Transcript National In OBS

“ Rate
and distance fairness in
OBS networks ”
Tananun Orawiwattanakul, Yusheng Ji
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Topics
• Optical Burst Switching (OBS) Networks
• Rate and Distance Fairness Preemption (RDFP)
• Simulation results
• Future works
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First OBS commercial product (2006)
Matisse Networks' EtherBurst™ is the world's first optical burst
switch, purpose-build for scaling metro and campus networks
from 10 to 640 gigabits-per-second (Gbps).
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Optical Burst Switching (OBS)
Offset = T
IP/ATM/GbE Ingress
edge
switch
BCP
Data Burst
(DB)
Burst
Assembly
Offset = T-D
Control
channel
Offset = T-2D
OEO
OEO
OEO
OOO
OOO
OOO
OBS core network
Egress IP/ATM/GbE
edge
switch
Data
channel Burst
De-assembly
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Challenge of OBS
Offset Time1
Offset Time5
C1
C2
C4
C5
DB5
Control Channels
C3
Offset Time4
Offset Time1
Offset Time3
Offset Time2
T1
T2
T3
T4
DB4
DB1
DB3
Data Channels
DB2
T5
Time
No Buffer -> High Losses
Void ->Network cannot be fully utilized
DB
C
Data Burst
Burst Control Packet
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Rate Fairness
E1
Flow1 – 8 Gbps
C1
E2
10 Gbps
E3
Flow2 – 4 Gbps
The fair rate of flow 1
and flow 2 is 5 Gbps.
It’s NOT FAIR!!! for me.
‘Rate fairness’ refers to the fair bandwidth allocation
(FBA) for each connection according to its offered 6
rate and available bandwidth in the network.
Distance fairness
S1
S3
S2
S6
Path of Flow 1
S4
S5
Path of Flow 2
S7
S8
The loss probability of longpath flow tends to be higher
than that of short path flow.
It’s NOT FAIR!!! for me.
‘Distance fairness’ refers to the fair performance in
terms of loss which respects to hop counts between
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the source and destination.
Rate and Distance Fairness Preemption (RDFP)
Provide both “Rate and Distance fairness”
in OBS networks.
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Rate and Distance Fairness Preemption (RDFP)
1. Allocate bandwidth to each flow according to the max-min
fairness.
2. If any of the connections send the input traffic higher than
their optimum fairly allocated bandwidth, the RDFP scheme
can protect and prevent well-behaved connections from
being degraded by misbehavior of other flows (rate
fairness).
3. In the meantime, RDFP also balances the loss probability
of bursts with different number of hops between the source
and destination (distance fairness) for transmitted traffic
amounts under the max-min rate.
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RDFP: Control Plane
Ai
FBCP
Ti
BBCP
Ingress
Edge Switch
Flow
id
Original
Arrival
Rate
Optimal
Fairly
Allocated
Bandwidth
i
Ai
Ti
FBCP
Core
Switch 1
Core
Switch 2
BBCP
Core
Switch N
Egress
Edge Switch
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RDFP: Burst Marking
Rate Fairness Preemption (RFP)
Ingress
Edge Switch
Input Rate
Flow
id
Original
Arrival
Rate
Optimal
Fairly
Allocated
Bandwidth
i
Ai
Ti
Ti
Ai
Under-rate bursts (HIGH PRIORITY)
Time
when Ai ≤ Ti,
all bursts are marked as “Under-rate bursts (HIGH PRIORITY)”
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RDFP: Burst Marking
Rate Fairness Preemption (RFP)
Ingress
Edge Switch
Input Rate
Ai
Flow
id
Original
Arrival
Rate
Optimal
Fairly
Allocated
Bandwidth
i
Ai
Ti
Over-rate bursts (LOW PRIORITY)
Ti
Under-rate bursts (HIGH PRIORITY)
when Ai > Ti
bursts are marked as
“Over-rate bursts (LOW PRIORITY)” with probability Pi-O = (Ai – Ti)/ Ai
“Unver-rate bursts (HIGH PRIORITY)” with probability Pi-U = 1- Pi-O
Time
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RDFP: Rate fairness preemption policy
When contention occurs in core networks, the “Under-rate (HIGH
PRIORITY)” bursts can preempt an original scheduled channel
from “Over-rate (LOW PRIORITY)” bursts with different flow ids.
Offset Time5
Under-rate Burst
DB5
C1
C2
C4
C5
Control Channels
C3
Offset Time1
DB4
Offset Time1
DB5
DB1
Offset Time1
Over-rate Burst
Data Channels
DB3
Offset Time1
DB2
T1
T2
T3
T4
T5
Time
If no original scheduled over-rate burst ->
determine the DISTANCE FAIRNESS preemption policy.
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RDFP: Distance fairness preemption policy
When contention occurs in core networks, the “Under-rate
(HIGH PRIORITY)” bursts can preempt an original scheduled
channel from bursts with lower of I.
Offset Time5
Under-rate Burst
DB5
C1
C2
C4
C5
Control Channels
C3
Offset Time1
DB4
Offset Time1
DB5
DB1
Offset Time1
Under-rate Burst with Lower I
Data Channels
DB3
Offset Time1
DB2
T1
T2
T3
T4
T5
Time
I = No of sucessful hops – Weight * (No. of remaining hops)
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Simulation networks
Edge
Switch 1
Core
Switch 1
Edge
Switch 7
Edge
Switch 6
No. of data wavelength = 16
Core
Switch 7
Core
Switch 2
Core
Switch 6
Edge
Switch 5
Edge
Switch 2
Core
Switch 3
Core
Switch 5
Core
Switch 4
Edge
Switch 3
Edge
Switch 4
The network consists of 42 flows: 3-hop flows = 14 flows,
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4-hop flows = 14 flows, and 5-hop flows = 15 flows.
RDFP: simulation results
Burst loss probability
0.035
0.03
0.025
3-HOP
4-HOP
5-HOP
Normalized rate 1 = 16 Gbps.
0.02
0.015
Input rate of each 3-hop and
4-hop flow = 0.05.
0.01
0.005
0
0.05
0.06
0.07
0.08
Input rate of each 5-hop =
0.05-0.08.
The normalized sending rate of each 5-hop flow
Burst loss probability
0.035
0.03
0.025
3-HOP
4-HOP
5-HOP
0.02
0.015
0.01
0.005
0
0.05
0.06
0.07
0.08
The normalized sending rate of each 5-hop flow
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Future works
• Extensively study the performance of TCP in RDFP-OBS based
network.
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Q&A
Thank you
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