| dbp:text
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- 1.0 (dbd:second)
- This field specifies whether the datagram can be fragmented or not. This can be used when sending packets to a host that does not have resources to perform reassembly of fragments. It can also be used for path MTU discovery, either automatically by the host IP software, or manually using diagnostic tools such as ping or traceroute. If the DF flag is set, and fragmentation is required to route the packet, then the packet is dropped. (en)
- Reserved. Should be set to 0. (en)
- For unfragmented packets, the MF flag is cleared. For fragmented packets, all fragments except the last have the MF flag set. The last fragment has a non-zero Fragment Offset field, so it can still be differentiated from an unfragmented packet. (en)
- Originally defined as the type of service , this field specifies differentiated services . Real-time data streaming makes use of the DSCP field. An example is Voice over IP , which is used for interactive voice services. (en)
- The IPv4 header is variable in size due to the optional 14th field . The IHL field contains the size of the IPv4 header; it has 4 bits that specify the number of 32-bit words in the header. The minimum value for this field is 5, which indicates a length of 5 × 32 bits = 160 bits = 20 bytes. As a 4-bit field, the maximum value is 15; this means that the maximum size of the IPv4 header is 15 × 32 bits = 480 bits = 60 bytes. (en)
- This field allows end-to-end notification of network congestion without dropping packets. ECN is an optional feature available when both endpoints support it and effective when also supported by the underlying network. (en)
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