A square design connects a pair of aggregation switches to another pair of aggregation switches. A square design becomes a full-mesh design if the aggregation switches are connected in a full-mesh. The switch supports Layer 3 IP multicast (PIM-SM only) over a full-mesh SMLT or RSMLT configuration.
In a square design, configure all switches with PIM-SM. Place the bootstrap router (BSR) and RP in one of the four core switches; and place the RP closest to the source. If using PIM-SM over a square or full-mesh configuration, enable the multicast smlt-square flag.
The following three figures show switch clustering configurations with two-switch cluster cores and dual-connected edge devices.
In the preceding figure, only one of the switch cluster cores performs Layer 3 multicast routing while the other is strictly Layer 2. Configure multiple VLANs on the edge devices, 802.1Q tagged to the switch cluster cores.
Use an edge device that supports a form of link aggregation. Disable spanning tree on the link aggregation group on the edge devices. Enable either the VRRP BackupMaster or RSMLT Layer 2 Edge on the switch cluster core.
In the preceding figure, both of the switch cluster cores performs Layer 3 multicast routing, while the edge devices are Layer 2 IGMP.
Use an edge device that supports a form of link aggregation. Disable spanning tree on the link aggregation group on the edge devices. Enable either the VRRP BackupMaster or RSMLT Layer 2 Edge on the switch cluster cores. Do not enable VRRP on the RSMLT VLAN between switch cluster cores.
In the preceding figure, both of the switch cluster cores and the edge devices perform Layer 3 multicast routing.
Use an edge device that supports a form of link aggregation. Disable spanning tree on the link aggregation group on the edge devices. Enable either the VRRP BackupMaster or RSMLT Layer 2 Edge on the switch cluster cores. Do not enable VRRP on the RSMLT VLAN between switch cluster cores.