Cisco Gigabit Ethernet Switch Module for HP BladeSystem p-Class Release Notes, Cisco IOS Release 12.2(40)SE

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Cisco Gigabit Ethernet Switch Module for HP BladeSystem p-Class Release Notes, Cisco IOS Release 12.2(40)SE
460160-001
Limitations and Restrictions
QoS
These are the quality of service (QoS) limitations:
• 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)
SPAN and RSPAN
These are the SPAN and Remote SPAN (RSPAN) limitations.
• An egress SPAN copy of routed unicast traffic might show an incorrect destination MAC address on
both local and remote SPAN sessions. This limitation does not apply to bridged packets. The
workaround for local SPAN is to use the replicate option. For a remote SPAN session, there is no
workaround.
This is a hardware limitation: (CSCdy72835)
• Egress SPAN routed packets (both unicast and multicast) show the incorrect source MAC address.
For remote SPAN packets, the source MAC address should be the MAC address of the egress VLAN,
but instead the packet shows the MAC address of the RSPAN VLAN. For local SPAN packets with
native encapsulation on the destination port, the packet shows the MAC address of VLAN 1. This
problem does not appear with local SPAN when the encapsulation replicate option is used. This
limitation does not apply to bridged packets. The workaround is to use the encapsulate replicate
keywords in the monitor session global configuration command. Otherwise, there is no
workaround.
This is a hardware limitation: (CSCdy81521)
• During periods of very high traffic, when two RSPAN source sessions are configured, the VLAN ID
of packets in one RSPAN session might overwrite the VLAN ID of the other RSPAN session. If this
occurs, packets intended for one RSPAN VLAN are incorrectly sent to the other RSPAN VLAN.
This problem does not affect RSPAN destination sessions. The workaround is to configure only one
RSPAN source session.
This is a hardware limitation: (CSCed24036)
• 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.
Spanning Tree
When the logging event-spanning-tree interface configuration command is configured and logging to
the console is enabled, a topology change might generate a large number of logging messages, causing
high CPU utilization. CPU utilization can increase with the number of spanning-tree instances and the
number of interfaces configured with the logging event-spanning-tree interface configuration
command. This condition adversely affects how the switch operates and could cause problems such as
STP convergence delay.