Speculative resource allocation for routing on interconnect fabrics

Methods and systems related to speculative resource allocation for routing on an interconnect fabric are disclosed herein. One disclosed method includes speculatively allocating a collection of resources to support a set of paths through an interconnect fabric. The method also includes aggregating a set of responses from the set of paths at a branch node on the set of paths. If a resource contention is detected, the set of responses will include an indicator of a resource contention. The method will then further include transmitting, from the branch node and in response to the indicator of the resource contention, a deallocate message downstream and the indicator of the resource contention upstream, and reallocating resources for the multicast after a hold period.