Comp 343/443-001 Week 4 notes

Servicing Netflix at 400 Gb/s on FreeBSD

That would be 5 GB/s, or 3.3 million packets/sec. 1 million packets/sec used to be an impressive feat. To put it another way, if one user's video stream is 5 Mb/s, this is 80,000 separate streams. Quite a few, but definitely not a large fraction of the Netflix traffic.

Like most fast networking, it turns out that the real issue is memory access. (Also making sure that you avoid copying data from user space to kernel space.)

Netflix still keeps forward "netflix appliances" within many ISPs; I'm not sure if this device is that, or if it acts at a more central location.

General DDoS on edpnet services [a European ISP]:

While we're on the subject of DDoS, got hit with a DDoS of 2 million HTTP GET requests per second. That's around 10 Gbps, assuming one request is 5,000 bits = ~600 bytes.

There are also POST attacks, which trigger more server back-end processing.

This is one reason we have captchas. Some sites include a CPU-intensive javascript to slow attackers down. But the basic technique is still

Homework 2

    Chapter 7: exercises 2.0, 6.0 (packet travel times)
    Chapter 8: exercises 7.0, 8.0 (sliding windows)
    Chapter 9: exercises 6.0, 8.0 (IPv4)
    Chapter 13: exercises 2.0, 4.0 (routing)

7: Packets

    Delay calculations
    Packet size revisited
        size and delay
        size and error recovery

    Checksums: Internet Checksum

    Error-Correcting codes (2D-parity)

Chapter 8: