Recovering From Lost Member Connectivity - Cisco Catalyst 3550 series Software Configuration Manual

Preventing Autonegotiation Mismatches

Recovering from Lost Member Connectivity

Some configurations can prevent the command switch from maintaining contact with member switches.
If you are unable to maintain management contact with a member, and the member switch is forwarding
packets normally, check for these conflicts:
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Preventing Autonegotiation Mismatches
The IEEE 802.3AB autonegotiation protocol manages the switch settings for speed (10 Mbps, 100 Mbps,
and 1000 Mbps excluding GBIC ports) and duplex (half or full). There are situations when this protocol
can incorrectly align these settings, reducing performance. A mismatch occurs under these
circumstances:
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To maximize switch performance and ensure a link, follow one of these guidelines when changing the
settings for duplex and speed:
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Note If a remote device does not autonegotiate, configure the duplex settings on the two ports to match. The
speed parameter can adjust itself even if the connected port does not autonegotiate.
GBIC Module Security and Identification
Cisco-approved Course Wave Division Multiplexer (CWDM) Gigabit Interface Converter (GBIC)
modules have a serial EEPROM that contains the module serial number, the vendor name and ID, a
unique security code, and cyclic redundancy check (CRC). When a CWDM GBIC or SFP module is
inserted in the switch, the switch software reads the EEPROM to check the serial number, vendor name
and vendor ID, and recompute the security code and CRC. If the serial number, the vendor name or
vendor ID, the security code, or CRC is invalid, the switch places the interface in an error-disabled state.
If you are using a non-Cisco approved CWDM GBIC module, remove the GBIC module from the switch,
Note
and replace it with a Cisco-approved module.
Catalyst 3550 Multilayer Switch Software Configuration Guide
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A member switch (Catalyst 3550, Catalyst 3500 XL, Catalyst 2955, Catalyst 2950, Catalyst 2940,
Catalyst 2900 XL, Catalyst 2820, and Catalyst 1900) cannot connect to the command switch
through a port that is defined as a network port.
Catalyst 3500 XL, Catalyst 2900 XL, Catalyst 2820, and Catalyst 1900 member switches must
connect to the command switch through a port that belongs to the same management VLAN.
A member switch (Catalyst 3550, Catalyst 3500 XL, Catalyst 2950, Catalyst 2940,
Catalyst 2900 XL, Catalyst 2820, and Catalyst 1900) connected to the command switch through a
secured port can lose connectivity if the port is disabled because of a security violation.
A manually set speed or duplex parameter is different from the manually set speed or duplex
parameter on the connected port.
A port is set to autonegotiate, and the connected port is set to full duplex with no autonegotiation.
Let both ports autonegotiate both speed and duplex.
Manually set the speed and duplex parameters for the ports on both ends of the connection.
Chapter 37 Troubleshooting
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