HP Cisco Catalyst Blade Switch 3020 Release Notes for the Cisco Catalyst Blade - Page 9
IP, IP Telephony, Multicasting, show sdm prefer, show ip igmp, snooping multicast-table
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Limitations and Restrictions IP IP Telephony Multicasting • 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) • 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) • 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: OL-22861-04 Release Notes for the Cisco Catalyst Blade Switch 3020 for HP, Cisco IOS Release 12.2(55)SE and Later 9