How to Troubleshoot Network Latency Using Netsight Network latency can cripple business operations, frustrate users, and degrade application performance. When packets delay, finding the root cause quickly is critical. Extreme Networks’ ExtremeCloud IQ – Site Engine (formerly known as NetSight) provides robust tools to isolate and resolve these delays.
Here is a step-by-step guide to troubleshooting network latency using Netsight. 1. Establish Your Baseline
Before diagnosing an active latency issue, you must understand what “normal” looks like for your infrastructure.
Review Historical Data: Use the Performance tab to look at past trends for the affected network segment.
Identify Thresholds: Check if current round-trip times (RTT) deviate significantly from your established baseline. 2. Isolate the Scope
Determine whether the latency is isolated or widespread to narrow your investigation.
Single User vs. Segment: Check if the delay affects one user, a specific VLAN, or an entire building.
Map the Path: Use the OneView topology maps to visually trace the path from the client to the destination asset. Look for any links highlighted in yellow or red, which indicate high utilization or errors. 3. Check Interface Statistics and Utilization
High bandwidth utilization is a primary driver of network latency. Packets queue up when a link hits capacity, causing delays.
Monitor Port Traffic: Drill down into the specific switches and routers along the data path.
Analyze Discards and Errors: Look closely at interface statistics for high counts of input/output errors, alignment errors, or packet discards. Discards usually point to micro-bursts or congested links. 4. Leverage Application Analytics (Purview)
Often, the network network isn’t at fault; the application or system host is. Netsight’s Application Analytics engine allows you to differentiate between network and application delays.
Inspect Application Response Time (ART): Review the time it takes for an application server to respond to a request.
Inspect Network Round Trip Time (NRTT): Compare ART against NRTT. If NRTT is low but ART is high, the latency resides on the application or server side, not the network. 5. Review Device Health and Events
Network infrastructure cannot process packets efficiently if its core hardware is overwhelmed.
Check CPU and Memory: View the device summary sheets in Netsight to ensure routers and core switches are not running at maximum CPU or memory capacity.
Examine Event Logs: Search the event log for recent configuration changes, spanning-tree topology changes, or routing flaps that could cause sub-optimal routing paths. 6. Implement Packet Captures
If the statistics do not reveal the root cause, you need to look directly at the traffic.
Trigger a Remote Capture: Use Netsight to initiate a packet capture on managed diagnostic ports.
Analyze TCP Handshakes: Look for TCP retransmissions and duplicate ACKs, which are definitive indicators of packet loss and latency.
To help tailor this approach, could you share a few more details?
What types of applications (e.g., VoIP, database, web browsing) are experiencing the latency? Is this latency occurring intermittently or is it constant?
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