Performance Metrics

Question 1

Monitoring the interface

Answer 1

• Often your first sign of trouble
  
  • The local problems are easy to attack
• Can sometimes indicate a bigger issue
  
  • Problem with a switch or congestion in the network
• View in the operating system
  
  • Interface details
• Monitor with SNMP
  
  • Remote monitoring of all devices
  • Most metrics are in MIB-II

Question 2

Interface monitoring

Answer 2

Link status - link up, or link down?
• May be a problem on the other end of the cable

• Error rate
  
  • Problems with the signal - CRC error, runt, giant
• Utilization
  
  • Per-interface network usage
  • Run bandwidth tests to view throughput

• Discards, packet drops
• No errors in the packet, but system could not
process

• Interface resets
  
  • Packets are queued, but aren’t sent
  • Connection is good, but line protocols aren’t talking
  • Reset and hope for the best

• Speed and duplex
  • These should match on both sides
  • Auto speed and auto duplex isn’t always the best 
     option
  • Check for expected throughput