ECSE6600: Internet Protocols Exam 3

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ECSE-6600 Internet Protocols Exam 3

• Time 90 min (strictly enforced)
• Points 50
• YOUR NAME
• Be brief, but DO NOT omit necessary detail
• Note Simply copying text directly from the
  slides or notes will not earn (partial) credit.
  Brief, clear and consistent explanation will.

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• I. Below, you are given a true or false statement
  and asked a follow up question.
• Topic ARP and Multicast
• 1. 5 pts True statement the address resolution
  problem (equivalent of ARP) in multicast is very
  easy
• Explain why multicast uses a very simple address
  resolution technique. Discuss why a technique
  like ARP would severely conflict with the
  multicast model.

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• Topic QoS vs Congestion Control
• 2. (5 pts) True statement The fundamental
  problems in QoS include the fact that FIFO does
  not provide isolation and differentiation in
  terms of delay or bandwidth leads to zero-sum
  games with fixed resources.
• Explain how the problem of QoS differs from the
  problem of congestion control (both of them
  manage resources!).

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• Topic OAM functions
• 3. (5 pts) True statement DHCP solves a variety
  of IP configuration problems elegantly.
• Explain why RARP and ICMP together were
  insufficient for solving the IP configuration
  problems? What are the new features that DHCP
  adds compared to RARP ICMP?

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• Topic IPv6 vs ARP, DHCP
• 4. (5 pts) True statement IPv6 provides powerful
  auto-configuration features
• Explain what new features IPv6 adds
  over-and-above DHCP. Explain why the neighbor
  discovery procedure (unlike ARP) also has a
  destination cache, prefix cache and router cache?

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• II. 5 pts QoS architecture
• (1 pts) State briefly why the decision to
  de-couple end-to-end QoS techniques from
  network-based QoS techniques was an important
  architectural decision?
• (4 pts) Discuss the tradeoffs between stateful,
  reduced state and stateless architectures (eg
  Intserv, Diffserv, DPS, Edge-based Closed-loop
  architectures).

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• III. 5 pts Routing (Unicast vs Multicast)
• (3 pts) Explain the key differences between
  unicast and multicast routing paradigms.
• (2 pts) Explain briefly how the source-specific
  multicast (SSM) model helps resolve some of the
  problems with the original IP multicast model.

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• IV. 20 pts Big Picture Revisited Scalability
  and Heterogeneity
• (7 pts) The first goal of internetworking was
  scalability. Explain how IP forwarding, intra-
  and inter-domain routing split, congestion
  control schemes, IPv6 larger address space,
  auto-configuration features, fast links and fast
  router designs contribute to the overall
  scalability of the Internet system.
• (7 pts) The second goal was heterogeneity in
  terms of the disparate networks and applications
  supported. Explain how the overlay paradigm,
  simple packet format, best-effort service design,
  fragmentation/reassembly, QoS architectures,
  multicast techniques contribute to the support of
  heterogeneity in the Internet system.
• (3 pts) What does scalability mean for a
  network-box-designer (eg Cisco)? What does
  scalability mean for a network operator/service
  provider?
• (3 pts) Explain why some aspects like address
  space shortage, NAT, QoS architectures, multicast
  routing, open group model of multicast, large BGP
  tables/update complexity/routing stability still
  pose problems in terms of scalability and
  heterogeneity?

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