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Top 25 network problems and their business impact

By Brad Reese on Thu, 05/15/08 - 3:12am.
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Download Poster - Top 25 Network Problems and Their Business Impact

Top 25 Network Problems and Their Business Impact:

1. Configuration not saved

Reboot will cause config to be lost


2. Saved configurations don’t meet corporate policy

Source of many problems from performance to reliability to security


3. Bloated firewall rule set; unused ACL entries

Poor firewall performance

Open, unused rules, creating potential security problems


4. Firewall connection count exceeded

New connections via the firewall fail

Business applications exhibit intermittent failure at high firewall loads

VPNs begin to fail


5. Link hog - someone downloading music or videos

Slower application response, impacting user productivity


6. Interface traffic congestion

Unpredictable application performance, impacting user productivity


7. Link problems & stability

Physical or DataLink errors cause slow or intermittent application performance

Link or interface stability can impact routing and spanning tree (see other examples)


8. Environmental limits exceeded

Fan failure, power supply problems, and high temperatures are indicators of problems that will likely cause a network device to reboot, affecting any applications relying on the device


9. Memory utilization increasing

A bug in the device’s operating system is consuming more memory and when no free memory exists, the device will reboot, disrupting applications that are transiting the device


10. Incorrect serial bandwidth setting

Causes routing protocols to make non-optimum routing decisions


11. No QoS

Important business applications are not prioritized, yielding unpredictable or poor performance during times of interface congestion


12. QoS Queue Drops

Important business applications are slow

Business needs may have changed since the queue definitions were created

VoIP is especially affected by this problem


13. Route flaps

Poor application performance as packets take the wrong or inefficient paths in the network


14. OSPF recalculations high

Routing protocol unstable; poor and inconsistent application performance


15. Poor VoIP quality

Due to high jitter, delay, or packet loss

Choppy voice calls

Calls mysteriously disconnect


16. Routing Neighbor changes high

Applications using paths via this router will be unstable or slow

Affects OSPF, EIGRP, and BGP


17. OSPF area not connected to backbone

The disconnected OSPF area will not be reachable from other OSPF areas, impacting applications that need to communicate between areas


18. Unidirectional traffic flow

Typically the result of misconfigured routing

Slower applications, strange failure odes, and complex troubleshooting due to asymmetric routing


19. Router interface down

Any router interface marked administratively up but is operationally down is likely to be a redundant connection that will cause an outage if the other connection also fails, affecting all applications that use it


20. Unstable root bridge

Bridge priority not set; applications quit working over unstable VLANs


21. Duplex mismatch

Increasing link errors

Applications get slower as traffic volume increases


22. Downstream hub or switch

Unauthorized devices added to the network

Compromise to network integrity and security

See 20, Unstable Root Bridge



23. Port in ErrDisable state

The set of end stations connected via this port are disconnected from the network until the port is enabled (either automatically or by user control)


24. Unbalanced & unused etherchannels

Increased latency & jitter affecting sensitive applications like VoIP

Compromised redundancy


25. HSRP or VRRP peer not found

Redundancy configured and not operating correctly

Outage when a second failure occurs

Redundancy compromised


Free Poster:

The above network problems are available as a snazzy FREE poster (ordered mine) that is suitable for office display and framing, it details the top 25 network problems that Netcordia's NetMRI detects.

It's a great resource for communicating between managers and technical staff, as it illustrates the business impact of common network problems.

Receive your free poster


Related story:

The major cause of failures are fingers

What do YOU think is a top network problem?

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