Types of Service Recall from last time tcP ys UDP >) Elastic apps that need reliability: remote login or emai >)Inelastic, loss-tolerant apps: real-time voice or video >)Others in between, or with stronger requirements Biggest cause of delay variation: re liable delivery Today's net: 100ms rtt Reliable delivery can add seconds Original Internet model: TCP/P one layer >) First app was remote login. >)But then came debugging, voice, etc. >)These differences caused the layer split, added UDP No Qos support assumed from below >)In fact, some underlying nets only supported reliable delivery Made Internet datagram service less useful! >)Hard to implement without network support >Qos is an ongoing debate.7 Types of Service Recall from last time TCP vs. UDP » Elastic apps that need reliability: remote login or email » Inelastic, loss-tolerant apps: real-time voice or video » Others in between, or with stronger requirements » Biggest cause of delay variation: reliable delivery – Today’s net: ~100ms RTT – Reliable delivery can add seconds. Original Internet model: “TCP/IP” one layer » First app was remote login… » But then came debugging, voice, etc. » These differences caused the layer split, added UDP No QoS support assumed from below » In fact, some underlying nets only supported reliable delivery – Made Internet datagram service less useful! » Hard to implement without network support » QoS is an ongoing debate…