C-26
Troubleshooting
Diagnostic Tools
Port Auto-Negotiation
When a link LED does not light (indicating loss of link between two devices),
the most common reason is a failure of port auto-negotiation between the
connecting ports. If a link LED fails to light when you connect the switch to a
port on another device, do the following:
1. Ensure that the switch port and the port on the attached end-node are
both set to
Auto mode.
2. If the attached end-node does not have an
Auto mode setting, then you
must manually configure the switch port to the same setting as the end-
node port. See Chapter 9, “Optimizing Traffic Flow with Port Controls,
Port Trunking, and Port-Based Priority”.
Ping and Link Tests
The Ping test and the Link test are point-to-point tests between your switch
and another IEEE 802.3-compliant device on your network. These tests can
tell you whether the switch is communicating properly with another device.
Note To respond to a Ping test or a Link test, the device you are trying to reach must
be IEEE 802.3-compliant.
Ping Test. This is a test of the path between the switch and another device
on the same or another IP network that can respond to IP packets (ICMP Echo
Requests).
Link Test. This is a test of the connection between the switch and a desig-
nated network device on the same LAN (or VLAN, if configured). During the
link test, IEEE 802.2 test packets are sent to the designated network device
in the same VLAN or broadcast domain. The remote device must be able to
respond with an 802.2 Test Response Packet.
!Software.book Page 26 Thursday, October 10, 2002 6:10 PM
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