thaul man- dates latencies of up to 100 us. When discussing the transport network, we need to differentiate between low average delay and bounded delay. In certain applications, including interactive audio or video, hav- ing a sufficiently low average delay is sufficient, with occasional high delay packets consid- ered lost and subject to packet loss concealment. In most cases of relevance here we need to focus on guaranteed (i.e. worst case) upper bounds to delay. Achieving low network traversal latencies generally entails combining two strategies: Finding potentially low-delay paths through the network (e.g. paths with short links, minimal number of active forwarding elements, etc.). 2. Ensuring low packet residence time for express traffic packets (i.e. packets whose for- warding must be expedited) at the forwarding elements. The former strategy may be accomplished using SDN techniques involving maintaining a network topology graph at a centralized computational resource, and performing graph optimization algorithms. Once a feasible path has been found, it must be deployed, and protected against failures. Protection mechanisms may be E2E (requiring an alternative feasible backup path) or local (requiring bypass alternatives for all possible failures). The latter strategy requires identifying and prioritizing express traffic packets, and may involve resource reservation at the forwarding elements. One-way E2E transport latency is made up of several contributions. The first is the physi- cal propagation latency of about 1 us for 200 m of fiber or 300 m of point-to-point microwave. The second is the residence times in each active NE, which we can define as the inter- val from the first bit arriving at the NE until the last bit exits it. Each residence time is composed of packetization time (time for all bits to arrive at line rate), processing time (time for memory accesses, to read header fields, to classify packet, to look up forwarding information, etc.), queuing time (the time the packet waits its turn to be 