C-4 APPENDIX C: TROUBLE-SHOOTING
You have added the Switch 1000 to an already
busy network, and respo nse times and traffic
levels have increased:
You may have added a group of users to one of the
Switch 1000 ports via a repeater or switch, and not
turned off IFM. Turn off IFM on any port that is con-
nected to multiple devices. Refer to “Setting Up the
Switch Ports” on page 4-12.
You have connected an endstation directly to
the Switch and the endstation fails to boot cor-
rectly:
The Switch has STP enabled, and the endstation is
booting before the STP initialization process is com-
plete. Specify that the port has Fast Start enabled,
and then reboot the endstation. For more informa-
tion about specifying Fast Start for a port, refer to
“Configuring the STP Parameters of Ports” on page
5-20.
The Switch keeps ageing out endstation entries
in the Switch Database (SDB):
The Switch has STP enabled, and STP is instructing
the Switch to age entries in the SDB faster because
topology changes are occurring in the network.
1Reduce the number of topology changes by
enabling Fast Start for all ports which are directly
connected to an endstation; refer to “Configuring
the STP Parameters of Ports” on page 5-20.
2Specify that the endstation entries are Non-ageing;
refer to “Setting Up the Switch Database (SDB)” on
page 4-16.
3If the network has less than 500 addresses, specify
that the bridging mode of the Switch is set to For-
ward to All; refer to “Setting Up the Switch Unit”
on page 4-9.
4Consider disabling STP on the Switch, and using
resilient links to provide network resilience; refer to
“Enabling STP on the Switch” on page 5-17 and
“Setting Up Resilient Links” on page 4-19.
You are trying to manage the Switch over a
network which has STP, and you are losing con-
tact with the management agent intermit-
tently:
As shown in Figure C-1, there is a SuperStack II
Switch unit (Switch A) between your management
workstation and the Switch 1000 (Switch B). You
have configured more than one VLAN on both
Switch units, and there is a parallel STP path for
each VLAN between the Switch units.
When Switch B transmits BPDUs across a VLAN
other than VLAN 1, Switch A learns the MAC
address of Switch B through the port on that
VLAN. The management agent of Switch B is only
accessible through VLAN 1, and so your manage -
ment workstation cannot communicate with Switch
B until it transmits BPDUs across VLAN 1. When that
occurs, Switch A learns the MAC address of Switch
B through the port on VLAN 1.