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QoS
These are the quality of service (QoS) limitations:
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SPAN and RSPAN
These are the SPAN and Remote SPAN (RSPAN) limitations.
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OL-8918-03
Incomplete multicast traffic can be seen under either of these conditions:
You disable IP multicast routing or re-enable it globally on an interface.
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A switch mroute table temporarily runs out of resources and recovers later.
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The workaround is to enter the clear ip mroute privileged EXEC command on the interface.
(CSCef42436)
After you configure a switch to join a multicast group by entering the ip igmp join-group
group-address interface configuration command, the switch does not receive join packets from the
client, and the switch port connected to the client is removed from the IGMP snooping forwarding
table.
Use one of these workarounds:
Cancel membership in the multicast group by using the no ip igmp join-group group-address
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interface configuration command on an SVI.
Disable IGMP snooping on the VLAN interface by using the no ip igmp snooping vlan vlan-id
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global configuration command. (CSCeh90425)
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)
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. (CSCea72326)
Release Notes for the Cisco Catalyst Blade Switch 3020 for HP, Cisco IOS Release 12.2(35)SE and Later
Limitations and Restrictions
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