11/10/2010 Ing. Manuel Benites 10 LAN Networks c. Project 802 and standards d. Network comparison 11 Switching a. Circuit switching b. Packet switching c. Message swihiitching 12 Telephone Line Applications a. PPP protocol b. ISDN service 1 11/10/2010 10 LAN Networks c. Project 802 and standards IEEE STANDARDS In 1985, 1985,thethe IEEE Computer Association started Project 802802,,consistingconsisting of aasetset of standards for the interconnection of equipment from different manufacturersacturers..ProProject 802 is a way of sppfygecifying the functions of the: physical and link layers in most LAN protocolsprotocols.. 10 LAN Networks c. Project 802 and standards IEEE standard for LANs 2 11/10/2010 10 LAN Networks c. Project 802 and standards IEEE Standards for LANs 10 LAN Networks c. Project 802 and standards ETHERNET STANDARD The original Ethernet standard was created in 1976 by the Xerox Palo Alto Research Centre (PARC)(PARC)..Since then, it has gone through four generationsgenerations.. 3 11/10/2010 10 LAN Networks c. Project 802 and standards Ethernet evolution in four generations 10 LAN Networks c. Project 802 and standards Layers in the 10-Mbps Ethernet 4 11/10/2010 10 LAN Networks c. Project 802 and standards Physical Layer 10 LAN Networks c. Project 802 and standards AUI Cable 5 11/10/2010 10 LAN Networks c. Project 802 and standards Categories of 10-Mbps, Baseband Ethernet 10 LAN Networks c. Project 802 and standards Segments in 10Base5 6 11/10/2010 10 LAN Networks c. Project 802 and standards Segments in 10Base2 10 LAN Networks c. Project 802 and standards Bandwidth Sharing 7 11/10/2010 10 LAN Networks c. Project 802 and standards Fast Ethernet was designed to compete with LAN protocols such as FDDI or Fiber ChannelChannel..IEEEIEEE created Fast Ethernet under the name 802802..33uu..ItIt is compatible with the Standard Ethernet, but can send data ten times faster, at aaraterate of 100 Mbpsps.. 10 LAN Networks c. Project 802 and standards Fast Ethernet layers 8 11/10/2010 10 LAN Networks c. Project 802 and standards Fast Ethernet physical layer 10 LAN Networks c. Project 802 and standards Fast Ethernet implementations 9 11/10/2010 10 LAN Networks c. Project 802 and standards The need to send data at a higher rate resulted in the creation of the Gigabit Ethernet protocol ((10001000 Mbps)Mbps).. The IEEE Committee called it Standard 802802..33zz.. 10 LAN Networks c. Project 802 and standards Gigabit Ethernet topologies 10 11/10/2010 10 LAN Networks c. Project 802 and standards Gigabit Ethernet layers 10 LAN Networks c. Project 802 and standards Two approaches to medium access in Gigabit Ethernet 11 11/10/2010 10 LAN Networks c. Project 802 and standards Gigabit Ethernet physical layer 10 LAN Networks c. Project 802 and standards Gigabit Ethernet implementations 12 11/10/2010 10 LAN Networks c. Project 802 and standards Coding in Gigabit Ethernet implementations 10 LAN Networks c. Project 802 and standards A Token Bus Network 13 11/10/2010 10 LAN Networks c. Project 802 and standards Token Passing in a Token Bus Network 10 LAN Networks c. Project 802 and standards Token Passing in a Token Bus Network 14 11/10/2010 10 LAN Networks c. Project 802 and standards Token Bus layers 10 LAN Networks c. Project 802 and standards 802.11 Point-to-point infrared LAN 15 11/10/2010 10 LAN Networks c. Project 802 and standards Diffuse infrared LAN 10 LAN Networks c. Project 802 and standards 16 11/10/2010 10 LAN Networks c. Project 802 and standards IEEE 802.15: BLUETOOTH LANs 10 LAN Networks c. Project 802 and standards Scatternet 17 11/10/2010 10 LAN Networks d. Comparison of networks Comppfarison of Standard Ethernet implementations 10 LAN Networks d. Comparison of networks Comparison of Fast Ethernet implementations 18 11/10/2010 10 LAN Networks d. Comparison of networks Comparison of Gigabit Ethernet implementations 11 Network Switching a. Circuit switching Switched networks 19 11/10/2010 11 Network Switching a. Circuit switching Network Switching y Long‐distance transmission is normally done over a switched‐node network. y Nodes are not related to the contents of the data. y The end devices are stations y Computer, terminals, telephone, etc. y A collection of nodes and connections make up a communication network. y Data will be switched from one node to the other. 11 Network Switching a. Circuit switching y Nodes may be connected only to other nodes. y Node‐to‐node links are usually multiplexed. y Usually, networks are partially connected y Some redundant connections are implemented to enhance reliability. y There are two different switching technologies y Circu it swihiitching y Packet switching 20 11/10/2010 11 Network Switching a. Circuit switching 11 Network Switching a. Circuit switching Circuit switching y Communication between two stations y Three phases y Establishment y Transfer y Disconnecti on y Switching and channel capacity to establish a connection. 21 11/10/2010 11 Network Switching a. Circuit switching Circuit switching y Inefficient y Capacity of the dedicated channel while connected y If there are no data, the capacity is lost y Setting up the connection takes time y Once connected, the transfer is seamless y Developed for voice traffic (telephony) 11 Network Switching a. Circuit switching PbliPublic ciitircuit switchi ng netktwork 22 11/10/2010 11 Network Switching a. Circuit switching Setting‐up a circuit 11 Network Switching a. Circuit switching In‐channel signalling y Uses the same channel for sigggnalling and for the call y Does not require additional transmission facilities y In‐band y Uses the same frequencies as the voice channel y Can go where the voice channel goes y Impossible to establish a call in a defective channel y Off‐band y Voice signals do not use the whole 4kHz bandwidth y Narrow‐band signal used for control y Needs additional electronics y Low signal rate (narrow bandwidth) 23 11/10/2010 11 Network Switching a. Circuit switching y Control signals are carried over channels that are independent from voice channels y One control signal channel can carry signals to a number of subscriber channels. y Common control channel for those subscriber lines y Associated medium y Close d common chlhannel for tktrunk lines btbetween switc hes y Dissociated mode y Additional nodes (signal transfer points) y They are really two separate networks 11 Network Switching a. Circuit switching Example of a circuit-switching network 24 11/10/2010 11 Network Switching a. Circuit switching Example of a circuit-switching network 11 Network Switching a. Circuit switching Traditional Circuit Switching 25 11/10/2010 11 Network Switching a. Circuit switching Softswitch 11 Network Switching b. Packet switching 26 11/10/2010 11 Network Switching b. Packet switching Packet‐switching principles y Circuit switching is designed for voice communications. y Resources dedicated to a particular call y Many times, the time of a data connection is wasted. y Fixed data rate. 11 Network Switching b. Packet switching Packet‐switching basic operation y Data is sent in small packets y Typically 1,000 octets y Longer messages are divided in a series of packets y Each packet contains a portion of user data and some control information y IfInformati on contltrol y Routing (addressing) information y Packets are received, briefly stored (buffer) and sent to the next node (store and forward) 27 11/10/2010 11 Network Switching b. Packet switching Use of packets 11 Network Switching b. Packet switching Packet‐switching components 28 11/10/2010 11 Network Switching b. Packet switching Advantages y Line efficiency y The link between nodes can be shared by several packets. y Packet queues are formed and packets are sent as soon as possible y Data rate conversion y Each station connects to the local node at its own rate y The data buffer in the nodes must match rates y Packets aaere accepted even if ttehe network is busy y Delivery may lower the rate y Priorities may be used 11 Network Switching b. Packet switching Packet‐switching technique y The station divides large messages into packets y Packets are sent to the network one at a time y Packets are handled via two paths: y Datagrams y Virtual circuits 29 11/10/2010 11 Network Switching b. Packet switching Datagram y Each packet is handled independently. y Packets may take any practical route. y Packets may arrive in a different order. y Packets can get lost. y Packets are received for re‐ordering and recovery of lost ones. 11 Network Switching b. Packet switching Datagram packet‐ switching diagram 30 11/10/2010 11 Network Switching b. Packet switching Virtual‐circuit packet switching y Pre‐planned routes are established before packets are sent y The call‐start request and the call‐acceptance request require the establishment of a connection for packet delivery y Each packet contains a virtual circuit identifier instead of the destination address y Routing decisions for each packet are not required y Clear requirement concerning circuit breakdown y Does not require a dedicated path 11 Network Switching b. Packet switching Virtual circuit packet‐ switching diagram 31 11/10/2010 11 Network Switching b. Packet switching Source-to-destination data transfer in a virtual circuit switching network 11 Network Switching b. Packet switching Setup requirement in a virtual circuit switching network 32 11/10/2010 11 Network Switching b. Packet switching Setup acceptance in a virtual circuit switching network 11 Network Switching b. Packet switching Virtual circuits versus Datagram y Virtual Circuits y Networks can provide sequencing and error control y Faster delivery of packets y No need for making routing decisions y Loss of reliability y If a node is lost, all circuits through that node are lost too y Datagram y There is no call setup phase y The lesser the packets the better the performance y More flexible y Routing may be used for avoiding congestion in parts of the network 33 11/10/2010 11 Network Switching b.