Cisco Gigabit Ethernet Switch Module for HP BladeSystem p-Class Release Notes, Cisco IOS Release 12.2(25)SE1

Multicasting

These are the multicasting limitations:

•

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 IG MP 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)

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)

10 Cisco Gigabit Ethernet Switch Module for HP BladeSystem p-Class Release Notes, Cisco IOS Release 12.2(25)SE1