Application

1
Application

• Outline
• Domain Naming System
• Traditional Applications
• Multimedia Applications

2
Name Service

• What do names do?
• identify objects
• help locate objects
• define membership in a group
• specify a role
• convey knowledge of a secret
• Name space
• defines set of possible names
• consists of a set of name to value bindings

3
Properties

• Names versus addresses
• Location transparent versus location-dependent
• Flat versus hierarchical
• Global versus local
• Absolute versus relative
• By architecture versus by convention
• Unique versus ambiguous

4
Examples

• Hosts
• cheltenham.cs.princeton.edu 192.12.69.17
• 192.12.69.17 8023A8335B9F
• Files
• /usr/llp/tmp/foo (server, fileid)
• Users
• Larry Peterson llp_at_cs.princeton.edu

5
Examples (cont)

• Mailboxes
• Services
• nearby ps printer with short queue and 2MB

User
1
2
user _at_ cs.princeton.edu
cs.princeton.edu
Name
Mail
server
program
192.12.69.5
4
192.12.69.5
3
TCP
192.12.69.5
5
IP
6
Domain Naming System

• Hierarchy
• Name
• flower.ce.cnu.ac.kr

edu
com
gov
mil
org
net
uk
kr











princeton
mit
cisco
yahoo
nasa
nsf
arpa
navy
acm
ieee
ac
co


snu
cnu
cs
ee
physics
ce
ee
ux01
ux04
flower
rose
7
Name Servers

• Partition hierarchy into zones

edu
com
gov
mil
org
net
uk
fr










princeton
mit
cisco
yahoo
nasa
nsf
arpa
navy
acm
ieee
cs
ee
physics
ux01
ux04
Root
name server

• Each zone implemented by two or more name servers

Princeton
Cisco
name server
name server

CS
EE
name server
name server
8
Resource Records

• Each name server maintains a collection of
  resource records
• (Name, Value, Type, Class, TTL)
• Name/Value not necessarily host names to IP
  addresses
• Type
• NS Value gives domain name for host running name
  server that knows how to resolve names within
  specified domain.
• CNAME Value gives canonical name for particle
  host used to define aliases.
• MX Value gives domain name for host running mail
  server that accepts messages for specified
  domain.
• Class allow other entities to define types
• TTL how long the resource record is valid

9
Root Server

• (princeton.edu, cit.princeton.edu, NS, IN)
• (cit.princeton.edu, 128.196.128.233, A, IN)
• (cisco.com, thumper.cisco.com, NS, IN)
• (thumper.ciscoe.com, 128.96.32.20, A, IN)

10
Princeton Server

• (cs.princeton.edu, optima.cs.princeton.edu, NS,
  IN)
• (optima.cs.princeton.edu, 192.12.69.5, A, IN)
• (ee.princeton.edu, helios.ee.princeton.edu, NS,
  IN)
• (helios.ee.princeton.edu, 128.196.28.166, A, IN)
• (jupiter.physics.princeton.edu, 128.196.4.1, A,
  IN)
• (saturn.physics.princeton.edu, 128.196.4.2, A,
  IN)
• (mars.physics.princeton.edu, 128.196.4.3, A, IN)
• (venus.physics.princeton.edu, 128.196.4.4, A, IN)

11
CS Server

• (cs.princeton.edu, optima.cs.princeton.edu, MX,
  IN)
• (cheltenham.cs.princeton.edu, 192.12.69.60, A,
  IN)
• (che.cs.princeton.edu, cheltenham.cs.princeton.edu
  , CNAME, IN)
• (optima.cs.princeton.edu, 192.12.69.5, A, IN)
• (opt.cs.princeton.edu, optima.cs.princeton.edu,
  CNAME, IN)
• (baskerville.cs.princeton.edu, 192.12.69.35, A,
  IN)
• (bas.cs.princeton.edu, baskerville.cs.princeton.ed
  u, CNAME, IN)

12
Name Resolution

• Strategies
• forward
• iterative
• recursive
• Local server
• need to know root at only one place (not each
  host)
• site-wide cache

Root
2
name
server
cicada.cs.princeton.edu
3
princeton.edu, 128.196.128.233
4
1
Princeton
Local
cicada.cs.princeton.edu
cicada.cs.princeton.edu
name
name
Client
server
server
cs.princeton.edu, 192.12.69.5
192.12.69.60
8
5
cicada.cs.princeton.edu
192.12.69.60
cicada.cs.princeton.edu,
6
CS
name
server
7
13
Traditional Applications

• Electronic Mail
• SMTP(Simple Mail Transfer Protocol)
• MIME(Multipurpose Internet Mail Exchange)
• Defines format of email massages

Mail
Mail gateway
Mail
reader
reader
Mail
Mail
Mail
daemon
daemon
daemon
SMTP/TCP
SMTP/TCP
14
Traditional Applications

• World Wide Web
• HTTP request
• OPTION request information on available options
• GET retrieve document
• HEAD retrieve metainformation
• POST give information to server
• PUT store document
• DELETE delete the specified URL
• TRACE loopback request message
• CONNECT used by proxy
• HTTP response
• Informational
• Success
• Redirection
• Client Error
• Server Error
• Cache
• TCP connections
• persistent connections

15
Traditional Applications

• Network Management
• SNMP(Simple Network Management Protocol)
• Request / Reply Protocol
• Request message GET / SET / GET-NEXT
• MIB (Management Information Base)
• 10 different groups
• System
• Interface
• Address translation
• IP
• UDP
• TCP

16
Multimedia Applications

• Require deliver on time assurances
• must come from inside the network
• Example application (audio)
• sample voice once every 125us
• each sample has a playback time
• packets experience variable delay in network
• add constant factor to playback time playback
  point

Sampler
,
Microphone
Buffer
,
A D
D A
converter
Speaker
17
Playback Buffer
Packet
arrival
Packet
generation
Playback
Sequence number
Buffer
Network
delay
T
ime
18
Taxonomy
Applications
Real time
Elastic
Interactive
Asynchronous
Interactive
T
olerant
Intolerant
bulk
Adaptive
Nonadaptive
Rate-adaptive
Nonadaptive
Delay-
Rate-
adaptive
adaptive
19
Integrated Services

• Service Classes
• guaranteed
• controlled-load
• Mechanisms
• signalling protocol
• admission control
• policing
• packet scheduling

20
Differentiated Services

• Problem with IntServ scalability
• Idea support two classes of packets
• premium
• best-effort

P(drop)

• Mechanisms
• packets in and out bit
• edge routers tag packets
• core routers RIO (RED with In and Out)

1.0
MaxP
A
vgLen
Min
Max
Max
Min
in
in
out
out
21
RTP

• Application-Level Framing
• Data Packets
• sequence number
• timestamp (app defines tick)
• Control Packets (send periodically)
• loss rate (fraction of packets received since
  last report)
• measured jitter

22
RTP

• Header Format

Length as carried in UDP header
UDP header
R
TP header
R
TP payload
Padding
Pad count
Pad count bytes
23
Session Control and Call Control

• Session Control
• SDP(session description protocol)
• SAP(session announcement protocol)
• SIP(session initiation protocol)
• SCCP(session conference control protocol)
• Call Control
• H.323

Conventional telephone
network
H.323
H.323
gatekeeper
gateway
H.323
H.323
terminal
terminal