Reference Guide

Figure 143. Example of PIM-Sparse Mode on VLT
On each VLAN where the VLT peer nodes act as the first hop or last hop routers, one of the VLT peer
nodes is elected as the PIM designated router. If you configured IGMP snooping along with PIM on the
VLT VLANs, you must configure VLTi as the static multicast router port on both VLT peer switches. This
allows multicast traffic that originates from the source that is connected to the VLT ports to reach the
PIM router which has downstream neighbors.
The VLT peer nodes can also act as normal PIM routers on Layer 3 ports and on VLANs that do not have
any VLT port members. In addition to being first-hop or last -hop routers, the peer node can also act as
an intermediate router.
To route traffic to and from the multicast source and receiver that are connected to VLT ports, enable
PIM-Sparse mode on the VLANs to which the VLT ports belong using the ip pim sparse-mode
command. If you configure IGMP snooping on these VLANs, the VLTi must be configured as a static
multicast router port on both VLT peers.
Each VLT peer runs its own PIM protocol independently of other VLT peers. To ensure the PIM protocol
states or multicast routing information base (MRIB) on the VLT peers are synced, if the incoming interface
(IIF) and outgoing interface (OIF) are Spanned, the multicast route table is synced between the VLT peers.
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Virtual Link Trunking (VLT)