1. Experiment with LBE Quality of Service on GÉANT
Experiments with Less than Best Effort (LBE) Quality of Service on GÉANT
Tiziana Ferrari
Experiment with LBE Quality of Service on GÉANT

2. Experimental set-up (cont)
Experiment with LBE Quality of Service on GÉANT

3. Performance without congestion
Experiment with LBE Quality of Service on GÉANT

4. Experiment with LBE Quality of Service on GÉANT
One-way delay
Experiment with LBE Quality of Service on GÉANT

5. Experiment with LBE Quality of Service on GÉANT
IPDV
traffic volume: [10, 50] %
2 flows (1 LBE, 1 BE)
maximum IPDV (BE): 11 usec
sample of 100 consecutive packets
IPDV negligible for both LBE and BE
Experiment with LBE Quality of Service on GÉANT

6. Experiment with LBE Quality of Service on GÉANT
Packet reordering
- proportional to packet rate
affecting both LBE and BE
maximum IPDV (BE): 11 usec
sample of 100 consecutive packets
packet reordering due to the M-160 architecture
Experiment with LBE Quality of Service on GÉANT

7. Performance with congestion
Experiment with LBE Quality of Service on GÉANT

8. Experiment with LBE Quality of Service on GÉANT
Packet loss
3 LBE streams (75% of traffic load), 1 BE stream (25%), plus BE production
traffic
in case of LBE congestion:
no BE packet loss
no IP Premium packet loss (when IP Premium traffic is injected)
only LBE packet loss, proportional to the amount of LBE
traffic injected
Experiment with LBE Quality of Service on GÉANT

9. Experiment with LBE Quality of Service on GÉANT
Throughput
7 LBE streams, 2 BE streams, 1 IPP stream
load: [50, 100] %
in case of LBE congestion (traffic load: 100% of a STM-16) :
BE and IPP per-flow throughput equals the UDP input rate
only LBE throughput affected by LBE congestion
Experiment with LBE Quality of Service on GÉANT

10. Experiment with LBE Quality of Service on GÉANT
One-way delay
100 streams, 98 streams DE2 -> IT, 2 streams DE2 -> DE1 (LBE and BE)
LBE:
increase in both average and max one-way delay in case of congestion
max delta (max – min): msec
BE:
Slight increse of average and max one-way delay
Max delta (max – min): msec
Experiment with LBE Quality of Service on GÉANT

11. One-way delay frequency distributions (LBE)
test duration: 10 sec
time divided in time intervals of 0.1 sec each -> 100 intervals
for each interval, min/avg/max one-way delay is recorded
Experiment with LBE Quality of Service on GÉANT

12. One-way delay frequency distributions (BE)
Experiment with LBE Quality of Service on GÉANT

13. Experiment with LBE Quality of Service on GÉANT
IPDV (LBE)
2 streams: 1 LBE stream, 1 BE stream (DE2 -> IT)
considerable increase in maximum LBE IPDV
no difference in IPDV frequency distributions with and without congestion
(100 consecutive packets)
Experiment with LBE Quality of Service on GÉANT

14. Experiment with LBE Quality of Service on GÉANT
Packet reordering
BE queue priority = LBE queue priority = high
extremely high percentage of out-of-order packets in case of congestion
percentage is a function of the packet rate of a given stream
it affects both BE and LBE traffic
the configuration of different queue priorities solves the problem of throughput loss
of BE end-to-end TCP streams
Experiment with LBE Quality of Service on GÉANT

15. Experiment with LBE Quality of Service on GÉANT
Conclusions
LBE DSCP transparency on GEANT is possible
Correct isolation of BE traffic from LBE congestion
Negligible impact on BE one-way delay and IPDV
Packet reordering can be greatly reduced so that end-to-end TCP throughput is preserved, by:
assigning a lower weight to the EF queue
Configuring different priorities to the LBE and BE queues
Packet reordering seems to affect TCP best-effort throughput if the parameters are wrong.
Experiment with LBE Quality of Service on GÉANT