If one or more downstream subscribers to a track have Forward=1, the relay MUST set Forward=1 upstream in order to receive and forward the requested Objects. When no downstream subscriber has Forward=1, the relay chooses the upstream Forward value at its discretion, considering the following tradeoffs and deployment considerations:
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Setting Forward=1 upstream starts object delivery and pre-warms the relay's cache, so objects are available when a downstream subscriber sets Forward=1. This reduces latency but consumes upstream and publisher resources for content no downstream subscriber is currently receiving.
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Setting Forward=0 upstream avoids that work, at the cost of higher latency when forwarding is later enabled.