ATM and Frame Relay Services Computer Science Department University of Crete HY536 - Network Technology Lab II 2000 - 2001

Broadband Application Requirements Application Type

File transfer

Bandwidth (Mbps)

Voice

up to link speed .064

Videoconferencing

nX.064

Compressed video (Standard MPEG-1) Compressed video (High Quality)

1-5 5-60

Average delay (msec) Insensitive

Delay Variation (msec) Insensitive

Very sensitive Very sensitive Moderately sensitive Moderately sensitive

Very sensitive Very sensitive Very sensitive Very sensitive

Information Loss Rate Very sensitive ( Discard frame

ATM Technology, Protocols, and Services - 81

Frame Relay conformance checking Bits Bc + Be

AR = access rate Drop

Rate AR

DE = 1 Bc

CIR

DE = 0

T0 Load in interval

T0 + Tc

CIR = Bc/Tc

1: DE = 0

2: DE = 0

Guaranteed

t 3: DE = 1

4: Drop

Excess ATM Technology, Protocols, and Services - 82

Frame Relay/ATM Traffic Parameter Conversion ●

●

Different methods using 2 or 3 GCRAs Method 1: 3 GCRAs to characterize ■ ■ ■

●

peak (= frame relay access line rate) CIR, Bc EIR, Be

Method 2: 2 GCRAs to characterize ■ ■

first GCRA: peak (= frame relay access line rate) second GCRA: CIR, Bc

or ■ ■

●

first GCRA: CIR+EIR second GCRA: CIR, Bc

Need to take into account the cell overhead (tax) ATM Technology, Protocols, and Services - 83