DESIGN & IMPL COMP COM NETWK
DESIGN & IMPL COMP COM NETWK CDA 4506
University of Central Florida
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This 61 page Class Notes was uploaded by Genoveva Bogisich on Thursday October 22, 2015. The Class Notes belongs to CDA 4506 at University of Central Florida taught by Staff in Fall. Since its upload, it has received 71 views. For similar materials see /class/227528/cda-4506-university-of-central-florida in Computer Design Architecture at University of Central Florida.
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Date Created: 10/22/15
CDA 4506 Design and Implementation of Data Communication Networks Lecture Notes 1 Dr R Lent Getting Organized Laboratories You must be in one No food or drink allowed in the lab l Text Kurose amp Ross 2nol edition Schedule and class notes WebCT and httpwwwcsucfeducoursecda4506 check regularly Average use of time per week I 35 hours of lecturelabs I 3 hours reading I 25 hours working on homework Grade F1O labs 2 tests 2 3 HW 1 final exam 6 First Assignment Read Chapter1 Basic Communication Model Message Noise Message Interceptor Shannon1949 Chapter 1 Introduction Our goal Overview get context overview feel of 39 what s the Internet networking what s a protocol more depth detail later in a network edge course network core 7 approaCh I access net physical media descr39 t39 e I 39p N InternetISP structure I use Internet as example performance loss delay I Understand basnc concepts 7 protocol layers service models Internet nuts and bolts view millions of connected computing a deVIces or nodes FOUter workstation hosts endsystems server I PCs workstations servers I PDAs phones toasters running network apps communication links I fiber copper radio satellite I transmission rate I bandwidth routers forward packets chunks of data and protocols FTP TCP HTTP etc company network Cool internet appliances lP picturfrme httpwwwceivacom Webenabled toasterweather forecaster World s smallest web server httpwww ccscsumassedushriiPichtml What s a protocol human protocols network protocols what s the time i machines rather than humans l have a question gt all communication activity in introductions Internet governed by protocols specific msgs sent specific actions taken when msgs received or other events protocols de ne format order of msgs sent and received among network entities and actions taken on msg transmission receipt What s a protocol a human protocol and a computer network protocol TCP connection req TCP connection quot response Get httpwwwcsucfeduindexhtml ltfilegt Internet A Service View 7 communication infrastructure enables distributed applications I Web email games e commerce database voting file MP3 sharing communication services provided to apps I connectionless I connectionoriented How Large is the Internet 9 Networks 150000 140001 12030 100000 30000 50000 40mm 20000 a Hebbes39 Internet Timeline Copyright DDS Robert H Zaken h rtpffrnruru39W39uu39rzalrnzmturgp rnzrhertfin rerrreta tirneliner O 0 1k o 0 0 0 9 39P I Tlll IlllllllllllllllllllIllllllllllllllllllllllllllllllllllllllllllllllllllIlllllllllllllll m m D D w W N W m m 1 r r L Ln LE u r ra ce on D 133 Cf 0397 m m up 0quot an an m an 0 an 6391 Calquot m m 3 Q E 395 f6 539 393 E E a Q 5 3 U 5 as 639 E C OJ 0 3 m 3 CI cu cu CD 0 3 as 3 CI E 5 12 J J 2 m L C E E 1 u Growth of Hosts in the Internet masts Hubbes 1mm Twehne Cupyngm Una Ruben H 1am mm WWW 2am uvgvubenmt vnetHmehne 1annnnnnn n us7u 9 1 uaaa 552 1 Hutu 1u7u 11 1 1u14 1u24 127u 13 1 Juas 1951 2 u471 23 1 uzas 23ua 1n DEEMED 72 1 1 1115 5uas u173 3 1 12 7 21174 Ennnnnnn us74 52 1 u7aa 33uuu u377 111 1 1uaa 55uuu Bunnn nn 1279 111 1 u7as uuuu 111 213 1 JUas 1ssuuu n n nn 21111111111111 5 5 5 Growth of WW servers Huhhes39 Internet Timeline Cupyright 003 Hubert H Zakun http wzaknnurgfmhertfinternetftimeline 40000000 Om 35 Elm IUD DATE SITES I DATE SITES 2quot 90 05x93 120 I 12294 10022 r 39190303 39 09293 204 I 05295 23500 g 25lgggln g 10393 220 01296 100000 4 E 12293 623 062 96 252000 20 000 000 4r 3 39 39 06294 2730 0Tg 96 299403 1 2 15000000 itquot a 4 10 000 000 all 5000000 L A m 25050500022202333355553333 E0 530amp0333030308550335003308 00cE moE mt E moE m E moE mo Internet Structure Network of Networks LAN WAN MAN Roughly hierarchical 7 At center tier1 lSPs eg UUNet BBNGenuity Sprint ATampT nationalinternational coverage I treat each other as equals Tier1 providers Tler 1 ISP interconnect peer privately Tier1 providers also interconnect at public network access points NAPs Tier 1 ISP Tier 1 ISP Tier1 ISP eg Sprint Sprint US backbone network 397 r 711quotquot1 s L LZ 93 L39 y Internet structure network of networks Tier2 ISPs smaller often regional lSPs l Connect to one or more tier1 lSPs possibly other tier2 lSPs Tier2 ISPs also peer privately with each other interconnect at NAP Tier2 ISP pays tier1 ISP for connectivity to rest of Internet V Tier1ISP vNAP El tier2 ISP is customer of 39 tier1 provider 0 Tier1 ISP Tler1 ISP Internet structure network of networks Tier3 ISPs and local ISPs I last hop access network closest to end systems Local and tier 3 ISPs are customers of higher tier ISPs connecting them to rest of Internet Tier 1 ISP 6 Tier 1 ISP Internet structure network of networks i a packet passes through many networks I Check Internet stats wwwcaidaorg toeal ISP A closer look at network structure network edge applications and hosts network core I routers I network of networks access networks physical media communication links The Network Edge end systems hosts run application programs Models I clientserver model 1 client host requests receives service from alwayson server I peerpeer model 1 minimal or no use of dedicated servers Service I Connection oriented TCP I Connectionless UDP The Network Core mesh of interconnected routers the fundamental question how is data transferred through net I circuit switching dedicated circuit per call telephone net I packetswitching data sent thru net in discrete chunks Network Core Circuit Switching Network resources eg bandwidth divided into pieces pieces allocated to calls ra resource piece idle if not used by owning call no sharing dividing link bandwidth into pieces I frequency division I time division I Code division Circuit Switching TDMA and TDMA Example FDMA 4 users I time TDMA frequency time Network Core Packet Switching each endend data stream divided into resource contention PaCketS aggregate resource demand can user A B packets share network exceed amount available resources L congestion packets queue wait each packet uses full link for link use bandWldth i store and forward packets move resources used as needed one hop at a time I transmit over link I wait turn at next link Ba dwidth 39vision into 39eces Packet Switching Statistical Multiplexing 10 Mbs J Ethernet queue of packets waiting for output link Sequence of A amp B packets does not have fixed pattern statistical multiplexing In TDM each host gets same slot in revolving TDM frame Packet switching versus circuit switching Packet switching allows more users to use network l 1 Mbitlink v each user I 100 kbps when active I active 10 of time a circuitswitching N users u packet switching I with 35 users probability gt 10 active less than 0004 Packet switching versus circuit switching Is packet switching a slam dunk winner Great for bursty data I resource sharing I simpler no call setup Excessive congestion packet delay and loss I protocols needed for reliable data transfer congestion control Q How to provide circuitlike behavior I bandwidth guarantees needed for audiovideo apps Packetswitching storeandfonNard Takes LR seconds to transmit w push out packet of L bits on to l 75 Mbits link or R bps 7 R 15 Mbps Entire packet must arrive at router before it can be transmitted on next link store and forward i delay 3LR delay 15 sec Packet Switching Message Segmenting Packet Switch 4999 15000 Packet switch Destination Tlme sec Now break up the message into 5000 packets Each packet 1500 bits 1 mseo to transmit packet on one link pipeining each link works in parallel Delay reduced from 15 sec to 5002 sec Packetswitched networks forwarding M move packets through routers from source to destination I we ll study several path selection ie routing algorithms chapter 4 datagram network I destination address in packet determines next hop I routes may change during session I analogy driving asking directions virtual circuit network I each packet carries tag virtual circuit ID tag determines next hop I fixed path determined at call setup time remains fixed thru call I routers maintain percall state Network Taxonomy Datagram network is not either connectionoriented or connectionless Internet provides both connectionoriented TCP and connectionless services UDP to apps Protocol Layers Networks are complex many pieces hosts routers links of various media applications protocols hardware software Question Is there any hope of organizing structure of network Or at least our discussion of networks Layering Example USA Germany I Spanish Spanish I A different view USA mg quotflKg fa Ggw English If P7 TrigQR m y t v w r J I S anish S anish Layers each layer implements a service I via its own internallayer actions I relying on services provided by layer below Another view USA Germany I English German I r gr ipfx39zh L M44 x I FrenCh I Spanish Why layering Dealing with complex systems explicit structure allows identification relationship of complex system s pieces I layered reference model for discussion modularization eases maintenance updating of system I change of implementation of layer s service transparent to rest of system I eg change in gate procedure doesn t affect rest of system layering considered harmful Internet protocol stack application supporting network applications I FTP SMTP STTP 1 transport hosthost data transfer I TCP UDP network routing of datagrams from source to destination I IP routing protocols s link data transfer between neighboring network elements I PPP Ethernet physical bits on the wire application Transport Network link physical Layering logical communication take data from application add addressing reliability check info to form datagram send datagram to peer wait for peer to ack receipt Emmi vans on 0 physical A l ll 1511i V physical network link physical data Wail transport network link physical Layering physical communication Protocol layering and data Each layer takes data from above adds header information to create new data unit passes new data unit to layer below source destination llil application application El message Ht M transport transport III segment mm M network network IQEM datagram Hnt v link link HI n t Ml frame physical physical Physical Layer Bit propagates between Twisted Pair TP transmitterrcvr pairs H two insulated copperwires physical link what lies between transmitter amp receiver I category 3 trad39t39onal d d d phone wires 10 Mbps gm 6 me Ia39 Ethernet I signals propagate in solid I Category 5 TP 100Mbps media copper fiber coax Ethernet unguided media I signals propagate freely eg radio m Physical Media coax fiber Coaxial cable Fiber optic cable 9 two concentric copper conductors 1 glass fiber carrying light pulses L bidirectional eaCh PUISG a bit l baseband l highspeed operation I single channel on cable 39 highSpeed POinttOPOint I legacy Ethernet transmission eg 5 Gps i broadband i7 low error rate repeaters spaced far apart immune to electromagnetic I multiple channel on cable I HFC noise Example Physical media radio signal carried in electromagnetic Radio nk types spectrum i terrestrial microwave no physical wire I eg up to 45 Mbps channels bidirectional 1 LAN eg WaveLAN propagation environment effects I 2Mbps 11Mbps I reflection i widearea eg cellular I obstruction by objects I eg 3G hundreds of kbps I interference 7 satellite I up to 50Mbps channel or multiple smaller channels I 270 msec endend delay I geosynchronous versus LEOS Access networks and physical media Q How to connection end systems to edge router residential access nets institutional access networks school company mobile access networks Keep in mind bandwidth bits per second of access network shared or dedicated Residential access point to point access Dialup via modem I up to 56Kbps direct access to router often less I Can t surf and phone at same time can t be always on ADSL asymmetric digital subscriber line I up to 1 Mbps upstream today typically lt 256 kbps I up to 8 Mbps downstream today typically lt 1 Mbps I FDM 50 kHz 1 MHz for downstream 4 kHz 50 kHz for upstream 0 kHz 4 kHz for ordinary telephone Residential access cable modems 7 HFC hybrid ber coax I asymmetric up to 10Mbps upstream 1 Mbps downstream network of cable and fiber attaches homes to ISP router I shared access to router among home I issues congestion dimensioning 1 deployment available via cable companies eg Road Runner Cable Network Architecture Overview Typically 500 to 5000 homes r39 iF r home cable headend cable distribution network simplified Cable Network Architecture Overview sennp Box Home Environment PC 1 Spline imi rm rm cableheadend Lm Lmkm home cable distribution network simplified Cable Network Architecture Overview WWW tm Lmim home cable headend cable distribution network Cable Network Architecture Overview FDNl V l D E O 6 V l D E O 3 4 Channels LLmLm cable distribution network cable headend Company access local area networks companyuniv local area network LAN connects end system to edge router Ethernet I shared or dedicated link connects end system and router I 10 Mbs 1OOMbps Gigabit Ethernet deployment institutions home LANs happening now LANs chapter 5 Wireless access networks shared Wireless access network connects end system to router I via base station aka access point wireless LANs I 80211bWiFi 11 Mbps widerarea wireless access I provided by telco operator I 3G 384 kbps a Will it happen I WAPGPRS in Europe router Cm base station 1m Home networks Typical home network components a ADSL or cable modem routerfirewaIINAT Ethernet i wireless access F point wireless 39 Ia to s tgg n cable router 390 p modem firewall headend Wireless access Ethernet point switched How do loss and delay occur packets queue in router buffers r packet arrival rate to link exceeds output link capacity packets queue wait for turn packet being transmitted delay packets queueing delay free available buffers arriving packets dropped loss if no free buffers Four sources of packet delay j 1 nodal processing 3 2 queueing I check bit errors I time waiting at output link I determine output link fortransmiSSion I depends on congestion level of router propagation nodal processing queueing Delay in packetswitched networks 3 Transmission delay 439 Prepagat39on delay I J Rlink bandwidth bps d length fphys39ca39 quotbk i Lpacket length bits 739 S Prepagat39on Speed m medium 2x108 msec i time to send bits into link i propagation delay ds LR Note s and R are very different quan es A propagation nodal processing queueing Nodal delay d d d d d nodal proc queue trans prop d processing delay pnoc I typically a few microsecs or less d queuing delay queue I depends on congestion i d transmission delay vans I LR significant for lowspeed links I d propagation delay PFOP I a few microsecs to hundreds of msecs Queueing delay revisited average Rlink bandwidth bps iUEUBing E39E39EY I i Lpacket length bits aaverage packet arrival i rate a traffic IntenSIty LaR Lam i LaR 0 average queueing delay small LaR gt 1 delays become large LaR gt 1 more work arriving than can be serviced average delay infinite Real Internet delays and routes What do real lnternet delay amp loss look like Traceroute program provides delay measurement from source to router along endend Internet path towards destination For all i I sends three packets that will reach router i on path towards destination I router iwill return packets to sender I sender times interval between transmission and reply Real Internet delays and routes traceroute gaiacsumassedu to wwweurecomfr Three delay measements from gaiacsumassedu to csgwcsumassedu 1 csgw 128119240254 1 ms 1 ms 2 ms 2 border1rtfa510gwumassedu 31281193145 1 ms 1 ms 2 ms 3 chtvbnsgwumassedu 128119 130 6 ms 5 ms 5 ms 4 jn1at10019worvbnsnet 204147132129 16 ms 11 ms 13 ms 5 jn1so7000waevbnsnet 204147136136 21 ms 18 ms 18 ms 6 abilenevbnsabieneucaidedu19832119 22 ms 18 ms 22 ms 7 nycm washabileneucaidedu 19832846 22 ms 22 ms 22 ms transoceanic 8 6240103253 6240103253 104 ms 109 ms 106 ms I k 9 de21de1degeantnet 624096129 109 ms 102 ms 104 ms m 0 defr1frgeantnet 62409650 113 ms 121 ms 114 ms 1 renater gwfr1frgeantnet 624010354 112 ms 114 ms 112 ms 2 nion2cssirenaterfr 1935120613 111 ms 114 ms 116 ms 3 nicecssirenaterfr 1 522098102 123 ms 125 ms 124 ms 14 r3t2nicecssirenaterfr19522098110 126 ms 126 ms 124 ms 15 eurecomvalbonner3t2ftnet 193485054 135 ms 128 ms 133 ms 16 19421421125 19421421125 126 ms 128 ms 126 ms 4 18 means no reponse probe lost router not replying 19 fantasiaeurecomfr19355113142 132 ms 128 ms 136 ms 4444 Packet loss Typical queue aka buffer preceding link in buffer has finite capacity when packet arrives to full queue packet is dropped aka lost lost packet may be retransmitted by previous node by source end system or not retransmitted at all
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