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2000년 2학기 B-ISDN and ATM (보충) 2
Reference Site
• http://myhome.netsgo.com/hl3qvh/ho/ppt/q2931
• http://home.yeojoo.ac.kr/~dwhyun/atm
2000년 2학기 B-ISDN and ATM (보충) 3
Characteristics of ATM
• Uses small, fixed-sized cell• Connection oriented• Bandwidth allocation on demand• Supports multiple service types• Applicable to LAN and WAN
2000년 2학기 B-ISDN and ATM (보충) 4
ATM Signaling
• UNI : User to Network Interface• NNI : Network to Network Interface• Different protocol in the different domain
2000년 2학기 B-ISDN and ATM (보충) 5
Virtual Path / Virtual Channel
• Connection Identifier : VPI/VCI• Physical Link : Contains multiple VPs• Virtual Path : Contains multiple VCs• Virtual Channel : Logical path between ATM endpoint
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VP and VC Switching
2000년 2학기 B-ISDN and ATM (보충) 7
ATM Cell Header
PTI Payload Type Identifier(3 Bits)- 1 bit : User/Control Data. - 2 bit : Congestion flag.- 3 bit : Last Cell flag
CLP Cell Loss Priority Bit
HEC Header Error Check(8 Bits)
2000년 2학기 B-ISDN and ATM (보충) 8
Permanent Virtual Circuit
• Manual updates of VPI/VCI tables in network equipment
2000년 2학기 B-ISDN and ATM (보충) 9
Switched Virtual Curcuit
• Setup connection using UNI/NNI signaling
2000년 2학기 B-ISDN and ATM (보충) 10
ATM Reference Model
Signaling ATM Adaptation Layer
Q.2931, Q2971
SAAL
ATM
PHY
SAAL
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ATM Service Criteria
• Traffic parameters– Peak Cell Rate(PCR), Sustainable Cell Rate(SCR)
– Maximum Burst Size(MBS), Minimum Cell Rate(MCR)
• Quality of Service– Maximum Cell Transfer Delay(MCTD)
– Cell Delay Variation Tolerance(CDVT)
– Cell Loss Ratio(CLR)
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ATM Service Categories
2000년 2학기 B-ISDN and ATM (보충) 13
Traffic Management - I
• CAC(Connection Admission Control)
• Determine whether a connection can be progressed or not
- satisfy the traffic contract of the connection- not disturb traffic contracts of the other connections
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Traffic Management - II
• UPC(Usage Parameter Control)
• Protect network resources from malicious as well as unintentional misbehavior- based on traffic contract of the connection- action : cell discard, cell tagging
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Traffic Management - III
• CLP(Cell Loss Priority) Control
• In Congestion state- EFCI(Explicit Forward Congestion Control)
- CLP(Cell Loss Priority)
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Traffic Management – IV
• CAC / Connection Management• UPC (Policing)• CLP / EFCI control• Frame Discard• Traffic Shaping• ABR Congestion Feedback
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ATM Signaling Protocol
• Point-to-Point ATM Connection(Q.2931)
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Reserved VPI/VCI
Q.2931
Q.2971
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Message StructureInformation Element Length
Protocol discriminator Distinguish Message 1
Call reference Identify call at the local UNI 4
Message type Identify the function of message 2
AAL parameter 4-21
ATM traffic descriptor 12-20
Broadband bearer capability
6-7
QoS parameter 6
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