Multiple Protocol Use, Poor Configuration, Server Overload

Network analysis

1. Symptoms

This story takes place at a machinery and electronics import/export company, where Mr. Lin, the head of the IT department, reported network issues after a recent upgrade from 10Mbps Ethernet to 100Mbps Ethernet. The local area network experienced slower network access speeds compared to before the upgrade, with some connections taking a long time and others failing. Network traffic detection software showed no issues, and Ping tests to the servers returned an average latency of less than 1ms, which should have indicated normal performance.

2. Diagnostic Process

While the issue seemed straightforward, diagnosing it proved to be more complex. The network consisted of four routers connected to the domestic headquarters and international branches via frame relay lines, spanning four floors. It included two Gigabit core switches, five second-level workgroup switches (one on each floor), and twenty desktop switches (four on each floor). Since the issue affected all network members, they decided to inspect the cabling system first, as it was recently upgraded. The certification tests of twenty cabling links using a cable certification tester surprisingly returned all passed results.

When they conducted a network tester’s artificial load test, even at 75% network load, the collision rate stayed below 5%. The cable installation and quality seemed to be fine. However, the servers were significantly overloaded with network traffic, with an average load of 91%. They noticed that the problem likely lay in the protocol processing between the servers and workstations. They ran ICMP Ping tests, Scan Host tests, ICMP Monitor tests, which confirmed that network connectivity was fine, but the issue was above the transport layer.

Enabling the Protocol Mix detection feature on the network tester revealed that AppleTalk and Banyan Vines protocols contributed to 47% and 39% of network traffic, respectively. These protocols were primarily used by two main servers, which should not have been the case according to the network configuration based on the Windows environment and single IP protocol. It was unclear why AppleTalk and Banyan Vines protocols were present in the network.

After contacting the software developer and receiving confirmation that their software only operated on the Windows platform and did not use AppleTalk and Banyan Vines, they decided to uninstall these protocols. Once removed, network access immediately returned to normal.

3. Conclusion

Non-essential protocols, often referred to as “zombie protocols,” can consume network bandwidth and potentially lead to performance issues. The management of multiple protocols can be a challenging task, and it’s crucial to monitor the network to detect and eliminate unnecessary protocols. The presence of unsupported protocols can disrupt network operations, leading to slower speeds and increased errors.

4. Afterword

After a week of observation and the removal of unnecessary protocols, the network continued to operate without any issues. Cleaning up unnecessary protocols helped optimize network speed, ensuring a smoother network operation. Mr. Lin also performed additional protocol clean-up, resulting in a significantly improved network experience.

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