AF & TCPTesting on LAN

Octavio MedinaENSTB / IRISA

2

Test Simulated Tested

WRED calibration

BW sharing: UDP

BW sharing: TCP

Aggregation

Remarking

AF Testing: Roadmap

3

• To check out if AF can be used to control BW sharing among TCP aggregates.

• To check how TCP is affected by UDP in an AF scenario.

• To calibrate the parameters of the TCM.

No relationship with RTT dependency.– All flows have the same RTT.

Goal of this tests

4

• Single station generates test flows– UDP background traffic– TCP test flows (differentiated by port no.)

• Differentiation is assured by router before bottleneck– Classification/Marking on input interface– Color-based discrimination (WRED) on output iface.

WREDtrTC

M

50 Mbps

TCP Flows

Test Topology

UDP

5

WRED

50 Mbps

aggregatemarking

4 Mbps

3 Mbps

2 Mbps

1 Mbps

Logic Topology

tcp

tcp

tcp

tcp

tcp

tcp

tcp

tcp

UDP

TCP: 4 aggregates10 flows/aggregateTCM

UDP: single stream@ 0, 15, 30, 45 Mbps.always Red

6

WRED Configuration

• Same as last time

20

random-detect random-detect exp3 random-detect precedence 2 1 20 2 random-detect precedence 4 25 50 10 random-detect precedence 6 63 64 100

25 50 64

0.5

0.1

7

TCM Configuration• TCM uses 2 token buckets

– Tc(rc , bc)

– Te(re , be)

• Idea: Use rc as reference parameter

– Tc(rc , rc)

– Te(rc , rc)

• Test to find best valuesof and .

bebc

rc

re

8

• BW is shared equally among aggregates

• TCP considerably affected by UDP

Test 0: TCP without AFTCP aggregate BW, no DiffServ

0.000

2.000

4.000

6.000

8.000

10.000

12.000

udp0 udp15 udp30 udp45

BG traffic (Mbps)

Mb

ps

aggr A

aggr B

aggr C

aggr D

9• Results almost independent of !

Test 1: find the right

BW share vs. b/r

0.00%

5.00%

10.00%

15.00%

20.00%

25.00%

30.00%

35.00%

40.00%

45.00%

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

a= b/r

BW

sh

are

aggr A 40% aggr B 30%

aggr C 20% aggr D 10%

• defines the size of the bucket• = b/r (Ex: r= 500KB/s, =0.1 b=50KB) (tested from 0.1 to1.0)

10

Test 2: find the right • defines the behavior of 2nd token bucket

• = Te/Tc =2.0

0%

10%

20%

30%

40%

udp0 udp15 udp30 udp45

=2.5

0%

10%

20%

30%

40%

udp0 udp15 udp30 udp45

=3.0

0%

10%

20%

30%

40%

udp0 udp15 udp30 udp45

=3.5

0%

10%

20%

30%

40%

udp0 udp15 udp30 udp45

11

Test 2: find the right • When is too small, more red packets are produced.

“Red” bandwidth is shared equally.Differentiation is reduced in the absence of BG traffic=2.0

0%

10%

20%

30%

40%

udp0 udp15 udp30 udp45

=2.5

0%

10%

20%

30%

40%

udp0 udp15 udp30 udp45

=3.0

0%

10%

20%

30%

40%

udp0 udp15 udp30 udp45

=3.5

0%

10%

20%

30%

40%

udp0 udp15 udp30 udp45

12

Test 2: find the right • When is too big, differentiation is reduced in high

congestion scenarios.There are too many yellow packets.

=2.0

0%

10%

20%

30%

40%

udp0 udp15 udp30 udp45

=2.5

0%

10%

20%

30%

40%

udp0 udp15 udp30 udp45

=3.0

0%

10%

20%

30%

40%

udp0 udp15 udp30 udp45

=3.5

0%

10%

20%

30%

40%

udp0 udp15 udp30 udp45

13

Test 2: find the right • However, increasing the value of increases the BW

obtained by TCP.

• Less TCP packets at the same level as UDP (red).

Total BW vs. Re/Rc

0

5

10

15

20

25

30

35

40

45

udp0 udp15 udp30 udp45

BG traffic (Mbps)

BW

(M

bp

s)

1.5 2.0 2.5

3.0 3.5 4.0

14

WRED

50 Mbps

aggregatemarking

6 Mbps

1.5 Mbps

1.5 Mbps

1 Mbps

Test 3: test another sharing policy

tcp

tcp

tcp

tcp

tcp

tcp

tcp

tcp

UDP

Test with chose values = 0.1 = 2.5

Found out that can not be too big. IOS limits the token size to 200KB.

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• Differentiation is more effective when UDP is active (if no UDP, when does WRED start?).

• Under congestion, there is good differentiation, but high-rate aggregate fails to obtain desired rate (60%).

Test 3: test another sharing policy

Aggregate TCP BW sharing

42%

52%

55% 55%

19%17% 16% 17%

20%

17% 17% 17%19%

14%12% 12%

0%

10%

20%

30%

40%

50%

60%

udp0 udp15 udp30 udp45

BG traffic (Mbps)

BW

sh

are

aggr A 60%

aggr B 15%

aggr C 15%

aggr D 10%

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• TCP can effectively be protected from UDP if flows use different marking.– Application 1.

• BW sharing can be controlled at the aggregate level, specially in congested links.– Application 2.

• We must be aware that this results were obtained on an homogeneous RTT scenario.

Conclusion

17

• Try smaller values for .– IOS also limits bucket size to 8KB.

• Try other marking schemes– Excess TB before committed TB…

• Imagine scenario for testing with different RTTs.

Perspectives