Evaluation 9 Flashcards
(10 cards)
[Unit 9] Write steps in making a remote procedure call.
Step 1 is the client calling the client stub. This call is a local procedure call, with the parameters pushed onto the stack in the normal way.
Step 2 is the client stub packing the parameters into a message and making a system call to send the message. Packing the parameters is called marshaling.
Step 3 is the operating system sending the message from the client machine to the server machine.
Step 4 is the operating system passing the incoming packet to the server stub.
Finally, step 5 is the server stub calling the server procedure with the unmarshaled parameters. The reply traces the same path in the other direction.
[Unit 9] What is a purpose of Slow-Start?
Slow‐start works well over a range of link speeds and round‐trip times, and uses an ack clock to match the rate of sender transmissions to the network path.
[Unit9 ] Write how to manage windows in the TCP sliding window protocol.
TCP window management controls the flow of data between sender and receiver by regulating how much data can be sent before requiring an acknowledgment. The receiver advertises available buffer space (window size), and the sender must pause when the window size reaches zero until more space becomes available.
[Unit 9] The Internet protocol suite supports a connectionless transport protocol called __________.
a. Ports
b. RTP
c. Transmission Control Protocol
d. User Datagram Protocol
user datagram protocol
[Unit 9] When a process on machine 1 calls a procedure on machine 2, the calling process on 1 is suspended and execution of the called procedure takes place on 2. Information can be transported from the caller to the callee in the parameters and can come back in the procedure result. No message passing is visible to the application programmer. What is this technique called?
a. Calling Technique
b. Message Passing Technique
c. Remote Procedure Call
d. Virtual Procedure Call
remote procedure protocol
[Unit 9] Once the media information reaches the receiver, it must be played out at the right time. In general, this will not be the time at which the RTP packet arrived at the receiver because packets will take slightly different amounts of time to transit the network. Even if the packets are injected with exactly the right intervals between them at the sender, they will reach the receiver at different relative times. What is this variation in delay called?
a. RTP Variation
b. Receiver and Sender Delay
c. Jitter
d. QoS
jitter
[Unit 9] When the sender gets an acknowledgement, it increases the congestion window by one and immediately sends two packets into the network. (One packet is the increase by one; the other packet is a replacement for the packet that has been acknowledged and left the network. At all times, the number of unacknowledged packets is given by the congestion window.) However, these two packets will not necessarily arrive at the receiver as closely spaced as when they were sent. What is this protocol called?
a. Burst Acknowledge
b. Slow Start
c. Traffic Control
d. Flow Control
slow start
[Unit 9] Because packets can take different paths through the network, they can arrive out of order. This will trigger duplicate acknowledgements even though no packets have been lost. However, this is uncommon in the Internet much of the time. When there is reordering across multiple paths, the received packets are usually not reordered too much. Thus, TCP somewhat arbitrarily assumes that three duplicate acknowledgements imply that a packet has been lost. The identity of the lost packet can be inferred from the acknowledgement number as well. It is the very next packet in sequence. This packet can then be retransmitted right away, before the retransmission timeout fires. What is this mechanism called?
a. Burst acknowledge
b. Fast retransmission
c. Quick retransmission
d. Multiple acknowledge
fast retransmission
[Unit 9] . At every clock tick, the counter in the head entry is decreased. When it hits zero, its event is processed and the next item on the list becomes the head. Its counter does not have to be changed. This way, inserting and deleting timers are expensive operations, with execution times proportional to the length of the list. A much more efficient approach can be used if the maximum timer interval is bounded and known in advance. To implement this, an array is used. What is this array called?
a. Ring array
b. Linear array
c. Recursive wheel
d. Timing wheel
timing wheel
[Unit 9] The main assumption in the Internet that DTNs seek to relax is that an end to end path between a source and a destination exists for the entire duration of a communication session. When this is not the case, the normal Internet protocols fail. DTNs get around the lack of end-to-end connectivity with an architecture that is based on message switching. What is this message called?
a. End to end message
b. DTN message
c. Bundle
d. Contact
bundle
