588 Section 8 Neil Spring May 25, 1999

Schedule Notes Homework 3 Reservations?

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

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

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

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

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

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

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

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

Homework 3 - 8 Straightforward… questions?

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

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.

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