Circuit issues are often the cause of widespread network outages in today’s business environment. When the network is down, a large part of the business is impacted because organizations rely on the network to connect to services, process daily transactions, and perform other deliverables required to run the business. As a result, it can incur a huge amount of loss to the business. In some situations, circuit issues can be prevented by implementing redundancies, but regardless if there’s an immediate impact or not, it is important that network administrators know how to troubleshoot circuit issues to avoid further damage to the business.
Before we delve into how to troubleshoot the different circuit issues commonly occurring in the enterprise environment, let us quickly discuss how circuits are used in an organization, the common warning signs, and how organizations are notified when a circuit issue occurs.
How Circuits are Used in an Organization
Organizations connect to the internet through direct internet circuits such as broadband and DSL. Regardless of the circuit provider, organizations always have the option to choose how much bandwidth they are willing to purchase or subscribe on a monthly or yearly basis. This is what we call the subscribed speed which will be important later on when troubleshooting network congestion or latency in circuits.
If an organization has multiple sites that are geographically separated from each other, it can utilize leased lines or point-to-point circuits to establish a connection between them.
Both the direct internet circuits and leased lines are responsible for the end-to-end forwarding of packets being sent out to and from the internet, and across the intranet, or the internal network of an organization.
Common Warning Signs when a Circuit Issue Occur
When there is an issue on the circuit, traffic passing through them are either being dropped or not passing through at all. Below are the common warning signs that users may experience when there is a circuit issue:
- Latency or slowness
- Intermittent connection
- No connection
How Circuits are Being Monitored
In an enterprise environment, there are network monitoring tools in place that keeps an eye on all the network devices being managed by an organization. Depending on the requirements of the business, different alarms with their respective criticalities can be configured and generated when specific thresholds are met. Network monitoring tools can also be configured to automatically send auto-generated e-mails to defined recipients, such as network administrators, to notify them in case of any network issues that may occur.
Since circuits are connected to network devices managed by an organization, it can be monitored using the same network monitoring tool. So let’s say, for example, a circuit experienced a fiber cut, most likely, there will be packet drops and that will trigger an alert to the interface where the circuit is connected. The network monitoring tool will then disseminate the alert it received from the interface and generate an alarm specific to the situation at hand, notifying the network administrators that a circuit issue has occurred.
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3 Common Circuit Issues and How to Troubleshoot them
We have listed three common circuit issues being experienced in any enterprise environment, each with defined warning signs that users usually experience, possible causes, and steps on how to troubleshoot them.
Circuit is Down
Warning Signs:
- No internet or intranet connection
Causes:
- Power issue or power outage onsite
- Fiber cut
- Down BGP (Border Gateway Protocol) peering with a circuit provider
Troubleshooting Steps:
- Verify the network device where the circuit is connected.
- Verify if the device has power by simply pinging or accessing the device.
- If the power is good, physically check if the cable is properly connected to the network device.
- If cabling is good, escalate to your circuit provider by providing them with the circuit ID that you can either get from the interface description in the actual network device or from the network documentation where you keep circuit information. It’s either there is misconfiguration from their end or a fiber cut has occurred.
Note: It is highly recommended that organizations keep network documentation updated at all times.
Circuit is Congested
Warning Signs:
- Latency in accessing the internet or intranet
- Packet drops
- Intermittent connection
Causes:
- Circuit is 100% utilized
- High amount of traffic are being generated by users than normal
- Circuit subscription is incorrect
Troubleshooting Steps:
- Verify the circuit utilization and if you are reaching the subscribed speed, or the internet speed your organization has subscribed from your circuit provider.
- If the utilization is nearly reaching 100% but is less than the subscribed speed, escalate the issue to the circuit provider for corrective action.
- If the utilization is nearly reaching 100% and the speed is reaching the subscribed speed, check what application is contributing the highest traffic.
- Limit or block non-business and non-critical applications if possible.
- Request for a circuit upgrade to accommodate more traffic.
Incorrect network configuration
Warning Signs:
- No internet or intranet connection
Causes:
- User misconfigurations
Troubleshooting Steps:
- Check the BGP (Border Gateway Protocol) status and configuration.
- Check interface status and configuration.
- Verify recent changes done in the network and rollback if there needed.
- Escalate to the circuit provider to verify configuration and status on their end.
Final Thoughts
Circuit issues are usually critical since they carry most of the network traffic. In order to minimize business impact when a circuit issue occurs, it is important for an organization to implement redundant circuits. With redundant circuits, you are ensured to have at least one backup circuit in case one of the circuits encounter an issue. This will incur an additional cost but it saves the business from larger damage should the circuit issue cause a widespread network outage. It is also important that network monitoring tools are doing its job in notifying network administrators whenever there’s a critical alert that might greatly impact the business; even better if the tool can do predictive analytics so network administrators can get insights they can use in the proactive maintenance of circuits and network devices alike.
