9
Release Notes for the Cisco Catalyst Blade Switch 3020 for HP, Cisco IOS Release 12.2(55)SE and Later
OL-22861-04
Limitations and Restrictions
IP
•
When the rate of received DHCP requests
exceeds 2,000 packets per minute for a long time, the
response time might be slow when you are using the console. The workaround is to use rate limiting
on DHCP traffic to prevent a denial of service attack from occurring. (CSCeb59166)
IP Telephony
•
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)
Multicasting
•
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)
•
When IGMP snooping is disabled and you enter the
switchport block multicast
interface
configuration command, IP multicast traffic is not blocked.
The
switchport block multicast
interface configuration command is only applicable to non-IP
multicast traffic.
There is no workaround. (CSCee16865)
•
Incomplete multicast traffic can be seen under either of these conditions:
–
You disable IP multicast routing or re-enable it globally on an interface.
–
A switch mroute table temporarily runs out of resources and recovers later.
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:
