Transcript Document

Sidevõrgud
IRT 0020
loeng 7 30. okt. 2006
Avo Ots
telekommunikatsiooni õppetool
raadio- ja sidetehnika instituut
[email protected]
1
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
QoS – Quality of Service
ITU-T E.800 Recommendation
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Teenusekvaliteedi aspektid (2)
QoS
Teenuse
Kättesaadavus
Teenuse
Püsivus
Teenuse
Terviklikus
(Accessibility)
(Retainability)
(Integrity)
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 lowpriority
• 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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IP Packet Structure
4-bit
8-bit
4-bit
Version Header Type of Service
Length
(TOS)
16-bit Identification
8-bit Time to
Live (TTL)
8-bit
Protocol
16-bit
Total Length (Bytes)
3-bit
Flags
13-bit Fragment Offset
16-bit Header Checksum
20-byte
Header
32-bit Source IP Address
32-bit Destination IP Address
Options (if any)
Payload
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TCP Header
16-bit source port number
16-bit destination port number
32-bit sequence number
32-bit acknowledgement number
4-bit
header
length
U A P R S F
R C S S Y I
G K H T N N
16-bit TCP checksum
20-byte
Header
16-bit window size
16-bit urgent pointer
Options (if any)
Payload
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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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Mobile IP
Routing (Ad-hoc)
QoS Agent
Registration Agent
QoS Manager
Metering
Ntw Monitor & Meter
Accounting
Fast Handover
Monitoring
Charging
Accounting
Accounting
Key Management
Authorization
Adv. Router Mech,
SIP User Agent
Adv. Router Mech.
Access Network 11
Location
QoS Manager
CAN
Service Platform 1
Location
Bridge Mesh and/or
Hierarchical PKI
Metering
SD&C Agent
Key Interconnection
Security Support
(Content Adaptation)
Service Provisioning Platform 1
AnQoS BrokerMMSP Paging Agent
MANET
Service
Composer
Service
Composer
Access Router
Candidate links
Access Router
Access
Point
HA
CnQoS Broker
A4C
PBNMS
Core Router
(3P)SP Applications/Content
Federation/SLA
Access Network 12
CMS
KDC
t
PerSP
Currently used link
Access
Point Access Router
MMSPP
Core Router
Core Router
Access Network 13
Access
Point
Service Register
PerSP
Edge Router
Administrative Domain 2
Security
Sensor
QoS Manager
Monitoring
DPA
Mobile Network
Sensor
Integration
Platform
Noise
Level
Proximity
Sensor
Accounting
Mobile
router
Lighting
Situation
Lighting
Tempe
rature
Activity
(phone/mouse)
Health+
Body
Sensor
Adv. Router Mech,
Metering
Software
Sensors
GPS
location
Inertia
Cube
Authorization
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Mobile Terminal
Technologies
IPv6++/MIPv6/Multicast
Terminal
Intelligence
QoS
IIS
User
GUI
CARD
FHO
Handover
QoSC
MTC
IAL
UDLR
DVB-T
QoSAL
MBMS
TD-CDMA
WLAN
WiMAX
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Access Router / Access Point
FHO
CT
Technologies
D&M
IPv6++/
MIPv6/
PIM
AM
Terminal
Intelligence
Network
Intelligence
QoS
CARD
PA
MM
QoSM
Handover
QoSAL
ENC
UDLR
DVB-T
MBMS
TD-CDMA
WLAN
WiMAX
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Handover
• Mobile Initiated Handover
Triggered
Accounts for
• At startup
• user preferences
• Upon losing signal
• candidate APs load (QoS)
• signal strengths
• Network Initiated Handover
Triggered by
Accounts for
• Overloaded AP (QoS)
• signal strengths of MTs
• losing signal
• APs load (QoS)
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Wi-Fi Alliance Roadmap
[Amer Hassan, Microsoft, jaanuar 2005]
802.11j
2004
2005 Q1
Baseline
802.11h+d
Security
QoS
Applications
802.11k
802.11e
Q2
Q3
Q4
Extended EAP
2006
Simple Config
WMM
Scheduled Access
CE Public Access WCC CE
Phase1
Phase2
WMM Power Save
Voice/Wi-Fi
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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.
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Roadmap – WLAN
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