Simplified Virtual-IST (vIST) is for conventional switch clustering deployments that use SMLT and not SPB. The Simplified vIST feature provides a single CLI command to enable the virtual IST for SMLT deployments.
Simplified vIST is available for conventional multicast deployments with PIM and IGMP only when the boot flag (spbm-config-mode) is disabled.
Important
PIM is supported with Simplified vIST only, not with SPB vIST.
When the spbm-config-mode boot flag is enabled (default setting), Simplified vIST is not available. This means that you continue to configure SPB/IS-IS for vIST as described in Creating a Virtual IST and Create a Virtual IST using EDM.
Simplified VIST requires that the two vIST devices be directly connected.
For legacy IGMP snooping and IGMP snooping over Simplified vIST, the IGMP sender information is NOT synchronized across the vIST. This means that show ip igmp sender displays the sender record only on the switch that the multicast stream actually ingresses.
In Simplified vIST mode, you should not use LACP on vIST MLT.
Note
For Simplified vIST deployment, if a VLAN is part of an SMLT it must be configured on both the IST peers.
Important
Do not change the system MTU to less than the default value of 1950 bytes. The system MTU must be 1950 or jumbo because of a header size increase.
For configuration information, see Configuring Simplified vIST in SMLT topologies or Configuring Simplified vIST in SMLT topologies.
For information about how to configure Simplified vIST with multicast, see Enabling multicast on the switch.