IP Telephony
This is the IP telephony limitation:
After you change the access VLAN on a port that has IEEE 802.1x enabled, the IP phone address is
removed. Because learning is restricted on IEEE 802.1x-capable ports, it takes approximately 30
seconds before the address is relearned. No workaround is necessary. (CSCea85312)
logging event-spanning-tree Command
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.
High CPU utilization can also occur with other conditions, such as when debug messages are logged at
a high rate to the console.
Use one of these workarounds:
•
•
Remove the logging event spanning-tree interface configuration command from the interfaces.
MAC Addressing Multicasting
These are the multicasting limitations:
•
•
•
OL-14761-01
Disable logging to the console.
Rate-limit logging messages to the console. (CSCsg91027)
If the number of multicast routes and Internet Group Management Protocol (IGMP) groups are more
than the maximum number specified by the show sdm prefer global configuration command, the
traffic received on unknown groups is flooded in the received VLAN even though the show ip igmp
snooping multicast-table privileged EXEC command output shows otherwise. The workaround is
to reduce the number of multicast routes and IGMP snooping groups to less than the maximum
supported value. (CSCdy09008)
IGMP filtering is applied to packets that are forwarded through hardware. It is not applied to packets
that are forwarded through software. Hence, with multicast routing enabled, the first few packets are
sent from a port even when IGMP filtering is set to deny those groups on that port. There is no
workaround. (CSCdy82818)
If an IGMP report packet has two multicast group records, the switch removes or adds interfaces
depending on the order of the records in the packet:
If the ALLOW_NEW_SOURCE record is before the BLOCK_OLD_SOURCE record, the
–
switch removes the port from the group.
If the BLOCK_OLD_SOURCE record is before the ALLOW_NEW_SOURCE record, the
–
switch adds the port to the group.
There is no workaround. (CSCec20128)
Release Notes for the Cisco Catalyst Blade Switch 3020 for HP, Cisco IOS Release 12.2(44)SE
Limitations and Restrictions
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