Datasheet

Release Notes for Catalyst 4500 Series Software Release 7.x

OL-1983-28

Usage Guidelines, Restrictions, and Troubleshooting

• IEEE 802.1Q trunks with several hundred active VLANs take a few minutes to become operational.

The time increases with the number of VLANs on the trunk. During this time, you might see

unexpected behavior, such as the console hanging or other ports not going into forwarding. After the

trunks become operational, the unexpected behavior disappears and operation returns to normal. The

operation remains normal as long as the trunks remain operational.

EtherChannel

This section contains usage guidelines, restrictions, and troubleshooting information that apply to Fast

and Gigabit EtherChannel:

• With a large number of channels, trunks, or VLANs, or a change of channel configuration (for

example, off to auto), or upon Fast EtherChannel module reboot, ports might take up to five minutes

to form a channel and to participate in spanning tree. (During this interval, the port does not appear

in show spantree command output.) If it takes more than ten minutes for a channel to form and

appear on spanning tree, disable and reenable the ports. In addition, it might take up to two minutes

to unbundle a channel after changing the channel mode.

• If a syslog message like “SPANTREE-2: Channel misconfig - x/x-x will be disabled” is displayed

while running Fast EtherChannel, it indicates that one of the two ports is not configured correctly.

We recommend that you reenable the ports by entering the set port enable command, and configure

the two ports with one of these valid EtherChannel configurations.

SPAN

This section contains usage guidelines, restrictions, and troubleshooting information that apply to the

Switched Port Analyzer (SPAN):

• By default, incoming traffic on the SPAN destination port is disabled. You can enable it using the

set span command with the inpkts enable keywords. However, while the port receives traffic for its

assigned VLAN, it does not participate in spanning tree for that VLAN. To avoid creating spanning

tree loops with incoming traffic enabled, assign the SPAN destination port to an unused VLAN.

• A SPAN destination port receives flooded unicasts and broadcasts for the VLAN of the source SPAN

port.

• A SPAN session cannot be configured through SNMP with the monitorGrp MIB. The SPAN

configuration can be read from the monitorGrp MIB.

Workaround: Use the PortCopyTable MIB to configure SPAN sessions through SNMP.

Port Channel Mode Valid Neighbor Port Channel Modes

desirable desirable or auto

auto desirable

on on

off off