[nsp] IP throughput over ATM link

From: Strakadounas Kostas (strakad@forthnet.gr)
Date: Wed Feb 07 2001 - 08:21:58 EST


Does anyone know what is the IP throughput
over an ATM VC with 80179 cps CBR capacity?
Normaly I would expect this to be
80179cps X 48 bytes per cell X 8 = 30788736 bps.
So we have made the following config:
atm pvc 1 4 53 aal5snap 30789 30789

However, the IP throughput I get is only 26Mbps and when
I push traffic the number of output drops increases.
Is this normal, or the ATM service is not operating as it should?
Below you can find some output of the "sh int" and "sh atm vc"
commands.

Thank you in advance,

Kostas Strakadounas
FORTHnet SA

forthnet#sh int atm4/0
 Input queue: 0/75/0 (size/max/drops); Total output drops: 198960
  Queueing strategy: Per VC Queueing
  30 second input rate 12756000 bits/sec, 7451 packets/sec
  30 second output rate 26138000 bits/sec, 5493 packets/sec
     17326410 packets input, 3618820122 bytes, 0 no buffer
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
     11828133 packets output, 2430453178 bytes, 0 underruns
     0 output errors, 0 collisions, 0 interface resets
     0 output buffer failures, 0 output buffers swapped out

forthnet#sh atm vc
VCD
/
Peak Avg/Min Burst
Interface Name VPI VCI Type Encaps SC Kbps Kbps
Cells Sts
4/0.1 1 4 53 PVC SNAP UBR
30789 UP



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