Enhancing SWAN QoS Model
By Adopting Destination-Based Regulation (ESWAN)

Agenda

Ad-Hoc QoS Independent Models

SWAN Building Blocks

SWAN Dynamic Regulation Issues

ESWAN Basic Terms

Observations On SWAN Model

ESWAN Destination-Based Regulation

Evaluation of ESWAN

Conclusion

Ad-Hoc QoS Independent Models

FQMM (IntServ + DiffServ)

dQoS (Fair Dynamic Bandwidth Percentages)

INSIGNIA (Stat-full Model)

SWAN

Stateless

AIMD

Pragmatic Conservative Expectation of Bandwidth

No Resource Allocation

Distributed

Soft QoS Guarantees

E2E RT-Delays ??? Effective BW ???

SWAN Building Blocks

Admission Controller

Classifier

Shaper

Rate Controller

SWAN Admission Controller (AC)

Conservative look at BW availability.

Use MIN BW available between SRC/DST.

Slack of BW used by BE.

Use of probe req. reply.

Admission provides soft guarantees only.

Intermediate nodes do not allocate resources.

SWAN Packet Classifier

Simply forwards unmarked packets
to the Shaper

Forward marked packets to the MAC layer

SWAN Rate Controller (RC)

Follows conservative AIMD approach.

Limit throughput to the knee of AIMD chart.

Relies on information from MAC layer (packet delay).

SWAN Dynamic Regulation Issues

Congestion Due to Mobility

SWAN Source-Based Regulation

Congested node must mark all passing RT packets with CE.

Destination nodes inform source nodes with the congestion via QoS reporting mechanism.

Source nodes slows down transmission rates.

If new rate is unsatisfactory, source nodes re-establish the QoS flow.

Fast recovery, aggressive and disruptive to many QoS flows.

SWAN Network-Based Regulation

Congested node selects only subset of passing RT-flows (victim flows).

Same consequences as in Source-Based

If congestion is not resolved in time T, select new (victim flows).

Victim flows are selected randomly.

Slower recovery, less aggressive to RT-flows.

ESWAN Basic Terms

Define MAPD (Max Acceptable Packet Delay)

Define Effective BW = BW without expired packets.

Define Effective BW Ratio

Define Limited and High QoS

Define Effective Delay Ratio

Observations On SWAN Model

About 10% of RT-packets arrive expired.

No parameters to measure flow QoS.

No mechanism designed to respond to degraded QoS.

Expired BW consumes network resources.

ESWAN Destination-Based Regulation

Preemptive Behavior

Performed by DST node on flows experiencing Limited QoS (no congestion).

Limited QoS condition is triggered when (b < b_L)_T.

DST node issues regulate message to SRC node.

SRC node performs re-initiate procedure to locate new (better) route.

Preemptive behavior is a preventative measure.

Preemptive behavior maintains QoS levels.

ESWAN Destination-Based Regulation

Recovery Behavior

Congested node marks all RT-packets with CE until node realizes sufficient decrease in arriving BW.

DST nodes having (d > d₁) will issue regulate message.

Other DST nodes wait for time T. If packets keep arriving with CE, nodes having (d > d₂) will regulate.

After another time T, if packets keep arriving with CE, nodes having (d > d₃) will regulate.

Values (d_i) are network constants, and (d_i > d_i+1).

Evaluation of ESWAN 1

Preemptive behavior limited amount of expired BW in ESWAN compared to SWAN.

Recovery behavior caused smoother recovery from congestion in ESWAN compared to SWAN.

Evaluation of ESWAN 2

Preemptive behavior caused limited effect on BE traffic.

Recovery behavior caused a much less congested node in ESWAN compared to SWAN. The recovery is smoother in ESWAN.

Evaluation of ESWAN 3

The delay chart of RT-packets in ESWAN shows less congested packets and fewer expired.

Cumulative RT-packet delay % in ESWAN shows about 1.2% only of delivered packets are unusable.

Evaluation of ESWAN 4

Higher EBR in ESWAN due to preemptive behavior.

Lower EDR in ESWAN due to recovery behavior.

Better NW utilization in ESWAN.

Conclusion

Preemptive behavior decreases chances of congestion.

ESWAN facilitates a way to upgrade provided services.

Gradual recovery less disrupting to RT-flows.

Shaping Rate T is empirical value (2 sec).

MAPD is a flow specific value (known to DST).

EBR (b) & EDR (d) are important QoS measures.

Larger ad-hoc NW need the MAPD to limit expired BW.

Future investigation on the effect of imbalanced load bet. RT and BE traffic in SWAN enabled ad-hoc NW.

Questions & Remarks


	Ad-Hoc QoS Independent Models

	SWAN Building Blocks

	SWAN Dynamic Regulation Issues

	ESWAN Basic Terms

	Observations On SWAN Model

	ESWAN Destination-Based Regulation

	Evaluation of ESWAN

	Conclusion


	FQMM (IntServ + DiffServ)
	dQoS (Fair Dynamic Bandwidth Percentages)
	INSIGNIA (Stat-full Model)
	SWAN
		Stateless
		AIMD
		Pragmatic Conservative Expectation of Bandwidth
		No Resource Allocation
		Distributed
		Soft QoS Guarantees
		E2E RT-Delays ??? Effective BW ???


	Conservative look at BW availability.
	Use MIN BW available between SRC/DST.
	Slack of BW used by BE.
	Use of probe req. reply.
	Admission provides soft guarantees only.
	Intermediate nodes do not allocate resources.


	Simply forwards unmarked packets to the Shaper
	Forward marked packets to the MAC layer


	Follows conservative AIMD approach.
	Limit throughput to the knee of AIMD chart.
	Relies on information from MAC layer (packet delay).


	Congested node must mark all passing RT packets with CE.
	Destination nodes inform source nodes with the congestion via QoS reporting mechanism.
	Source nodes slows down transmission rates.
	If new rate is unsatisfactory, source nodes re-establish the QoS flow.
	Fast recovery, aggressive and disruptive to many QoS flows.


	Congested node selects only subset of passing RT-flows (victim flows).
	Same consequences as in Source-Based
	If congestion is not resolved in time T, select new (victim flows).
	Victim flows are selected randomly.
	Slower recovery, less aggressive to RT-flows.


	Define MAPD (Max Acceptable Packet Delay)
	Define Effective BW = BW without expired packets.
	Define Effective BW Ratio
	Define Limited and High QoS
	Define Effective Delay Ratio


	About 10% of RT-packets arrive expired.
	No parameters to measure flow QoS.
	No mechanism designed to respond to degraded QoS.
	Expired BW consumes network resources.



	Preemptive Behavior

	Performed by DST node on flows experiencing Limited QoS (no congestion).
	Limited QoS condition is triggered when (b < b_L)_T.
	DST node issues regulate message to SRC node.
	SRC node performs re-initiate procedure to locate new (better) route.
	Preemptive behavior is a preventative measure.
	Preemptive behavior maintains QoS levels.



	Recovery Behavior

	Congested node marks all RT-packets with CE until node realizes sufficient decrease in arriving BW.
	DST nodes having (d > d₁) will issue regulate message.
	Other DST nodes wait for time T. If packets keep arriving with CE, nodes having (d > d₂) will regulate.
	After another time T, if packets keep arriving with CE, nodes having (d > d₃) will regulate.
	Values (d_i) are network constants, and (d_i > d_i+1).


	Preemptive behavior limited amount of expired BW in ESWAN compared to SWAN.
	Recovery behavior caused smoother recovery from congestion in ESWAN compared to SWAN.


	Preemptive behavior caused limited effect on BE traffic.
	Recovery behavior caused a much less congested node in ESWAN compared to SWAN. The recovery is smoother in ESWAN.


	The delay chart of RT-packets in ESWAN shows less congested packets and fewer expired.
	Cumulative RT-packet delay % in ESWAN shows about 1.2% only of delivered packets are unusable.


	Higher EBR in ESWAN due to preemptive behavior.
	Lower EDR in ESWAN due to recovery behavior.
	Better NW utilization in ESWAN.


	Preemptive behavior decreases chances of congestion.

	ESWAN facilitates a way to upgrade provided services.

	Gradual recovery less disrupting to RT-flows.

	Shaping Rate T is empirical value (2 sec).

	MAPD is a flow specific value (known to DST).

	EBR (b) & EDR (d) are important QoS measures.

	Larger ad-hoc NW need the MAPD to limit expired BW.

	Future investigation on the effect of imbalanced load bet. RT and BE traffic in SWAN enabled ad-hoc NW.