CCNA - CCNA Exam question

Author

CCNA Exam question

king_ram

2002-03-24, 4:58 am

In the exam there was a question in TCP that is whether the window size is set with respect

Packet size
Byte size
Segment size

people who know the answer can kindly help

cannoe

2002-03-24, 6:16 am

I think the answer is segment size, because the PDU used by a transport layer to communicate to its peers is Segment.

defcon1111

2002-03-24, 11:33 am

good answer.

TCP sliding window is set up so that the buffer doesn't overrun at TRANSPORT layer so yes it goes by segment size.

nisarg

2002-03-25, 3:17 am

well, i had read in lammle that tcp/ip quantifies windowing of data segments by counting the number of bytes

but even than let us c, what r the views from other posts

~~~~~~~~~~~~~~~~~~~~~~~

Never say impossible because impossible itself says "I M POSSIBLE'

thonguyen

2002-03-25, 10:24 am

I think it's segment size. Here is what the source says:
"Processes transmit data by calling on the TCP and passing buffers of
data as arguments. The TCP packages the data from these buffers into
segments and calls on the internet module to transmit each segment to
the destination TCP. The receiving TCP places the data from a segment
into the receiving user's buffer and notifies the receiving user. The
TCPs include control information in the segments which they use to
ensure reliable ordered data transmission."

Killercavecow

2002-03-25, 2:36 pm

the only problem is that in the exam it refers to a number of 3000 or 4000..would you actually want 3000 segments to go by without acknowledgement? I've read sybex and know that windows is at the transport layer with segments and all that too..but the numbering thing is what is throwing us.

ROUTERRIP

2002-03-25, 3:22 pm

Um, guys, there's no way you're going to send 3000 to 4000 segments without acknowledgment. That's you're answer right there. If the question itself is referring to a 3000 or 4000 number, you're talking BYTES.

Here's an excerpt from CISCO PRESS, CCNA Guide, Chapter 5, TCP/IP, page 221:

Flow Control Using Windowing
TCP implements flow control by taking advantage of the sequence and acknowledgment fields in the TCP header, along with another field called the window field. This window field implies the maximum number of unacknowledged bytes outstanding at any instant in time. The window starts small and then grows until errors occur. The window then “slides” up and down based on
network performance. When the window is full, the sender will not send, which controls the flow of data. Figure 5-6 shows windowing, with a current window size of 3000. Each TCP segment has 1000 bytes of data.

cannoe

2002-03-26, 11:47 am

Im sorry my first answer was wrong but this is my final answer now!

, TCP which is a protocol in a trasport layer communicates with its peer using a PDU which we called them as SEGMENT, but the question is
"where to set the Window size", Window size must be set on a "BYTE SIZE" ( sorry for the caps,just wanna emphasize ), because window size refers to the number of bytes that are transmitted before recieving an acknowledgement. After a host transmits the window-size number of bytes, it must receive an acknowledgment before any more data can be sent.

for example : With a window size of 3, each segment carries only 3 bytes of data and must be acknowledged before another segment is transmitted. This results in inefficient host use of bandwidth.

Sponsored Links