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سؤال يا شباب؟؟؟؟؟؟؟
شو الفرق بين ال CRC CYCLIC REDUNDANCY CHEK
و
FRame chek sequence
و
cheksum
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و بارك الله فيكم
ويييييييييييييينكم شباب !!!!!!!!!!!!!!!!!!
alslam alekmlook my friend
the FCS is afield is used to determine if errors happen while transmitting so The error detection mechanism provided by the use of the FCS field discovers most errors caused on the media.
To ensure that the content of the received frame at the destination matches that of the frame that left the source node
a transmitting node creates a logical summary of the contents of the frame. This is known as the cyclic redundancy check (CRC) value. This value is placed in the Frame Check Sequence (FCS) field of the frame to represent the contents of the frame.
When the frame arrives at the destination node, the receiving node calculates its own logical summary, or CRC, of the frame. The receiving node compares the two CRC values. If the two values are the same, the frame is considered to have arrived as transmitted. If the CRC value in the FCS differs from the CRC calculated at the receiving node, the frame is discarded.
i hope i answer u
thanks bro ! u really answered me !!!!!!!!!!!اقتباس:
المشاركة الأصلية كتبت بواسطة supermezo7
ok br0, that mean that the data link layer only chek the errors but does n0t make error correction, but i wana ask how the transport layer does error recovery????
and wt about the cheksum that exist in the ip header of the packet???
alslam alekmfirst i happy to can answer your question
look my friend
second about the your question that the transport layer its make error correction its like that
first u must know tow concept
the window size and the acknowledgement number
1 the tcp uses window size to determine the number of segments sent by the sending devise before the receiving devices sends a confirmation
2 acknowledgment are sent by receiving stations to sending stations to confirm receipt of data
so if the segment is lost and dont arrive the window size will be diff so its go to resend it again and tell the sender make the window size small something
this is about the first question
second one that say
and wt about the cheksum that exist in the ip header of the packet???
the answer will be like that
ip Header Checksum - is used for error checking the packet header only not check the data its only for header of packet
:)i hope if i can answer u hun
have a nice time .
thanks br0 :ah40:اقتباس:
المشاركة الأصلية كتبت بواسطة supermezo7
i understood now that in the packet & in the tcp segment we have a cheksum that specialized for the headers n0t data , but if an error exist????????????how the recovery will be done>>>>>>>>>>you said that the recovery is based on the sequence number & acknowledgments .................its okay but if the error was in the data itself................ will the reciver inform the transmitter to resend it .......... is the recovery as that perspective???????????
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im s0rrry bro i may annoyed u with this questions
:D:D:D:D:D:D:D:D:D:D:D:D:D:D:D:D:D:D:D
noooooooooooo
in frame its so diff to packet in frame it chek all frame that include the data but jn packet its only see the header
so u can find the packet low overhead cause its not resend it if its wrong its like the udp in transport layer
but the frame and transport layer care about the all PDU (data and what with it from fields ) so ita as u say its make the receiver request to resend it again it can make
it know that by ack and seq
if i can upload the pic to explain it more i was do but icant upload pics
if u feel that u are confused u can call me or get my mail to explain it to u hun and feel free to ask i will be happy
1stly it was just a typo about the packet & frame and i ve corrected it its tcp segment &the packet that contains the cheksum , also thaks 4 ur
feeedback
nice to know that the cheksum in the segment is done on both header & data but in the packe its 0nly done on ip header
:)
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thanks s000 much bro i really go benefit this night and it was happy chance to discuss with u
&
i ask allah ALLAH to be certified ccna as s00n as possible
:):):)
:)
انشاء الله وان الله لا يضيع اجر من احسن عملا
:):):):):)اقتباس:
المشاركة الأصلية كتبت بواسطة supermezo7