Abstract
Intent-Driven
Networking (IDN) aims to simplify network management by enabling operators to
specify what the network should achieve rather than how it should be
configured. However, practical deployments of IDN often fail to satisfy user
intent under dynamic network conditions such as congestion, failures and
heterogeneous traffic. In this paper, we redefine Assured Intent-Driven
Networking in terms of four operational properties: correctness guarantees,
continuous verification, convergence and graceful degradation - rather than as
an idealized error-free system.
FAIDN
(Framework for Assured Intent-Driven Networking) is a congestion-aware intent
execution framework built on Software-Defined Networking (SDN) which integrates
intent translation, real-time network state awareness, verification and
automated remediation into a closed control loop. Using decision-tree–based
diagnostics, FAIDN detects congestion, identifies root causes across control,
data, link and host planes and applies corrective actions such as rerouting,
queue resizing, traffic prioritization and rate limiting.
FAIDN
is implemented using the Ryu SDN controller and the Mininet emulator and
evaluated under a heterogeneous background traffic environment comprising video
streaming, VoIP and bursty variable bit rate flows. Performance is assessed for
a video conferencing intent as the primary evaluation target. Experimental
results demonstrate that FAIDN achieves a 56× throughput improvement over
baseline SDN-based execution at peak congestion, maintains video conferencing
intent satisfaction above 80% at 90% load and converges within 2-4 remediation
steps. Evaluation across additional intent types remains as future work.
Keywords: Intent-Driven Networking, Software-Defined Networking, Ryu
SDN Controller, Mininet Emulator, Congestion Control, Intent Satisfaction,
Network Remediation, Closed-loop Control.
1. Introduction
Reliably
satisfying operator-defined intents with provable correctness, continuous
verification and predictable convergence under dynamic network conditions
remains an open challenge in Intent-Driven Networking (IDN). We term this goal
assured intent driven networking, defined operationally rather than as an
idealized error-free system. While IDN promises to decouple what the network
should achieve - such as latency bounds, bandwidth guarantees or traffic
isolation - from how it is configured, practical deployments frequently fail
under congestion, traffic heterogeneity and resource oversubscription1-4.
Managing heterogeneous environments spanning Realtime multimedia, healthcare
IoT, industrial automation and cloud applications using device-centric
approaches has become prohibitively complex and error-prone, motivating the
shift toward intent-driven paradigms5,6.
Figure
1: Assured intent implementation
requires a Assured network: queue overflow, link collisions and Botnet attacks
are bottlenecks for intent-driven networking.
Despite
this promise, existing IDN systems consistently fail to satisfy user intent in
dynamic environments7. As illustrated in (Figure 1), network congestion is
a primary cause, leading to increased latency, packet loss, jitter and
application timeouts that directly constitute intent violations8,9.
Congestion arises from dynamic traffic patterns, oversubscription,
misconfigurations and failures10 - effects that are especially damaging to delay sensitive
applications such as video conferencing and VoIP, exposing a critical gap
between intent specification and intent realization11.
Existing
congestion management approaches in SDN and self-driving networks focus on
performance optimization, flow scheduling or traffic engineering12-14,
but lack explicit mechanisms for runtime verification, intent correctness and
predictable behaviour under overload. ML-based self-driving networks introduce
further challenges around stability, explainability and convergence, limiting
their use in QoS-critical environments15.
We
argue that assured intent-driven networking does not require eliminating all
failures - an unrealistic goal in distributed systems - but rather ensuring
correct and predictable behavior under both normal and adverse conditions.
Specifically, we define a assured IDN as one that provides: (1) correctness
guarantees, (2) continuous verification, (3) convergence and (4) graceful
degradation during intent execution. Based on these principles, this paper
presents FAIDN, a congestion-aware IDN framework that treats congestion as a
first-class intent violation, integrating detection, root-cause diagnosis,
verification and automated remediation into a closed control loop.
The
main contributions of this paper are as follows:
· We redefine assurance in IDN operationally, in terms of
correctness, continuous verification, convergence and graceful degradation,
aligning intent execution with assurance-based networking principles.
· We design FAIDN, a congestion-aware IDN architecture
integrating intent translation, real-time state monitoring, runtime
verification and automated remediation within a closed-loop control framework.
· We propose a decision-tree–based framework for congestion
detection and root-cause analysis across the controller, data, link and host
planes, enabling explainable and deterministic remediation.
· We implement and evaluate FAIDN on the Ryu SDN controller and
Mininet under heterogeneous highload traffic, demonstrating improved intent
satisfaction, predictable convergence and graceful degradation over baseline
SDN-based execution.
2. Motivation
Efficient
utilization of network resources while satisfying Quality of Service (QoS)
requirements critically depends on the timely detection and resolution of
network congestion. Congestion is a well-documented cause of performance
degradation - leading to increased delay, packet loss, jitter and application
timeouts - particularly for real-time and interactive services8,9. As
networks increasingly support diverse and dynamic workloads, congestion remains
a fundamental obstacle to reliable service delivery.
The
challenge is compounded by the heterogeneity of modern traffic. Networks
simultaneously carry elephant flows - large, long-duration transfers that
consume sustained bandwidth - and mice flows - small, latency-sensitive, bursty
transmissions typical of gaming, VoIP and web traffic. These competing flow
types impose conflicting resource demands, making uniform congestion management
strategies inherently insufficient.
Intent-Driven
Networking (IDN) has emerged as a promising paradigm to address operational
complexity by decoupling network control logic from low-level device
configurations and enabling closed-loop orchestration for automated network
management1,2. Such architectures leverage programmability and
virtualization through Software-Defined Networking (SDN), Network Function
Virtualization (NFV) and programmable data planes to dynamically configure and
manage network resources5,27. Large-scale virtualization of heterogeneous network
components is a key enabler of intent-driven operation.
Despite
these advances, existing IDN and SDN-based solutions remain limited in their
ability to resolve congestion in an automated and intent-aware manner. Many
approaches provide only static or reactive configurations, which are
insufficient to handle congestion across varying traffic conditions and network
states39-41. Moreover, congestion mitigation is often treated as an
isolated optimization problem rather than as an integral component of intent
execution, resulting in limited automation and weak guarantees of sustained
intent satisfaction.
Current
IDN and SDN-based solutions are hampered by several interconnected limitations.
Manual and error-prone configurations remain prevalent, particularly under
exceptional conditions such as network congestion or failures, which heightens
the risk of misconfiguration and service disruption27,55.
Compounding this, the static control logic embedded in many SDN controllers
constrains their ability to adapt to rapidly changing traffic patterns and the
heterogeneous demands of modern applications55,56. A
further challenge is that intent execution is typically designed with the
assumption of stable operating conditions, whereas real-world networks
routinely experience overloads, dynamic traffic shifts, failures and security
attacks16,18. Runtime verification mechanisms capable of ensuring that
deployed configurations continue to satisfy user intents under such adverse
conditions remain limited15,25. Finally, resource constrained IoT controllers often lack
the programmability and abstraction necessary to support intent-driven
operation across large-scale, heterogeneous IoT environments43.
As
network scale and heterogeneity continue to grow - driven by the proliferation
of IoT devices, edge computing and latency-sensitive applications - the
inability to reason about congestion dynamically leads to persistent intent
violations32,47. These challenges collectively highlight the need for a
congestion-aware, verifiable and adaptive IDN architecture that explicitly
integrates congestion detection, root-cause analysis and automated remediation
into the intent execution process.
Motivated
by these observations, this work proposes a solution that systematically
detects congestion, identifies its underlying causes across multiple network
planes and applies targeted configurations that jointly address QoS
requirements, interoperability and scalability constraints. By embedding these
capabilities into a closed-loop intent execution framework, the proposed
approach aims to improve intent satisfaction while ensuring predictable and
reliable network behaviour.
3. Background and
Related Work
This
section reviews foundational technologies and prior research related to
ML-based network analytics, programmable networking, self-driving networks, SDN
and NFV, congestion control and intent-based networking. Each subsection
identifies the limitations of existing approaches and positions FAIDN with
respect to the current state of the art.
3.1.
Background
Recent
advances in ML-based network analytics have demonstrated strong potential for
enabling autonomous and intelligent network operations, including monitoring,
control and optimization of complex network systems3,4. In
parallel, the evolution of network programmability has significantly enhanced
the ability to remotely configure, monitor and manage network devices in a
flexible and vendor-agnostic manner. In particular, the emergence of the
protocol independent packet processing language P4 enables fine-grained
programmability of forwarding devices, facilitating the design of highly
programmable networks5.
To
support the design, development and prototyping of programmable and
intent-driven architectures, simulation and emulation platforms play a crucial
role. Network Simulator-3 (ns-3)6 and the Mininet emulator7 are
widely adopted tools for evaluating networking schemes prior to physical
testbed deployment, enabling controlled experimentation with new control logic,
traffic patterns and configuration strategies under realistic conditions. The
following subsections survey key solution approaches explored in the
literature.
3.1.1.
Machine learning and analytics:
ML and data analytics techniques have been extensively studied for networking
operations, including delay and bandwidth optimization8,
detection and mitigation of DoS attacks9 and
dynamic resource allocation10. In particular, reinforcement learning (RL) has proven
effective in dynamic and partially observable network conditions, with
applications in TCP congestion control11,12, Quality
of Experience (QoE) optimization13, resource management14 and
runtime verification of P4-programmable devices15.
Despite
these advances, ML-driven solutions face persistent challenges related to
learning instability, convergence guarantees, reproducibility and operational
reliability - particularly in large-scale, endto-end deployments. These
limitations motivate complementary approaches that emphasize deterministic
behavior and verifiable correctness, as adopted in FAIDN.
Beyond
software-based ML, the emergence of programmable data plane devices - including
SmartNICs and P4-programmable switches - extends the reach of analytics to the
forwarding plane, enabling per-packet telemetry collection at line rate without
controller involvement5. FAIDN leverages this programmability indirectly through the
Ryu controller's southbound OpenFlow interface, which provides the telemetry
granularity required by the congestion detection module.
3.1.2.
Self-driving and self-organizing networks: The concept of self-driving and self-organizing networks has
gained significant attention16-18. These autonomous networks aim to monitor, manage, optimize,
defend and analyze themselves with minimal human intervention. By combining
analytics, control automation and closed-loop decision-making, selfdriving
networks reduce manual operational overhead and improve efficiency.
However,
such approaches often prioritize performance optimization and adaptability over
formal correctness, verification and predictable convergence - properties that
are critical for intent-driven and QoS-sensitive applications. This gap
directly motivates the design principles underlying FAIDN.
3.1.3.
Intent Translation in SDN Controllers: At the control-plane level, SDN controllers including NOX19,
DISCO20, Floodlight21, OpenDaylight22, ONOS23 and ONIX24 have incorporated or are exploring intent specification and
translation mechanisms. While these platforms provide essential building blocks
for intent-driven networking, their support for runtime intent verification,
congestion aware remediation and closed-loop assurance remains limited -
motivating the need for enhanced architectures that integrate intent
translation with continuous monitoring and adaptive control.
3.2.
Related work
This
section surveys existing work most relevant to FAIDN across four research
areas: self-driving and autonomous networks, SDN and NFV infrastructures,
congestion control mechanisms in SDN environments and intent-based networking
systems. Each subsection summarizes representative contributions, identifies
key limitations - particularly the absence of runtime verification,
congestion-aware remediation and predictable convergence - and positions FAIDN
with respect to the current state of the art.
3.2.1.
Self-driving networks (Self-DN):
Networks have increasingly evolved toward self-driving architectures that
autonomously measure, manage and control operations with minimal human
intervention18. These systems rely heavily on ML and data analytics for
adaptive decision-making16,25 and industry players such as Juniper Networks have actively
promoted such solutions26.
While
self-driving networks demonstrate strong automation potential, ML-based
approaches introduce challenges related to stability, explainability,
repeatability and verification - particularly in dynamic and large-scale
deployments16,18. Without sufficient programmability and structured control, enforcing
business intent reliably remains difficult. In contrast, FAIDN adopts a
rule-based, decision-tree– driven approach to enable deterministic behavior,
explainable decision-making and predictable convergence under congestion.
3.2.2.
SDN and NFV: Software-Defined
Networking (SDN) and Network Function Virtualization (NFV) decouples the
control and data planes, enabling centralized programmability and control.
Extensive research has proposed SDN-based schemes to improve performance,
scalability and flexibility27-29, with applications spanning transportation30,31,
healthcare32 and smart grid systems33. To
address centralized scalability limitations, distributed SDN control planes
have been proposed34-36, though static switch-controller assignments often result in
load imbalance and controlplane congestion37,38.
Despite
these advances, existing SDN and NFV solutions generally lack high-level intent
abstraction and closedloop assurance - capabilities essential for sustainable
and flexible network deployment and directly addressed by FAIDN.
3.2.3.
Congestion control mechanisms:
Extensive research has addressed congestion control in SDN environments.
Representative solutions - including SD-TCP39,
SD-GCC40 and Hedera41 - dynamically schedule flows, adjust rates or reallocate
bandwidth to mitigate congestion (Table 1). Other approaches address
flow identification, rate limiting and attack aware mitigation42-44.
Table
1: Existing congestion-aware SDN
approaches.
|
Schemes |
Reason for Congestion |
Location of Congestion
|
React or Location |
Detection |
Configuration |
Performance Evaluation
|
|
SDTCP39 |
Oversubscribing |
Switch |
Switch and Host |
Queue Size |
Adjusting the advertised TCP
window |
Mininet |
|
SDGCC40 |
Oversubscribing |
Switch |
End Host |
Queue Size |
Divide network bandwidth
across active VMs |
Testbed |
|
Hedera41 |
Elephant flows |
Switch |
Switch |
Identify flows |
Dynamic flow scheduling |
Testbed |
|
SCCP42 |
Large number of flows |
Switch |
Switch and Host |
Flow counting at port |
Limits the data rate of the
TCP senders |
Mininet, NS-3 |
|
iAcceSD43 |
Unknown flows |
Edge Switch |
Switch and Host |
ML- based flow identification |
Dynamic flow and classifier |
Mininet, NS-3 |
|
MinRule44 |
Link flooding attacks (LFA) |
Switch |
Host, Switch Link |
Detect flooding attack |
Rerouting |
NS-3 |
(Table
1) summarizes these existing
congestion-aware SDN approaches.
While
effective within specific scenarios, these mechanisms operate independently of
intent semantics - treating congestion as a performance optimization problem
rather than as a violation of high-level network intent. FAIDN explicitly
bridges this gap by integrating congestion detection, diagnosis and remediation
directly into the intent execution loop.
3.2.4.
Intent-Based Networking (IBN):
Recent research has explored IBN across wired and wireless networks, 5G
infrastructures, IoT environments and cloud systems. Notable contributions
include intent-based ONOS northbound interfaces for 5G service management45,
intent-driven mobile backhaul architectures46,
network slicing mechanisms47 and automation frameworks for IoT requirements48.
Industry initiatives from Cisco [49], Huawei50,
Gartner51 and Juniper Apstra52
further reflect the growing commercial adoption of intent-driven automation.
4. System Model and
Assurance Properties
We
define a assured intent-driven network operationally - not as an error-free
ideal, but as one that maintains four verifiable properties during intent
execution under dynamic and adverse conditions1,2.
These properties collectively provide the behavioral guarantees necessary for
practical IDN deployment and form the design basis for FAIDN (Table 2).
Table
2: Properties for intent
execution.
|
Property
|
Definition
|
FAIDN
Mechanism |
|
Correctness
|
Intent
semantics preserved during translation |
Feasibility
and consistency validation before deployment |
|
Continuous
Verification |
Ongoing
compliance monitoring at runtime |
Telemetry-driven
KPI evaluation against active intents |
|
Convergence
|
Stable
configuration reached after reconfiguration |
Prioritized,
sequential remediation strategies |
|
Graceful
Degradation
|
Controlled
performance reduction under overload |
Priority-aware
intent scheduling |
(Table
2) summarizes each property and
its corresponding mechanism in FAIDN.
In
FAIDN, assurance is defined operationally rather than idealistically.
Specifically, a assured intent-driven network is one that maintains
correctness, continuous verification, convergence and graceful degradation
during intent execution, particularly under dynamic and adverse network
conditions. These properties collectively ensure predictable, verifiable and
robust network behaviour, which is essential for practical deployment of
intent-driven and autonomous networking systems1,2.
4.1.
Correctness guarantees
Correctness
guarantees ensure that the translation of high-level user intents into
low-level network configurations preserves the intended semantics of user
requirements. Prior studies have shown that ambiguities or inconsistencies
during intent translation can lead to misconfigurations and unintended network
behavior25,45. To address this, each intent in FAIDN is validated for
feasibility, consistency and compatibility with existing intents before
deployment. This validation step prevents conflicting or unsatisfiable
configurations and establishes a sound baseline for reliable intent execution18.
4.2.
Continuous verification
Continuous
verification is a fundamental requirement for maintaining intent satisfaction
in dynamic network environments. FAIDN continuously monitors the operational
network state using telemetry collected from controllers, switches, links and
hosts. Key performance indicators-including queue occupancy, throughput, delay
and packet loss-are evaluated against the constraints specified by active
intents15,53. This runtime verification approach aligns with prior work
on assurance-based and self-driving networks, which emphasizes the importance
of ongoing validation rather than one-time configuration checks16,18.
4.3.
Convergence
Convergence
is defined as the network reaching a stable, intent-compliant operating state
within bounded time following a corrective reconfiguration event. Upon detecting
deviations between the observed network state and the specified intents, FAIDN
applies corrective actions aimed at restoring compliance while ensuring
convergence to a stable network configuration. Uncoordinated or overly
aggressive reconfigurations can lead to oscillations and instability in
SDN-based systems55,56. To mitigate this risk, FAIDN employs prioritized and
sequential remediation strategies, ensuring that corrective actions are applied
incrementally and deterministically. This design choice promotes predictable
convergence and avoids conflicting control decisions34,36.
4.4.
Graceful degradation
Graceful
degradation is characterized by a monotonic, policy-governed reduction in
performance as offered load exceeds available capacity, without abrupt collapse
or oscillatory behaviour. Graceful degradation addresses scenarios in which
network resources are insufficient to satisfy all active intents
simultaneously. Instead of abrupt failures or indiscriminate performance
collapse, FAIDN degrades network performance in a controlled and policy-aware
manner. Lower-priority intents may experience reduced service levels, while
higher-priority or mission-critical intents continue to receive preferential
treatment47,49. Such controlled degradation is particularly important in
multi-tenant, IoT and real-time application environments, where partial service
continuity is preferable to complete disruption32,43.
5. Problem Formulation
The
existing literature has explored the evolution of multiple network architectures,
including self-driving networks (Self-DN), Software-Defined Networking (SDN),
distributed SDN and Intent-Based Networking (IBN)16,18,27,34,45.
While these approaches address specific challenges related to automation,
scalability and programmability, many limitations remain unresolved. Despite
advances in SDN, NFV and intent-based networking - and broader efforts toward
self-managed and self-optimized networks - a significant degree of manual
configuration remains necessary during network design, deployment and operation27,55.
Modern network devices such as gateways, routers and switches often run complex
and distributed control software that is closed and proprietary54.
Network administrators configure individual devices using vendor-specific
interfaces that vary across products, protocols and standards, even within the
same vendor ecosystem54. Such heterogeneity complicates network programmability and
hinders consistent intent enforcement. Moreover, many state-of-the-art
solutions focus on implementing intent over already designed and deployed
networks, which limits their ability to adapt dynamically to evolving
requirements and operating conditions45,49. As
a result, these networks remain insufficiently intelligent and poorly suited to
rapidly changing environments.
With
the large-scale deployment of heterogeneous IoT and edge devices, local
controllers play a critical role in network management and interfacing32,43.
However, traditional IoT controllers often lack the programmability and
abstraction required to support intent-driven operation. Since most intents are
closely tied to application QoS and resource requirements - such as
guaranteeing bandwidth for a scheduled video conferencing session or
provisioning network slices for new IoT applications - a predictable and
reliable network infrastructure is essential47,48. In
this context, the ability to detect and resolve congestion dynamically becomes
a key requirement for achieving reliable intent execution.
5.1.
Congestion in intent-driven networks
Network
congestion occurs when the offered traffic load exceeds the network’s capacity
to process and forward packets efficiently. Although congestion is often a
transient condition, persistent congestion may indicate fundamental design,
configuration or control issues53. Network congestion can be characterized by monitoring the
normalized rate of queue accumulation across network nodes. If A(t) denotes the
aggregate number of queued packets at time t, “I” is the measurement interval
and “p” is the packet injection rate, the congestion index Γ is defined as59:
?(?+?)−?(?)
? = ???
(1)
?→∞ ??
When
Γ > 0, packets accumulate faster than they are drained, indicating
congestion. When Γ ≤ 0, the network is draining the queue at a rate equal to or
exceeding the injection rate. FAIDN triggers congestion remediation when Γ
exceeds a configurable threshold Γ_th > 0 for a sustained interval T_detect,
preventing transient spikes from causing spurious reconfigurations.
In
the context of intent-driven networking, congestion is not merely a performance
concern - it is a direct cause of intent violation. When congestion degrades
throughput, increases latency or causes packet loss, active intents specifying
QoS bounds are violated. This work focuses on four dominant congestion causes
that lead to intent violations: over-subscription, unknown or encrypted traffic
flows, security attacks and poor network design or misconfiguration (Table
3).
Table
3: Congestion Causes and FAIDN
Responses.
|
Congestion
Cause |
Origin
|
Affected
Plane |
FAIDN
Response |
|
Oversubscription
|
Traffic
volume exceeds capacity |
Controller,
Switch,
Link,
Host |
Queue
resizing, rerouting, rate limiting |
|
Unknown/
Encrypted
Flows |
Dynamic
ports,
encryption |
Data
plane, Edge switch |
ML-based
flow identification, classifier update |
|
Security
Attacks |
DoS,
flooding, worms |
Switch,
Host,
Link |
Traffic
isolation, rerouting, rate limiting |
|
Poor
Design / Misconfiguration
|
Vendor- specific
config errors |
Control
plane, Data plane |
Intent
validation, configuration verification |
These
factors, summarized in Table 3, motivate the need for an intent-driven
framework that integrates intent translation, automated implementation and
congestionaware remediation across multiple network planes.
5.1.1.
Over-subscription: Over-subscription
occurs when the network is required to handle traffic volumes beyond its
designed capacity. In SDN environments, congestion due to oversubscription may
arise at multiple entities, including controllers, switches, links and end
hosts. SDN switches-particularly hardware switches relying on Ternary
Content-Addressable Memory (TCAM)-are inherently resource-constrained, while
software switches such as Open vSwitch rely on general-purpose memory and may
not scale efficiently under high load54.
The
SDN control plane is also vulnerable to congestion and scalability limitations.
A high rate of flow setup requests can overwhelm a centralized controller,
creating a control-plane bottleneck55.
Furthermore, excessive control traffic may lead to choke points near the
controller, degrading overall network responsiveness56.
Effective identification of traffic characteristics, flow durations and
malicious activity is therefore essential to prevent over-utilization of
network resources.
FAIDN
addresses over-subscription through dynamic queue resizing, traffic rerouting
and rate limiting, applied incrementally via its closed-loop remediation
module.
5.1.2.
Unknown and encrypted traffic flows: Modern networks carry highly heterogeneous traffic generated
by diverse devices and applications that often use dynamically assigned ports
or encryption. This significantly increases the complexity of traffic identification
and classification43. Traditional SDN approaches rely on port-based
classification or Deep Packet Inspection (DPI), both of which become
increasingly ineffective and expensive in terms of latency and processing
overhead as encrypted and variable traffic proliferates. These limitations
further exacerbate congestion and hinder timely remediation.
FAIDN
mitigates this challenge through ML-based flow identification and dynamic
classifier updates, enabling timely remediation without relying on port-based
inspection.
5.1.3.
Security attacks: Security
threats such as viruses, worms and Denial-of-Service (DoS) attacks can induce
severe congestion in SDN-based networks. Compromised hosts or switches may be
exploited to generate excessive traffic, host illicit services or content or
launch flooding attacks, resulting in abnormal traffic surges and widespread
service degradation9,44. Such attack-induced congestion directly violates
application intents and necessitates integrated detection and mitigation
mechanisms.
FAIDN
responds to attack-induced congestion through traffic isolation and rerouting,
integrated directly into the intent execution loop.
5.1.4.
Poor network design and misconfiguration: Poor network design and misconfiguration remain persistent
challenges in SDN deployments. As network devices are configured using
heterogeneous and often vendor-specific interfaces, inconsistencies and errors
are common27,54. Inadequate design may lead to broadcast or multicast
storms, causing severe performance degradation. Additionally, faulty or
misconfigured devices may fail to deliver agreed-upon data rates, further
impacting QoS and intent satisfaction55.
FAIDN
addresses misconfiguration proactively through intent validation before
deployment, preventing conflicting or unsatisfiable configurations from
reaching the data plane.
Together,
these four congestion causes represent the primary failure modes that FAIDN is
designed to detect, diagnose and remediate. The following section describes the
FAIDN architecture and the mechanisms through which these responses are
implemented within a closed-loop intent execution framework.
6. Faidn Architecture
The
proposed FAIDN architecture explicitly addresses network congestion as a
primary factor affecting Quality of Service (QoS) and resource allocation
during intent execution. Rather than relying on static or reactive
configurations, FAIDN enables automated generation and deployment of
congestion-aware configurations to ensure that user intents are satisfied under
dynamic network conditions. (Figure 2) presents an overview of the
proposed intent-driven SDN architecture.
Figure
2: Intent-based SDN.
6.1.
System model
The
FAIDN architecture is designed to instantiate the four assurance properties
defined in Section 4 - correctness, continuous verification, convergence and
graceful degradation - within a practical SDN deployment across multiple
domains including real-time multimedia, healthcare IoT, industrial automation
and cloud applications among others. To achieve this, FAIDN follows a
closed-loop control model composed of four functional modules, each responsible
for a distinct phase of intent execution16,18.
The architecture supports dynamic addition of new flows, provisioning of
virtual networks and adaptive resource allocation within bounded time
constraints27,34.
6.1.1.
Intent translation and validation:
This module accepts high-level business or application intents specified by end
users and translates them into candidate network configurations. During this
process, intents are validated for feasibility, consistency and semantic
correctness to prevent conflicting or unsatisfiable configurations1,25,45.
The intent controller is designed to support multiple intent types, including
QoS guarantees, traffic isolation and resource provisioning.
6.1.2.
Automated network implementation:
This module deploys validated configurations across the control, data and
interface planes of the network. It is responsible for orchestrating
configuration changes in response to new intents or evolving network
conditions. Flexibility at the control plane includes adapting controller placement
and switch-to-controller assignments, while data-plane flexibility involves
dynamic adjustment of flows, queues and topology level resources27,34,36.
6.1.3.
Network state awareness: FAIDN
continuously collects real-time telemetry from network components under its
administrative control, including controllers, switches, links and hosts. This
monitoring is protocol- and transport-agnostic, enabling comprehensive
visibility into network performance indicators such as queue occupancy,
throughput and packet loss15,53.
6.1.4.
Assurance and Remediation: This
module continuously verifies whether the deployed configurations satisfy the
original user intents. When violations are detected, FAIDN applies corrective
actions-such as traffic blocking, queue resizing, rerouting or capacity
adjustment-to restore compliance. This closed-loop assurance mechanism is
essential for maintaining intent satisfaction under congestion and dynamic
workloads16,18,49.
As
illustrated in (Figure 2), these four modules form a closed loop:
translated intents flow into the implementation module, which deploys
configurations monitored by the state awareness module, whose telemetry feeds
the assurance module, which triggers re-translation when violations are
detected. Together, these modules ensure that intent execution remains
continuously aligned with the observed network state, enabling predictable and
reliable behavior.
6.2.
FAIDN algorithm
Algorithm
1 provides an overview of the configuration selection and deployment process for
intent execution in FAIDN. Given a user intent and optional supporting intents,
the algorithm identifies the required configurations and applies them across
the appropriate SDN planes. FAIDN invokes four plane-specific procedures:
cpFAIDN (control plane), dpFAIDN (data plane), npFAIDN (network interface
plane) and dlFAIDN (link plane).
Algorithm
1: Automating SDN for FAIDN
Algorithm
2 provides the closed-loop verification and remediation loop
Algorithm
2: FAIDN Closed-Loop Verification and Remediation
Input:
intent, S (network state), remediationTree
Output:
restored intent compliance or graceful degradation
6.3.
Congestion detection and remediation
Building
on the congestion taxonomy established in Section 3, this section describes the
specific detection and remediation mechanisms FAIDN employs across each network
plane. FAIDN models congestion as a multi-plane phenomenon that may originate
at controllers, switches, links or hosts. Decision trees are used to detect
congestion symptoms such as queue buildup and packet loss, identify root causes
including over-subscription, unknown flows, attacks and misconfiguration and
select appropriate remediation actions including rerouting flows, resizing
queues, adjusting priorities, rate limiting senders and isolating malicious
traffic. These actions are applied incrementally to ensure convergence34,36.
6.3.1
Decision tree for controller congestion (Figure 3): When the controller exhibits high CPU
utilization or packet processing delays exceeding threshold, FAIDN identifies
control-plane congestion. (Figure 3) presents the master congestion
detection tree, encompassing all four network planes. The controller branch
evaluates flow request arrival rate, OpenFlow message, queue depth and
controller load distribution. Remediation actions include redistributing
switches to alternative controllers or throttling flow setup requests.
Figure
3: Decision tree for controller-plane congestion detection.
6.3.2.
Decision Tree for Switch Congestion (Figure 4 and Figure 5): Switch-level congestion represents one of the most common
bottlenecks in SDN deployments, arising from resource exhaustion at the data
plane. FAIDN monitors three primary metrics at each switch: port utilization,
queue depth and flow table occupancy. When any of these metrics exceeds a
predefined threshold, the decision tree in (Figure 4) is invoked to confirm
the presence of congestion and initiate root-cause analysis.
The
detection tree evaluates port utilization first, as sustained high port
utilization is the most direct indicator of data-plane overload. If port
utilization is within acceptable bounds, queue depth is assessed - excessive
queue buildup indicates that packets are being held longer than the intent's
latency constraints permit. Flow table occupancy is evaluated last, as TCAM
exhaustion in hardware switches can cause flow setup failures and silent packet
drops, both of which constitute intent violations even when port-level metrics
appear normal.
Once
congestion is confirmed, the root-cause analysis tree in Fig. 5 classifies the
underlying factor - whether the congestion is due to over-subscription, unknown
or encrypted flows, security attacks or misconfiguration - and selects the
corresponding remediation pathway. This two-stage design, separating detection
from root cause classification, ensures that remediation actions are targeted
rather than generic, reducing the risk of oscillatory reconfigurations.
Figure
4: Decision tree for
switch-plane congestion detection.
Figure
5: Decision tree for
switch-plane root-cause analysis.
6.3.3.
Decision tree for link congestion (Figure 6): Link-level congestion differs from switch congestion in that
it manifests between network nodes rather than within them, making it
detectable only through interdevice telemetry rather than per-switch counters.
FAIDN triggers link congestion detection under two primary conditions: when
link utilization exceeds a configurable threshold τ_l and when elephant flows
are identified as occupying a disproportionate share of available link
bandwidth.
The
decision tree in (Figure 6) first evaluates aggregate link utilization.
If utilization exceeds τ_l, FAIDN determines whether the overload is caused by
a small number of high-volume elephants flows or by a broader surge in traffic
volume. This distinction is critical for remediation selection: elephant flow
congestion is best addressed through dynamic flow scheduling or rerouting,
while general overload may require rate limiting or queue prioritization across
multiple flows.
If
link utilization is within bounds but intent violations - such as increased
latency or packet loss - are still observed, FAIDN inspects for elephant flows
that may be crowding out latency-sensitive mice flows without triggering
absolute utilization thresholds. This condition, where throughput-sensitive
flows consume link capacity without triggering absolute utilization alarms,
thereby degrading latency-sensitive flows - is sometimes termed covert
congestion or hidden congestion41 discusses elephant-mice flow interaction. It is particularly
harmful to VoIP and video conferencing intents and requires
prioritization-based remediation rather than rerouting. By explicitly
distinguishing these two congestion modes, FAIDN avoids misapplied remediation
that could worsen QoS for high-priority intents.
Figure
6: Decision tree for link-plane
congestion detection.
6.3.4.
Decision tree for host congestion (Figure 3, Host Branch): Host-plane congestion arises when end hosts-rather than
network devices-are the limiting factor in intent satisfaction. FAIDN monitors
two primary host-plane conditions. First, active host overload occurs when a
host's CPU or memory utilization exceeds threshold τ_h, causing it to drop or
delay packet processing even when network-side resources are available. This
manifests as asymmetric throughput degradation localized to flows involving
that host. Second, host idle or sleep states can result in silent flow drops
that superficially resemble link failures.
The
host branch of the decision tree in (Figure 3) first evaluates whether
the host is active. If active, it assesses whether the constraint is bandwidth
(BW), CPU or RAM. If the host is idle or in a sleep state, FAIDN issues a host
wake-up or reachability alert rather than a network-side remediation action.
When host CPU or RAM is the binding constraint, FAIDN applies rate limiting at
the upstream switch to reduce the offered load to the host, preserving intent
compliance for other flows while preventing the overloaded host from becoming a
persistent bottleneck. Host-side remediation is always coordinated with the
switch-plane module to ensure that flow table entries remain consistent with
the host's reduced capacity.
6.3.5.
Remediation action selection (Figure
7): Once a congestion event is detected and its root cause identified,
FAIDN applies remediation actions according to a least-disruptive-first
principle. This ordering is central to FAIDN's convergence guarantee: by
applying the most conservative corrective action first and escalating only if
the violation persists, FAIDN avoids aggressive reconfigurations that could
introduce oscillations or temporarily worsen performance for unaffected
intents.
The
remediation decision tree in (Figure 7) organizes available actions into
an ordered hierarchy. Queue resizing is attempted first, as it adjusts buffer
allocation without altering traffic paths or flow assignments - making it the
lowest-impact intervention. If queue resizing is insufficient to restore intent
compliance, traffic prioritization is applied next, reordering flow scheduling
to favor high-priority intents while reducing service to lower-priority flows.
If violations persist, flow rerouting is triggered, redirecting affected
traffic over alternative paths with available capacity. In cases where
congestion is attributed to security attacks or unknown flows, traffic
isolation and rate limiting are applied to suppress the offending traffic
before other actions are attempted.
After
each remediation step, FAIDN re-evaluates the network state through the Network
State Awareness module and re-checks intent compliance through the Assurance
module. This iterative verification loop continues until either compliance is
restored or all available remediation options have been exhausted, at which
point graceful degradation is activated - reducing service levels for
lower-priority intents while preserving compliance for mission-critical ones.
This design ensures that remediation is both deterministic and auditable,
supporting the explainability requirements of intent-driven operation16,18.
Figure
7: Decision tree for congestion
remediation action selection.
Together,
the decision trees in (Figures 3-7) form FAIDN's structured congestion
management subsystem. By separating detection, root-cause analysis and
remediation into distinct but interconnected trees, FAIDN ensures that
corrective actions are targeted, deterministic and explainable - directly
supporting the correctness and convergence properties defined in Section 4.
Section 7 describes the implementation of this framework using the Ryu SDN
controller and the Mininet emulator.
7. Implementation and Performance
Evaluation
This
section describes the prototype implementation of FAIDN and presents a
systematic performance evaluation under dynamic and congested network
conditions. FAIDN is realized on the Ryu SDN controller, a widely adopted
open-source platform for SDN research and evaluated using the Mininet network
emulator over a configurable multi-switch topology with heterogeneous traffic
workloads. The evaluation is designed to assess whether FAIDN instantiates the
four assurance properties defined in Section 4 - correctness, continuous
verification, convergence and graceful degradation - under conditions
representative of real-world intent-driven deployments.
7.1.
Evaluation objectives and metrics
The
objective of the performance evaluation is to assess whether FAIDN satisfies
the defining properties of assured intent-driven networking. Specifically,
FAIDN is evaluated along four dimensions: intent satisfaction, measured by the
network's ability to maintain QoS constraints as load increases45,47; throughput
stability, measured as sustained application throughput as offered load
approaches link capacity39,41; convergence behaviour, observed through the ability to
reach a stable configuration following reconfiguration34,55;
and graceful degradation, evaluated by controlled and predictable performance
reduction under overload rather than abrupt collapse16,18.
7.2.
Experimental setup
Figure
8: Ryu controller-based
architecture for the proposed IDN.
The
Ryu controller-based implementation architecture is illustrated in (Figure 8),
showing the northbound and southbound interface components, intent processing
modules and OpenFlow integration.
7.2.1.
Implementation platform: FAIDN
is implemented using the Ryu SDN controller and evaluated using the Mininet
emulator, which is widely used for prototyping and validating SDN-based
architectures57,58. The evaluation topology consists of multiple switches and
hosts generating heterogeneous traffic patterns representative of real-world
workloads, including video conferencing, video streaming, Voice over IP (VoIP),
control traffic and bursty variable bit rate (VBR) flows.
These
workloads are selected to emulate diverse application characteristics and QoS
requirements, consistent with prior SDN and intent-based networking studies39,43.
Each experiment is repeated five times under identical conditions. Results
report the mean throughput across runs; observed variance was below 3% in all
cases, confirming reproducibility.
As a
baseline, we compare FAIDN against traditional SDN-based intent execution. In
the baseline, the Ryu controller installs forwarding rules using reactive OpenFlow
flow setup (packet-in / flow-mod) with default queue configuration (single FIFO
queue, 75packet depth), no QoS queue differentiation, no DSCP or priority
marking, no congestion monitoring and no automated remediation. Intents are
translated to initial forwarding rules at deployment time but are not
reverified or updated in response to congestion. This baseline represents the
current practice in SDN deployments where intent translation is a one-time
configuration step rather than a closed-loop process. Both FAIDN and the
baseline operate on identical sixswitch Mininet topologies with identical
traffic workloads, differing only in the presence or absence of FAIDN's
monitoring, verification and remediation modules.
7.2.2.
Network topology
Figure
9: Mininet Topology.
The
evaluation topology is designed to support dynamic reconfiguration and
congestion remediation across heterogeneous traffic flows. Congestion scenarios
are emulated using Mininet57, which enables controlled experimentation under reproducible
conditions. The overall implementation architecture and evaluation topology are
illustrated in (Figure 9). Each inter-switch link is configured with a
bandwidth of 10 Mbps and a propagation delay of 5 ms. Host-to-switch links
operate at 10 Mbps. OpenFlow switch buffers are configured with a default queue
depth of 75 packets. This is derived as follows: at 10 Mbps with 1000-byte
video conferencing packets, each packet incurs a serialization delay of (1000 ×
8) / 10^7 = 0.8 ms. With a 5 ms propagation delay per link, the remaining
queuing budget to satisfy the 60 ms end-to-end latency intent is 55 ms,
permitting a maximum of floor (55 / 0.8) = 68 packets. A default of 75 packets
provides headroom for smaller-packet flows (e.g., VoIP at 60 bytes, ICMP at 64
bytes) while remaining within the constraint. During active remediation, FAIDN
adjusts queue depth to 40 packets for latency-sensitive flows (VoIP, video
conferencing) and up to 250 packets for throughputpriority flows (video
streaming, file transfer).
The
evaluation topology consists of six switches (S1-S6) and 18 hosts
interconnected as illustrated in Fig. 9. Heterogeneous traffic is generated as
follows: all hosts generate background ICMP traffic to randomly selected peers;
Hosts 1 and 6 conduct a video conferencing session using iperf (tool to measure
network bandwidth and performance); Hosts 4 and 5 stream video using VLC media
player; Hosts 2 and 11 and Hosts 3 and 18, establish two VoIP connections using
iperf; and Hosts 7 and 17 and Hosts 8 and 16, generate bursty VBR flows using
D-ITG (Distributed Internet Traffic Generator). Loop handling among switches is
managed by the Ryu STP module (ryu.app.simple_switch_stp). FAIDN automates
three classes of configuration in the evaluation: queue resizing, flow
prioritization and load balancing across available paths.
7.2.3.
Traffic generation: To
generate heterogeneous traffic workloads, multiple hosts in the topology employ
a range of traffic generation tools, including VLC, iperf, Ping and D-ITG.
These tools are used to emulate application-specific traffic such as video
streaming, video conferencing, VoIP, control packets and bursty flows (Table
4).
Table
4: Traffic generation parameters
for evaluation workloads.
|
Tools |
Application |
Traffic Type |
Data Rate |
Packet Size |
Packet Interval |
QoS |
|
VLC |
Video Streaming |
MPEG |
32-600 Kbps |
128 - 1518 Bytes |
60 ms(Max) |
Throughput |
|
iperf |
Video Conferencing |
CBR |
500 Kbps |
1000 Bytes |
60 ms (Max) |
Throughput, Delay, Jitter |
|
iperf |
VoIP |
CBR |
64 Kbps |
60 Bytes |
60 ms (Max) |
Throughput, Delay, Jitter |
|
Ping |
- |
CBR |
0.5 Kbps |
64 Bytes |
- |
Delay |
|
D-ITG† |
VBR |
VBR |
Dynamic VBR |
Dynamic VBR |
Dynamic VBR |
Dynamic VBR |
|
D-ITG† |
File Transfer |
VBR |
Dynamic VBR |
Dynamic VBR |
Dynamic VBR |
Dynamic VBR |
†D-ITG
parameters vary dynamically to simulate bursty traffic; no fixed rate, packet
size or interval is preconfigured. QoS objectives: throughput and delay (VBR),
throughput (File Transfer).
The
corresponding traffic characteristics, including data rates, packet sizes and
QoS objectives, are summarized in (Table 4).
7.3.
Results
This
section presents experimental results evaluating FAIDN along the four
dimensions defined in Section 5. Results are compared against the baseline SDN
configuration defined in Section 7.2.1.
7.3.1.
Intent satisfaction under increasing load: To evaluate intent satisfaction, we gradually increase the
offered load for latency- and throughput-sensitive applications while
monitoring achieved throughput and compliance with QoS constraints. As traffic
load increases, baseline SDN-based intent execution exhibits significant
throughput degradation and frequent intent violations due to unmanaged
congestion.
Table
5: Nominal bandwidth allocation
across concurrent traffic classes (10 Mbps link).
|
Traffic
Class |
Allocation
|
Tool
|
Protocol
|
|
Video
Conferencing
|
5.0
Mbps |
iperf
|
UDP
/ CBR |
|
Video
Streaming
|
2.0
Mbps |
VLC
|
MPEG
|
|
VoIP
(x2 sessions) |
0.128
Mbps |
iperf
|
UDP
/ CBR |
|
Bursty
VBR (x2) |
2.0
Mbps |
D-ITG
|
VBR
|
|
ICMP
Background
|
0.001
Mbps |
Ping
|
ICMP
|
Table
6: Throughput of the video
conferencing intent flow (iperf, UDP, 1000byte packets) under increasing
aggregate offered load.
|
Loads
(%) |
FAIDN
(Mbps) |
Intent
in SDN (Mbps) |
|
10
|
7.83
|
7.76
|
|
30
|
6.56
|
3.89
|
|
50
|
5.87
|
1.06
|
|
70
|
5.43
|
0.91
|
|
90
|
5.05
|
0.09
|
†
Link bandwidth: 10 Mbps shared across all traffic classes (see Table 5).
FAIDN configurations applied: queue resizing, flow prioritization and
rerouting.
Table
7: Intent satisfaction rate
comparison between FAIDN and baseline SDN for a video conferencing intent.
|
Loads
(%) |
FAIDN
Intent Satisfaction Rate (%) |
Baseline
Intent Satisfaction Rate (%) |
|
10
|
100
|
98
|
|
30
|
96
|
61
|
|
50
|
91
|
18
|
|
70
|
87
|
14
|
|
90
|
82
|
1 |
In
contrast, FAIDN dynamically applies congestion remediation actions-including
traffic rerouting, queue resizing and flow prioritization-in response to
observed violations. As a result, intents remain satisfied over a wider range
of operating conditions. (Table 6) presents quantitative throughput
results and Table 7 presents the corresponding intent satisfaction rate -
defined as the percentage of time the active intent's QoS constraints are met -
across the same load levels. The results demonstrate that FAIDN sustains higher
effective throughput for intent-related traffic, particularly under moderate to
high load, indicating improved intent satisfaction compared to the baseline39,41.
Table
8: Latency comparison between
FAIDN and baseline SDN for a video conferencing intent.
|
Loads
(%) |
FAIDN
Latency (ms) |
Baseline
latency (ms) |
|
10
|
12
|
13
|
|
30
|
18
|
45
|
|
50
|
24
|
180
|
|
70
|
31
|
390
|
|
90
|
38
|
>=820
† |
†
Latency exceeded 820 ms at 90% load; exact measurement unavailable due to
frequent packet drops.
(Tables
5-7) report throughput and
latency for the video conferencing intent flow only (iperf CBR, 1000-byte
packets, UDP), which operates alongside the other classes listed above. The
video conferencing flow competes for bandwidth under increasing offered load;
FAIDN's remediation actions (queue resizing, prioritization, rerouting)
selectively protect this highpriority intent.
(Table
8) presents the corresponding
end-to-end latency, further illustrating the contrast between FAIDN's
controlled behavior and the baseline's collapse under increasing load.
Table
9: VoIP intent performance
(jitter and packet loss) - FAIDN vs. baseline SDN.
|
Loads
(%) |
FAIDN
Jitter (ms) |
Baseline
Jitter (ms) |
FAIDN
Loss (%) |
Baseline
Loss (%) |
|
10
|
2.1
|
2.3
|
0.0
|
0.1
|
|
30
|
3.8
|
12.4
|
0.1
|
4.2
|
|
50
|
5.2
|
38.1
|
0.3
|
14.7
|
|
70
|
7.1
|
89.3
|
0.8
|
31.2
|
|
90
|
9.4
|
>
150 (estimated) |
1.4
|
58.6
|
†
Latency exceeded 820 ms at 90% load; exact measurement unavailable due to
frequent packet drops.
As
illustrated iu=n Table 9, FAIDN also preserves VoIP intent performance under
increasing load. While baseline SDN allows VoIP jitter to rise above 38 ms at
50% load - approaching the 60 ms bound - FAIDN's priority-aware queue
management maintains jitter below 10 ms across all evaluated load levels. This
confirms that FAIDN's 'covert congestion' detection (Section 6.3.3)
successfully identifies and remediates elephant-flow interference with
latency-sensitive mice flows.
(Table
6) presents throughput results
for a video conferencing intent under increasing load. At low load (10%), both
FAIDN and baseline SDN achieve comparable throughput (7.83 Mbps vs. 7.76 Mbps),
confirming that FAIDN introduces negligible overhead under non-congested
conditions. As load increases to 30%, the baseline degrades sharply to 3.89
Mbps - a 50% reduction - while FAIDN maintains 6.56 Mbps through queue resizing
and flow prioritization. At 50% load and beyond, the baseline collapses to
near-zero throughput (0.09 Mbps at 90% load), indicating persistent intent
violations. FAIDN, by contrast, sustains 5.05 Mbps at 90% load — a 56×
improvement over the baseline at peak congestion - demonstrating robust intent
satisfaction through congestion-aware remediation. As shown in Table 7, FAIDN
maintains an intent satisfaction rate above 80% even at 90% load, while the baseline
drops to 1%, confirming robust intent correctness under congestion. FAIDN's
monitoring module polls network state every 500 ms, detecting intent violations
within one polling cycle (≤500 ms) in all evaluated scenarios, confirming the
continuous verification property defined in Section 3.
7.3.2.
Convergence and stability
Table
10: FAIDN convergence behavior across evaluated
congestion scenarios.
|
Congestion
Event |
Remediation
Steps |
Time
to Stable State (s) |
Baseline
Oscillations |
|
Over-subscription
(30% load) |
2 |
1.4
|
7 †
|
|
Over-subscription
(70% load) |
3 |
2.1
|
12
† |
|
Unknown
flow injection |
4 |
2.8
|
9 †
|
†
Baseline did not converge within the observation window; oscillation count
reflects the number of conflicting reconfigurations observed.
Upon
detecting congestion, FAIDN applies corrective actions sequentially using
decision-tree–guided remediation strategies. This structured approach prevents
conflicting reconfigurations and mitigates oscillatory behavior, which is
commonly observed in reactive SDN control systems55,56. As
shown in (Table 10), FAIDN converged to a stable configuration within 2-4
reconfiguration steps and approximately 1.4-2.8 seconds across all evaluated
congestion scenarios, compared to persistent oscillation observed in the
baseline. These observations confirm that FAIDN achieves predictable
convergence, an essential requirement for operationally reliable intent-driven
networks34,36.
7.3.3.
Graceful degradation under overload: As shown in (Table 6), as network load approaches and
exceeds link capacity, FAIDN throughput declines monotonically from 7.83 Mbps
at 10% load to 5.05 Mbps at 90% load - a controlled 35% reduction - while the
baseline collapses from 7.76 Mbps to 0.09 Mbps, an uncontrolled 99% reduction.
Rather than abrupt collapse, FAIDN degrades gracefully while preserving
preferential treatment for higher-priority intents, ensuring partial service
continuity under resource-constrained conditions16,18,47. As
network load increases from 10% to 90%, FAIDN exhibits graceful degradation
across all key performance dimensions. Throughput declines gradually from 7.83
to 5.05 Mbps (Table 6), the intent satisfaction rate decreases
moderately from 100% to 82% (Table 7) and latency grows in a controlled
manner from 12 ms to 38 ms (Table 8). Taken together, these trends
collectively confirm that FAIDN upholds the graceful degradation property
formally defined in Section 3.
The
evaluation results collectively confirm that FAIDN successfully instantiates
the four assurance properties under realistic heterogeneous traffic conditions.
The current evaluation focuses on a single intent type (video conferencing) and
a fixed six-switch topology; future work will extend the evaluation to
multi-intent scenarios, larger topologies and additional congestion causes
including security attacks and misconfiguration. Section 8 discusses broader
implications and limitations of the proposed approach.
8. Discussion and
Limitations
While
FAIDN demonstrates significant improvement over baseline SDN-based intent
execution, several aspects warrant further discussion. First, the decision tree–based
diagnostic approach provides determinism and explainability but may require
manual updates as new congestion patterns emerge - a limitation that ML based
approaches partially address at the cost of stability and convergence
guarantees. Second, the current evaluation is conducted on a six-switch Mininet
topology with a single link bandwidth of 10 Mbps; scaling to larger,
multi-domain topologies with diverse link capacities remains an open question.
Third, the current implementation and evaluation address oversubscription,
unknown flows and misconfiguration induced congestion; security attack-induced
congestion is modelled in the decision trees (Section 6.3) but not yet
exercised in the evaluation. Extending the implementation to cover all four
congestion causes identified in Section 5.1 represents the most immediate
direction for future work. Finally, formal verification of FAIDN's convergence
guarantee - that the network always reaches a stable state within bounded steps
- remains an open theoretical challenge.
Compared
to the congestion control approaches surveyed in (Table 1), FAIDN
addresses a dimension none of them cover: intent semantics. SD-TCP39 and
SDGCC40 manage congestion at the transport level without awareness
of application intents; Hedera41 optimizes flow scheduling but provides no runtime
verification. FAIDN's 56× throughput advantage over unmanaged SDN at 90% load,
combined with an intent satisfaction rate above 80%, demonstrates that
embedding remediation directly into the intent execution loop provides
substantially better QoS preservation than isolated congestion management.
7.3.4.
Multi-intent priority and graceful degradation: As illustrated in (Table 11), to validate FAIDN's
priorityaware graceful degradation under resource contention, we configure two
simultaneous primary intents: a video conferencing intent (H1↔H6, priority
level 2) and a VoIP intent (H2↔H11, priority level 1, higher priority). The
network is loaded to 90% capacity with background traffic, creating a scenario
where both intents cannot be simultaneously satisfied at full QoS.
Table
11: Multi-intent satisfaction
under 90% load.
|
Intent
|
FAIDN
Satisfaction (%) |
Baseline
Satisfaction (%) |
|
VoIP
(Priotity 1) |
91
|
3 |
|
Video
Conference (Priority 2) |
74
|
1 |
FAIDN
preserves the higher-priority VoIP intent at 91% satisfaction while gracefully
reducing the video conferencing intent to 74% - a controlled trade-off governed
by the priority scheduler. The baseline provides near-zero satisfaction for
both intents, confirming that without explicit priority-aware remediation, all
intents fail equally under overload.
9.
Conclusion
This
paper presented FAIDN, a congestion-aware framework for assured intent-driven
networking, where assurance is defined operationally in terms of four
properties: correctness guarantees, continuous verification, convergence and
graceful degradation. Unlike existing SDN and intent-based networking solutions
that treat congestion as an isolated performance problem, FAIDN integrates
congestion detection, root-cause diagnosis and automated remediation directly
into the intent execution loop through a structured decision-tree–based
approach. Implemented on the Ryu SDN controller and evaluated using the Mininet
emulator under heterogeneous highload traffic, FAIDN demonstrates a 56×
throughput improvement over baseline SDN-based intent execution at peak
congestion, converges to stable configurations within 2-4 remediation steps and
degrades gracefully under overload conditions. These results demonstrate that
intent-driven networks can be made predictable and resilient through careful
system design rather than idealized assumptions. Future work will extend FAIDN
to multi-intent scenarios, larger topologies and formal convergence
verification.
10. Acknowledgment
The
authors express sincere gratitude to colleagues and reviewers for their
valuable feedback and guidance throughout this research.
10.1.
Funding statement
This
research did not receive any specific grant from funding agencies in the public,
commercial or not-for-profit sectors.
10.2.
Conflict of interest statement
The
authors declare no conflict of interest related to the research, authorship or
publication of this manuscript.
11. References
2.
Pang L, Yang C, Chen D, et
al. A Survey on Intent-Driven Networks. IEEE Access, 2020;8: 22862-22873.
6.
https://www.nsnam.org/overview/what-is-ns-3/
17. https://www.juniper.net/us/en/dm/infographic/how-a-self-driving-network-works/
21. http://www.projectfloodlight.org/floodlight
22. http://www.opendaylight.org
23.
Berde P,
Gerola M, Hart J, et al. ONOS: Towards an Open, Distributed SDN OS. Proceedings
of the third workshop on Hot topics in software defined networking, 2014: 1-6.
24.
Koponen
T, Casado M, Gude N, et al. ONIX: A Distributed Control Platform for
Large-scale Production Networks. OSDI, 2010;10: 1-6.
25.
Jacobs
AS, Pfitscher RJ, Ferreira RA, et al. Refining Network Intents for Self-driving
Networks. Proceedings of the Afternoon Workshop on Self-Driving Networks, 2018:
15-21.
26. https://www.juniper.net/us/en/dm/the-self-driving-network/
27.
Kim H,
Feamster N. Improving Network Management with Software defined Networking. IEEE
Communications Magazine, 2013;51: 114-119.
28.
Lin S,
Wang P, Akyildiz IF, et al. Towards Optimal Network Planning for
Software-defined Networks. IEEE Transactions on Mobile Computing, 2018;17: 2953-2967.
29.
Nam J,
Jo H, Kim Y, et al. Operator defined Reconfigurable Network OS for
Software-defined Networks,” IEEE/ACM Transactions on Networking, 2019;27: 1206-1219.
32.
Wang B,
Sun Y, Yuan C, et al. Lesla: A Smart Solution for SDN-enabled MMTC e-health
Monitoring System. Proceedings of the 8th ACM MobiHoc 2018 Workshop on
Pervasive Wireless Healthcare Workshop, 2018: 1-6.
33.
Akkaya
K, Uluagac AS, Aydeger A. Software defined Networking for wireless local
networks in smart grid,” in the IEEE 40?ℎ Local Computer Networks Conference Workshops (LCN Workshops), 2015:
826-831.
37.
Chahlaoui
F, El-Fenni MR, Dahmouni H. Performance Analysis of Load Balancing Mechanisms
in SDN Networks. Proceedings of the 2nd International Conference on Networking,
Information Systems Security, NISS19, (New York, NY, USA), Association for
Computing Machinery, 2019.
40.
Abdelmoniem
AM, Bensaou B. SDN-based Generic Congestion Control Mechanism for Data centers:
Implementation and Evaluation. Dept Computer Science Eng, 2016.
41.
Al-Fares
M, Radhakrishnan S, Raghavan B, et al. Hedera: Dynamic Flow Scheduling for Data
Center Networks. Nsdi, 2010;10: 89-92.
42.
Hwang J,
Yoo J, Lee SH, et al. Scalable Congestion Control Protocol based on SDN in data
centre networks. 2015 IEEE Global Communications Conference (GLOBECOM), 2015: 1-6.
43.
Ahmed
N, Misra S. Collaborative Flow-identification Mechanism for Software-defined
Internet of Things. IEEE Internet of Things Journal, 2021: 1.
44.
Biswas
R, Wu J. Minimizing the Number of Rules to Mitigate Link Congestion in
SDN-based Datacenters. Proc. of 15th International Conference on Networking,
Architecture and Storage, 2021.
45.
Addad
RA, Dutra DLC, Bagaa M, et al. Benchmarking the ONOS Intent Interfaces to Ease
5G Ser vice Management. 2018 IEEE Global Communications Conference (GLOBECOM), 2018:
1-6.
46.
Subramanya
T, Riggio R, Rasheed T. Intent-based Mobile Back Hauling for 5G Networks. 2016
12th International Conference on Network and Service Management (CNSM), 2016: 348-352.
47.
Aklamanu
F, Randriamasy S, Renault E, et al. Intent-Based Real-Time 5G Cloud Service
Provisioning,” in 2018 IEEE Globecom Workshops (GC Wkshps), 2018: 1-6.
48.
Nagendra
V, Bhattacharya A, Yegneswaran V, et al. An Intent-based Automation Framework
for Securing Dynamic consumer IoT infrastructures. Proceedings of The Web
Conference, 2020: 1625-1636.
49.
https://www.cisco.com/c/en_in/solutions/intent-based-networking.html
50.
https://e.huawei.com/in/products/network-management-and-analysis-software
51.
https://blogs.gartner.com/andrew-lerner/2017/02/07/intent-based-networking/
52.
https://www.juniper.net/documentation/us/en/software/apstra/apstra4.0.0/
53.
Mills K,
Dabrowski C, et al. The need for realism when simulating network congestion.
SpringSim (CNS), 2016: 1.
54.
Nguyen
X-N, Saucez D, Barakat C, et al. Rules Placement Problem in OpenFlow Networks:
A survey,” IEEE Communications Surveys & Tutorials, 2015;18: 1273-1286.
55.
Voellmy
A, Wang J. Scalable Software defined Network controllers. Proceedings of the
ACM SIGCOMM 2012 conference on Applications, technologies, architectures and
protocols for computer communication, 2012: 289-290.
56.
Macapuna
CAB, Rothenberg CE, Maurício MF. In-packet Bloom Filter-based Data center
Networking with distributed OpenFlow Controllers. 2010 IEEE Globecom Workshops,
2010: 584-588.
59. Kleinrock L. Queueing
Systems, Volume 1: Theory. New York: Wiley-Interscience, 1975.