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∙ 10y agoLength, Checksum and Source port
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Why does the TCP header have a header length field and UDP header does not?
in tcp header (32 bits) we have a field that is called options and padding that has variable in length and the header length shows the actual header size i.e size of 20 octets+size of options and padding field and in UDP we dont have any field like that and its header is fixed of 8 OCTETS (32 bits header size) refrence: WIRELESS COMMUNICATIONS AND NETWORKS by William Stallings Second Edition pg 91(see fig)
What is the maximum and minimum size of a UDP datagram?
maximum size is 512 bytes without header
How does a client computer determine what source port number to assign to a UDP header?
The port number is random
Contrast the IPv4 and the IPv6 header fields?
Simplified header format. IPv6 has a fixed length header, which does not include most of the options an IPv4 header can include. Even though the IPv6 header contains two 128 bit addresses (source and destination IP address) the whole header has a fixed length of 40 bytes only. This allows for faster processing. Options are dealt with in extension headers, which are only inserted after the IPv6 header if needed. So for instance if a packet needs to be fragmented, the fragmentation header is inserted after the IPv6 header. The basic set of extension headers is defined in RFC 2460.
What are the pieces of communication in UDP called?
UDP, or User Datagram Protocol is a very simple communication protocol. It is a part of the Transport Layer of the OSI model - the same as the well known TCP. UDP is very straight forward, containing very few features. There is no hand shaking, no security, no ordering of packets and very little error detection (if any at all). The structure of a UDP packet is as follows: Bits 0-15: Source Port Number (optional - leave as all zeros if unused) Bits 16-31: Destination Port Number Bits 32-47: The length of the entire UDP datagram (note that the maximum size is 2^16-1) Bits 48-63: The checksum (optional under IPv4 - leave as all zeros if unused) Bits 64-??: The actual data. About the checksum: this is the confusing part about UDP. When a checksum is computed, the UDP software creates a fake header to include in the checksum calculation - but this fake header is not actually transmitted. The structure of this fake header (officially called the "pseudo header") is: For IPv4: Bits 0-31: Source IP address (taken from the IP header) Bits 32-63: Destination IP address (taken from the IP header) Bits 64-71: Reserved - leave as all zeros Bits 72-79: Protocol (taken from the IP header) Bits 80-95: Length (taken from the UDP datagram) Bits 96-??: The UDP datagram described above. For IPv6: Bits 0-127: Source IP address Bits 128-255: Destination IP Address Bits 256-287: Length Bits 288-311: Reserved (leave as all zeros) Bits 312-319: Next header Bits 320-???: The UDP datagram described above NOTES: -this is only the structure of the UDP packet - and does not include the IP header. -Since it is possible for the checksum to end up as 0, the standard dictates that a checksum of zero be changed to 0xFFFF in order not to confuse with a checksum field which is disabled. This is true even under IPv6, where the checksum MUST be used. A checksum field value of zero is an error and the datagram should be discarded. -UDP makes no guarantees that the datagram will arrive, nor does it make any guarantees about the order that the datagram arrives in. If the user wants these features, then these will need to be implemented by the applications using UDP to communicate, or use a different communication protocol such as TCP.
The fields in TCP header that are missing from UDP header?
The sequence number, acknowledge number, and Window fields.
How many fields are there in IPv4 header?
UDP is a Transport layer protocol or fourth layer protocol. UDP is a connection less protocol used in transport layer. UDP header have four fields in total .
Which three fields are used in a UDP segment header?
• checksum • destination port • source port
What is a layer four header?
In the commonly used TCP/IP communications, that would either be a TCP header, or a UDP header.In the commonly used TCP/IP communications, that would either be a TCP header, or a UDP header.In the commonly used TCP/IP communications, that would either be a TCP header, or a UDP header.In the commonly used TCP/IP communications, that would either be a TCP header, or a UDP header.
What is udp header?
8 bytes
Compare the TCP header and the UDP header?
Both TCP and UDP have origin and destination ports - and that is about all the similarity there is between the two. TCP has several other fields that UDP doesn't have, including window size; a consecutive byte numbering (to figure out where to place a TCP segment in a data stream); the bytes that the other side is expected to send; and others.
What has port numbers in its header?
both tcp and udp
How do you get IP header of a UDP message?
Did you try Wireshark?
Why does the TCP header have a header length field and UDP header does not?
in tcp header (32 bits) we have a field that is called options and padding that has variable in length and the header length shows the actual header size i.e size of 20 octets+size of options and padding field and in UDP we dont have any field like that and its header is fixed of 8 OCTETS (32 bits header size) refrence: WIRELESS COMMUNICATIONS AND NETWORKS by William Stallings Second Edition pg 91(see fig)
How does the dns server add a udp header to the contexts of a dns query?
anonymous systems
What information is found in both the TCP and UDP header information?
souce and destination ports
Which information is found in both the udp and the tcp header information?
source and destination port
