Square and full-mesh topology multicast guidelines

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.

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Multicast SMLT square 1

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.

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Multicast SMLT square 2

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.

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Multicast SMLT square 3

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.