IP merupakan protokol yang mendefinisikan unit transfer data (datagram), proses routing, dan pengiriman paket secara tidak handal di Internet. Datagram IP berisi header yang mencakup versi, panjang header, tipe layanan, panjang total, identifikasi, flag, offset fragmen, waktu hidup, protokol, checksum, alamat sumber dan tujuan, serta opsi. Header digunakan untuk fragmentasi, penyusunan kembali, dan pelacakan rute datagram di jaringan.
4. ET5044 – T2N – Telematics Lab. ITB IP Datagram Header 0 31 24 19 16 8 4 VERS HLEN SERVICE TYPE TOTAL LENGTH IDENTIFICATION FLAGS FRAGMENT OFFSET TIME TO LIVE PROTOCOL HEADER CHECKSUM SOURCE IP ADDRESS DESTINATION IP ADDRESS IP OPTIONS (IF ANY) PADDING DATA . . .
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16. DATAGRAM HEADER data 1 600 octets data 2 600 octets data 3 200 octets FRAGMENT 1 HEADER FRAGMENT 2 HEADER FRAGMENT 3 HEADER data data data Fragment 1 (offset 0) Fragment 2 (offset 600) Fragment 3 (offset 1200) (a) (b)
21. Mari kita lihat kembali header datagram IP 0 31 24 19 16 8 4 VERS HLEN SERVICE TYPE TOTAL LENGTH IDENTIFICATION FLAGS FRAGMENT OFFSET TIME TO LIVE PROTOCOL HEADER CHECKSUM SOURCE IP ADDRESS DESTINATION IP ADDRESS IP OPTIONS (IF ANY) PADDING DATA . . .
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24. Option Class Option Number Length Description 0 0 End of option list 0 1 Used to align octets in a list of options 0 2 11 Used for Security in IPv4 0 3 variable Loose Source Routing 0 7 variable Record Route (used to trace a route) 0 8 4 Stream Identifier (obsolete) 0 9 variable Strict Source Routing 2 4 variable Internet Timestamp (timestamps along a route)
37. Flag Value Meaning 0 Record only timestamps, not IP addr. 1 Record IP addr., then timestamp 3 Record timestamp if IP address is found in the list of addresses specified.