Protocols and Services 2 the original draft of a diplomatic document, - - PowerPoint PPT Presentation

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Protocols and Services 2 the original draft of a diplomatic document, - - PowerPoint PPT Presentation

Protocol 1 the official procedure or system of rules governing affairs of state or diplomatic occasions : protocol forbids the prince from making any public statement in his defense. the accepted or established code of procedure or behavior in


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SLIDE 1

Communications Research Group

Protocols and Services

  • Dr. Christian Rohner

Protocol

1 the official procedure or system of rules governing affairs of state or diplomatic

  • ccasions : protocol forbids the prince from making any public statement in his defense.
  • the accepted or established code of procedure or behavior in any group,
  • rganization, or situation : what is the protocol at a conference if one's neighbor dozes off

during the speeches?

  • Computing a set of rules governing the exchange or transmission of data

electronically between devices. 2 the original draft of a diplomatic document, esp. of the terms of a treaty agreed to in conference and signed by the parties.

  • an amendment or addition to a treaty or convention : a protocol to the treaty allowed

for this Danish referendum. 3 a formal or official record of scientific experimental observations.

  • a procedure for carrying out a scientific experiment or a course of medical

treatment. ORIGIN late Middle English (denoting the original record of an agreement, forming the legal authority for future dealings relating to it): from Old French prothocole, via medieval Latin from Greek protokollon.’ Sense 1 derives from French protocole, the collection of set forms of etiquette to be observed by the French head

  • f state, and the name of the government department responsible for this (in the

19th cent.).

Source: Oxford American Dictionary

Protocol: getTime

IDLE WAIT_DATE WAIT_BYE from_above (what's the time?)

  • send_msg(server, HI)

rcv_msg(TIME)

  • to_above (the time is TIME)

send_msg(server,BYE) rcv_msg(BYE)

  • WAIT_HI

rcv_msg(HI)

  • send_msg(server, TIME?)

Hi! Hi! What's the time? It's 12:30 Thanks, bye! Bye! client

t_struct getTime(dest) { send_msg(dest, “Hi!”); rcv_msg(); send_msg(dest, “Time?”); t_struct time = rcv_msg(); send_msg(dest, “Bye!”); return time; }

Protocols and Services

getTime(dest)

Protocol Service

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SLIDE 2

Protocols and Services

getTime(dest) send_msg(dest) rcv_msg()

Protocols and Services

Layer N Layer N+1

N Entity N PDU Service Primitive(s)

  • Services provided to N+1
  • Services expected from N-1
  • internal operation (Protocol)

Layer N:

N Entity N+1 Entity N+1 Entity N+1 PDU

OSI Reference Model

7 - Application 6 - Presentation 5 - Session 4 - Transport 3 - Network 2 - Link 1 - Physical

OSI Reference Model

7 - Application user or server applications 6 - Presentation syntax and semantics of information (datastructures, encoding, etc.) 5 - Session dialog control, token management, synchronisation 4 - Transport co-ordinates communication “end-to-end” multiplexing 3 - Network find a path to the destination forward messages 2 - Link co-ordinates communication on a link. co-ordinates access to the physical layer 1 - Physical modulation, transmission, etc.

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SLIDE 3

Layering Analogy

  • Collaboration between two distracted professors

"#$%&' "#$%()

Source: Matthias Grossglauser, EPFL

  • Prof. Tournesol
  • Prof. Einstein

Layering: Transport Service

  • So distracted, they rely on their assistants to keep

track

"##$#%&'% “Can you please get this paper to Einstein? And let me know what he responds!”

Source: Matthias Grossglauser, EPFL

Layering: Transport Protocol

  • The assistants remember and track the entire

exchange during the collaboration

"##$#%&'%() "##$#%&'%(* +,$-(./0(12%(%32(4&425 65/7(85/69(:/05'2#/;(6/5 85/69(<$'#%2$'(%3&% =(#2'%(./0(;&#%(>22?@A +B/C(/';.(%32(/'2 65/7()D(-&.#(&1/9 E&'(./0(#2'-(72 &'/%325(F/4.@A

Source: Matthias Grossglauser, EPFL

Layering: Network Service

  • The assistants use the postal service to carry letters

back and forth between their offices

ck and forth between their offices

#$%&'())*+,

  • %%*%&./&

'01$23 !"#$%&!'$(#)*+$, !-"./ !/0(+0))* 4$3 "#$%&!-1)+2*1)

  • '3

4(#156

Source: Matthias Grossglauser, EPFL

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SLIDE 4

Layering: Network Protocol

  • Postal service forwards the letter through multiple

centers

"#$% &'() *+,-+./! &'() *+,-+./0 "123 415/6+-/-7(8 )+--+./-5/39.(:7; </,++=/-5 >5.?'.=/(-/-5 &'()/*+,-+./0@

Source: Matthias Grossglauser, EPFL

Layering: Link Layer Service

#$%&'()* +,-./)0 1,234566(&7 89$()*43:(2 ;7337$43, </(;4+7)37$4"=

Source: Matthias Grossglauser, EPFL

Layering: Link Layer Protocol

  • Trucking company carries letter to next mail center,

where another routing decision is made

#$%&'()*+,-$. /.+0/(1+23).3$+! #$%&'()*+,-$. /.+0/(1+23).3$+4

Source: Matthias Grossglauser, EPFL

Layering Analogy

  • Profs. Tournesol and

Einstein’s collaboration Application Assistants 1+2, keeping track

  • f letters

Transport layer: reliable message exchange. Post office Network layer: best-effort datagram delivery service Trucking company Link layer

Source: Matthias Grossglauser, EPFL

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SLIDE 5

Message Encapsulation

Application Transport Network Link Physical

Message Segment Dataframe Frame

Depending on the protocol, the header includes protocol type, addresses, size of the payload, identifier, checksum, etc.

Header Payload

Example Network Layer: IP Header The Internet Protocol Stack

  • A collection of protocols
  • Concentration at the Network Layer

future: will everything have an IP address?

Application Transport Network Link Physical

IP TCP UDP WiFi Bluetooth 3G Ethernet ... WWW IM P2P Mail ...

Multiplexing

  • A system or signal involving simultaneous transmission
  • f several messages along a single channel of

communication.

  • Several applications access the network

simultaneously: Use transport layer port numbers to distinguish them.

IP TCP UDP Mail WWW IM

???

incoming message

???

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SLIDE 6

Well-Known Port Numbers (0..1023)

www.iana.org/assignments/port-numbers (IANA: coordination) /etc/services (extract) echo 7/udp # Echo ftp-data 20/tcp # File Transfer [Default Data] ftp 21/udp # File Transfer [Control] ssh 22/tcp # SSH Remote Login Protocol smtp 25/tcp # Simple Mail Transfer time 37/udp # Time name 42/udp nameserver # Host Name Server http 80/tcp www www-http # World Wide Web HTTP pop3 110/tcp # Post Office Protocol - Version 3 ntp 123/udp # Network Time Protocol snmp 161/udp # SNMP https 443/tcp # http protocol over TLS/SSL