Comp 388/488: Advanced TCP/IP Networks

Final exam study guide

The final exam will be Wednesday, Dec 12, at our usual time.

Here is a brief outline of the material that may be covered:

You will still need to know the basics of congestion-window management
of Reno TCP.

Multicast: Section 4.4 of Peterson & Davie.
        Link-state multicast (easiest case)
        Distance-Vector multicast (trickier)
        Protocol-independent multicast (sparse mode)

TCP and fairness
        consequences of longer RTT for slower bandwidth increase
        How does Reno TCP bias against long-RTT connections?
        queue size and bandwidth share

RED gateways: P&D 6.4.2
        What problem is it that these attempt to address?
        What are some of the fairness issues regarding DECbit,
        as a per-connection queue management technique?
        
Bottleneck link
        Packetpair as a technique for probing the bottleneck link
        Link bandwidth can be the actual bitrate, eg 56Kbps, or it
        can be the average fraction of bandwidth available to one 
        connection; eg a 1.5mbit line shared among ten connections
        means that each connection gets 0.15mbit.

TCP vegas, P&D 6.4.3
        basic ideas
        what Vegas uses as congestion indicators; how Vegas responds
        costs of errors/misinterpretation in the TCP Vegas measurements
        
TCP models
        What assumptions does the network "fluid" model (eg in Mo & Walrand's
        paper) make? 
        If packets are very tiny, what is meant by congestion window?
        How do tiny packets affect transfer A--R--B, from A to B via router R?
        What happens to "bandwidth delay"?
        
Integrated Services (RSVP; P&D 6.5.2) v Differentiated Services (6.5.3)
Why RSVP is "expensive"
Token bucket filters
        What token-bucket bucket depth is needed to send the following
                Average rate: 1 packet/sec
                Each 8 seconds:
                        T=3:    3 packets
                        T=8:    5 packets
                        
Issues with figuring out the path
"Premium bit" in Differentiated-Services headers

Fair Queuing: basic rules (P&D 6.2.2)
        How Fair Queuing changes the rules re per-connection queue management
        
RTP/RTCP: realtime protocol (P&D 9.3.2)
        Application-level control over framing & transmission
        Living without ACK self-clocking
        RTCP "5% rule": may limit frequency of "ACKs"
        Comparison of RTCP receiver reports with TCP-style ACKs
        Possibility of use of jitter information
        How RTP competes with TCP

TCP-Friendly Rate Control (TFRC)
        basic operation
        how equation-based rate control works
        how we get from a window size to *rate* control
        What happens if congestion suddenly gets worse
        What happens if (old rate) > (new avail bandwidth)
        How AI/MD works with different decrease factors / increment amounts

Security issues - P&D ch 8
        RSA and DES algorithms will *not* be on the exam!
        Encryption v Authentication
        Why Key Management is an issue
        How cryptographically secure checksums (eg md5) can be used
           to authenticate messages from A to B if they share a key.
        Man-in-the-middle attacks