Overview

Introduction to Ethernet CommunicationsWhat is EthernetLayers in the TCP/IP ModelNetwork Architectures & TopologiesPhysical SupportEthernet Protocols and ServicesSummary


What is Ethernet?Invented in 1973-1975 by Xerox

Complex networking technology that defines wiring and signaling standards for the physical layer through the means of the data link layer and a common addressing format (IP address)Standardized as IEEE 802.3

Allows computers and equipment to communicate to one another over a common medium for Local Area Networks

Term derived from the combination of the Greek word aether (to burn/shine/disperse) and network


CSMA/CDCarrier Sense Multiple Access with Collision DetectionEthernet originally made the use of a shared co-axial cable to networkProne to collision problemsGoverns the way computers share information on the same channelFollowing procedure was used when a computer needed to transmit information

Main procedure/AlgorithmFrame ready for transmissionIs medium idle? If not, wait until it becomes ready and wait the interframe gap period (9.6 s in 10 Mbit/s Ethernet)Start transmittingDoes a collision occur? If so, go to collision detected procedureEnd successful transmission


CSMA/CDCarrier Sense Multiple Access with Collision DetectionCollision detected procedureContinue transmission until minimum packet time is reached (jam signal) to ensure that all receivers detect the collisionIs maximum number of transmission attempts reached? If so, abort transmission.Calculate and wait random back off periodRe-enter main procedure at stage 1


Types of TransmissionFull duplex transmission: simultaneous two-wayHalf duplex transmission: alternating two-waySimplex transmission: one-way


MAC AddressMedia Access Control AddressA unique identifier attached to most network adapters (NICs)A number that acts like a name for a particular network adapterThe network cards (or built-in network adapters) in two different computers will have different names, or MAC addresses, as would an Ethernet adapter and a wireless adapter in the same computer, and as would multiple network cards in a router. However, it is possible to change the MAC address on most of today's hardware.

Example: MAC Address = 00-14-A5-60-A4-96


MAC AddressEthernet HeaderFCS CheckApplications:HTTP, IEC 61850, Modbus TCP, etcPreambleMAC Destination LLC (Type)MAC SourceIPTCP@ IP = network address


Format des tramesSize of the frames (with prambule) :minimal : 72 octets (46 octets of DATA)maximal : 1526 octets26 octets for the protocol


Format of the framesFlow direction of octetsFirst : first octet of prambulelast : last octet of the control sequenceFlow direction of bits for one octetFirst : less significant bit (bit 0)last : most significant bit (bit 7)Time between frames : 9.6 s minimum10 Mbits/s = 10 bits / sTime between frame 9.6 s --> 9.6 x 10 = 96 bits time (12 octets)


Different field of the framePrambule7 octets: synchronisation 7 * (10101010)SFD (Start Frame Delimiter)1 octet: 10101011Start the begining of the frame

Destination Addressunique address of a station (unicast)or group of stations address (multicast)or all stations address (broadcast) source Addressphysical adresse of the sending station


Les diffrents champs de la trameSize of the data zone (spcifique 802.3)between 1 et 1500 octetsor Type of protocol (specifique Ethernet)Valeur 0x0600 (=1536)

Data + paddingsize 1500 octetssize 46 octetspadding (octets sans signification) when less of 46 octets of data to send FCS : Frame Control Sequence4 octets of control : CRC (Cyclic Redundancy Check)Polynme de degr 32, for the fields : addresses (destination and source) size of the data zone data + padding


Diffrent field of the framefield "type" in the frame Ethernet2 octets in hxadcimal format XX-YY ou XXYYfield types known 0800 IP 0806 ARP 6000 6009 DEC (6004 LAT) 8019 DOMAIN (Apollo) 8038 DEC LANBridge management 88B8 IEC 61850 GOOSEOrfield size" in the frame IEEE802.3all the number of protocols are higher than the maximum size of the data zone in a frame (1500)a station can identify the frames if value > 1500 frame Ethernet if not frame IEEE802.3


the Addresses MACAddresse MAC = 6 octets (48 bits)Unicast :first bit (sent) = 0--> 1er octet of @ is even : 08:00:20:06:D4:E8 00:00:0C:00:5B:372nd bit (sent) = 0 shows a universal address (given by IEEE) 1er octet = x0, x1, x4, x5, x8, x9, xC, xD ...Multicast :first bit (sent) =1 ---> 1er octet of @ is odd :Shows a group of stations : 09-00-2B-00-00-0F protocol LAT de DEC 09-00-2B-01-00-00 LANbridge (pont) de DEC


Les Adresses MACBroadcast = diffusion = FF:FF:FF:FF:FF:FFAll the stations of a network (all segments)

IEEE has given sections of addresses to the manufacturers:The 3 first octets show the origine of the device 00:00:0C:XX:XX:XX : Cisco 08:00:20:XX:XX:XX : Sun 08:00:09:XX:XX:XX : HP 08:00:14:XX:XX:XX : ExcelanBut there are addresses "non IEEE" : AA:00:04:XX:XX:XX: DECthe adresses Ethernet and IEEE802.3 are uniquesETHERNET dont know adresses IP !!!


IP address version 4 (IPv4)IPv4 is a best effort delivery protocol because it Does not guarantee deliveryDoes not ensure packets will arrive in the correct orderDoes not check for duplicate packet deliveryHas possible addresses (around 4.2 billion)Will run out of address by 2010 or 2011


SubnetMask3 classes of networksnetIDhostIDnetIDhostIDhostIDnetID31313124268000Class AClass BClass CClass AClass BClass C

Min ValueMax ValuePossible # of NetworksMax # of devices per NetworkTypical Use0.0.0.0126.255.255.25512616777214Large networks128.0.0.0191.255.255.2551638465534Big organizations192.0.0.0223.255.255.2552097152254Small networks


Ladressage IPCLASSE Anetidhostid31024netidhostid310801631hostidnetidCLASSE CCLASSE B Class A: larger Host ID = local network bigger01101 0Multicast et usages spciaux310CLASSE D11100


SubnetMaskEx: Extraction of Network Address 10.194. 1.30255.255.255. 011111111111111111111111100000000000010101100001000000001000111100000101011000010000000010000000010.194.1.0IP AddressSubnet MaskIP AddressSubnet Mask


adresses IP subnetingsame subnet => frame sent directly to destination

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 255 255 254 00 0 0 0 1 0 1 0 1 1 0 0 0 0 1 0 0 0 0 0 0 1 0 0 1 0 0 0 1 0 1 00 0 0 0 1 0 1 0 1 1 0 0 0 0 1 0 0 0 0 0 0 1 0 1 0 0 0 1 1 0 1 1other subnet => frame sent directly to routeur

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 00 0 0 0 1 0 1 0 1 1 0 0 0 0 1 0 0 0 0 0 0 1 0 0 1 0 0 0 1 0 1 00 0 0 0 1 0 1 0 1 1 0 0 0 0 1 0 0 0 0 0 0 1 1 0 0 0 0 1 1 0 1 1


Ladressage IPparticular Case0.0.0.0 no adress127.0.0.1 itself (loopback, localhost)all bits of hostid at 0 : the networkall bits of hostid at 1 : all the devices of the network (broadcast)Private networks : usefull adresses free to use for internal network no connected directly to Internet (connection possible via a proxy)10.0.0.0 10.255.255.255 (10/8)172.16.0.0 172.31.255.255 (172.16/12)192.168.0.0 192.168.255.255 (192.168/16)Adresses automatic (no routables)169.154.0.0 169.154.255.255 (169.154/16)


ARP (Address Resolution Protocol)Ethernet only knows adresses MACARP allows to change IP address to a MAC addressPrinciplethe station source sends a request in broadcast mode at level MAC who has address (IP) x.y.z.t ?The station concerned answers it is me that is my address MACThe association IP/MAC is stored in a cache ARPEach inputof this cache is erased after 30s to 2mnARP allows to detect / prevent the double adress IPAt the begining, the device sends a request ARP with its own adress (Gratuitous ARP)Normaly this request must stay without any answerRARP (reverse ARP) ralise la fonction inverse


Address Resolution Protocol (ARP)Method for finding a host's hardware address based on its network layer address.It is possible to view a list of all addresses registered in the ARP table by using the ARP a command in the DOS command prompt


ARP (continued)ARP is used in four cases when two hosts are communicatingTwo hosts are on the same network and one sends a packet to the otherTwo hosts are on different networks and must use a gateway to reach each otherA router needs to forward a packet from a host through another routerA router needs to forward a packet from a host to another host on the same networkThe last three cases are mostly used over the Internet as two computers on the internet are typically separated by more than 3 hops.

Imagine computer A sends a packet to computer D and there are two routers, B & C, between themCase 2 covers A sending to DCase 3 covers B sending to CCase 4 covers C sending to D1234


automatic allocation of adress IPCertains quipements ne possdent pas dadresse IP pr attribueIncapacit de la stockerOptimisation de la gestion des adressesBOOTP permet un quipement de rcuprer une adresse IP auprs dun serveurDHCP est une volution de BOOTP (mmes trames)PrincipeLa station met une requte en broadcast de niveau MAC qui peut me donner une adresse IP ?Le serveur du rseau rpond en indiquant ladresse attribue soit partir dune table dassociation MAC/IP prconfigure soit par allocation dynamique (DHCP)Ladresse gateway est aussi communique par le serveurLa rfrence dun fichier de paramtres peut-tre donneBOOTP: Boot ProtocolDHCP: Dynamic Host Configuration Protocol


Schneider Electric workstations are configured to obtain an IP address automatically from the networkAttribution automatique dadresse IP


IP Address version 6 (IPv6)0000 : 00000010 : 2a8c : 003b : 90ad : 0cb7 : 0000 : 0000 : 10040010 : 2a8c : 003b : 90ad : 0cb7 : 0000 : 0000 : 100410 : 2a8c : 3b : 90ad : cb7 : : 100410 : 2a8c : 3b : 90ad : cb7 : 0000 : 0000 : 1004IPv6 has been designed to replace IPv4 in the futureOriginally planned for 2010 or 2011Has been very slow to adoptHas possible addresses (around ) for every person in the world for every visible star in the known universe


IPv6 Networks0010 : 2a8c : 003b : : / 480010 : 2a8c : 003b : 0000 : 0000 : 0000 : 0000 : 00000010 : 2a8c : 003b : ffff : ffff : ffff : ffff : ffffNetworks are written in CIDR (Classless Inter-Domain Routing) notation


Mapping IPv4 to IPv600001010110000100000000100011110 10 194 1 30The first 80 bits are set to 0The next 16 bits are set to 1The last 32 bits is the IPv4 address 0 a c 2 0 1 1 e: : ffff : 0ac2 : 011e




Open System Interconnection OSI7 Layer ArchitectureHARDWARESOFTWARE


Layer 7: Application layerIt interfaces directly to and performs common application services for the application processesIssues requests to the presentation layer.The common application layer services provide semantic (language) conversion between associated application processes. Note: Examples of common application services of general interest include the virtual file, virtual terminal, and job transfer and manipulation protocols.

The application layer of the four layer and five layer TCP/IP models corresponds to the application layer, the presentation layer and session layer in the seven layer OSI models.

APPLICATION LAYERPRESENTATION LAYERSESSION LAYERTRANSPORT LAYERNETWORK LAYERDATA LINK LAYERPHYSICAL LAYER


Layer 6: Presentation layerTransforms data to provide a standard interface for the Application layer. MIME encoding, data encryption and similar manipulation of the presentation is done at this layer to present the data as a service or protocol developer sees fit.

Examples: Converting an EBCDIC-coded text file to an ASCII-coded fileSerializing objects and other data structures into and out of XML



Layer 5: Session layer Controls the dialogues/connections (sessions) between computersEstablishes, manages and terminates the connections between the local and remote application. It provides for either full-duplex or half-duplex operation, and establishes checkpointing, adjournment, termination, and restart procedures. This layer is responsible for "graceful close" of sessions, which is a property of TCP, and also for session checkpointing and recovery, which is not usually used in the Internet protocols suite.



Layer 4: Transport layer Provides transparent transfer of data between end usersControls the reliability of a given link through flow control, segmentation/de-segmentation, and error controlSome protocols are state and connection oriented. This means that the transport layer can keep track of the packets and retransmit those that fail.

Example: Transmission Control Protocol (TCP). The transport layer is the layer that converts messages into TCP segments or User Datagram Protocol (UDP)Analogy:Post Office, which deals with the dispatching and classification of mail and parcels sent.



Couche TransportPortsJust as every IP device has an IP address each service on Ethernet has a port address.The port address is needed to allow a end devices network stack to pass the correct data to the correct application.Ports allow a single Ethernet stack can handle data for many different applications at the same time.The port used by the source device to send the data is assigned randomly from a pool.The destination port that the data is sent to is defined for each Ethernet service.Some protocols are assigned well known numbers like FTP, HTTP, ModbusOther protocols take a socket from the available pool - this does not guarantee compatibility across different networks and systems.


Couche TransportPorts (cont.)The port numbers are divided into three ranges: the Well Known Ports, the Registered Ports, and the Dynamic and/or Private Ports. The Well Known Ports are those from 0 through 1023. Well Known ports SHOULD NOT be used without IANA registration. The Registered Ports are those from 1024 through 49151. Registered ports SHOULD NOT be used without IANA registration.The Dynamic and/or Private Ports are those from 49152 through 65535.


Couche TransportPorts (cont.)Les ports usuels :21 (tcp) : FTP (parfois coupl 20/tcp) 23 (tcp) : Telnet. On trouve par exemple des modems/routeurs en telnet. 25 (tcp) : SMTP, envoi d'email. 53 (tcp et udp) : DNS 67 (tcp et udp) : DHCP, gestion automatique des IP d'un rseau. 80 (tcp et udp) : HTTP 102 (tcp et udp) : ISO-TSAP Class 0 IEC 61850 / MMS over TCP/IP110 (tcp et udp) : POP3, lecture de courrier. 123 (tcp et udp) : NTP (Network Time protocol), synchronisation de l'heure. 502 (tcp et udp) : asa-appl-proto (Dennis Dube) Modbus


Couche Transport UDPUDP - User Datagram Protocol.The UDP layer requires that an application build the single packet of data is then put into a UDP header and sent onto the Ethernet network. No retry or delivery order services are provided.UDP allows a packet to be broadcast, unlike TCP that requires a dedicated socket between the endpoints.Retries and data integrity can still be provided but must be handled by the application layer protocol.

Troubleshooting commands for the TCP/UDP LayerNetstat, using switches.


Couche Transport TCPTCP - Transmission Control ProtocolTCP allows a reliable transport of data from one device to the other by :Transporting data along a socket using sequence numbers to record the amount of data sent.Implementing a send/acknowledge system where each packet of data is acknowledged.Implementing an adaptive retry system where a lost packet can be resent or a lost section of data resent without having to abort the entire transmission.Provides re-ordering of the IP datagrams at the destination based on sequence number - this is needed as IP datagrams can arrive in a different order to what they are sent.Providing flow control that prevents a receiving device from being overloaded with data.Providing a checksum on the header and data sent.A TCP socket connection must be established between two devices before data can be sent. The socket connection must be closed after all data is sent.


- TCP : segmenter, encapsuler, ordonnancermetteurMessageIPIPRcepteurMessage12432143


Couche Transport TCPSocket Setup and Take Down.A socket setup follows these steps :Client device chooses a random socket number and sends a SYN packet to the Server IP and Socket address.The Server responds with a ACK of the request plus a SYN to open the socket in the other direction, so two way communications are possible.The Client and Server both specify a window at this point, this is the amount of data that the device is able to accept at this time.The window can be set to 0 to prevent any more data being sent.The Client then sends an ACK of the SYN from the Server, this completes the Socket establishment.


Layer 3: Network layer Provides the means of transferring data sequences from a source to a destination via one or more networks while maintaining the quality of service requested by the Transport layer. Performs network routing functions, and might also perform segmentation/de-segmentation, and report delivery errors. Routers operate at this layersending data throughout the extended network and making the Internet possible. This is a logical addressing scheme values are chosen by the network engineer

Example: Internet Protocol (IP). Analogy:Air Mail or Consolidated Carrier that transfers the mail from Point A to Point B



Layer 2: Data Link layerProvides the functional and procedural means to transfer data between network entities and to detect and possibly correct errors that may occur in the Physical layerIt arranges bits from physical layer into logical chunks of data, known as framesThis is the layer at which the bridges and switches operateConnectivity is provided only among locally attached network nodes forming layer 2 domains for unicast or broadcast forwarding. Other protocols may be imposed on the data frames to create tunnels and logically separated layer 2 forwarding domain



Layer 1: Physical layer Defines all the electrical and physical specifications for devicesThis includes the layout of pins, voltages, and cable specificationsHubs, repeaters, and network adapters are physical-layer devicesMajor functions and services performed by the physical layer are:Establishment and termination of a connection to a communications medium.Sharing communication resources among multiple users.Modulation, or conversion between the representation of digital data in user equipment and the corresponding signals transmitted over a communications channel. These are signals operating over the physical cabling or over a radio link.Various physical-layer Ethernet standards are also in this layer; Ethernet incorporates both this layer and the data-link layer. The same applies to other local-area networks, such as IEEE 802.11



OSI: 7 Layer ArchitectureTCPChecking & CorrectionTCP/IPHARDWARESOFTWARE




Types of Area NetworksWAN: Wide Area NetworkComputer network that covers a large area: Metropolitan, regional, or nationalMAN: Metropolitan Area NetworkComputer networks usually spanning a cityTypically use wireless or optical fibreLAN: Local Area NetworkComputer network covering a small area: Home, office, or group of buildingsCurrent LANs are likely based on IEEE 802.3 Ethernet technology, running at 10, 100 or 1000 Mbit/sVLAN: Virtual Local Area NetworkA grouping of devices that arent on the same physical LANAllows re-grouping of devices via software instead of physically


Why are VLANs Important?VLANs are used to create logical groups of devices as if they were on the same LANRouter needed to connect two VLANs together

FlexibleEasy management and administration of logical groups of devices.Easier to add/remove and modify devices on the LAN through software

Cost EffectiveFewer switches are needed in multi-LAN networks

InteroperableIs an IEEE standard adopted across the industry


VLAN NetworkL3L2L2L2L2


Trunks and TagsTrunkA VLAN trunk carries packets from multiple VLANs on a single cable

TagEach packet is identified by a VLAN tagThe tag is 4 bytes and identifies the VLAN numberUsed to differentiate the packets between the different networksOne VLAN is allowed to stay untagged


VLAN TermsEdge PortCarries packets belonging to a single LANA port connected to an end station or device on the same LANDoes not carry any VLAN tagsTrunk PortCarries packets belonging to multiple VLANS. Packets must be tagged with VLAN numbers, except the Trunk Native VLANUsed to connect layer 2 devices (typically switches)Tagged VLANVLAN packets sent from a trunk portEach packet contains a tag with the VLAN IDUntagged VLANVLAN packets sent from a trunk port without a VLAN tagTrunk Native VLANEach trunk port can define a native VLANUntagged packets received on a trunk port are associated to the native VLAN defined for that port


Adding a VLAN tagCFIVIDPreambleMAC Destination LLC (Type)MAC SourceIPTCPPreambleMAC Destination LLC (Type)MAC SourceIPTCPTPIDPCPSTANDARD FrameTAGGED Frame


Tagged vs. UntaggedUntaggedStandard Ethernet packet/frame in a networkUsed with end devices on edge portsTaggedInserts a 4 byte tag into the header of the frameUsed by trunk ports to identify which VLAN the packet belongs toVLAN ID has a range of 1-4095Tag Protocol Identifier Set to 0x8100 to identify the frame as belonging to a VLANPriority Code Point Set (0-7) to identify the traffic as data, voice, video, etcCanonical Format Indicator Used for compatibility between Ethernet and Token Ring framesVLAN Identifier Indicates which VLAN the frame belongs to. Has range of 1-4095TPIDPCPCFIVID1 Bit16 Bits3 Bits12 Bits


Types of Networking Topologies




Hardware: HubDevice for connecting multiple twisted pair or fibre optic Ethernet devices together, making them act as a single segment. A form of multiport repeater that restores timing and signal strength. Responsible for forwarding a jam signal to all ports if it detects a collision. All devices are in the same collision domain (CSMA/CD)Half duplex onlyOperates in the physical layer (layer 1) of the OSI model.


Hardware: SwitchConnects devices within the same LANIs a networking device that performs transparent bridging (connection of multiple network segments with forwarding based on MAC addresses) at up to the speed of the hardware Operates in the data link layer (layer 2) of the OSI model. Each physical port is in a different collision domainAllows full duplexStores MAC addresses in a database for fast referencingManages traffic by directing frames on necessary ports only


Hardware: Hubs vs. SwitchesWhat is the difference between a Hub & Switch?An Ethernet hub unsophisticated broadcast device. Hubs do not manage any network traffic Any packet entering any port is broadcast out on every other portPacket collisions may result since no traffic is managed--which greatly impedes the smooth flow of traffic.

A switch isolates ports, meaning that every received packet is sent out only to the port on which the target may be found

Since the switch intelligently sends packets where they need to go, the performance of the network can be greatly increased.


Hardware: RouterOperates in the network layer (layer 3) of the OSI model.Connects devices between different networks, making the internet possible.A router is a computer networking device that buffers and forwards data packets across an inter-network toward their destinations, through a process known as routing.


Hardware: Switches vs. RoutersA router acts as a junction between two or more networks to buffer and transfer data packets among them.

A switch connects devices to form a Local area network (LAN) (which might, in turn, be connected to another network via a router).


Hardware: Server / ClientServerComputer system or piece of hardware that provides services to clientsUsed for dedicated applicationsData storage/aggregationEmailFile sharingPrintingDHCPHardware configuration is particular to application

ClientComputer system that accesses a (remote) service on another computer by some kind of network


Ethernet Physical SupportOriginal Ethernet used Co-Axial cableNot reliable for large extended networksDamage or a single bad connector, could make the whole Ethernet segment unusable. Prone to electrical discontinuity (signal reflections) Difficult to debugSecurity: Information is transmitted across a common medium to all therefore a single node can eavesdrop on all traffic.Performance: Use of a single cable also means that the bandwidth is shared, so that network traffic can slow to a crawl when, for example, the network and nodes restart after a power failure.


Ethernet Physical Support3 common standards used today10BASE-T100BASE-TX(100BASE-T) : Fast Ethernet1000BASE-T : Gigabit Ethernet

All use the same connections and cable typeRJ-45 connectorCategory 5 (4 pair cable)


Ethernet Physical Support10Base-T/100Base-T10BASE-T1st vendor independent Ethernet standard developed from AT&TSupports data transmission rates up to 10Mbits/sTypical cable standards: 100m segment length with 24AWG (0.205mm) cableHigh quality cable: 150m100BASE-T (100BASE-TX, 100BASE-T4)Supports data transmission rates up to 100Mbits/sWorks on the same cable standards as 10BASE-TUses 2 pairs for data transmission1000BASE-TSupports data transmission rates up to 1000Mbits/sUses all fours for simultaneous data transmission


Ethernet Physical Support: Straight vs. CrossoverT586A to T586A are referred to as straight through cablesSame for T586B -T586BT586A to T586B are referred to as crossover cables or patch cables


Ethernet Physical SupportFibre Optic100BASE-FX functions the same as 100BASE-T but uses 2 strands of fibre optic to receive and transmitNot compatible with 10BASE-FL10BASE-FL uses a 850nm100BASE-FX uses a 1300nm near-infrared (NIR) light wavelengthMax distance: 400m1000BASE-SXOperates over multi-mode fibre using a 850nm NIR wavelengthMax distance: 220m (500m with good quality cable)1000BASE-LXUses a long wavelength laserWavelength: 1270 to 1355 nmSpecified to work up to 2 km over 9 m single-mode fibre




Internet ServicesTCP: Transmission Control ProtocolAllows applications on networked hosts to establish connections to one anotherGuarantees reliable delivery of data from sender to receiverDistinguishes data for multiple connections by concurrent applications running on the same hostUses the notion of port numbers to identify sending and receiving application end-points on a hostSome examples include: FTP (21), TELNET (23), SMTP (25) and HTTP (80)

UDP: User Datagram ProtocolAllows programs on networked computers can send short messages sometimes known as datagrams to one anotherNetwork applications that use UDP include the Domain Name System (DNS), streaming media applications such as IPTV, VoIP, Trivial File Transfer Protocol (TFTP) and online gamesUtilizes ports to allow application-to-application communication


HTTPHyper Text Transfer ProtocolUsed to transfer or convey information on the World Wide WebRequest/response protocol between clients and serversClient: Web browserServer: Web server containing images and documentsHTTP client initiates a request by establishing a Transmission Control Protocol (TCP) connection to a particular port on a remote host TCP port 80 by default

ECI850 and ACE850 supports HTTP to provide a configuration and diagnostic interface


FTPFile Transfer ProtocolUsed to transfer data from one computer to another over the Internet, or through a networkClient computer, running FTP client software, initiates connection to server allowing client to perform various file manipulationsSome file managers and web browsers can support this functionFTP server listens on TCP port 21 for incoming connectionsInsecure method for transferring dataPassword information + data can sniffed out using a packet snifferSolution to this problem is to use either SFTP (SSH File Transfer Protocol), or FTPS (FTP over SSL)

ECI850 and ACE850 supports FTP for uploading configuration filesCID: Configured IED Description


DHCPDynamic Host Configuration ProtocolAllows a client device to request and obtain an IP address, subnet mask, and gateway IP address from a server which has a list of addresses available for assignmentClient sends out query prior to any IP communicationsDHCP server to the client with the above information Facilitates automatic network configuration that would otherwise have to be configured manuallyDHCP server ensures that all IP addresses are uniqueIP Address = 10.195.229.130Subnet Mask = 255.255.252.0Gateway IP = 10.195.288.1IP Address?Subnet Mask?Gateway IP?


SNMPSimple Network Management ProtocolSNMP is used by network administrators to manage devices on a networkPerformanceFind / Solve network problemsPlan network growth

Where?Servers / WorkstationsRouters / Switches / HubsFirewallsPrinters / IP Phones / Appliances


SNMP (cont)Resides in the Application layer of the OSI modelConsists of managers and agents

ManagerSoftware / Network Management System running on a network componentInterface between the system administrator and the management systemAgentIntegrated firmware running on a network componentInterface between the manager and the physical managed deviceProvides data about themselves to managers using Management Information dataBases (MIB)Ex. How many packets are sent/received through the deviceMIBMIBMIB


MMSManufacturing Message SpecificationISO 9506 (TC184) standard that defines how communications are handled

Application level protocol that provides for 'peer to peer' real-time and supervisory control communications over a network Allows interoperable products to communicate between applications and devices of different developersFacilitates mapping between objects/registers using other protocolsSupports multiple communication linksTCP/IP, RS-232C, Token Bus, OSI, etc.

Used in client-server requests (reads)


SNTPSimple Network Timing ProtocolProtocol for synchronizing the clocks of computer systems over data networksLess complex form of NTPUses UDP port 123 as its transport layer

Uses NTP timestamp formatUnsigned 64bit 32 bits for seconds32 bits for fractions of seconds# of seconds from Jan.1 1900AccuracyOn the order of milliseconds (10) over the InternetOn the order of microseconds (~200) over the LAN under ideal conditions


RSTP: Rapid Spanning Tree ProtocolIEEE Open StandardRSTP EvolutionSTP802.1d1990RSTP802.1w1998RSTP802.1d-20042004


Why is it Important?Bridge Loops - Broadcast StormCan occur if there is a loop in the physical LANA single packet can travel through the loop without reaching a destinationTakes up bandwidth and floods the network with traffic


What is STP?The Spanning Tree Protocol (STP) creates efficient links within a mesh network of layer-2 devices called Bridges (typically switches)It disables the ports on the switch that are not part of the tree, leaving a single active path between devices

FlexibleAllows for redundant connections to provide automatic backup paths, without creating bridge loopsThe algorithm automatically changes based on the physical topologyEfficientDevices automatically use the fastest connections between devicesEasy to configureInteroperableIs an IEEE standard adopted across the industryDevices from different vendors can work together


How it WorksSelect a Root BridgeThe Bridge with the lowest Bridge IDRoot Bridge sets all ports to forwardingSelect a Root Port for each BridgeHas the lowest path cost to the Root BridgeSelect a Designated Port per LAN segmentReports the lowest path cost to the Root BridgeAll other ports on all devices are set to blocking


BPDU Bridge Protocol Data UnitBridges exchange information with BPDU packets Are regular Ethernet packets, but are used by bridges to share spanning tree topologiesAre distributed to all devices in the network (PCs and edge devices), but will be discarded if not using RSTPAre sent periodically based on the Hello Time parameter (default 2 seconds)Are generated by the root bridge and passed to all other bridges in the network


RSTP NetworkBridge BMAC: 0000.0000.3021Priority: 32,768Bridge DMAC: 0000.0000.8117Priority: 32,768Bridge CMAC: 0000.0000.4362Priority: 32,768Bridge EMAC: 0000.0000.9901Priority: 32,768Bridge AMAC: 0000.0000.1001Priority: 32,768BlockingRootDesignatedDesignatedDesignatedRootRootRootROOTDesignatedDesignated


Selecting a Root BridgeWhen first powered, every switch assumes that it is the Root Bridge and sends BPDUs indicating this every 2 secondsIf a better BPDU is received, the switch will:Modify the port cost to the Root BridgeStart forwarding the new roots received BPDUsThe Root Bridge of the network is the bridge with the smallest Bridge ID.At any time, a switch can become the root bridge by lowering its Bridge IDIf manually selecting the Root Bridge, it should be as close to the center of the network as possible


Bridge IdentifierThe Bridge ID is a unique identifier used to select the root bridge in the network and is made of two parts:Priority 0 - 61,440 in steps of 4096 with default of 32,768MAC Address The Switch MAC Address - 6 bytes To compare two Bridge IDs, the priority is compared first. If both bridges have the same priority, the MAC addresses are comparedUsed in tie-breakers when determining port roles and path costs Switches A (MAC=0000.0000.1000) and B (MAC=0000.0000.2000) both have a priority of 32,768. Switch A will automatically be selected as the root bridge If the user would like Switch B to become the root bridge, its priority must be set less than 32,768


What does RSTP add to STP?RSTP is a refinement of STP which means it has the same basic operating characteristicsDetection of root bridge failure is done in 1 hello time (default hello time is 2 seconds)Ports can be configured as edge ports if they are not connected to another bridge. Edge ports go into the forwarding state (still monitored for BPDUs incase a bridge is attached)Faster convergence times (steady state condition)A bridge will send its spanning tree information to its designated ports. If a second bridge receives this information and decides that it is superior root information, the bridge will set all of its other ports to the discarding state. The second bridge can then send an acknowledgment to the first bridge. When the first bridge receives the acknowledgement, it will change that port to the forwarding state, by-passing the usual listening/learning states. This can create a cascade where each bridge proposes to its neighbors to determine if they can rapidly change to the forwarding state.


What does RSTP add to STP? (cont)Backwards compatible with STPActively performs handshakes to determine port state instead of waiting for timers to expire (Faster)Uses alternate ports for fast recovery. If a fault is detected on the root port, an alternate or a backup port will take over.Ring size limited to 30 switchesSignals a topology change with port up (online), but not port down (offline)


RSTP Port RolesRootThe forwarding port that has the lowest path cost to the root bridge. Each bridge can have only one root port.DesignatedA port on a LAN segment whos bridge has the lowest path cost back to the root bridge. Each LAN segment (collision domain) can have only one designated port, but a bridge could have multiple designated ports.NOTE: If a segment has a root port, the other segment will automatically be a designated portNon-designatedAll other ports that are not the root port or designated. Automatically in the blocking state

AlternateA port that presents an alternate path to the root bridge without using the root port. Will become the root port if the original fails.BackupA port that is a backup for the designated ports


RSTP Port StatesBlockingDoes not send or receive user data, but can change into the Forwarding state if another link fails and this port is needed. BPDU data is still received in blocking state. ListeningThe port processes BPDUs, but not data frames.LearningThe port still doesnt forward data frames, but will learn the source MAC Addresses and add them to the switchs databaseForwardingThe port that sends and receives data normally. It will still monitor BPDUs that might tell the port to return to the blocking stateDiscardingThe port doesnt forward data frames or learn MAC AddressesDisabledA port that is manually disabled by a network administrator


How Much is it?Determine the Port / Path CostPort Cost Each port has a cost associated with it based on its speed and according to a table in the standard. This value can be manually configured to make it more/less preferred. Lower values indicate a more preferred port.

Path Cost An accumulated value based on the Port Cost values from other ports in the segment. Its calculated by adding the cost received in the BPDU to the port cost

Messages from any device in the network to the root bridge will travel on the path with the least cost.


Path Cost (cont)Manufacturers can use different values for the ports, but these are the recommendations from the standard

Link SpeedRecommended ValueRecommended RangeRange100 Kb/s200 000 000 20 000 000 200 000 0001-2000000001 Mb/s20 000 000 2 000 000 200 000 0001-20000000010 Mb/s2 000 000200 000 20 000 0001-200000000100 Mb/s200 00020 000 2 000 0001-2000000001 Gb/s20 0002 000 200 0001-20000000010 Gb/s2 000200 20 0001-200000000100 Gb/s20020 2 0001-2000000001 Tb/s202 2001-20000000010 Tb/s21 201-200000000


Path Cost (cont)100 Mb/s2000001 Gb/s20000ROOT1 Gb/s2000010 Gb/s2000100 Mb/s20000010 Mb/s200000010 Mb/s2000000RDRRRDDDDDD




SummaryCSMA/CD is used to avoid packet collisionsMAC Addresses are unique identifiers programmed into all Network devices and used to send packets from one device to anotherIP addressing is used to send packets across networks and the internet


Network TerminologyImportant to be able to understand the various terms/acronyms used for describing todays networking principlesCSMA/CD =Carrier Sense Multiple Access with Collision DetectionMAC Address = Media Access Control AddressTCP = Transmission Control ProtocolUDP = User Datagram ProtocolARP= Address Resolution ProtocolHTTP = Hyper Text Transfer ProtocolFTP = File Transfer ProtocolSNMP = Simple Network Management ProtocolSNTP = Network Timing ProtocolDHCP = Dynamic Host Configuration Protocol (In Sepam is not present)RSTP = Rapid Spanning Tree Protocol

IEEE = Institute of Electrical and Electronics Engineers

The Ethernet operating principle CSMA/CD involves random access to the medium with collision control, and# stands for Carrier Sense Multiple Access # .with # Collision Detection This is how it works....Each station # listens and waits for the bus to be free in order to send data. # If more than one station sends data at the same time, there is a collision.# 1 - A collision is detected# 2 - Transmission of the frame is stopped# 3 - A jam sequence frame is sent# 4 - The transmitter waits for a random time interval# 5 - The frame is transmitted again

AnalogyThis can be likened to what happens at a dinner party, where all the guests talk to each other through a common medium (the air). Before speaking, each guest politely waits for the current speaker to finish. If two guests start speaking at the same time, both stop and wait for short, random periods of time (in Ethernet, this time is generally measured in microseconds).The type of transmission is defined by the direction or directions in which the data are conveyed. This has an effect on the transmission speed.# SIMPLEX data transmission is only one-way.With # HALF DUPLEX, data are transmitted both ways, but one after the other.With # FULL DUPLEX, data may be transmitted in both directions at the same time.

In order for # any type of data (Modbus, FTP and so on) to be transmitted via Ethernet, a # particular frame structure is created, with the data encapsulated between # headers and # check bits.The # Ethernet header includes # the MAC addresses of the receiving and # source machines. Each machine has its own # MAC (Medium Access Control or physical) address. It is # given this address for good, when it is built. The MAC address is # independent of the location or network in which the machine is used. It is found in the # network connection properties menu.The first 3 bytes represent the manufacturer and the last 3 are dedicated to the machine (for example, the PC).Be careful not to confuse MAC addresses, which are machine addresses, with # IP (Internet Protocol) addresses, which are network addresses.We'll talk about IP addressing in a chapter later onLLC Logic Link Control

The IP address is made up of # 4 groups of numbers separated by # dots. It is assigned by the network administrator and is the # Internet address. The value of each group is between 0 and 255. It is encoded in # 32 bits, or # 4 x 1 bytes.The first part of the address identifies a # network, the net.id. The rest identifies the # equipment on the network, the host.id.Only # the network address (net.id) is acknowledged by the routers in conveying the data from # gateway to # gateway, all the way to the intended recipient.

The distribution of the # NetID and HostID varies depending on the size of the network concerned. It's the network administrator who decides according to the announced requirements. IP addresses are split into # 3 classes. A # larger portion is assigned to the HostID if the network is bigger.

This # table gives the number of connections possible according to the chosen classes.Please note: # not all the addresses are available.

The use of three classes, A, B and C, makes it easier to find a computer on the network.With the Subnetwork mask system, we know which network is linked to an IP address.

How does a router extract the network address (net.id) from the IP address for the message to be sent to the intended recipient? Let's take the case of a # Class C network. Its # net.id is encoded in the first 3 bytes. In order for it to be extracted, # the host.id has to be concealed.The router uses a # subnetwork mask. This is a mask of bits, # consisting of ones for the net.id and zeros for the host.id. Like the IP address, the mask comprises # 4 numbers.The net.id, however, is extracted by the router in binary code. So let's take the # IP address and the # subnetwork mask in binary code. The router extracts the net.id using an # AND function between them. The # result is the # net.id in binary code, .which can then be # transformed according to the IP addressing standard.

The IP address is made up of # 4 groups of numbers separated by # dots. It is assigned by the network administrator and is the # Internet address. The value of each group is between 0 and 255. It is encoded in # 32 bits, or # 4 x 1 bytes.The first part of the address identifies a # network, the net.id. The rest identifies the # equipment on the network, the host.id.Only # the network address (net.id) is acknowledged by the routers in conveying the data from # gateway to # gateway, all the way to the intended recipient.

The # OSI (or Open Systems Interconnection) model is a network architecture made up of seven complementary layers. It includes: # data transmission at the starting point, # management of data transfer from end-to-end, and # data processing at the point of arrival.- The # physical layer manages the signal, adapting it to fit the physical medium,- The # data link layer conveys the frames from point to point,- The # network layer manages data routing and switching,- The # transport layer ensures data transfer,- The # session layer organizes and synchronizes exchanges between users,- The # presentation layer provides code conversion to enable different types of entities to dialogue (for example PCs and Macs),And the # application layer manages the various applications of the other layers and provides user services.#, #.Layers 1 and 2 are related to the # data bus concept. RS485 and RS232 play a role in layer 1, and Ethernet in layer 2.Layers 3 & 4 involve the # network.An # example of the application layer is ModBus.

TCP est un protocole universel de transport : il est capable de transporter un # message sans se proccuper de lapplication ou du protocole metteurs. Son # principe consiste : dabord # segmenter le message en morceaux calibrs suivant les limites du protocole; puis les # encapsuler pour leur transport, en les # numrotant pour reprer et conserver lordre initial. Les informations sont # transmises, et # circulent sur le rseau.Le # TCP rcepteur reoit # le message dans un # ordre alatoire. Il le # reconstitue dans le bon ordre pour # restaurer lintgralit du # message.Venons en # IP qui est le protocole dadressage de linformation.On IEEE 802 local area networks, and some non-IEEE 802 networks such as FDDI, this layer may be split into a Media Access Control (MAC) layer and the IEEE 802.2 Logical Link Control (LLC) layer.

Ethernet incorporates both this layer and the data-link layer. The same applies to other local-area networks, such as Token ring, FDDI, and IEEE 802.11, as well as personal area networks such as Bluetooth and IEEE 802.15.4.

TCP-IP is a # network architecture.# IP is the routing and addressing part of the protocol and, # TCP takes care of checking and correction.These services are # independent of the transmission medium and can adapt to all sorts of media. The data is conveyed by routers, without knowing what applications are supported

(maybe expand on how TCP and IP work with data checking, etc would only take one or two slides each)We distinguish different types of networks according to the area they cover: - # LANs are local area networks. They can be split into 2 categories:# Corporate LANsAnd # Industrial LANs- At the # town level, there are MANs, Metropolitan Area Networks.- On the worldwide scale, there are # WANs: Wide Area Networks.

Networks are also differentiated by the topology between components. They may be connected as follows:Ring: nodes of the network is connected to two other nodes in the network, with two connections to each of these nodes, and with the first and last nodes being connected to each other with two connections, forming a double ring Mesh(DeCentralized): Some nodes are interconnected to other nodes in the networkStar(Centralized): all nodes connected to a singular point/node, the central node being a HUBFull Connected: All nodes have a dedicated connection to all other nodes in the networkLinear Bus: all of the nodes of the network are connected to a common transmission medium which has exactly two endpointsDistributed bus: all of the nodes of the network are connected to a common transmission medium which has more than two endpoints that are created by adding branches to the main section of the transmission mediumTree: network where a central node is connected to one or more nodes

MIBCHOIX DU BLOCKING QUE SE PASSE TIL SI VLANNOMBRE DE STATION S

01 - ethernet tcpip - v5.1.ppt

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