Cisco Systems 2820 Switch User Manual


 
8
Release Notes for the Catalyst 1900 and Catalyst 2820 Series Switches, Version 9.00.06
OL-2901-01
Caveats
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Networks that use IBM Type 1 cabling with ports configured as monitor ports can have problems if
the cable becomes disconnected.
The workaround is to configure ports for half-duplex operation because the switch does not detect
a loopback if the hermaphroditic connector on the cable is disconnected.
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In a full-duplex configuration with STP disabled, the switch does not detect a loop if an IBM Type 1
cable is disconnected.
The workaround is to configure ports for half-duplex operation if you must have STP disabled.
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If a 100-Mbps switch port has a disconnected IBM Type 1 cable, a change to the Port Fast mode
does not take effect.
The workaround is to reset the switch.
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If a full-duplex port is assigned to more than one bridge group and an IBM Type 1 cable is
disconnected, the switch might not detect a loopback.
There is no workaround.
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If a nonroot switch is bridged to a root switch through full-duplex ports using IBM Type 1 cabling,
the root port on the nonroot switch might take longer to reach the STP blocking state if the cabling
is disconnected and creates a loopback.
There is no workaround.
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If a dynamic port that is assigned to a VLAN is disconnected and reconnected to a different station,
the VLAN of the port is not rediscovered.
The workaround is to change the port to half duplex so that the switch assigns the port to a new
VLAN.
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If there are two or more Catalyst 1900 or Catalyst 2820 switches connected to a Catalyst 5000
switch by using Fast EtherChannel—and if there are two stations communicating through the
Catalyst 5000 switch—the switches learn the addresses of both stations from the broadcast packets
sent from those stations. Flooding of unknown unicast packets can occur if one of the stations
becomes disconnected from the Catalyst 5000 switch and the other station continues to send packets
to that station. The flooding stops when the switches reach the specified aging time for retaining the
address of the disconnected station.
The workaround is to use the port-channel preserve-order command to preserve the frame
transmission order on the switch port.
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When using the Fast EtherChannel feature with VLAN trunking between two Catalyst 1900 or
Catalyst 2820 switches, changing the active link might cause flooding. You can change an active
link either by changing the Port Aggregation Protocol (PAgP) port priority or by disconnecting one
of the high-speed links and reconnecting it.
The workaround is to disconnect both ports to change the active link.