{"id":191,"date":"2014-07-18T18:59:43","date_gmt":"2014-07-18T11:59:43","guid":{"rendered":"https:\/\/beta.engisv.info\/?p=191"},"modified":"2014-07-18T18:59:43","modified_gmt":"2014-07-18T11:59:43","slug":"giao-thuc-ip-internet-protocol-ipv4-header","status":"publish","type":"post","link":"https:\/\/www.engisv.info\/?p=191","title":{"rendered":"Giao th\u1ee9c IP (Internet Protocol) – IPv4 Header"},"content":{"rendered":"

Giao th\u1ee9c li\u00ean m\u1ea1ng IP l\u00e0 m\u1ed9t trong nh\u1eefng giao th\u1ee9c quan tr\u1ecdng nh\u1ea5t c\u1ee7a b\u1ed9 giao th\u1ee9c TCP\/IP. M\u1ee5c \u0111\u00edch c\u1ee7a giao th\u1ee9c li\u00ean m\u1ea1ng IP l\u00e0 cung c\u1ea5p kh\u1ea3 n\u0103ng k\u1ebft n\u1ed1i c\u00e1c m\u1ea1ng con th\u00e0nh li\u00ean m\u1ea1ng \u0111\u1ec3 truy\u1ec1n d\u1eef li\u1ec7u. IP l\u00e0 giao th\u1ee9c cung c\u1ea5p d\u1ecbch v\u1ee5 ph\u00e2n ph\u00e1t datagram theo ki\u1ec3u kh\u00f4ng li\u00ean k\u1ebft v\u00e0 kh\u00f4ng tin c\u1eady ngh\u0129a l\u00e0 kh\u00f4ng c\u1ea7n c\u00f3 giai \u0111o\u1ea1n thi\u1ebft l\u1eadp li\u00ean k\u1ebft tr\u01b0\u1edbc khi truy\u1ec1n d\u1eef li\u1ec7u, kh\u00f4ng \u0111\u1ea3m b\u1ea3o r\u1eb1ng IP datagram s\u1ebd t\u1edbi \u0111\u00edch v\u00e0 kh\u00f4ng duy tr\u00ec b\u1ea5t k\u1ef3 th\u00f4ng tin n\u00e0o v\u1ec1 nh\u1eefng datagram \u0111\u00e3 g\u1eedi \u0111i.
\n\"\"\u00dd ngh\u0129a c\u00e1c tham s\u1ed1 trong IP header:
\n\u2212 Version (4 bit): ch\u1ec9 phi\u00ean b\u1ea3n (version) hi\u1ec7n h\u00e0nh c\u1ee7a IP \u0111\u01b0\u1ee3c c\u00e0i \u0111\u1eb7t.
\n\u2212 IHL – Internet header length<\/span><\/span>\u00a0(4 bit): ch\u1ec9 \u0111\u1ed9 d\u00e0i ph\u1ea7n header t\u00ednh theo \u0111\u01a1n v\u1ecb t\u1eeb (word – 32 bit)
\n\u2212 Type of Service (8 bit): \u0111\u1eb7c t\u1ea3 tham s\u1ed1 v\u1ec1 y\u00eau c\u1ea7u d\u1ecbch v\u1ee5
\n\u2212 Total length (16 bit): ch\u1ec9 \u0111\u1ed9 d\u00e0i to\u00e0n b\u1ed9 IP datagram t\u00ednh theo byte. D\u1ef1a v\u00e0o tr\u01b0\u1eddng n\u00e0y v\u00e0 tr\u01b0\u1eddng header length ta t\u00ednh \u0111\u01b0\u1ee3c v\u1ecb tr\u00ed b\u1eaft \u0111\u1ea7u c\u1ee7a d\u1eef li\u1ec7u trong IP datagram.
\n\u2212 Indentification (16 bit): l\u00e0 tr\u01b0\u1eddng \u0111\u1ecbnh danh, c\u00f9ng c\u00e1c tham s\u1ed1 kh\u00e1c nh\u01b0 \u0111\u1ecba ch\u1ec9 ngu\u1ed3n (Source address) v\u00e0 \u0111\u1ecba ch\u1ec9 \u0111\u00edch (Destination address) \u0111\u1ec3 \u0111\u1ecbnh danh duy nh\u1ea5t cho m\u1ed7i datagram \u0111\u01b0\u1ee3c g\u1eedi \u0111i b\u1edfi 1 tr\u1ea1m. Th\u00f4ng th\u01b0\u1eddng ph\u1ea7n \u0111\u1ecbnh danh (Indentification) \u0111\u01b0\u1ee3c t\u0103ng th\u00eam 1 khi 1 datagram \u0111\u01b0\u1ee3c g\u1eedi \u0111i.
\n\u2212 Flags (3 bit): c\u00e1c c\u1edd, s\u1eed d\u1ee5ng trong khi ph\u00e2n \u0111o\u1ea1n c\u00e1c datagram.
\n\"\"\u2212 Fragment Offset (13 bit): ch\u1ec9 v\u1ecb tr\u00ed c\u1ee7a \u0111o\u1ea1n ph\u00e2n m\u1ea3nh (Fragment) trong datagram t\u00ednh theo \u0111\u01a1n v\u1ecb 64 bit.
\n\u2212 TTL –Time to live<\/span> \u00a0(8 bit): thi\u1ebft l\u1eadp th\u1eddi gian t\u1ed3n t\u1ea1i c\u1ee7a datagram \u0111\u1ec3 tr\u00e1nh t\u00ecnh tr\u1ea1ng datagram b\u1ecb qu\u1ea9n tr\u00ean m\u1ea1ng. TTL th\u01b0\u1eddng c\u00f3 gi\u00e1 tr\u1ecb 32 ho\u1eb7c 64 \u0111\u01b0\u1ee3c gi\u1ea3m \u0111i 1 khi d\u1eef li\u1ec7u \u0111i qua m\u1ed7i router. Khi tr\u01b0\u1eddng n\u00e0y b\u1eb1ng 0 datagram s\u1ebd b\u1ecb h\u1ee7y b\u1ecf v\u00e0 s\u1ebd kh\u00f4ng b\u00e1o l\u1ea1i cho tr\u1ea1m g\u1eedi.
\n\u2212 Protocol (8 bit): ch\u1ec9 giao th\u1ee9c t\u1ea7ng tr\u00ean k\u1ebf ti\u1ebfp
\n\u2212 Header checksum (16 bit): \u0111\u1ec3 ki\u1ec3m so\u00e1t l\u1ed7i cho v\u00f9ng IP header.
\n\u2212 Source address (32 bit): \u0111\u1ecba ch\u1ec9 IP tr\u1ea1m ngu\u1ed3n
\n\u2212 Destination address (32 bit): \u0111\u1ecba ch\u1ec9 IP tr\u1ea1m \u0111\u00edch
\n\u2212 Option (\u0111\u1ed9 d\u00e0i thay \u0111\u1ed5i): khai b\u00e1o c\u00e1c t\u00f9y ch\u1ecdn do ng\u01b0\u1eddi g\u1eedi y\u00eau c\u1ea7u, th\u01b0\u1eddng l\u00e0:<\/p>\n