[e-mail]

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B-ISDN and ATM (??)

• ??? ???
• jmpark_at_cs.chonbuk.ac.kr

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Reference Site

• http//myhome.netsgo.com/hl3qvh/ho/ppt/q2931
• http//home.yeojoo.ac.kr/dwhyun/atm

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Characteristics of ATM

• Uses small, fixed-sized cell
• Connection oriented
• Bandwidth allocation on demand
• Supports multiple service types
• Applicable to LAN and WAN

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ATM Signaling

• UNI User to Network Interface
• NNI Network to Network Interface
• Different protocol in the different domain

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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



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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)






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Permanent Virtual Circuit

• Manual updates of VPI/VCI tables in network
  equipment

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Switched Virtual Curcuit

• Setup connection using UNI/NNI signaling

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ATM Reference Model
Q.2931, Q2971
SAAL
ATM
PHY
SAAL
Signaling ATM Adaptation Layer
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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



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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.2971
Q.2931
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Message Structure
Information 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