1. 588 Section 8
Neil Spring
May 25, 1999

2. Schedule
Notes
Homework 3
Reservations?

3. Reminders & Notes Homework 3 due June 1
Project 3 or final project will be due June 11
Word documents OK.
Next week: 422

4. Homework 3 -1 Read Reflections on Trusting Trust, by Ken Thompson
Figure 1 might give you some clues about how to answer this question.

5. Homework 3 - 2 Sample denial of service attacks: syn flooding
name service attacks, possibly pretending map to your favorite (ahem) ‘adult entertainment’ site.
Infrastructure attacks:
smurfing: broadcast icmp echo with a forged source address
end host attacks
internet worm

6. Homework 3 - 3 Multicast source routing packet header format
Efficiency: size, complexity
can you get both?
Evaluation
Could it be deployed?
Would it help?

7. Homework 3 - 4 Incompatible routing protocols: Two questions
How does it happen?
How do you fix it? S G1 R G2 N1 N2

8. Homework 3 - 5 End to end If lost should be of the form
(i) if lost (ii) how to recover
If lost should be of the form
the x doesn’t get his update
have to multicast everywhere
To recover should be of the form
we send the update to x again, x asks for an update…
pruning is initiated again

9. Homework 3 - 6 DNS asynchronous update
a. write, but read the before image?
b. to get processor order?
c. to get total order?

10. Homework 3 - 7 Distance vector updates
This is NOT link state, also NOT distance vector as described in the book:
The initial table contains no 1’s!!!
Routers don’t know about their direct links!!!
A) tables like on page 167
B) flooding direction might change if a new route is there

11. Homework 3 - 8
Straightforward…
questions?

12. Real Time Problem: Maybe want multicast Routers, links fail
Want interactive video, audio,
Interactive means buffering (normal technique) is bad
Maybe want multicast
Routers, links fail
Congestion happens

13. The Story of RSVP
Senders deliver flow specifications to receivers, over predictable routes. Receivers send resource reservations back toward the sender. Routers along the way do admission control to decide whether guarantees can be made, then packet scheduling to meet those guarantees.

14. The Feature Sheet Receiver-driven Soft-state
scalable for multicast
heterogeneity
Soft-state
tolerates failures, changes
path state - forward, using existing routing
reservation state - reverse path
timeout & refresh
Filters: differentiate between senders