sidevõrgud irt 0020 loeng 730. okt. 2006
DESCRIPTION
Sidevõrgud IRT 0020 loeng 730. okt. 2006. Avo Ots telekommunikatsiooni õppetool raadio- ja sidetehnika instituut [email protected]. Market. End-Users. Content and Service Providers. Service operators/ Telecommunications Networking Solutions. Physical Telecommunication Network. QoS. - PowerPoint PPT PresentationTRANSCRIPT
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Sidevõrgud IRT 0020
loeng 7 30. okt. 2006
Avo Ots
telekommunikatsiooni õppetoolraadio- ja sidetehnika instituut
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Market
End-Users
Content and Service Providers
Service operators/Telecommunications Networking Solutions
Physical Telecommunication Network
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QoS• Pakettvõrkudes liikluse korralduse (traffic
engineering) mõiste “garanteeritud teenuse kvaliteet” (QoS, Quality of Service) tähendab tõenäosuslikku hinnangut, et sidevõrk jälgib liikluslepet.
• Paljudel juhtudel kasutatakse QoS tõenäosusena, et pakett läbib võrku saatjast vastuvõtjani oma ettemääratud ajavahemiku jooksul.
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Teenusekvaliteedi aspektid (2)
Teenuse Kättesaadavus
(Accessibility)
TeenusePüsivus
(Retainability)
TeenuseTerviklikus
(Integrity)
QoS
QoS parameetrid QoS parameetrid QoS parameetrid
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QoS rules
• QoS doesn't create bandwidth --it just determines who will get poor service at congestion points.
• The most important QoS question is: how many "busy" signals constitute success for your network?
• Given a busy signal, users will want to proceed anyway.• Network Managers will not trust end systems.• Biggest need is on WAN links, where it’s hardest to do!
(scaling, settlements, signalling interoperability).
• Multiplexing priorities on a channel improves efficiency at the cost of certainty.
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Link Scheduling: FIFO• First-in first-out scheduling
– Simple to implement
– But, restrictive in providing guarantees
• Example: two kinds of traffic– Video conferencing needs high bandwidth and low
delay• E.g., 1 Mbps and 100 msec delay
– E-mail transfers are not that sensitive about delay
• Cannot admit much e-mail traffic– Since it will interfere with the video conference traffic
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Link Scheduling: Strict Priority• Strict priority
– Multiple levels of priority– Always transmit high-priority traffic, when present– .. and force the lower priority traffic to wait
• Isolation for the high-priority traffic– Almost like it has a dedicated link– Except for the (small) delay for packet transmission
• High-priority packet arrives during transmission of low-priority
• Router completes sending the low-priority traffic first
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Link Scheduling: Weighted Fairness
• Limitations of strict priority– Lower priority queues may starve for long periods
– … even if the high-priority traffic can afford to wait
• Weighted fair scheduling– Assign each queue a fraction of the link bandwidth
– Rotate across the queues on a small time scale
– Send extra traffic from one queue if others are idle
50% red, 25% blue, 25% green
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4-bitVersion
4-bitHeaderLength
8-bitType of Service
(TOS)
16-bitTotal Length (Bytes)
16-bit Identification3-bitFlags 13-bit Fragment Offset
8-bit Time to Live (TTL)
8-bitProtocol
16-bit Header Checksum
32-bit Source IP Address
32-bit Destination IP Address
Options (if any)
Payload
20-byteHeader
IP Packet Structure
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16-bit destination port number
32-bit sequence number
32-bit acknowledgement number
16-bit TCP checksum
Options (if any)
Payload
20-byteHeader
16-bit source port number
16-bit window size4-bit
headerlength
FIN
SYN
RST
PSH
ACK
URG
16-bit urgent pointer
TCP Header
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Teenusekvaliteedi aspektid (3)
• Iga teenuse jaoks oma nõuded
• QoS profiil
• Erinevad teenusekvaliteedi tasemed vastavalt nõuetele
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Näidsvõrgud• Coexistence of heterogeneous networks
– Home networks, WLAN, 2G/3G, Campus-wide, satellite, …
– The development of multimode handsets is a major challenge
– Currently discussed standards fall short– Tomorrow user’s will expect the technology structure to
“disappear” and be of no concern
• Network architecture designed by IST project Daidalos– Provide seamless services accessible anytime anywhere
across heterogeneous technologies– Enhanced Mobile IPv6 platform for mobility and QoS– Support for optimized mobility– Integration with QoS resource management
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Sensor Integration
Platform
Administrative Domain 2
t
Access Network 13
Service Provisioning Platform 1
Access Network 12
Access Network 11
Core Router
Core Router
Core Router
Access Router
Access Router
Mobile IP
Routing (Ad-hoc)
QoS Agent
Registration Agent
Metering
Accounting
Charging
Key Management
SIP User Agent
SD&C Agent
Security Support
(Content Adaptation)
AnQoS BrokerMMSP Paging Agent
PBNMSA4CCnQoS BrokerHA
KDC CMSMMSPP
Edge Router
QoS Manager
Monitoring
Accounting
Adv. Router Mech,
Metering
QoS Manager
Ntw Monitor & Meter
Fast Handover
Accounting
Authorization
Adv. Router Mech.
QoS Manager
Monitoring
Accounting
Adv. Router Mech,
Metering
Authorization
Key Interconnection
(3P)SP Applications/Content
Service Platform 1
Fe
de
ratio
n/S
LA
Bridge Mesh and/or Hierarchical PKI
Service Composer
AccessPoint
Access Router
AccessPoint
AccessPoint
Currently used link
Candidate links
Mobilerouter
DPA
Mobile Network
Service Composer
MANET
Service Register
GPSlocation
Temperature
Health+Body
Sensor
InertiaCube
SecuritySensor
NoiseLevel
LightingSituation
ProximitySensor
SoftwareSensors
Activity(phone/mouse)
Lighting
GPSlocation
Temperature
Health+Body
Sensor
InertiaCube
SecuritySensor
NoiseLevel
LightingSituation
ProximitySensor
SoftwareSensors
Activity(phone/mouse)
Lighting
Location
Location
CAN
PerSP
PerSP
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Mobile Terminal
IAL
DVB-T MBMSTD-CDMA
WLAN WiMAX
QoSAL
UDLR
QoSCMTC
IISUserGUI
CARD FHO
IPv6++/MIPv6/Multicast
Technologies
TerminalIntelligence
QoS
Handover
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Access Router / Access Point
DVB-T MBMSTD-CDMA
WLAN WiMAX
QoSAL
UDLR
QoSMCARD PA
Technologies
TerminalIntelligence
QoS
NetworkIntelligenceAM
MM
FHO CT D&M
Handover
IPv6++/
MIPv6/PIM
ENC
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Handover
• Mobile Initiated Handover
• Network Initiated Handover
Triggered
• At startup
• Upon losing signal
Accounts for
• user preferences
• candidate APs load (QoS)
• signal strengths
Triggered by
• Overloaded AP (QoS)
• losing signal
Accounts for
• signal strengths of MTs
• APs load (QoS)
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Wi-Fi Alliance Roadmap[Amer Hassan, Microsoft, jaanuar 2005]
Baseline
Security
QoS
Applications
Q1 Q2 Q4Q32005
802.11e
WMMScheduled Access
Public Access CEPhase2
2004
Extended EAP
2006
802.11h+d
Simple Config
Voice/Wi-FiWCC
802.11j 802.11k
CEPhase1
WMM Power Save
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QoS vajadus• QoS vajadus esmases tähenduses tuleneb
video ja suure edastuskiirusega (mobiilsetest) andmesessioonidest
• Lõplikult kavatsetakse realiseerida standardina IEEE 802.11n, vahevariant realiseeriti standardina IEEE 802.11e, mida toetab Proximi AP-4000.