ieee srp fa mar8 - LMSC, LAN/MAN Standards Committee ... · 2 of 21 Cisco Systems IEEE 802 LAN/MAN...
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1 of 21 Cisco Systems IEEE 802 LAN/MAN SRP-fa Simulation Results on SRP Fairness Algorithm (SRP-fa) Byoung-Joon (BJ) Lee March 8, 2000
Transcript of ieee srp fa mar8 - LMSC, LAN/MAN Standards Committee ... · 2 of 21 Cisco Systems IEEE 802 LAN/MAN...
IEEE 802 LAN/MAN
SRP-fa
RP-fa)
1 of 21 Cisco Systems
Simulation Resultson
SRP Fairness Algorithm (S
Byoung-Joon (BJ) Lee
March 8, 2000
IEEE 802 LAN/MAN
SRP-fa
trate the under various
2 of 21 Cisco Systems
Overview
• Provide simulation results to demonsbehavour of SRP fairness mechanismtraffic pattern and load scenarios.
• Cases considered:
❖ Homogeneous traffic
- Mesh, Worst-case, Aggregation, Best-case
❖ Heterogeneous traffic - Aggregation
❖ Large number of nodes
IEEE 802 LAN/MAN
SRP-fa
1
0
4
st-Case
1
0
4
rst-Case 120%
500%
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Traffic Pattern Scenarios
1
2
3
0
4
Mesh
2
3Be
2
3Wo
1
2
3
0
4
Aggregation
200%
100%
IEEE 802 LAN/MAN
SRP-fa
Traffic Pattern Scenarios (cont’d)
1
5 % 25 % 50 % 75 %
Total: 155%)
2
5 % 15 % 30 % 45 %
Total: 95%)
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1
2
3
0
4
Aggregation (heterogeneous input)
❖ case
1 -> 0:2 -> 0:3 -> 0:4 -> 0:
(
❖ case
1 -> 0:2 -> 0:3 -> 0:4 -> 0:
(
IEEE 802 LAN/MAN
SRP-fa
Simulation Parameters
distanced
s)
ential)ential)nential)nential)
2)
2)
ss filetering weight)
Coefficient Value)
yte times, 100µS)
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* 5 nodes with outer ring traffic only and equal-
Ring circumference : 16, 3000 (in mileHi/Low priority ratio : variesAvg pkt rate : 161979 pkts/sec (exponAvg pkt size : 480 Bytes (exponBurst ON duration : varies (expoBurst OFF duration : varies (expo
Tx high priority size : 2.7 KBTx low priority size : 1 MBTB high priority size : 2.7 KBTB low priority size : 512 KB (OC-1TB low threshold : 256 KBTB high threshold : 500 KB (OC-1
LP_FWD : 64 (low paLP_MU : 512LP_ALLOW : 64AGECOEFF : 4 (Aging
Decay Interval : 32000 (in bUsage Interval : Decay Interval + ∆
IEEE 802 LAN/MAN
SRP-fa
Results: Mesh, Homogeneous, Overloaded , OC-12
ty (spatial reuse)
16 vs 3000 miles)
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• Throughput achieves 160% of link capaci
• With small ring size, faster convergence (
161979 pkts/s480 bytes
IEEE 802 LAN/MAN
SRP-fa
Results: Mesh, on/off (240/760 uS) , 3000 miles, OC-12
euse)
ed condition
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• 24% x 5 = 120% of link capacity (spatial r
• TB and Tx occupancy indicate underload
IEEE 802 LAN/MAN
SRP-fa
Results: Mesh, on/off (300/700 uS) , 3000 miles, OC-12
euse)
ilization
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• 30% x 5 = 150% of link capacity (spatial r
• TB and Tx occupancy indicate heavier ut
IEEE 802 LAN/MAN
SRP-fa
Results: Worst Case, Overloaded , OC-12
25% of link cap.)
mesh pattern
50ms (2τ)
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• Each node can source 622/4=155Mbps (
• Convergence is worse when compared to
IEEE 802 LAN/MAN
SRP-fa
Results: Worst Case, on/off (240/760 uS) , OC-12
e average
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• Each node transmit 24% of link cap. on th
• Heavy traffic condition with bursty input
IEEE 802 LAN/MAN
SRP-fa
Results: Asymmetric (case 1), 155%, OC-12
re 30% each,all their inputs.
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• Under overload, 75% and 50% nodes shawhile small input nodes are able to send SRP achieves total of 90% link utilization.
IEEE 802 LAN/MAN
SRP-fa
OC-12
ble to send their fullith 16 and 3000 miles.
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Results: Asymmetric (case 2), 95%,
• Under 95% input load, all the nodes are ainput trraffic. Similar performance both w
IEEE 802 LAN/MAN
SRP-fa
Results: Asymmetric (case 2), 95%, OC-12
gregation point), (upstream node)
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• TB Congestion only occurs at node 4 (agand as a result, the allow usage at node 3is often throttled.
IEEE 802 LAN/MAN
SRP-fa
Results: WAN, Triggered Input, OC-48
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IEEE 802 LAN/MAN
SRP-fa
Results: WAN, Triggered Input, OC-48
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IEEE 802 LAN/MAN
SRP-fa
ring capacityd load
n thele with
ll and large
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Summary
• SRP-fa achieves fair share of under various traffic pattern anscenarios.
• SRP-fa’s fair share is based omaximum throughput achievabspatial reuse property.
• SRP-fa is effective in both smageographical coverage.
IEEE 802 LAN/MAN
SRP-fa
Appendix I: SRP-fa Nutshell (One)
g
is blocked:
Fwd_rate
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• Layer 2 MAC Transmission Schedulin
❖ Transmission order:
❖ 4 Conditions when Low priority Host traffic
- TB occupancy >= TB_Low_Threshold- My_usage > Allow_usage- My _usage > Max_allow- TB low priority is non-empty && My_usage >
TB_Low_ThTB_High_Th
High TransitHigh HostLow HostLow Transit
High TransitHIgh Host
Low Transit
High TransitLow Transit
IEEE 802 LAN/MAN
SRP-fa
Appendix I: SRP-fa Nutshell (Two)
en congested,nd usage controlsser of the two) torottle upstreamdes
t congested here,t it is somewherewnstream.
rottle upstreamen the forward
te is more than myowed usage
t congested, and allowed usage is
eater than theward rate, sendLL
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• Generating Usage Packets(once every decay interval)
Congested = (TB_low_depth > TB_low_TH /2)
if (Congested) {
if ( (Lp_my_usage < Rcvd_usage) ||
(Rcvd_usage == Null) )
Usage_upstream = Lp_my_usage;
else
Usage_upstream = Rcvd_usage;
} else if ( (Rcvd_usage != Null) &&
(Lp_fwd_rate > allow_usage) )
Usage_upstream = Received_usage;
else
Usage_upstream = Null;
if (Usage_upstream > Max_Lrate)
Usage_upstream = Null;
(1) whse(lethno
(2) Nobudo
Thwhraall
(3) NomygrforNU
1
2
3
IEEE 802 LAN/MAN
SRP-fa
Appendix I: SRP-fa Nutshell (Three)
_ALLOW
xt,” IETF Internet Draft,
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• Updating Allow Usage(once every decay interval)
Max_Lrate = AGECOEFF * Decay_Interval
if ( Rcvd_usage != NULL)
Allow_usage = Rcvd_usage;
else
Allow_usage + (Max_Lrate - Allow_usage)/ LP
Reference:
D. Tsiang and G. Suwala, “draft-tsiang-srp-01.tMarch 1, 2000
IEEE 802 LAN/MAN
SRP-fa
Appendix II: E2E Delay of High Priority Traffic
igh priority packet is received at thenets1:
_delay + Qd
Qd
te_delay
ents: 8 µS/mile.
e in # of packets, and Qd is theority Max Transmit Unit in bytes.
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• E2E delay is measured from the time a his queued at the source to the time that itdestination. There are three delay compo
❖ Access Delay (Ad)
WC (Worst Case) = N x Bf * HP_MTU * byte
BC (Best Case) = HP_MTU * byte_delay +
❖ Nodal Delay (Nd)
WC = N * LP_MTU * byte_delay+ N * TB_High * byte_delay
+ N * HP_MTU * byBC = N x HP_MTU x byte_delay
❖ Fiber Delay (Fd)Propagation delay through N fiber link segm
1. N is the number of nodes traversed, while Bf is the token bucket burst sizaccess queueing delay. HP_MTU and LP_MTU are high and low pri
IEEE 802 LAN/MAN
SRP-fa
Appendix II: E2E Delay of High Priority Traffic (cont’d)
1500 (bytes)
9000 (bytes)
es.
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Numerical Examples (SRP delay at OC-12):
N = 8 nodes traversed (16 nodes actual)Bf = 2 (in HP_MTU)
Qd = 50 µS (estimated)
(1) HP_MTU = 128, TB_High = 2700, LP_MTU=
WC= 77.3 + 460.8 = 538.1 µSBC = 51.7 + 13.6 = 65.3 µS
(2) HP_MTU = 128, TB_High = 2700, LP_MTU=
WC= 77.3 + 1261.3= 1338.6 µSBC = 51.7 + 13.6 = 65.3 µS
(2a) Same as (2) but at OC-48
WC= 56.8 + 315.4 = 372.2 µSBC = 50.4 + 3.4 = 53.8 µS
• Simulation results provide similar range of valu
