Juniper Networks Juniper Networks Many ISIS deployments run on overlay networks provisioned by means of pseudo-wires or L2-circuits. when the devices in the underlying network go for maintenance, it is useful to divert the traffic away from the specific node(s), to some alternate paths, before the maintenance is actually scheduled. Since the nodes in the underlying network are not visible to ISIS, existing Avoidance of traffic blackhole mechanism described in [RFC3277] cannot be used. It is useful for routers in IS-IS routing domain to be able to advertise a link being in overload state to indicate impending maintenance activity in the underlying network devices. This document describes the protocol extensions to disseminate link overload information in IS-IS protocol.