Cisco APIC Layer 3 Networking Configuration Guide, Release 6.2(x)

VRF GIPo allocation

Updated: April 17, 2026

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Explains how VRF GIPo is allocated implicitly based on configuration for multicast traffic forwarding in ACI fabric.

VRF GIPo allocation is a fabric multicast addressing mechanism that

provides one GIPo for the VRF and one GIPo for every BD under that VRF
allows GIPo sharing between multiple BDs or multiple VRFs, but not a combination of VRFs and BDs
requires APIC to ascertain allocation and IS-IS modification to handle VRF GIPo and build GIPo trees.

VRF GIPo traffic forwarding behavior

VRF GIPo handles different traffic types based on BD configuration:

All multicast traffic for PIM/PIM6 enabled BDs is forwarded using the VRF GIPo, including both Layer 2 and Layer 3 IPv4/IPv6 multicast
Any broadcast or unicast flood traffic on the multicast enabled BDs continues to use the BD GIPo
Non-IPv4/IPv6 multicast enabled BDs use the BD GIPo for all multicast, broadcast, and unicast flood traffic

Note

For the same VRF, VRF GIPo is common for both IPv4 and IPv6.

The APIC GUI displays a GIPo multicast address for all BDs and VRFs. The address displayed is always a /28 network address (the last four bits are zero). When the VXLAN packet is sent in the fabric, the destination multicast GIPo address will be an address within this /28 block and is used to select one of 16 FTAG trees. This achieves load balancing of multicast traffic across the fabric.

This table shows GIPo usage for different traffic types:

Table 1. GIPo usage
Traffic	Non-MC Routing-enabled BD	MC Routing-enabled BD
Broadcast	BD GIPo	BD GIPo
Unknown Unicast Flood	BD GIPo	BD GIPo
Multicast	BD GIPo	VRF GIPo

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