UDP/TCP

IP does not provide reliability / specify application
UDP ... User Datagram Protocol
TCP ... Transmission Control Protocol

UDP ... minimum mechanism

Port specifies application on the host
Checks only length and checksum
Short transaction
Streaming of multimedia (audio/video)
Limited usage in LAN
Broadcast/Multicast

Major Applications

DHCP (67,68) ... Dynamic Host Configuration Protocol
TFTP (69) ... Trivial File Transfer Protocol
NFS (2049) ... Network File System
NTP (123) ... Network Time Protocol
DNS (53) ... Domain Name System (Server)

TCP

RFC 793
Connection-Oriented
End-to-end Reliability
16 bit port number
Specifies application (same as UDP)

Sequence Number

the sequence number of the first data of this segment
if SYN
- syncronize to this number
- Next number is (this number) + 1
if ACK
- I expect your next sequence number to be this value + 1

Control bits (Flags)

URG: Urgent Pointer field significant
ACK: Acknowledgment field significant
PSH: Push Function
RST: Reset the connection
SYN: Synchronize sequence numbers
FIN: No more data from sender

Major Applications

telnet (23) ... old, lame
ftp (21) ... old, lame, hard to handle in firewall
ssh (22) ... remote terminal, file transfer
SMTP (25) ... Simple Mail Transfer Protocol
POP (110) ... Post Office Protocol
HTTP (80) ... HyperText Transfer Protocol
whois (43) ... whois (nicname)

HTTP

HyperText Transfer Protocol
HyperText Markup Language = HTML
Uniform Resource Locator = URL

HTTP version 1.0

Connection to HTTP server
```
GET / HTTP/1.0
 
```

HTTP/1.0 200 OK
Content-Type: text/html
...  (header)
 
<html>
...  (content)
</html>

RFC for HTTP/1.1

Hypertext Transfer Protocol. Ver. 1.1 RFC2616

Request/Response

one response for one request
request/response chain (1.4)

    request chain ------------------------>
 UA -----v----- A -----v----- B -----v----- O
    <----------------------- response chain

Protocol Parameters

HTTP Version
Uniform Resorce Identifier (URI/URL)
Date/Time
Character Sets
Content Coding / Transfer Encoding
Media Types
Quality / Language

HTTP Version

HTTP-Version   = "HTTP" "/" 1*DIGIT "." 1*DIGIT

URI

also URL

http URL

http_URL = "http:" "//" host [ ":" port ] [ abs_path [ "?" query ]]

Character sets

charsets for japanese
- iso-2022-jp
- shift_jis
- euc-jp
- utf-8
Other
- iso-8859-1 (Latin), euc-kr, gb2312, koi8-r

Media Types

type/subtype
text ... plain, html, css, xml
image ... jpeg, gif, png
audio ... mpeg, midi, x-wav
model ... vrml

Languages

ja ... Japanese
en ... English
en_US ... English in the United States

HTTP Message

Request / Response
Message Headers
Message Body

Message Headers

message-header = field-name ":" [ field-value ]

General-Header, Request-Header, Response-Header, Entity-Header

Request

Request-Line   = Method SP Request-URI SP HTTP-Version CRLF

Method

OPTIONS
GET, HEAD, POST
PUT, DELETE
TRACE, CONNECT

Request-URI

Request-URI    = "*" | absoluteURI | abs_path | authority

Response

Status-Line = HTTP-Version SP Status-Code SP Reason-Phrase CRLF

Status Code

1xx: Informational - Request received, continuing process
2xx: Success - The action was successfully received, understood, and accepted
3xx: Redirection - Further action must be taken in order to complete the request
4xx: Client Error - The request contains bad syntax or cannot be fulfilled
5xx: Server Error - The server failed to fulfill an apparently valid request

Content Negotiation

Accept-Language: ja
Return Japanese document
Accept-Language: en
Return English document

Others

Authentication
Caching
Header Fields
Security

Quiz of the day

Select appropriate statements.
HTTP takes place over TCP
HTTP takes place over UDP
Port number 80 is used mostly
Port number 25 is used mostly

Homework for master students

Connect www.is.kochi-u.ac.jp with a telnet client
Try following requests (and others which you think of)
OPTIONS * HTTP/1.0
HEAD / HTTP/1.1
Host: www.is.kochi-u.ac.jp
HEAD / HTTP/1.0

HyperText Transfer Protocol

Tokio Kikuchi

UDP/TCP

UDP ... minimum mechanism

Major Applications

TCP

Sequence Number

Control bits (Flags)

Major Applications

HTTP

HTTP version 1.0

RFC for HTTP/1.1

Request/Response

Protocol Parameters

HTTP Version

URI

Character sets

Media Types

Languages

HTTP Message

Message Headers

Request

Method

Request-URI

Response

Status Code

Content Negotiation

Others

Quiz of the day

Homework for master students