Key Points
- Definition of Route Flapping: Route flapping occurs when network routes or adjacencies constantly fluctuate, resulting in instability and increased CPU and bandwidth consumption.
- Detection and Confirmation: Detect instability via RMM telemetry, centralized logging, and CLI checks (OSPF neighbors, BGP summary, log filters for “flap”).
- Root Cause Analysis by Layer: inspect physical cabling/optics, data-link MTU or errors, and network-layer OSPF/BGP timers and configs.
- Permanent Fixes: Replace faulty optics, adjust SPF timers, and summarize OSPF routes to simplify topology and eliminate recurring route flaps.
- How NinjaOne Can Help: NinjaOne RMM provides automated monitoring, alerting, and script-based remediation to help MSPs streamline operations and maintain SLA performance.
When data is transferred over a network, its path may be recalculated to find the fastest possible route. However, certain factors can cause this process to repeat rapidly or “flap”, causing excessive CPU usage and bandwidth waste.
This article explains how to fix route flapping with RMM features for stable data transfers and increased network performance.
What is route flapping?
Route flapping happens when a network path or adjacency repeatedly fluctuates, resulting in an unstable control plane. Possible causes include:
- BGP (Border Gateway Protocol) resets and repetitive route resets, and frequent updates
- OSPF (Open Shortest Path First) and SPF (Shortest Path First) recalculations
- LSAs (Link-State Advertisements) are exchanged between OSPF routers to share routing and topology data.
- CRC (Cyclic Redundancy Check) errors from faulty cables or optics.
- MTU (Maximum Transmission Unit) mismatches.
- HSRP (Hot Standby Router Protocol) and VRRP (Virtual Router Redundancy Protocol) role-switching
- Lack of BGP Route Dampening to suppress unstable routes
How to fix route flapping efficiently
Find evidence of constant rerouting, identify the cause(s), and apply stabilizing quick fixes before implementing sustainable changes. To learn how to fix route flapping, follow these steps:
📌 Prerequisites:
- Access to router and firewall telemetry: BGP and OSPF neighbor state, interface counters, CPU, and memory
- Centralized logs or NMS capable of tracking “flaps per peer,” adjacency resets, and interface up or down events
- Change control windows and a rollback plan for timer, policy, or topology changes
- A standard “how to fix route flapping” evidence template with show commands, graphs, and ticket timestamps attached
Step 1: Confirm and quantify the flap
Fixing network route fluctuations is a highly technical process that involves several factors, so you’ll need to confirm that it’s happening and understand its scope first.
📌 Use Cases: To measure network management failures and validate route flapping concerns.
📌 Prerequisites: Windows 11, Administrative privileges, PowerShell 5.1 or higher.
- Press Win + R, type PowerShell, and press Ctrl + Shift + Enter.
- To initiate a Secure Shell (SSH) session to your network device, run the following:
Replace admin with your device username and 192.168.1.1 with the IP address of your router or switch.
💡 Note: This allows your Windows machine to interact with network devices.
- To show interface states and neighbor adjacencies, run these CLI commands:
show ospf interface
show ospf neighbor
show ospf route
- To check the number of SPF recalculations, run this CLI command:
show ospf database
- To check for CRC errors that indicate faulty hardware, run the following:
show interfaces diagnostics optics
show system processes extensive
- To export your logs and summaries for ticketing, run the following:
show log messages | match "flap"
show bgp summary
💡Note: Command syntax may vary slightly depending on the network vendor or operating system. The examples in this guide reflect commonly used, vendor-neutral formats. Consider using the following commands:
show ospf interface
show ospf neighbor
show ospf route
show ospf database
show interfaces diagnostics
show system processes
show log | match flap
show bgp summary
Step 2: Localize the cause by layer
Once you’ve identified evidence of route flapping, examine every aspect of your network connection to determine the root cause.
💡 The 1st and 2nd layers deal with physical factors and network signal strength (e.g., cables, MTU mismatches) while the 3rd layer focuses on routing protocols (e.g., OSPF timers, SPF). The last layers consist of your network policies and Internet Service Provider (ISP) setups.
📌 Use Cases: To detect and document any vulnerabilities that could be causing OSPF flapping.
📌 Prerequisites: Windows 11, Administrative privileges, PowerShell 5.1 or higher.
- Press Win + R, type PowerShell, and press Ctrl + Shift + Enter.
- To initiate an SSH session to your network device, run the following:
Replace admin with your device username and 192.168.1.1 with the IP address of your router or switch.
- To check on the health of your fiber optics, run the following CLI command:
show interfaces diagnostics optics
``
- To validate OSPF or BGP timers, run the following:
show configuration protocols ospf
show configuration protocols bgp
💡 Note: Commands can vary depending on your vendor(Cisco, Arista, MikroTik, etc.) and the device being used.
- To adjust SPF options, run the following:
set protocols ospf spf-options delay 200 holddown 5000 rapid-runs 3
```
- Run this CLI command to audit maps and summarization:
show policy-options
show route summary
- To summarize routes and lessen LSA churn, run this command:
set protocols ospf area 0.0.0.4 area-range 10.0.8.0/28
```
💡Note: The OSPF area numbers and IP ranges used in this example are only placeholders. The actual values you must configure will depend on your network design and the vendor you are working with. Always verify the correct syntax and supported parameters in your device’s official documentation.
- To check for upstream ISP instability, run the following:
show bgp neighbor
Step 3: Stabilize quickly with minimal risk
Before working on permanent fixes, apply quick “bandaid” solutions to control the spread of unstable routes. This ensures stability while you future-proof your infrastructure in the next step.
Here’s how to fix route flapping with short-term system tweaks:
💡Note: The commands in this step use Juniper syntax. CLI commands and recommended values vary widely across vendors. Check your device’s documentation for the correct equivalent commands.
📌 Use Cases: To help stabilize network routing across your organization.
📌 Prerequisites: Windows 11, Administrative privileges, PowerShell 5.1 or higher.
- Press Win + R, type PowerShell, and press Ctrl + Shift + Enter.
- To initiate an SSH session to your network device, run the following:
Replace admin with your device username and 192.168.1.1 with the IP address of your router or switch.
- To increase BGP hold time, run the following CLI command:
set protocols bgp hold-time 180
```
- To enforce dampening, create damping profiles with this command:
set policy-options damping aggressive half-life 30 suppress 3000 reuse 750 max-suppress 60
set protocols bgp damping
set protocols bgp group ext import damp
```
- To disable preemption for HSRP (Hot Standby Router Protocol) and VRRP (Virtual Router Redundancy Protocol), run the following:
- For Cisco devices:
no standby preempt
- For Juniper devices:
clear bgp neighbor <IP> soft out
Step 4: Fix the root cause and simplify design
In a US-wide survey involving senior management respondents, 55% report higher overhead from network downtime alone. Focus on the source of the problem with definitive fixes that target hold timers, faulty optics, and LSA churn.
💡Note: The commands in this step use Juniper syntax. CLI commands and recommended values vary widely across vendors. Check your device’s documentation for the correct equivalent commands.
📌 Use Cases: To eliminate underlying issues that cause route flapping.
📌 Prerequisites: Windows 11, Administrative privileges, PowerShell 5.1 or higher.
- Press Win + R, type PowerShell, and press Ctrl + Shift + Enter.
- To initiate an SSH session to your network device, run the following:
Replace admin with your device username and 192.168.1.1 with the IP address of your router or switch.
- To check optics status, run the following.
show interfaces diagnostics optics
- If the temperatures or signal strength of your optical fiber cables are abnormal, replace them.
- To redesign SPF and hold timers, run this command:
set protocols ospf spf-options delay 200 holddown 5000 rapid-runs 3
```
- Adjust timer values to reflect your client’s SLA thresholds.
- To summarize OSPF routes, run the following:
set protocols ospf area 0.0.0.3 area-range 10.0.4.0/28
```
- Change to a broader subnet to reduce churn.
Step 5: Monitor, alert, and review
Detect network issues early and fast-track improvements with telemetry tools and unified endpoint management solutions.
📌 Use Cases: To catch early signs of instability for proactive visibility and enhanced Quarterly Business Reviews (QBRs).
📌 Prerequisites: Windows 11, Administrative privileges, PowerShell 5.1 or higher.
- Press Win + R, type PowerShell, and press Ctrl + Shift + Enter.
- To initiate an SSH session to your network device, run the following:
Replace admin with your device username and 192.168.1.1 with the IP address of your router or switch.
- Use Simple Network Management Protocol (SNMP) to monitor:
- Flap counts
- SPF bursts
- Adjacency resets
- Run the following to track high error rates:
show interfaces statistics
show system processes extensive
- Audit monthly using a tailored scorecard.
NinjaOne streamlines route flapping troubleshooting
Diagnosing network issues and route flapping requires continuous monitoring and reliable documentation. Here’s how NinjaOne streamlines the process for MSPs and IT professionals:
| Step | Without NinjaOne | With NinjaOne |
| Enable early problem detection and alerting. | Manually initiate SSH, run CLI commands, and parse routes manually. | Supports hardware performance monitoring and provides real-time alerts on route flap behavior through SNMP polling and syslog monitoring. |
| Localize the cause by layer. | Manually inspecting network layers requires time and expertise. | SNMP monitoring and device metrics give you clearer visibility into network performance, helping you identify issues across interfaces and layers more quickly than manual inspection. |
| Stabilize quickly with minimal risk. | Quick fixes have to be applied per device manually. | Applies policies at scale to reduce operational risk. |
| Helps fix the root cause and simplify the design. | Manually redesign SPF timers, replace broken optics, and summarize routes for every endpoint. | The automation engine enabled administrators to schedule and enforce configuration changes while keeping track of SLA compliance. |
| Monitor, alert, and review. | Manual CLI checks can lead to human error; ad hoc scorecards for QBRs. | Unified endpoint telemetry; automated reporting provides both visuals and customizable templates. |
Implement RMM features for a faster route flapping fix
Knowing how to fix route flapping lets IT professionals proactively search for operational risks that can impact transfer speeds and overall SLA compliance. For the fastest route flapping fix, prove the problem exists, apply temporary solutions, establish long-term workflows, and document for future audits.
Optimized network connections are vital for client environments, highlighting the need for modern solutions that keep workflows smooth. Integrating NinjaOne’s centralized dashboard helps you keep tabs on your system’s health.
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