CSE 123 Lecture Notes - Lecture 18: Network Congestion, Speedup, Explicit Congestion Notification

• School: UCSD
• Department: Computer Science and Engineering
• Course: CSE 123
• Professor: Alex Snoeren

Document Summary

Each input wire can simultaneously be sending a signal to any one of the output wires. Full bandwidth - permuted the order of each input port to each output port! Every line card has memory to store packets, as well as forwarding tables. Special i/o pari for the cpu card (for packets it receives as its dest) Have to drop packets if the queues are full (but only @ the port that is being flooded) N inputs may send to the same output! Requires speedup of n (i. e. output ports must be n times faster than input ports!) Switch actually runs faster than the line rate (packets coming in) All of the buffering on the input side. Must implement flow control (slow down the senders so they don"t send too much traffic) Low utilization due to head-of-line (hol) blocking. Output ports that can service certain packets are being blocked b/c they"re not at the head of the queue (line)!