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

8
IP telephony
These are the IP telephony limitations:
• When a Cisco IP Phone is connected to the switch, the port VLAN ID (PVID) and the voice VLAN ID (VVID)
both learn its MAC address. However, after dynamic MAC addresses are deleted, only the VVID relearns
the phone MAC address. MAC addresses are manually or automatically deleted when a topology change
occurs or when port security or an 802.1x feature is enabled or disabled. There is no workaround.
(CSCea80105)
• After you change the access VLAN on a port that has 802.1x enabled, the IP Phone address is removed.
Because learning is restricted on 802.1x capable ports, it takes approximately 30 seconds before the
address is relearned. No workaround is necessary. (CSCea85312)
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 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)
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