Please complete the following sentences correctly. One correct answer per question. 1. An IPv4 address ... a. is structured into a part that addresses the Autonomous System (AS) and a part that addresses the host. b. has no structure! c. is structured into a part that addresses the network and a part that addresses the host. 2. Which one is not a "second level goal" according to design philosophy of the DARPA in- ternet Protocols according to D. Clark: a. Internet communication must continue despite loss. b. Traffic engineering must be facilitated by flows. c. The Internet architecture must accommodate a variety of networks. 3. The CSMA/CA protocol... a. is prone to the Hidden Node Problem. b. Is used for WANs. c. enables cooperation with Bluetooth. 4. The minimum Ethernet frame length in [meters] ... a. must be larger than two times the maximum bus length in [meters]. b. is independent of the bus length c. must be smaller than two times the maximum bus length in [meters]. 5. The term "resilience" describes in communication networks ... a. the ability to provide and maintain an acceptable level of data transmission even in the case of network, node or link failures. b. the pure error state when a network, node or link fails. c. the use of multi-homing protocols. 6. The OpenFlow protocol ... a. replaces fully any ordinary IP routing b. is an network layer protocol. c. separates between control plane and data plane 7. The BGP (Border Gateway Protocol) is ... a. is an encryption protocol. b. an exterior gateway protocol. c. an interior gateway protocol. 8. The concept of "multi-homing" can't be used for ... a. increasing resilience. b. Aloha-based local area networks. c. increasing throughput. 9. The Cellular concept which was developed in 1978 for mobile communication network ... a. assigns a set of frequencies to a transmitter and these frequencies can only be reused in non-adjacent cells b. does not require handovers between transmitters. c. is outdated due to the use of CDMA transmission. 10.4G-based mobile communication networks... a. differ from 3G mobile communication networks only by transmission speeds in the radio access network b. use two separate core networks for voice and data communication. C. use the IP protocol to transport voice and data. Question B.1 (15 points): Performance of Packet Switching Assume data transmission based on Packet Switching from a node in Eastern Europe (A), through two nodes in Central Europe (B and B), to a node in Western Europe, i.e. two intermediate hops (AB1 B2 C). The distance between the East coast (A) and the West coast (C) is 4500 km and all hops are equally spaced. The propagation speed in copper and fiber is 2/3 the speed of light in vacuum. The speed of light is assumed here to be 300000km/sec. The synchronization rate, i.e. the maximum link capaci- ty, is 10Gbps (1010 bps). This transmission technique assumes a packet size of 10kbyte. How long does it take to transmit a message of 1GByte (109 bytes)? Provide a figure to explain the calculation. Question B.2 (10 points): Clos Networks Draw a three-stage Clos switching network with these parameters (4 points): Number of n of input/output lines: 3 Number of m switches in second/middle stage: 5 Number of r of switch in input/output stage: 3 Why does a Clos network scale in comparison to a non-layered matrix switching networks? (2 points) Explain with your own words why the "Clos requirement" of m>= 2n -1 achieves a blocking- free switching network! (4 points) Question B.3 (15 points): Routing Algorithms We will consider the network which is depicted in Figure 1. Please calculate the routing table of node E using the Link State algorithm (Dijkstra algorithm). Describe in each step the set of "Confirmed" and "Tentative" nodes and describe which nodes are added to the set of tentative nodes and which nodes are selected for the set of "confirmed" nodes. Provide the full routing table (destination, distance, next hop). 2 A 4 F 5 B 1 1 D E 2 Figure 1: Network with links weights