3Com 9100 manual You forget your password and cannot log, Excessive RX CRC errors

152APPENDIX C: TROUBLESHOOTING

You forget your password and cannot log in:

If you are not an administrator, another user having administrator access level can log in, delete your user name, and create a new user name for you, with a new password.

Alternatively, another user having administrator access level can log in and initialize the device. This will return all configuration information (including passwords) to the initial values.

In the case where no one knows a password for an administrator level user, contact your supplier.

Port Configuration No link light on 100/1000BASE-TX port:

If patching from a hub or switch to another hub or switch, ensure that you are using a CAT5 cross-over cable. This is a CAT5 cable that has pins 1 and 2 on one end connected to pins 3 and 6 on the other end.

Excessive RX CRC errors:

When a device that has auto-negotiation disabled is connected to a Switch 9100 that has auto-negotiation enabled, the switch links at the correct speed, but in half duplex mode. The switch 100/1000 physical interface uses a method called parallel detection to bring up the link. Because the other network device does not participating in auto-negotiation (and does not advertise its capabilities), parallel detection on the switch is only able to sense 100Mbps versus 1000Mbps speed, and not the duplex mode. Therefore, the switch establishes the link in half duplex mode using the correct speed.

1000Mbps can operate only in full duplex mode. Viewing using the show port txerrors command on the Switch 9100 may display txlate collision counter increment errors.

The only way to establish a full duplex link is to either force it at both sides, or run auto-negotiation on both sides (using full duplex as an advertised capability, which is the default setting on the Switch 9100).