In service flow capability updating in a guaranteed bandwidth multicast network may be provided. First, a node may determine that a bandwidth requirement of a flow has changed to a new bandwidth value. Then, in response to determining that the bandwidth requirement of the flow has changed to the new bandwidth value, an ingress capacity value may be updated in an interface usage table for a Reverse Path Forwarding (RPF) interface corresponding to the flow. The RPF interface may be disposed on a network device. Next, in response to determining that the bandwidth requirement of the flow has changed to the new bandwidth value, an egress capacity value may be updated in the interface usage table for an Outgoing Interface (OIF) corresponding to the flow. The OIF may be disposed on the network device.