Telecom
formulas
ATM
service categories:
CBR Constant
Bit Rate
rt-VBR Realtime
Variable Bit Rate
nrt-VBR Nonrealtime
Variable Bit Rate
ABR Available
Bit Rate
UBR
GFR
Traffic
parameters
PCR/SCR/MCR Peak/Sustained/Minimum
Cell Rate
CDVT Cell
Delay Variation Tolerance
BT Burst
Tolerance
Qos Parameters
CLR Cell
Loss Ration
CDV Cell
Delay Variation
CTD Cell
Transfer Delay (Max, Mean)
CER Cell
error ratio
|
Params: → Svc Category ↓ |
CLR |
CDVT/CTD |
PCR, CDVT |
SCR, BT |
MCR |
Congestion control |
|
CBR |
specified |
CDVT + MaxCTD |
specified |
n/a |
n/a |
no |
|
rt-VBR |
specified |
CDVT + MaxCTD |
specified |
specified |
n/a |
no |
|
nrt-VBR |
specified |
MeanCTD |
specified |
specified |
n/a |
no |
|
ABR |
specified |
no |
specified |
n/a |
specified |
yes |
|
UBR |
no |
no |
specified |
n/a |
n/a |
no |
GCRA(T, τ): Compute
theoretical arrival time, tat, for each cell, starting with tat=0 for 1st cell.
Let t = actual arrival time.
Case 1: t < tat - τ: too early: cell
is nonconforming; do not change tat
Case 2: t ≥ tat - τ: conforming; tatnew = max(t, tat) + T
Effective bandwidth requirement for a connection
with max delay D and max queue M: max(1/T, M/D)