Cisco Cisco IOS Software Release 12.2(55)SE

Some switch queues are disabled if the buffer size or threshold level is set too low with the mls qos 
queue-set output global configuration command. The ratio of buffer size to threshold level should 
be greater than 10 to avoid disabling the queue. The workaround is to choose compatible buffer sizes 
and threshold levels. (CSCea76893)

When auto-QoS is enabled on the switch, priority queuing is not enabled. Instead, the switch uses 
shaped round robin (SRR) as the queuing mechanism. The auto-QoS feature is designed on each 
platform based on the feature set and hardware limitations, and the queuing mechanism supported 
on each platform might be different. There is no workaround. (CSCee22591)

If you configure a large number of input interface VLANs in a class map, a traceback message 
similar to this might appear:

01:01:32: %BIT-4-OUTOFRANGE: bit 1321 is not in the expected range of 0 to 1024

There is no impact to switch functionality.

There is no workaround. (CSCtg32101)

Cisco Discovery Protocol (CDP), VLAN Trunking Protocol (VTP), and Port Aggregation Protocol 
(PAgP) packets received from a SPAN source are not sent to the destination interfaces of a local 
SPAN session. The workaround is to use the monitor session session_number destination 
{interface interface-id encapsulation replicate} global configuration command for local SPAN. 
(CSCed24036)

The switch treats frames received with mixed encapsulation (IEEE 802.1Q and Inter-Switch Link 
[ISL]) as frames with FCS errors, increments the error counters, and the port LED blinks amber. 
This happens when an ISL-unaware device receives an ISL-encapsulated packet and forwards the 
frame to an IEEE 802.1Q trunk interface. There is no workaround. (CSCdz33708)

IP traffic with IP options set is sometimes leaked on a trunk port. For example, a trunk port is a 
member of an IP multicast group in VLAN X but is not a member in VLAN Y. If VLAN Y is the 
output interface for the multicast route entry assigned to the multicast group and an interface in 
VLAN Y belongs to the same multicast group, the IP-option traffic received on an input VLAN 
interface other than one in VLAN Y is sent on the trunk port in VLAN Y because the trunk port is 
forwarding in VLAN Y, even though the port has no group membership in VLAN Y. There is no 
workaround. (CSCdz42909).

For trunk ports or access ports configured with IEEE 802.1Q tagging, inconsistent statistics might 
appear in the show interfaces counters privileged EXEC command output. Valid IEEE 802.1Q 
frames of 64 to 66 bytes are correctly forwarded even though the port LED blinks amber, and the 
frames are not counted on the interface statistics. There is no workaround. (CSCec35100).

If the number of VLANs times the number of trunk ports exceeds the recommended limit of 13,000, 
the switch can fail. 

The workaround is to reduce the number of VLANs or trunks. (CSCeb31087)