Troubleshooting

Troubleshooting

Unusual Network Activity

 

Problems Related to Spanning-Tree Protocol (STP)

 

 

C a u t i o n

If you enable STP, it is recommended that you leave the remainder of the STP

 

parameter settings at their default values until you have had an opportunity

 

to evaluate STP performance in your network. Because incorrect STP settings

 

can adversely affect network performance, you should avoid making changes

 

without having a strong understanding of how STP operates. To learn the

 

details of STP operation, refer to the IEEE 802.1d standard.

 

Broadcast Storms Appearing in the Network. This can occur when

 

 

there are physical loops (redundant links) in the topology.Where this exists,

 

you should enable STP on all bridging devices in the topology in order for the

 

loop to be detected.

 

STP Blocks a Link in a VLAN Even Though There Are No Redundant

 

Links in that VLAN. In 802.1Q-compliant switches such as the Switch 2512

 

and Switch 2524, STP blocks redundant physical links even if they are in

 

separate VLANs. A solution is to use only one, multiple-VLAN (tagged) link

 

between the devices. Also, if ports are available, you can improve the band-

 

width in this situation by using a port trunk. See "STP Operation with 802.1Q

 

VLANs" on page 9-110.

 

Stacking-Related Problems

 

The Stack Commander Cannot Locate any Candidates. Stacking oper-

 

ates on the primary VLAN, which in the default configuration is the

 

DEFAULT_VLAN. However, if another VLAN has been configured as the

 

primary VLAN, and the Commander is not on the primary VLAN, then the

 

Commander will not detect Candidates on the primary VLAN.

 

Timep or Gateway Problems

 

The Switch Cannot Find the Timep Server or the Configured

 

Gateway . Timep and Gateway access are through the primary VLAN, which

 

in the default configuration is the DEFAULT_VLAN. If the primary VLAN has

 

been moved to another VLAN, it may be disabled or does not have ports

 

assigned to it.

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