CHAPTER
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39
Diagnostics on the Catalyst 4500 Switch
Diagnostics tests and verifies the functionality of the hardware components of your system (chassis,
supervisor engines, modules, and ASICs), while your Catalyst 4500 ser ies switch is connected to a live
network. Diagnostics consists of packet switching tests that test hardware components and verify the
data path and control signals. Diagnostic tests are non-disruptive (except POST) and run at different
times. Some tests run continuously in the background to monitor the status of your system ( such as the
test for switching modules), while others run only once.
This chapter describes the following types of diagnostics on the Catalyst 4500 series switch:
Online Diagnostics, page 39-17
Power-On-Self-Test Diagnostics, page 39-19
Note For complete syntax and usage information for the switch commands used in this chapter, refer to the
Catalyst 4500 Series Switch Cisco IOS Command Reference and related publications at
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/index.htm.

Online Diagnostics

An online diagnostic test verifies that all ports on a linecard are working correctly. The test can detect
whether or not the path to the front panel port on th e linecard is broken, but it cannot indicate where
along the path the problem occurred.
The test is termed online because it runs when your system is running.
Note This test is run only for linecards that have stub chips.
Online diagnostics runs on linecards only once, when they are booting.
This can happen when you insert a linecard or power up a chassi s.
Online diagnostics are performed by sending a packet from the CPU to every port on the linecard.
Because this packet is marked loopback, the CPU expects to see this packet return from the port. The
packet first traverses the ASICs on the supervisor engine card, then travels via the chassis backplane and
the stub chip on the linecards to the PHYs. The PHY sends it back down the same path.
Note The packet does not reach or exit the front panel port.