Application performance based path-selection using dynamic metrics
Embodiments herein disclose methods for selecting one or more paths for routing application traffic based on application performance metrics for hosted applications. In an embodiment, to select the best path, the available paths can be monitored to understand the performance of specific applications through those paths. Subsequently, the performance data is used to derive an application link score for any given combination of application and path, wherein the application link score is generated as a function of packet delay and packet loss. The ALS is then be used to determine the best path for a given application.
1. A method for selecting a path to an application through a Software-Defined Wide Area Network (SD-WAN), the method comprising:
monitoring available paths through the SD-WAN to reach a hosted application to obtain performance metrics associated with the available paths through the SD-WAN on a per-application and per-path basis;
generating an application link score for a combination of the hosted application and an available path through the SD-WAN for the available paths through the SD-WAN, wherein the application link score is generated as a function of packet delay and packet loss; and
selecting a path for traffic to travel through the SD-WAN to access the hosted application based on application link scores corresponding to the available paths through the SD-WAN;
wherein the application link scores are calculated using a logistic function; and
wherein the application link scores are generated as:
Application
Link
Score
(
A
L
S
)
=
V
*
e
lp
1
+
e
lp
where Linear Predictor,
lp=A+B*Delay+C*RTX+D*Delay*RTX,
V is a measurement constant that corresponds to an upper time limit, Delay corresponds to a time for a packet to travel across the available path, RTX corresponds to a retransmission ratio, and A, B, C, and D are constants.
2. The method of claim 1 , wherein V=4,320,000 milliseconds.
3. The method of claim 2 , wherein:
lp=− 7.151200+0.011821*Delay+4.669700*Loss+0.012558*Delay*Loss.
4. The method of claim 1 , further comprising calculating an application link rank that is a function of the application link score and the measurement constant, V.
5. The method of claim 4 , wherein the application link rank is calculated as:
A
L
R
=
log
(
(
A
L
S
V
)
*
(
C
nBins
-
1
)
+
1
)
/
log
(
C
)
where C is a constant and nBins is a number of bins.
6. The method of claim 1 , further comprising scaling RTX by:
Confidence
ratio
ϕ
=
#
packets
ConfThresh
if
packets
<
ConfThresh
1
if
packets
≥
ConfThresh
wherein #packets is a number of packets transmitted on a TCP session and ConfThresh is a confidence threshold in number of packets.
7. The method of claim 1 , wherein the Delay and the retransmission ratio (RTX) are obtained from Transmission Control Protocol (TCP) session information.
8. The method of claim 1 , wherein the delay and loss ratio information is collected from service level agreement (SLA) monitoring and wherein the application link scores are calculated using the delay and the loss ratio information collected from the SLA monitoring.
9. The method of claim 1 , wherein the delay and the loss ratio information is collected from service level agreement (SLA) monitoring and wherein the RTX is calculated as:
RTX
=
Loss
Ratio
L
V
where a Loss Ratio is packets lost/total packets transmitted and an LV is the linearity value.
10. A non-transitory computer readable medium that stores computer readable instructions, that when executed on one or more processors, implements a method for selecting a path to an application through a Software-Defined Wide Area Network (SD-WAN), the method comprising:
monitoring available paths through the SD-WAN to reach a hosted application to obtain performance metrics associated with the available paths through the SD-WAN on a per-application and per-path basis;
generating an application link score for a combination of the hosted application and an available path through the SD-WAN for the available paths through the SD-WAN, wherein the application link score is generated as a function of packet delay and packet loss; and
selecting a path for traffic to travel through the SD-WAN to access the hosed application based on application link scores corresponding to the available paths through the SD-WAN;
wherein the computer readable instructions, when executed on the one or more processors, implement the method, wherein the application link scores are calculated using a logistic function; and
wherein the computer readable instructions, when executed on the one or more processors, implement the method, wherein the application link scores are generated as:
Application
Link
Score
(
A
L
S
)
=
V
*
e
lp
1
+
e
lp
where Linear Predictor, lp=A+B*Delay+C*RTX+D*Delay*RTX, V is a measurement constant that corresponds to an upper time limit, Delay corresponds to a time for a packet to travel across the available path, RTX corresponds to a retransmission ratio, and A, B, C, and D are constants.
11. The non-transitory computer readable medium of claim 10 , wherein the computer readable instructions, when executed on the one or more processors, implement the method further comprising calculating an application link rank that is a function of the application link score and the measurement constant, V.
12. The non-transitory computer readable medium of claim 11 , wherein the computer readable instructions, when executed on the one or more processors, implement the method, wherein the application link rank is calculated as:
A
L
R
=
log
(
(
A
L
S
V
)
*
(
C
nBins
-
1
)
+
1
)
/
log
(
C
)
where C is a constant and nBins is a number of bines.
13. The non-transitory computer readable medium of claim 10 , wherein the computer readable instructions, when executed on the one or more processors, implement the method further comprising scaling RTX by:
Confidence
ratio
ϕ
=
#
packets
ConfThresh
if
packets
<
ConfThresh
1
if
packets
≥
ConfThresh
wherein #packets is a number of packets transmitted on a TCP session and ConfThresh is a confidence threshold in number of packets.
14. The non-transitory computer readable medium of claim 10 , wherein the computer readable instructions, when executed on the one or more processors, implement the method, wherein the Delay and the retransmission ratio (RTX) are obtained from Transmission Control Protocol (TCP) session information.
15. The non-transitory computer readable medium of claim 10 , wherein the computer readable instructions, when executed on the one or more processors, implement the method, wherein the delay and the loss ratio information is collected from service level agreement (SLA) monitoring and wherein the application link scores are calculated using the delay and loss ratio collected from the SLA monitoring.
16. A method for selecting a path to an application through a network, the method comprising:
monitoring available paths through a network to reach a hosted application to obtain performance metrics associated with the available paths through the network on a per-application and per-path basis;
generating an application link score for a combination of the hosted application and an available path through the network for the available paths through the network, wherein the application link score is generated as a function of packet delay and packet loss; and
selecting a path for traffic to travel through the network to access the hosted application based on application link scores corresponding to the available paths through the network;
wherein the application link scores are calculated using a logistic function; and
wherein the application link scores are generated as:
Application
Link
Score
(
A
L
S
)
=
V
*
e
lp
1
+
e
lp
where Linear Predictor, lp=A+B*Delay+C*RTX+D*Delay*RTX, V is a measurement constant that corresponds to an upper time limit, Delay corresponds to a time for a packet to travel across the available path, RTX corresponds to a retransmission ratio, and A, B, C, and D are constants.