Tcp transport layer Er. Vikram Dhiman lpu discussion from last topic

User Datagram Protocol is a simpler message-based connectionless protocol.

• User Datagram Protocol is a simpler message-based connectionless protocol.
• Unreliable – When a UDP message is sent, it cannot be known if it will reach its destination; it could get lost along the way. There is no concept of acknowledgment, retransmission, or timeout.

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Not ordered – If two messages are sent to the same recipient, the order in which they arrive cannot be predicted.

• Not ordered – If two messages are sent to the same recipient, the order in which they arrive cannot be predicted.
• Lightweight – There is no ordering of messages, no tracking connections, etc. It is a small transport layer designed on top of IP.
• Datagrams – Packets are sent individually and are checked for integrity only if they arrive. Packets have definite boundaries which are honored upon receipt, meaning a read operation at the receiver socket will yield an entire message as it was originally sent.

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• No congestion control – UDP itself does not avoid congestion, unless they implement congestion control measures at the application level.
• Broadcasts - being connectionless, UDP can broadcast - sent packets can be addressed to be receivable by all devices on the subnet.

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• A client has a packet of 68000 bytes, can this packet be transferred by a single UDP datagram?

• Example 23.2.2

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• A UDP header in hexadecimal format
• 06 32 00 0D 00 1C E2 17
• What is the source port number?
• What is the destination port number?
• What is the total length of the user datagram?
• What is the length of the data?

• Example 23.2.3

• Incoming and outgoing queue
• It will obtain only one port number
• Port unreachable icmp message (if queue is not created)

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• Figure 23.12 Queues in UDP