Cisco Cisco IOS Software Release 15.2(3)E

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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)

RADIUS change of authorization (COA) reauthorization is not supported on the critical auth 
VLAN.

There is no workaround. (CSCta05071)

When the RSPAN feature is configured on a switch, Cisco Discovery Protocol (CDP) packets 
received from the RSPAN source ports are tagged with the RSPAN VLAN ID and forwarded to trunk 
ports carrying the RSPAN VLAN. When this happens a switch that is more than one hop away 
incorrectly lists the switch that is connected to the RSPAN source port as a CDP neighbor.

This is a hardware limitation. The workaround is to disable CDP on all interfaces carrying the 
RSPAN VLAN on the device connected to the switch. (CSCeb32326)

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)

CSCtl60247 

When a switch or switch stack running Multiple Spanning Tree (MST) is connected to a switch 
running Rapid Spanning Tree Protocol (RSTP), the MST switch acts as the root bridge and runs 
per-VLAN spanning tree (PVST) simulation mode on boundary ports connected to the RST switch. 
If the allowed VLAN on all trunk ports connecting these switches is changed to a VLAN other than 
VLAN 1 and the root port of the RSTP switch is shut down and then enabled, the boundary ports 
connected to the root port move immediately to the forward state without going through the PVST+ 
slow transition. 

There is no workaround.

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