Cisco WS-C2960S-24PD-L Software Guide - Page 148

Configuring Static Addresses for EtherChannel Port Groups, Configuring CGMP

Page 148 highlights

Configuring CGMP Chapter 6 Configuring the System Configuring Static Addresses for EtherChannel Port Groups Follow these rules if you are configuring a static address to forward to ports in an EtherChannel port group: • For default source-based port groups, configure the static address to forward to all ports in the port group to eliminate lost packets. • For destination-based port groups, configure the address to forward to only one port in the port group to avoid the transmission of duplicate packets. Configuring CGMP CGMP reduces the unnecessary flooding of IP multicast packets by limiting the transmission of these packets to CGMP clients that request them. The Fast Leave feature accelerates the removal of unused CGMP groups. By default, CGMP is enabled, and the Fast Leave feature is disabled. End stations issue join messages to become part of a CGMP group and issue leave messages to leave the group. The membership of these groups is managed by the switch and by connected routers through the further exchange of CGMP messages. CGMP groups are maintained on a per-VLAN basis: a multicast IP address packet can be forwarded to one list of ports in one VLAN and to a different list of ports in another VLAN. When a CGMP group is added, it is added on a per-VLAN, per-group basis. When a CGMP group is removed, it is only removed in a given VLAN. Note The same multicast MAC addresses cannot belong to both CGMP and Multicast VLAN Registration (MVR) groups. CGMP does not dynamically learn addresses that are MVR group members. If you want CGMP to learn an address that is already an MVR group member, remove the address from the MVR group. Conversely, you cannot add an address to an MVR group if it is already a CGMP group member. If you want an address that is already a CGMP group member to be an MVR group member, remove the address from the CGMP group, and then statically add it to the MVR group. For information about MVR, see the "Configuring MVR" section on page 6-27. 6-20 Catalyst 2900 Series XL and Catalyst 3500 Series XL Software Configuration Guide 78-6511-08

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6-20
Catalyst 2900 Series XL and Catalyst 3500 Series XL Software Configuration Guide
78-6511-08
Chapter 6
Configuring the System
Configuring CGMP
Configuring Static Addresses for EtherChannel Port Groups
Follow these rules if you are configuring a static address to forward to ports in an EtherChannel
port group:
For default source-based port groups, configure the static address to forward to
all ports
in the port
group to eliminate lost packets.
For destination-based port groups, configure the address to forward to
only one port
in the port
group to avoid the transmission of duplicate packets.
Configuring CGMP
CGMP reduces the unnecessary flooding of IP multicast packets by limiting the transmission of these
packets to CGMP clients that request them. The Fast Leave feature accelerates the removal of unused
CGMP groups. By default, CGMP is enabled, and the Fast Leave feature is disabled.
End stations issue join messages to become part of a CGMP group and issue leave messages to leave the
group. The membership of these groups is managed by the switch and by connected routers through the
further exchange of CGMP messages.
CGMP groups are maintained on a per-VLAN basis: a multicast IP address packet can be forwarded to
one list of ports in one VLAN and to a different list of ports in another VLAN. When a CGMP group is
added, it is added on a per-VLAN, per-group basis. When a CGMP group is removed, it is only removed
in a given VLAN.
Note
The same multicast MAC addresses cannot belong to both CGMP and Multicast VLAN Registration
(MVR) groups. CGMP does not dynamically learn addresses that are MVR group members. If you want
CGMP to learn an address that is already an MVR group member, remove the address from the MVR
group.
Conversely, you cannot add an address to an MVR group if it is already a CGMP group member. If you
want an address that is already a CGMP group member to be an MVR group member, remove the address
from the CGMP group, and then statically add it to the MVR group. For information about MVR, see
the
“Configuring MVR” section on page 6-27
.