CS 547 Network Programming

[Pages:2]CS 547 Network Programming Spring 2023

Quiz #2 on January 26, 2023 (suggested solutions)

Your Last Three Digits: ________________

(please do NOT write all of your student ID or your name)

Grade: ______

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(1) What is "tunneling" (as a technical definition)?

Transmitting payload data by intentionally deviating from the standard protocol suites.

(2) What are the two major benefits in using tunneling? To extend the scopes of the existing networks To emulate transmission services not available in a network

Note: This question does not ask examples of the existing tunneling protocols (e.g., MBone, 6Bone, Soft-LAN, layer-3 VPN, and etc.)

(3) Describe the five activities "Soft-LAN" performs to let a remote host computer over the Internet to logically join a LAN over the Internet.

CS 547 Network Programming

Tunneling Example: Soft-LAN (4)

Host A CA

Host B

Host C

CA

CA

Transmit the encapsulated

Construct a LAN TCP packet to the packet (frame) for VLAN server at E

LAN-B

Host Z

Encapsulate the LAN packet by a TCP packet

"Soft-LAN Server"

Host D

Host E

Router A Internet

1,000 miles

CA

CA

Router B

LAN cable (i.e., IEEE-802.3 Ethernet) Z C

LAN-B

When C receives this LAN packet from E, C believes that it came from Z, who is another member of this LAN (LAN-B) The LAN server at E

extracts the encapsulated LAN packet

Tunneling/008

Host E releases the extracted LAN packet

to the LAN cable

Solution: activities through in the PPT slide above.

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(4) What is "Mbone"? How does "MBone" work? MBone is a layer-3 tunneling, (a) which transmits multicast packets ("IP multicast packets") using unicast packets through "unicast routers" (b) by encapsulating an IP multicast packet (not "multicast payload") in an IP unicast packet. Notes: (a) is required for answering the first question ("What is "Mbone"? "). (b) is required for answering the second question ("How does "MBone" work? ").

(5) What is "Virtual LAN hub"? How does it differ from "VLAN"? (a) "Virtual LAN hub" is a virtual (i.e., a software-implemented) LAN hub, that acts as a hub in the public network space (instead of within a local area network), such as the Internet. Each participating host computer establishes a Soft-LAN connection to a "virtual LAN hub". Multiple host computers that (logically) connect to a virtual LAN hub see that all of the participating host computers as if they were all connected to a LAN segment. (b) VLAN is a technique to split one hardware hub (LAN switch) into multiple LAN segments. VLANs do not extend the scopes of the existing networks, instead, they split existing networks. Notes: (a) is required for answering the first question ("What is "Virtual LAN hub"?"). (b) is required for answering the second question ("How does it differ from "VLAN"? ").

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CS 547 Network Programming, Spring 2023, Quiz #2, January 26, 2023

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