Feng Gang National Laboratory of Communication,UESTC Aug 2017 Ver 1.4 Admission for ATM Multiplexer An ATM multiplexer is a buffer and a high speed link;the buffer receives the cells generated by established VCs and transmits these cells,one after another onto the high-speed link 。 To guarantee that all establshed VCs meet their QoS requirements, the multiplexer need an admission policy may have to deny certain VC establishment requests VC VC High-speed link Finite buffer burst VC 2616009:Network Traffic Engineering 2:Call-level Models and Admission Control Page.11
2616009: Network Traffic Engineering Feng Gang National Laboratory of Communication, UESTC Aug 2017 Ver 1.4 2: Call-level Models and Admission Control Page.11 Admission for ATM Multiplexer • An ATM multiplexer is a buffer and a high speed link; the buffer receives the cells generated by established VCs and transmits these cells, one after another onto the high-speed link • To guarantee that all establshed VCs meet their QoS requirements, the multiplexer need an admission policy : may have to deny certain VC establishment requests High-speed link Finite buffer VC VC VC . . . burst
Feng Gang National Laboratory of Communication,UESTC Aug 2017 Ver 1.4 Admission Based on Peak Rates Notations: C:the transmission capacity of the high-speed link K:the number of services b:peak rates for class k service ()VC profile,where is the number of class-k VCs in progress Peak-rate admission: Anew service k is admitted if and only if +2bn,≤C Blocking Prob.:stochastic Knapsack model Ler sscc A=1-g where G=∑iP nes k=I n! 01 2616009:Network Traffic Engineering 2:Call-level Models and Admission Control Page.12
2616009: Network Traffic Engineering Feng Gang National Laboratory of Communication, UESTC Aug 2017 Ver 1.4 2: Call-level Models and Admission Control Page.12 Admission Based on Peak Rates • Notations: - C: the transmission capacity of the high-speed link - K : the number of services - : peak rates for class k service - : VC profile, where is the number of class-k VCs in progress • Peak-rate admission: A new service k is admitted if and only if • Blocking Prob.: stochastic Knapsack model bk ( ,..., ) 1 K n n nk K l bk blnl C 1 K k nK bknk C 1 ,..., : 1 S : n K l k nK bl nl C bk 1 ,..., : 1 S : n G G B k k 1 Let where n S 1 K k k n k n ρ G k ! k K l l l n l k n ρ G n S 1 !
Feng Gang National Laboratory of Communication,UESTC Aug 2017 Ver 1.4 More on Admission Based on Peak Rates Asymptotic Analysis:as capacity and demand approach infinity Let the transmission capacity and the offered traffic be large,and suppose that they are roughly equal: 含款c We have 8 is a constant that independent of k and C when the transmission capacity is large and nearly equal to the offered traffic, blocking probability for a service is roughly proportional to the service's peak rate;blocking probabilities decay at a rate of 1/C 2616009:Network Traffic Engineering 2:Call-level Models and Admission Control Page.13
2616009: Network Traffic Engineering Feng Gang National Laboratory of Communication, UESTC Aug 2017 Ver 1.4 2: Call-level Models and Admission Control Page.13 More on Admission Based on Peak Rates • Asymptotic Analysis: as capacity and demand approach infinity - Let the transmission capacity and the offered traffic be large, and suppose that they are roughly equal: - We have is a constant that independent of k and C when the transmission capacity is large and nearly equal to the offered traffic, blocking probability for a service is roughly proportional to the service’s peak rate; blocking probabilities decay at a rate of K l k k k C b 1 C b B k k 1/ C
Feng Gang National Laboratory of Communication,UESTC Aug 2017 Ver 1.4 Admission Based on Effective Bandwidth The multiplexer operates in the statistical multiplexing mode if the admission policy permits VC profiles whose aggregate peak rates exceed the transmission capacity of the link: ∑b,n>C k=1 。 Effective-bandwidth admission: (b,...,b):the effective bandwidth of the K-services A new service-k VC is admitted if and only if 2616009:Network Traffic Engineering 2:Call-level Models and Admission Control Page.14
2616009: Network Traffic Engineering Feng Gang National Laboratory of Communication, UESTC Aug 2017 Ver 1.4 2: Call-level Models and Admission Control Page.14 Admission Based on Effective Bandwidth • The multiplexer operates in the statistical multiplexing mode if the admission policy permits VC profiles whose aggregate peak rates exceed the transmission capacity of the link: • Effective-bandwidth admission: K k bknk C 1 K l l e l e bk b n C 1 ( ,..., ) 1 e K e b b : the effective bandwidth of the K-services A new service-k VC is admitted if and only if
Feng Gang National Laboratory of Communication,UESTC Aug 2017 Ver 1.4 Admission for ATM Multiplexer Example for admission regions The boundaries of the admission regions for three allowable polices n2 All allowable VCs Effective bandwidth Peak rate +n1 2616009:Network Traffic Engineering 2:Call-level Models and Admission Control Page.15
2616009: Network Traffic Engineering Feng Gang National Laboratory of Communication, UESTC Aug 2017 Ver 1.4 2: Call-level Models and Admission Control Page.15 Admission for ATM Multiplexer • Example for admission regions The boundaries of the admission regions for three allowable polices n2 n1 All allowable VCs Effective bandwidth Peak rate