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 |
Unspecified Bit Rate |
GFR |
Guaranteed Frame Rate |
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
ATM header (total Virtual Circuit ID = virtual path ID + virtual channel ID)
virtual path ID |
|
virtual path ID |
virtual channel ID |
Virtual Channel ID | |
Virtual Channel ID | Payload type(3) / CLP(1) |
crc-8 checksum |
realtime | non-realtime; no delay requirements |
||||
Attribute | CBR | rt-VBR | nrt-VBR | ABR | UBR |
CLR | specified | specified | specified | specified | no |
CDV/CTD MaxCTD |
CDV + maxCTD |
CDV + maxCTD |
MeanCTD [?], larger than for rt |
no | no |
PCR, CDVT | specified | specified | specified | specified | specified |
SCR, BT |
N/A |
specified |
specified, larger BT than rt-VBR |
N/A |
N/A |
MCR | N/A |
N/A |
N/A |
specified |
N/A |
Congestion control |
no |
no |
no |
yes |
no |
Effective bandwidth requirement for a connection with cell spacing T, maximum acceptable delay D and maximum queue M: max(1/T, M/D)