2001. Hae-Kwang Kim Sejong College.


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Web Official Protocol Standards RFC (1600) condition of institutionalization: standard, draft ... arrange to discard the consistent address and control fields and to ...
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Web Networking - 1-2001. Hae-Kwang Kim Sejong University

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Internet Addresses A 0 7 bits netid 24 bits hostid 0 .0.0.0 to 127 .255.255.255 B 1 0 14 bits netid 16 bits hostid 128 .0.0.0 to 191 .255.255.255 C 1 0 21 bits netid 8 bits hostid 192 .0.0.0 to 223 .255.255.255 D 1 0 28 bits multicast groupid 224 .0.0.0 to 239 .255.255.255 E 1 28 bits saved 240 .0.0.0 to 255 .255.255.255

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Encapsulation client information Appl. header client information TCP header Application information IP header TCP header Application information Ethernet header IP header TCP header Application information Ethernet tailer

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Header data for demultiplexing 8 bit convention field in IP header 1: ICMP, 2: IGMP, 6: TCP, 17: UDP 16bit port number for TCP/UDP header recognize applications 16bit edge sort fled in Ethernet header distinguish IP, ARP, RARP

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Demultiplexing User process User process User process User process TCP UDP ICMP IGMP IP ARP RARP Ethernet drive An Ethernet outline

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Client-Server Model Concurrent Server (all in all, TCP server) 1. Sit tight for a customer solicitation to arrive 2. Begin another server to handle this present customer\'s solicitation new process, undertaking, string 3. the new server handles this current customer\'s solicitation 4. Whenever complete, the new server ends Iterative server (all in all, UDP server) no various simultaneous customers

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Port numbers Application ID Well known port numbers FTP server: 21 Telnet server: 23 TFTP server: 69 IANA (Internet Assigned Numbers Authority) between 1 to 1023 Unix particular administrations 256:1023 Telnet versus Rlogin Client couldn\'t care less port numbers remarkable on the host vaporous ports (1024 - 5000) * solaris 2.2: begin at 32768

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Port number store on Unix File/and so forth/benefits grep telnet/and so on/administrations telnet 23/tcp grep space/and so on/administrations * saved ports: 1-1023 just utilized by procedure with superuser benefit

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Internet standard Organization ISOC IAB 15 individuals last publication and specialized audit board IETF create standard particulars IRTF long haul research ventures

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RFCs Official gauges and data purposes RFC list substitution or overhaul by a more current RFC Important RFCs The doled out Numbers RFC (1340) Internet Official Protocol Standards RFC (1600) condition of institutionalization: standard, draft standard, proposed standard, trial, enlightening, memorable prerequisite level: required, prescribed, elective, constrained client or not suggested Host Requirements RFC (1122/1123) join, system, transport, application layers Router necessities RFC (1009)

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Standard basic administrations Why Odd numbers for port number? NCP utilized pair of odd-even associations reverberation (port number 7) dispose of (port number 9) daytime (port number 13) chargen (port number 19) time (port number 37)

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TCP/IP usage UC at Berkely API attachments ("Berkely Sockets") TLI (Transport Layer Interface) - AT&T

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Link-Layer Conveys IP datagrams ARP/RARP asks for/answers numerous sorts of systems administration equipment token ring, FDDI, RS-232 Ethernet serial interfaces (SLIP and PPP) loopback driver

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Ethernet and IEEE802 1982 by DEC, Intel and Xerox CSMA/CD (Carrier Sense, Multiple Access with Collision Detection) 10 Mbits/sec 48-bit addresses IEEE 802 802.3 (CSMA/CD), 802.4(token transport), 802.5 (token ring), 802.2 (LLC) distinctive edge position from Ethernet

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Host Requirements RFC for Ethernet 10Mbits/sec Send and get parcels utilizing RFC 894 (Ethernet exemplification) Receive RFC 1042 (IEEE 802) bundles intermixed with RFC 894 parcels Send parcels utilizing RFC 1042 epitome

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Encapsulation (802.2/802.3) RFC 1042 Dest. address Source address length 802.3 MAC DSAP AA SSAP AA Cntr 03 802.2 LLC Org code 00 Type information CRC 802.2 SNAP Type IP datagram Type ARP ask for/answer PAD Type RARP ask for/answer PAD

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Encapsulation (Ethernet) RFC 894 Dest. address Source address length 802.3 MAC Type information CRC Type IP datagram Type ARP ask for/answer PAD Type RARP ask for/answer PAD

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IEEE 802 versus Ethernet 802.3 permits 16-bit addresses equipment address ARP/RARP map between 32-bit IP address/48-bit address non of the 802 length qualities is the same as the Ethernet sort values information size 802: 38-1492 bytes Ethernet: 46-1500 bytes

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Trailer exemplification (893) Rearrange the request of the fields in the IP datagram variable-length fields (IP header and the TCP header) were moved to the end, just before CRC information part of the casing to be mapped to an equipment page, sparing a memory-to-memory duplicate when the information is replicated in the portion TCP information that is a numerous of 512 bytes in size can be moved by simply controlling the piece\'s page tables Two hosts arranged the utilization of trailer epitome utilizing an expansion of ARP Different Ethernet outline sort qualities are characterized for these edges Deprecated

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SLIP: Serial Line IP (RFC 1055) Simple type of embodiment for IP datagrams Connecting Home frameworks to Internet RS-232, fast modems SLIP confining principles IP datagram is begun and ended by the extraordinary character END (0xc0) If a byte of the IP datagram levels with the END character, 2 byte succession 0xdb (SLIP ESC character), 0xdc is transmitted rather If a byte of the IP datagram meets the SLIP ESC character, the 2-byte grouping 0xdb, 0xdd is transmitted rather

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Difficiency of SLIP Each end must know the other\'s IP address No sort field No checksum upper layers give some type of CRC dependably a checksum for the IP header, TCP header and TCP information more up to date modems can distinguish and amend adulterated edges mainstream as the rate and dependability of modems increment

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Compressed SLIP is moderate (19200 bits/sec underneath) utilized for intuitive activity (Telnet, Rlogin) numerous little TCP bundles To convey on3 byte of information, a 20-byte IP header and a 20-byte TCP header CSLIP (Newer adaptation): RFC 1144 3 or head 5 bytes er keeps up the stae of up to 16 tCP associations on every end of the CSLIP interface a percentage of the fields in the two headers for a given conection regularly don\'t change Of the fileds that do change, most change by a little positive sum

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PPP: Point-to-Point Protocol Two sort of connections a nonconcurrent join with 8 bits of information and no equality bit-situated synchronous connections Link Control Protocol set up, design and test the information join association every end arrange different alternatives Family of system control conventions (NCPs) particular to various system layer conventions (RFCs for IP, OSI system layer, DECnet and AppleTalk) IP NCP: permits every end to determine in the event that it can perform header pressure)

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PPP exemplification (RFC 1548) banner 7E Address FF Control 03 802.3 MAC convention data CRC banner 7E Protocol 0021 IP datagram Protocol c021 Link control information Protocol 8021 Network control information

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Escaping for banner code, 0x7e Synchronous connection done by equipment utilizing bit stuffing Asynchronous connection 0x7d is utilized for departure character when 0x7d shows up in a PPP edge, the character has had its 6th piece supplemented 0x7e is transmitted by 0x7d, 0x5e 0x7d is transmitted by 0x7d, 0x5d for ASCII control character, the 6th piece is turned on, for instance, 0x01 is transmitted by 0x7d, 0x21 it\'s conceivable touse the connection control convention to indicate which, assuming any, of these 32 values must be gotten away

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SLIP-improvement Using Link control convention arrange to preclude the consistent address and control fields and to decrease the convention field structure 2 bytes to 1 byte. PPP overhead 3 bytes 1 byte for the convention field and 2 bytes for the CRC SLIP 2 bytes Using IP system control convention, arrange to utilize Van Jacobson header pressure

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Advantage of PPP over SLIP Support for numerous conventions on a solitary serial line CRC on each casing Dynamic transaction of the IP address for every end (utilizing the IP system control convention) TCP/IP header pressure a connection control convention for arranging numerous information join alternatives The value 3 bytes of extra overhead per outline a couple edges of arrangement when the connection is set up more perplexing usage

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Loopback interface Allows a customer and server on the same host to speak with each other utilizing TCP/IP The class A system ID 127 is saved for the loopback interface IP location of 127.0.0.1 to this interface (nearby host) An IP datagram sent to the loopback interface must not show up on any system No shortcircuiting a percentage of the vehicle layer rationale and the majority of the system layer rationale complete preparing of the information in the vehicle layer and system layer appears to be wasteful, rearranges the configuration considering the loopback interface shows up as simply one more connection layer

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Processing of IP datagrams by loopback interface IP info capacity IP yield capacity Destination IP address level with telecast address or multicast address? Place on IP info line Place on IP information line yes no yes Loop back driver Destination IP address break even with interface IP address? no ARP Demultiplex in view of Ethernet casing sort send recieve

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MTU (Maximum transmission unit) Ethernet (1500), IEEE 802 (1492) If IP datagram is bigger than the MTU discontinuity Path MTU littlest MTU of any information connect that parcels navigate between the two hosts relies on upon course being utilized whenever way MTU need not be the same in the two headings

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Serial Line Throughput Calculations Line speed: 9600 bits/sec, 8 bits/byte, 1 begin and 1 stop bits line pace is 960 bytes/sec exchanging a 1024-byte bundle brings 1066ms with SLIP for an intuitive application, alongside a FTP that sends or gets 1024-byte bundles, ought to attend to normal 533ms to send intelligent parcels kind of-administration queueing: place intelligent activity in front of mass information movement a

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