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Figure 132. PIM-Sparse Mode Support 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 ensures that for first hop routers, the packets from the source are
redirected to the designated router (DR) if they are incorrectly hashed. In addition to being first-hop or last -hop routers, the
peer node can also act as an intermediate router.
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 IGMP Snooping is configured on these
VLANs, the VLTi must be configured as a static multicast router port on both VLT peers.
To verify the PIM neighbors on the VLT VLAN and on the multicast port, use the show ip pim neighbor, show ip igmp
snooping mrouter, and show running config commands.
You can configure virtual link trunking (VLT) peer nodes as rendezvous points (RPs) in a Protocol Independent Multicast (PIM)
domain.
If the VLT node elected as the designated router fails, traffic loss occurs until another VLT node is elected the designated
router.
Virtual Link Trunking (VLT)
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