Cisco Cisco ATM Port Adapter Technical Manual
Troubleshooting Interface and VC Counter Issues
on ATM Port Adapters
on ATM Port Adapters
Document ID: 21450
Contents
Introduction
Prerequisites
Requirements
Components Used
Conventions
Understanding Statistics Reporting Mechanisms
Layer−2 vs Layer−3 Counters
Common Problems When Reporting Interface and VC Counter Statistics on ATM Port Adapters
Calculated Interface Rates Above the Physical Line Rate
Negative Counter for Input Queue
Double Accounting or Double the Expected Counter Values
Incorrect "InBytes" Value on PVC with QoS Service Policy
Incorrect or No Statistics on ATM Subinterfaces
Troubleshooting Steps
Related Information
Prerequisites
Requirements
Components Used
Conventions
Understanding Statistics Reporting Mechanisms
Layer−2 vs Layer−3 Counters
Common Problems When Reporting Interface and VC Counter Statistics on ATM Port Adapters
Calculated Interface Rates Above the Physical Line Rate
Negative Counter for Input Queue
Double Accounting or Double the Expected Counter Values
Incorrect "InBytes" Value on PVC with QoS Service Policy
Incorrect or No Statistics on ATM Subinterfaces
Troubleshooting Steps
Related Information
Introduction
This document describes how ATM port adapters report traffic statistics and resolve issues with incorrect
packet or byte counters displayed in the output of the show interface atm or show atm vc commands.
packet or byte counters displayed in the output of the show interface atm or show atm vc commands.
Prerequisites
Requirements
This document requires an understanding of the variable and fixed overhead fields on an ATM interface,
including the well−known 5−byte cell header. Refer to the following technical tips for more information on
this overhead:
including the well−known 5−byte cell header. Refer to the following technical tips for more information on
this overhead:
Measuring the Utilization of ATM PVCs
•
Implementing Network Management on ATM Interfaces
•
Understanding Maximum Transmission Unit (MTU) on ATM Interfaces
•
What Bytes Are Counted by IP to ATM CoS Queueing?
•
Components Used
This document is not restricted to specific software and hardware versions.
Conventions
Refer to Cisco Technical Tips Conventions for more information on document conventions.