{"id":505,"date":"2018-07-01T18:58:37","date_gmt":"2018-07-01T11:58:37","guid":{"rendered":"https:\/\/lagonet.vn\/?p=505"},"modified":"2018-07-01T18:58:37","modified_gmt":"2018-07-01T11:58:37","slug":"nhung-kien-thuc-co-ban-ve-bgp","status":"publish","type":"post","link":"https:\/\/kb.lagonet.vn\/?p=505","title":{"rendered":"NH\u1eeeNG KI\u1ebeN TH\u1ee8C C\u01a0 B\u1ea2N V\u1ec0 BGP"},"content":{"rendered":"

S\u1ef1 c\u1ea7n thi\u1ebft c\u1ee7a BGP<\/strong><\/p>\n

BGP l\u00e0 m\u1ed9t giao th\u1ee9c kh\u00e1 ph\u1ee9c t\u1ea1p \u0111\u01b0\u1ee3c d\u00f9ng nhi\u1ec1u tr\u00ean Internet v\u00e0 trong c\u00e1c c\u00f4ng ty \u0111a qu\u1ed1c gia. M\u1ee5c \u0111\u00edch ch\u00ednh c\u1ee7a BGP l\u00e0 k\u1ebft n\u1ed1i c\u00e1c m\u1ea1ng r\u1ea5t l\u1edbn ho\u1eb7c c\u00e1c Autonomous-System. C\u00e1c c\u00f4ng ty l\u1edbn c\u00f3 th\u1ec3 d\u00f9ng BGP nh\u01b0 l\u00e0 m\u1ed9t k\u1ebft n\u1ed1i gi\u1eefa c\u00e1c m\u1ea1ng \u1edf c\u00e1c qu\u1ed1c gia kh\u00e1c nhau. M\u1ee5c \u0111\u00edch c\u1ee7a c\u00e1c giao th\u1ee9c ngo\u1ea1i nh\u01b0 BGP l\u00e0 kh\u00f4ng ch\u1ec9 t\u00ecm ra m\u1ed9t \u0111\u01b0\u1eddng \u0111i v\u1ec1 m\u1ed9t m\u1ea1ng n\u00e0o \u0111\u00f3 m\u00e0 c\u00f2n cho ph\u00e9p ng\u01b0\u1eddi qu\u1ea3n tr\u1ecb t\u00ecm ra c\u00e1c AS c\u1ee7a c\u00e1c network. C\u00e1c giao th\u1ee9c n\u1ed9i nh\u01b0 EIGRP, RIP, OSPF v\u00e0 ISIS s\u1ebd t\u00ecm ra network m\u00e0 ng\u01b0\u1eddi qu\u1ea3n tr\u1ecb c\u1ea7n.
\n<\/a><\/div>\n

M\u1ed9t s\u1ed1 t\u00ednh ch\u1ea5t c\u1ee7a BGP
\nBGP l\u00e0 m\u1ed9t giao th\u1ee9c \u0111\u1ecbnh tuy\u1ebfn d\u1ea1ng path-vector n\u00ean vi\u1ec7c ch\u1ecdn l\u1ef1a \u0111\u01b0\u1eddng \u0111i t\u1ed1t nh\u1ea5t th\u00f4ng th\u01b0\u1eddng d\u1ef1a tr\u00ean m\u1ed9t t\u1eadp h\u1ee3p c\u00e1c thu\u1ed9c t\u00ednh \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 ATTRIBUTE. Do s\u1eed d\u1ee5ng metric kh\u00e1 ph\u1ee9c t\u1ea1p, BGP \u0111\u01b0\u1ee3c xem l\u00e0 m\u1ed9t giao th\u1ee9c kh\u00e1 ph\u1ee9c t\u1ea1p. Nhi\u1ec7m v\u1ee5 c\u1ee7a BGP l\u00e0 \u0111\u1ea3m b\u1ea3o th\u00f4ng tin li\u00ean l\u1ea1c gi\u1eefa c\u00e1c AS, trao \u0111\u1ed5i th\u00f4ng tin \u0111\u1ecbnh tuy\u1ebfn gi\u1eefa c\u00e1c AS, cung c\u1ea5p th\u00f4ng tin v\u1ec1 tr\u1ea1m k\u1ebf cho m\u1ed7i \u0111\u00edch \u0111\u1ebfn. BGP s\u1eed d\u1ee5ng giao th\u1ee9c TCP c\u1ed5ng 179. Nh\u01b0 c\u00e1c ch\u01b0\u01a1ng tr\u01b0\u1edbc \u0111\u00e3 \u0111\u1ec1 c\u1eadp, c\u00e1c giao th\u1ee9c nh\u00f3m distance vector th\u01b0\u1eddng qu\u1ea3ng b\u00e1 th\u00f4ng tin hi\u1ec7n c\u00f3 \u0111\u1ebfn c\u00e1c router l\u00e1ng gi\u1ec1ng, c\u00f2n path vector ch\u1ec9 ra ch\u00ednh x\u00e1c danh s\u00e1ch to\u00e0n b\u1ed9 \u0111\u01b0\u1eddng d\u1eabn \u0111\u1ebfn \u0111\u00edch. Ngo\u00e0i ra c\u00e1c giao th\u1ee9c \u0111\u1ecbnh tuy\u1ebfn ho\u1ea1t \u0111\u1ed9ng d\u00f9ng path vector gi\u00fap vi\u1ec7c x\u00e1c \u0111\u1ecbnh v\u00f2ng l\u1eb7p tr\u00ean m\u1ea1ng r\u1ea5t t\u1ed1t b\u1eb1ng c\u00e1ch xem x\u00e9t c\u00e1c con \u0111\u01b0\u1eddng m\u00e0 c\u00e1c router kh\u00e1c g\u1edfi v\u1ec1 xem c\u00f3 ch\u00ednh b\u1ea3n th\u00e2n AS trong \u0111\u00f3 hay kh\u00f4ng, n\u1ebfu c\u00f3 s\u1ebd bi\u1ebft \u0111\u01b0\u1ee3c ngay l\u00e0 l\u1eb7p, v\u00e0 s\u1ebd lo\u1ea1i b\u1ecf.
\nBGP h\u1ed7 tr\u1ee3 cho c\u00e1c \u0111\u1ecba ch\u1ec9 CIDR (Classless Interdomain Routing). BGP cho ph\u00e9p d\u00f9ng x\u00e1c th\u1ef1c v\u00e0 BGP c\u00f3 c\u00e1c c\u01a1 ch\u1ebf keepalive \u0111\u1ecbnh k\u1ef3 nh\u1eb1m duy tr\u00ec quan h\u1ec7 gi\u1eefa c\u00e1c BGP peers.
\nTrong giai \u0111o\u1ea1n ban \u0111\u1ea7u c\u1ee7a c\u1ee7a phi\u00ean thi\u1ebft l\u1eadp quan h\u1ec7 BGP, to\u00e0n b\u1ed9 c\u00e1c th\u00f4ng tin routing-update s\u1ebd \u0111\u01b0\u1ee3c g\u1eedi. Sau \u0111\u00f3, BGP s\u1ebd chuy\u1ec3n sang c\u01a1 ch\u1ebf d\u00f9ng trigger-update. B\u1ea5t k\u1ef3 m\u1ed9t thay \u0111\u1ed5i n\u00e0o trong h\u1ec7 th\u1ed1ng m\u1ea1ng c\u0169ng s\u1ebd l\u00e0 nguy\u00ean nh\u00e2n g\u00e2y ra trigger-update.
\nM\u1ed9t trong c\u00e1c \u0111\u1eb7c \u0111i\u1ec3m kh\u00e1c bi\u1ec7t nh\u1ea5t c\u1ee7a BGP l\u00e0 trong c\u00e1c routing-update c\u1ee7a n\u00f3. Khi ta xem x\u00e9t c\u00e1c BGP update, ta s\u1ebd nh\u1eadn th\u1ea5y c\u00e1c routing update n\u00e0y l\u00e0 kh\u00e1 ch\u00ednh x\u00e1c. BGP kh\u00f4ng quan t\u00e2m \u0111\u1ebfn vi\u1ec7c giao ti\u1ebfp \u0111\u1ec3 c\u00f3 \u0111\u1ea7y \u0111\u1ee7 ki\u1ebfn th\u1ee9c c\u1ee7a t\u1ea5t c\u1ea3 c\u00e1c subnet b\u00ean trong m\u1ed9t c\u00f4ng ty m\u00e0 BGP quan t\u00e2m \u0111\u1ebfn vi\u1ec7c chuy\u1ec3n t\u1ea3i \u0111\u1ea7y \u0111\u1ee7 th\u00f4ng tin \u0111\u1ec3 t\u00ecm m\u1ed9t AS kh\u00e1c. C\u00e1c BGP update th\u1ef1c hi\u1ec7n qu\u00e1 tr\u00ecnh summarization \u0111\u1ebfn m\u1ed9t m\u1ee9c t\u1ed1i \u0111a b\u1eb1ng c\u00e1ch cho ph\u00e9p m\u1ed9t s\u1ed1 AS, cho ph\u00e9p m\u1ed9t s\u1ed1 prefix v\u00e0 m\u1ed9t v\u00e0i th\u00f4ng tin \u0111\u1ecbnh tuy\u1ebfn. Tuy nhi\u00ean, m\u1ed9t ph\u1ea7n nh\u1ecf c\u1ee7a BGP update l\u00e0 kh\u00e1 quan tr\u1ecdng. BGP \u0111\u1ea3m b\u1ea3o r\u1eb1ng l\u1edbp transport \u0111\u00e3 truy\u1ec1n c\u00e1c update v\u00e0 c\u00e1c c\u01a1 s\u1edf d\u1eef li\u1ec7u v\u1ec1 \u0111\u01b0\u1eddng \u0111i \u0111\u00e3 \u0111\u01b0\u1ee3c \u0111\u1ed3ng b\u1ed9. BGP c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c hi\u1ec7n th\u1ef1c bao g\u1ed3m gi\u1eefa c\u00e1c AS kh\u00e1c nhau hay trong c\u00f9ng 1 AS. Khi d\u00f9ng BGP \u0111\u1ec3 k\u1ebft n\u1ed1i c\u00e1c AS kh\u00e1c nhau, BGP \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 eBGP. Giao th\u1ee9c n\u00e0y c\u0169ng c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ec3 mang th\u00f4ng tin gi\u1eefa c\u00e1c router eBGP trong m\u1ed9t AS. Khi \u0111\u00f3 BGP \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 iBGP.
\n\"\"
\nTrong m\u1ed9t AS ta s\u1eed d\u1ee5ng giao th\u1ee9c \u0111\u1ecbnh tuy\u1ebfn n\u1ed9i IGP (v\u00ed d\u1ee5 nh\u01b0 RIP, ISIS, EIGRP, OSPF) nh\u01b0ng khi ra ngo\u00e0i m\u1ed9t AS th\u00ec ph\u1ea3i s\u1eed d\u1ee5ng m\u1ed9t giao th\u1ee9c kh\u00e1c. V\u1ea5n \u0111\u1ec1 \u1edf \u0111\u00e2y ch\u00ednh l\u00e0 m\u1ee5c \u0111\u00edch c\u1ee7a c\u00e1c IGP v\u00e0 EGP kh\u00f4ng gi\u1ed1ng nhau. C\u00e1c IGP th\u1ef1c hi\u1ec7n \u0111\u1ecbnh tuy\u1ebfn g\u00f3i \u0111i t\u1eeb ngu\u1ed3n \u0111\u1ebfn \u0111\u00edch m\u00e0 kh\u00f4ng c\u1ea7n quan t\u00e2m \u0111\u1ebfn ch\u00ednh s\u00e1ch \u0111\u1ecbnh tuy\u1ebfn (policy). Trong khi ra kh\u1ecfi ph\u1ea1m vi m\u1ed9t AS th\u00ec ch\u00ednh s\u00e1ch \u0111\u1ecbnh tuy\u1ebfn l\u1ea1i l\u00e0 v\u1ea5n \u0111\u1ec1 quan tr\u1ecdng . X\u00e9t v\u00ed d\u1ee5 sau:<\/p>\n

AS4\u2014AS1\u2014AS2\u2014AS3\u2014(C Company)
\n|\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026.|
\n|\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026\u2026.|
\nB Company\u2014\u2014\u2014\u2013A Company<\/p>\n

Gi\u1ea3 s\u1eed A mu\u1ed1n truy\u1ec1n d\u1eef li\u1ec7u \u0111\u1ebfn AS4. A v\u00e0 B l\u00e0 2 \u0111\u1ed1i th\u1ee7 c\u1ee7a nhau. B kh\u00f4ng mu\u1ed1n chuy\u1ec3n d\u1eef li\u1ec7u cho c\u00f4ng ty A n\u00ean A ch\u1ec9 c\u00f3 th\u1ec3 chuy\u1ec3n d\u1eef li\u1ec7u th\u00f4ng qua AS3, AS2, AS1 \u0111\u1ec3 \u0111\u1ebfn \u0111\u01b0\u1ee3c AS4, m\u1eb7c d\u00f9 con \u0111\u01b0\u1eddng th\u00f4ng qua c\u00f4ng ty B c\u00f3 th\u1ec3 l\u00e0 t\u1ed1i \u01b0u nh\u1ea5t. Gi\u1ea3 s\u1eed C thu\u1ed9c AS3 c\u0169ng mu\u1ed1n \u0111\u1ebfn AS4 nh\u01b0ng C l\u00e0 \u0111\u1ed1i t\u00e1c c\u1ee7a B n\u00ean B s\u1eb5n s\u00e0ng cho qu\u00e1 giang. Nh\u01b0 v\u1eady A v\u00e0 C c\u00f3 c\u00f9ng m\u1ed9t \u0111\u00edch \u0111\u1ebfn nh\u01b0ng ph\u1ea3i \u0111i theo nh\u1eefng c\u00e1ch kh\u00e1c nhau. C\u00e1c IGP kh\u00f4ng th\u1ec3 l\u00e0m \u0111\u01b0\u1ee3c \u0111i\u1ec1u n\u00e0y v\u00ec m\u1ed9t nguy\u00ean nh\u00e2n ch\u1ee7 y\u1ebfu ch\u00ednh l\u00e0 c\u00e1c giao th\u1ee9c \u0111\u00f3 \u0111\u1ec1u li\u00ean quan \u0111\u1ebfn metric hay l\u00e0 cost m\u00e0 ho\u00e0n to\u00e0n kh\u00f4ng quan t\u00e2m \u0111\u1ebfn ch\u00ednh s\u00e1ch \u0111\u1ecbnh tuy\u1ebfn. N\u00f3 ch\u1ec9 bi\u1ebft c\u1ed1 g\u1eafng l\u00e0m sao chuy\u1ec3n \u0111\u01b0\u1ee3c c\u00e1c g\u00f3i d\u1eef li\u1ec7u \u0111\u1ebfn \u0111\u00edch m\u1ed9t c\u00e1ch hi\u1ec7u qu\u1ea3 v\u00e0 t\u1ed1i \u01b0u nh\u1ea5t.
\nC\u00e1c thu\u1eadt ng\u1eef BGP<\/p>\n

1
\nAggregation
\nL\u00e0 qu\u00e1 tr\u00ecnh t\u00f3m t\u1eaft c\u00e1c route \u2013 (summarization)<\/p>\n

2
\nAttribute
\nT\u01b0\u01a1ng t\u1ef1 nh\u01b0 metric. C\u00e1c bi\u1ebfn n\u00e0y s\u1ebd m\u00f4 t\u1ea3 c\u00e1c \u0111\u1eb7c \u0111i\u1ec3m c\u1ee7a \u0111\u01b0\u1eddng \u0111i t\u1edbi m\u1ed9t \u0111\u1ecba ch\u1ec9 \u0111\u00edch n\u00e0o \u0111\u00f3. Khi \u0111\u01b0\u1ee3c \u0111\u1ecbnh ngh\u0129a, c\u00e1c \u0111\u1eb7c \u0111i\u1ec3m n\u00e0y c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ec3 ra quy\u1ebft \u0111\u1ecbnh v\u1ec1 n\u00ean \u0111i theo \u0111\u01b0\u1eddng \u0111i n\u00e0o.<\/p>\n

3
\nAutonomous System
\n\u0110\u1ecbnh ngh\u0129a m\u1ea1ng c\u1ee7a m\u1ed9t t\u1ed5 ch\u1ee9c. Trong m\u1ed9t AS, c\u00e1c router s\u1ebd c\u00f3 c\u00f9ng giao th\u1ee9c \u0111\u1ecbnh tuy\u1ebfn. N\u1ebfu ta k\u1ebft n\u1ed1i ra Internet, ch\u1ec9 s\u1ed1 AS n\u00e0y ph\u1ea3i l\u00e0 duy nh\u1ea5t v\u00e0 \u0111\u01b0\u1ee3c cung c\u1ea5p b\u1edfi c\u00e1c \u1ee7y ban Internet.<\/p>\n

4
\nExterior Gateway Protocol (EGP)<\/p>\n

Thu\u1eadt ng\u1eef chung cho m\u1ed9t giao th\u1ee9c \u0111\u01b0\u1ee3c ch\u1ea1y gi\u1eefa c\u00e1c AS kh\u00e1c nhau. C\u0169ng c\u00f3 m\u1ed9t giao th\u1ee9c c\u00f3 t\u00ean l\u00e0 EGP l\u00e0 ti\u1ec1n th\u00e2n c\u1ee7a BGP<\/p>\n

5
\nEBGP
\nG\u1eedi th\u00f4ng tin \u0111\u1ecbnh tuy\u1ebfn gi\u1eefa c\u00e1c AS kh\u00e1c nhau<\/p>\n

6
\nInterior Gateway Protocol (IGP)<\/p>\n

\u0110\u00e2y l\u00e0 c\u00e1c giao th\u1ee9c \u0111\u1ecbnh tuy\u1ebfn ch\u1ea1y b\u00ean trong m\u1ed9t AS. Trong qu\u00e1 kh\u1ee9, thu\u1eadt ng\u1eef gateway th\u01b0\u1eddng \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ec3 \u0111\u1ecbnh ngh\u0129a m\u1ed9t router.<\/p>\n

7
\nIBGP
\nGiao th\u1ee9c n\u00e0y \u0111\u01b0\u1ee3c d\u00f9ng b\u00ean trong m\u1ed9t AS. C\u00e1c router kh\u00f4ng y\u00eau c\u1ea7u ph\u1ea3i l\u00e0 l\u00e1ng gi\u1ec1ng c\u1ee7a nhau v\u1ec1 ph\u01b0\u01a1ng di\u1ec7n k\u1ebft n\u1ed1i v\u1eadt l\u00fd v\u00e0 th\u01b0\u1eddng \u1edf ngo\u00e0i r\u00eca c\u1ee7a m\u1ed9t AS. IBGP \u0111\u01b0\u1ee3c d\u00f9ng gi\u1eefa c\u00e1c router ch\u1ea1y BGP trong c\u00f9ng m\u1ed9t AS.<\/p>\n

8
\nOriginator-ID<\/p>\n

\u0110\u00e2y l\u00e0 thu\u1ed9c t\u00ednh c\u1ee7a BGP. N\u00f3 l\u00e0 m\u1ed9t thu\u1ed9c t\u00ednh t\u00f9y ch\u1ecdn. Thu\u1ed9c t\u00ednh n\u00e0y s\u1ebd ch\u1ee9a gi\u00e1 tr\u1ecb routerID c\u1ee7a router \u0111\u00e3 ph\u00e1t sinh ra \u0111\u01b0\u1eddng \u0111i \u0111\u00f3. M\u1ee5c \u0111\u00edch c\u1ee7a thu\u1ed9c t\u00ednh n\u00e0y l\u00e0 ng\u0103n ng\u1eeba routing loop. N\u1ebfu m\u1ed9t router nh\u1eadn \u0111\u01b0\u1ee3c m\u1ed9t update t\u1eeb ch\u00ednh n\u00f3, router \u0111\u00f3 s\u1ebd b\u1ecf qua update \u0111\u00f3.<\/p>\n

9
\npolicy-based routing<\/p>\n

C\u01a1 ch\u1ebf n\u00e0y cho ph\u00e9p ng\u01b0\u1eddi qu\u1ea3n tr\u1ecb l\u1eadp tr\u00ecnh giao th\u1ee9c \u0111\u1ecbnh tuy\u1ebfn b\u1eb1ng c\u00e1ch \u0111\u1ecbnh ngh\u0129a traffic s\u1ebd \u0111\u01b0\u1ee3c route nh\u01b0 th\u1ebf n\u00e0o. \u0110\u00e2y l\u00e0 m\u1ed9t d\u1ea1ng c\u1ee7a \u0111\u1ecbnh tuy\u1ebfn t\u0129nh. PBR \u0111\u1ed9c l\u1eadp v\u1edbi c\u00e1c giao th\u1ee9c \u0111\u1ecbnh tuy\u1ebfn v\u00e0 d\u00f9ng route-map \u0111\u1ec3 t\u1ea1o ra c\u00e1c qu\u00e1 tr\u00ecnh ri\u00eang l\u1ebd \u0111\u1ec3 \u00e1p \u0111\u1eb7t c\u00e1c quy\u1ebft \u0111\u1ecbnh \u0111\u1ecbnh tuy\u1ebfn.<\/p>\n

10
\nprefix list<\/p>\n

Prefix list \u0111\u01b0\u1ee3c d\u00f9ng nh\u01b0 m\u1ed9t thay th\u1ebf cho distribute-list \u0111\u1ec3 ki\u1ec3m so\u00e1t BGP h\u1ecdc ho\u1eb7c qu\u1ea3ng b\u00e1 c\u00e1c c\u1eadp nh\u1eadt nh\u01b0 th\u1ebf n\u00e0o. Prefix-list th\u00ec nhanh h\u01a1n, uy\u1ec3n chuy\u1ec3n h\u01a1n v\u00e0 \u00edt t\u1ed1n t\u00e0i nguy\u00ean c\u1ee7a h\u1ec7 th\u1ed1ng h\u01a1n.<\/p>\n

11
\nRoute-reflector
\n\u0110\u00e2y l\u00e0 router \u0111\u01b0\u1ee3c c\u1ea5u h\u00ecnh \u0111\u1ec3 chuy\u1ec3n c\u00e1c routes t\u1eeb c\u00e1c router iBGP kh\u00e1c. Khi c\u1ea5u h\u00ecnh route-reflector, c\u00e1c iBGP kh\u00f4ng c\u1ea7n ph\u1ea3i fully-mesh n\u1eefa. M\u1ed9t m\u1ea1ng fully-mesh th\u00ec kh\u00f4ng c\u00f3 kh\u1ea3 n\u0103ng m\u1edf r\u1ed9ng.<\/p>\n

12
\nRoute-Reflector Client
\nM\u1ed9t client l\u00e0 m\u1ed9t router c\u00f3 m\u1ed9t TCP session v\u1edbi m\u1ed9t router kh\u00e1c ho\u1ea1t \u0111\u1ed9ng nh\u01b0 m\u1ed9t route-reflector-server. Client kh\u00f4ng c\u1ea7n thi\u1ebft ph\u1ea3i thi\u1ebft l\u1eadp peer v\u1edbi c\u00e1c client kh\u00e1c.<\/p>\n

13
\nRoute_reflector Clustor
\nM\u1ed9t cluster l\u00e0 m\u1ed9t nh\u00f3m bao g\u1ed3m m\u1ed9t route-reflector v\u00e0 clients. C\u00f3 th\u1ec3 c\u00f3 nhi\u1ec1u h\u01a1n m\u1ed9t route-reflector server trong m\u1ed9t cluster.<\/p>\n

14
\ntransit autonomous system<\/p>\n

L\u00e0 AS \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ec3 mang c\u00e1c BGP traffic qua c\u00e1c AS kh\u00e1c.<\/p>\n

Khi n\u00e0o th\u00ec d\u00f9ng BGP?<\/p>\n

Khi m\u1ea1ng c\u1ee7a m\u1ed9t c\u00f4ng ty k\u1ebft n\u1ed1i \u0111\u1ebfn nhi\u1ec1u ISP ho\u1eb7c c\u00e1c AS kh\u00e1c v\u00e0 \u0111ang d\u00f9ng c\u00e1c k\u1ebft n\u1ed1i n\u00e0y. Nhi\u1ec1u c\u00f4ng ty d\u00f9ng c\u00e1c k\u1ebft n\u1ed1i kh\u00e1c nhau nh\u1eb1m m\u1ee5c \u0111\u00edch d\u1ef1 ph\u00f2ng. Chi ph\u00ed c\u00f3 th\u1ec3 gi\u1ea3m thi\u1ec3u n\u1ebfu t\u1ea5t c\u1ea3 c\u00e1c k\u1ebft n\u1ed1i \u0111\u1ec1u \u0111\u01b0\u1ee3c d\u00f9ng. Trong tr\u01b0\u1eddng h\u1ee3p n\u00e0y, PBR c\u00f3 th\u1ec3 c\u1ea7n thi\u1ebft \u0111\u1ec3 tri\u1ec3n khai tr\u00ean t\u1eebng k\u1ebft n\u1ed1i. BGP c\u00f2n \u0111\u01b0\u1ee3c d\u00f9ng khi ch\u00ednh s\u00e1ch \u0111\u1ecbnh tuy\u1ebfn c\u1ee7a nh\u00e0 cung c\u1ea5p d\u1ecbch v\u1ee5 v\u00e0 c\u1ee7a c\u00f4ng ty kh\u00e1c nhau. Ho\u1eb7c traffic trong c\u00f4ng ty c\u1ea7n ph\u1ea3i \u0111\u01b0\u1ee3c ph\u00e2n bi\u1ec7t v\u1edbi traffic c\u1ee7a ISP. M\u1ea1ng c\u1ee7a hai t\u1ed5 ch\u1ee9c kh\u00f4ng th\u1ec3 xu\u1ea5t hi\u1ec7n nh\u01b0 m\u1ed9t AS. M\u1ed9t tr\u01b0\u1eddng h\u1ee3p kh\u00e1c ph\u1ea3i d\u00f9ng BGP l\u00e0 khi m\u1ea1ng c\u1ee7a ta l\u00e0 m\u1ed9t ISP. N\u1ebfu l\u00e0 m\u1ed9t ISP, h\u1ec7 th\u1ed1ng m\u1ea1ng n\u00e0y ph\u1ea3i cho ph\u00e9p c\u00e1c traffic kh\u00e1c \u0111i qua AS c\u1ee7a m\u00ecnh. L\u00fac n\u00e0y n\u00f3 ho\u1ea1t \u0111\u1ed9ng nh\u01b0 m\u1ed9t transit domain.<\/p>\n

Khi n\u00e0o th\u00ec kh\u00f4ng d\u00f9ng BGP?<\/p>\n

M\u1ed9t h\u1ec7 th\u1ed1ng m\u1ea1ng \u0111\u01a1n gi\u1ea3n l\u00e0 m\u1ed9t h\u1ec7 th\u1ed1ng m\u1ea1ng d\u1ec5 d\u00e0ng qu\u1ea3n l\u00fd v\u00e0 b\u1ea3o tr\u00ec. \u0110\u00e2y l\u00e0 l\u00fd do ch\u00ednh \u0111\u1ec3 tr\u00e1nh d\u00f9ng BGP trong m\u1ed9t h\u1ec7 th\u1ed1ng m\u1ea1ng. V\u00ec v\u1eady, n\u1ebfu h\u1ec7 th\u1ed1ng m\u1ea1ng c\u00f3 c\u00e1c \u0111\u1eb7c \u0111i\u1ec3m sau, n\u00ean d\u00f9ng nh\u1eefng c\u00e1ch th\u1ee9c kh\u00e1c, ch\u1eb3ng h\u1ea1n nh\u01b0 static ho\u1eb7c default-routing.<\/p>\n

\u2013 M\u1ea1ng c\u1ee7a ISP v\u00e0 m\u1ea1ng c\u1ee7a c\u00f4ng ty c\u00f3 chung m\u1ed9t ch\u00ednh s\u00e1ch \u0111\u1ecbnh tuy\u1ebfn<\/p>\n

\u2013 M\u1eb7c d\u00f9 c\u00f4ng ty c\u1ee7a b\u1ea1n c\u00f3 nhi\u1ec1u k\u1ebft n\u1ed1i \u0111\u1ebfn ISP, c\u00e1c k\u1ebft n\u1ed1i n\u00e0y l\u00e0 d\u1ef1 ph\u00f2ng v\u00e0 v\u00ec v\u1eady kh\u00f4ng c\u1ea7n m\u1ed9t k\u1ebf ho\u1ea1ch \u0111\u1ec3 k\u00edch ho\u1ea1t nhi\u1ec1u h\u01a1n m\u1ed9t k\u1ebft n\u1ed1i \u0111\u1ebfn Internet.<\/p>\n

\u2013 T\u00e0i nguy\u00ean m\u1ea1ng l\u00e0 c\u00f3 gi\u1edbi h\u1ea1n, ch\u1eb3ng h\u1ea1n nh\u01b0 b\u1ed9 nh\u1edb v\u00e0 CPU c\u1ee7a router.<\/p>\n

\u2013 B\u0103ng th\u00f4ng gi\u1eefa c\u00e1c AS l\u00e0 th\u1ea5p v\u00e0 c\u00e1c ph\u00ed t\u1ed5n cho \u0111\u1ecbnh tuy\u1ebfn s\u1ebd \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn qu\u00e1 tr\u00ecnh chuy\u1ec3n d\u1eef li\u1ec7u.<\/p>\n

M\u1ed9t s\u1ed1 thu\u1ed9c t\u00ednh quan tr\u1ecdng c\u1ee7a BGP
\nBGP \u0111\u1ecbnh tuy\u1ebfn traffic b\u1eb1ng c\u00e1ch s\u1eed d\u1ee5ng c\u00e1c thu\u1ed9c t\u00ednh. Vi\u1ec7c s\u1eed d\u1ee5ng c\u00e1c thu\u1ed9c t\u00ednh \u00e1m ch\u1ec9 \u0111\u1ebfn vi\u1ec7c s\u1eed d\u1ee5ng c\u00e1c bi\u1ebfn trong qu\u00e1 tr\u00ecnh ch\u1ecdn l\u1ef1a \u0111\u01b0\u1eddng \u0111i trong BGP. C\u00e1c thu\u1ed9c t\u00ednh c\u1ee7a BGP kh\u00f4ng ch\u1ec9 l\u00e0 danh s\u00e1ch c\u00e1c bi\u1ebfn m\u00e0 qua \u0111\u00f3 route \u0111\u01b0\u1ee3c ch\u1ecdn l\u1ef1a. M\u1ed9t v\u00e0i th\u00f4ng tin \u0111\u01b0\u1ee3c mang trong c\u00e1c th\u00f4ng \u0111i\u1ec7p c\u1eadp nh\u1eadt l\u00e0 quan tr\u1ecdng h\u01a1n c\u00e1c th\u00f4ng tin kh\u00e1c. M\u1ed9t s\u1ed1 th\u00f4ng tin kh\u00e1c l\u00e0 r\u1ea5t quan tr\u1ecdng cho ho\u1ea1t \u0111\u1ed9ng c\u1ee7a BGP, v\u00ec v\u1eady c\u00e1c th\u00f4ng tin n\u00e0y ph\u1ea3I \u0111\u01b0\u1ee3c mang \u0111\u1ebfn t\u1ea5t c\u1ea3 c\u00e1c router BGP trong m\u1ea1ng. Qu\u00e1 tr\u00ecnh ch\u1ecdn l\u1ef1a \u0111\u01b0\u1eddng \u0111i d\u1ef1a tr\u00ean nh\u1eefng thu\u1ed9c t\u00ednh v\u00e0 c\u00e1c gi\u00e1 tr\u1ecb c\u1ee7a n\u00f3. C\u00e1c thu\u1ed9c t\u00ednh \u0111\u01b0\u1ee3c chia th\u00e0nh hai nh\u00f3m: nh\u00f3m n\u1ed5I ti\u1ebfng (well-known) v\u00e0 nh\u00f3m t\u00f9y ch\u1ecdn (optional). C\u1ea3 hai nh\u00f3m n\u00e0y s\u1ebd \u0111\u01b0\u1ee3c ti\u1ebfp t\u1ee5c chia ra l\u00e0m c\u00e1c nh\u00f3m con.<\/p>\n

Nh\u00f3m
\nM\u00f4 t\u1ea3<\/p>\n

Well-known mandatory
\nC\u00e1c thu\u1ed9c t\u00ednh n\u00e0y l\u00e0 b\u1eaft bu\u1ed9c v\u00e0 \u0111\u01b0\u1ee3c c\u00f4ng nh\u1eadn b\u1edfi t\u1ea5t c\u1ea3 c\u00e1c router BGP<\/p>\n

Well-known Discretionary<\/p>\n

Kh\u00f4ng y\u00eau c\u1ea7u c\u00e1c thu\u1ed9c t\u00ednh n\u00e0y t\u1ed3n t\u1ea1i trong c\u00e1c c\u1eadp nh\u1eadt nh\u01b0ng n\u1ebfu ch\u00fang t\u1ed3n t\u1ea1i, t\u1ea5t c\u1ea3 c\u00e1c router s\u1ebd c\u00f4ng nh\u1eadn v\u00e0 s\u1ebd c\u00f3 h\u00e0nh \u0111\u1ed9ng t\u01b0\u01a1ng \u1ee9ng d\u1ef1a tr\u00ean th\u00f4ng tin \u0111\u01b0\u1ee3c ch\u1ee9a b\u00ean trong thu\u1ed9c t\u00ednh n\u00e0y.<\/p>\n

Optional Transitive
\nRouter c\u00f3 th\u1ec3 kh\u00f4ng c\u00f4ng nh\u1eadn c\u00e1c thu\u1ed9c t\u00ednh n\u00e0y nh\u01b0ng n\u1ebfu router nh\u1eadn \u0111\u01b0\u1ee3c thu\u1ed9c t\u00ednh n\u00e0y, n\u00f3 s\u1ebd \u0111\u00e1nh d\u1ea5u v\u00e0 g\u1eedi \u0111\u1ea7y \u0111\u1ee7 c\u1eadp nh\u1eadt n\u00e0y \u0111\u1ebfn router k\u1ebf ti\u1ebfp. C\u00e1c thu\u1ed9c t\u00ednh s\u1ebd kh\u00f4ng thay \u0111\u1ed5i khi \u0111i qua router n\u1ebfu thu\u1ed9c t\u00ednh n\u00e0y kh\u00f4ng \u0111\u01b0\u1ee3c c\u00f4ng nh\u1eadn b\u1edfi router.<\/p>\n

Optional Nontransitive
\nC\u00e1c thu\u1ed9c t\u00ednh n\u00e0y b\u1ecb lo\u1ea1i b\u1ecf n\u1ebfu c\u1eadp nh\u1eadt mang thu\u1ed9c t\u00ednh n\u00e0y \u0111i v\u00e0o router m\u00e0 router kh\u00f4ng hi\u1ec3u ho\u1eb7c kh\u00f4ng c\u00f4ng nh\u1eadn thu\u1ed9c t\u00ednh. C\u00e1c thu\u1ed9c t\u00ednh n\u00e0y s\u1ebd kh\u00f4ng truy\u1ec1n t\u1edbi c\u00e1c BGP.<\/p>\n

1. Thu\u1ed9c t\u00ednh AS_PATH: \u0110\u00e2y l\u00e0 thu\u1ed9c t\u00ednh quan tr\u1ecdng trong vi\u1ec7c x\u00e1c \u0111\u1ecbnh \u0111\u01b0\u1eddng \u0111i t\u1ed1i \u01b0u, mang 2 ch\u1ee9c n\u0103ng. Th\u1ee9 nh\u1ea5t, AS_PATH c\u00e0ng ng\u1eafn c\u00e0ng \u0111\u01b0\u1ee3c router \u01b0u ti\u00ean h\u01a1n. (v\u00ed d\u1ee5 t\u1eeb AS3 \u0111\u1ebfn AS4 c\u00f3 2 con \u0111\u01b0\u1eddng kh\u00e1c nhau: AS3 \u2013 B \u2013 AS4, ho\u1eb7c AS3 \u2013 AS2 \u2013 AS1 \u2013 AS4 th\u00ec router s\u1ebd \u01b0u ti\u00ean con \u0111\u01b0\u1eddng ng\u1eafn h\u01a1n l\u00e0 qua B). Ch\u1ee9c n\u0103ng th\u1ee9 hai l\u00e0 ng\u0103n ng\u1eeba v\u00f2ng l\u1eb7p. B\u1edfi v\u00ec thu\u1ed9c t\u00ednh AS_PATH r\u1ea5t quan tr\u1ecdng cho qu\u00e1 tr\u00ecnh ho\u1ea1t \u0111\u1ed9ng c\u1ee7a BGP n\u00ean t\u1ea5t c\u1ea3 c\u00e1c nh\u00e0 cung c\u1ea5p ph\u1ea3i h\u1ed7 tr\u1ee3 n\u00f3 v\u00e0 l\u00e0 m\u1ed9t thu\u1ed9c t\u00ednh mang t\u00ednh b\u1eaft bu\u1ed9c, ngh\u0129a l\u00e0 t\u1ea5t c\u1ea3 c\u00e1c b\u1ed9 \u0111\u1ecbnh tuy\u1ebfn ph\u1ea3i chuy\u1ec3n thu\u1ed9c t\u00ednh n\u00e0y \u0111\u1ebfn t\u1ea5t c\u1ea3 c\u00e1c l\u00e1ng gi\u1ec1ng trong m\u1ecdi th\u00f4ng \u0111i\u1ec7p c\u1eadp nh\u1eadt c\u1ee7a BGP.<\/p>\n

2. Thu\u1ed9c t\u00ednh ngu\u1ed3n g\u1ed1c (Origin-attribute): l\u00e0 m\u1ed9t thu\u1ed9c t\u00ednh x\u00e1c \u0111\u1ecbnh ngu\u1ed3n g\u1ed1c c\u1ee7a c\u00e1c routing th\u00f4ng tin c\u1eadp nh\u1eadt \u0111\u1ecbnh tuy\u1ebfn. N\u1ebfu l\u00e0 \u201ci \u201d th\u00ec ch\u1ec9 r\u1eb1ng routing th\u00f4ng tin c\u1eadp nh\u1eadt \u0111\u1ecbnh tuy\u1ebfn \u0111\u01b0\u1ee3c bi\u1ebft th\u00f4ng qua m\u1ed9t IGP (RIP, OSPF\u2026). N\u1ebfu gi\u00e1 tr\u1ecb \u201ce\u201d th\u00ec routing th\u00f4ng tin c\u1eadp nh\u1eadt \u0111\u1ecbnh tuy\u1ebfn \u0111\u01b0\u1ee3c bi\u1ebft th\u00f4ng qua m\u1ed9t EGP. N\u1ebfu gi\u00e1 tr\u1ecb \u201c?\u201d (incomplete) th\u00ec ch\u1ec9 r\u1eb1ng kh\u00f4ng bi\u1ebft ngu\u1ed3n g\u1ed1c c\u1ee7a routing th\u00f4ng tin c\u1eadp nh\u1eadt \u0111\u1ecbnh tuy\u1ebfn. (\u0110i\u1ec1u n\u00e0y c\u00f3 th\u1ec3 xu\u1ea5t hi\u1ec7n n\u1ebfu routing th\u00f4ng tin c\u1eadp nh\u1eadt \u0111\u1ecbnh tuy\u1ebfn \u0111\u01b0\u1ee3c bi\u1ebft th\u00f4ng qua IGP r\u1ed3i sau \u0111\u00f3 l\u1ea1i \u0111\u01b0\u1ee3c th\u00f4ng b\u00e1o qua EGP.). Khi n\u00f3 h\u1ecdc \u0111\u01b0\u1eddng b\u1eb1ng l\u1ec7nh network th\u00ec n\u00f3 \u0111\u1ec3 thu\u1ed9c t\u00ednh n\u00e0y l\u00e0: i. Khi n\u00f3 h\u1ecdc \u0111\u01b0\u1eddng qua c\u00e1c l\u1ec7nh nh\u01b0 redistribute v.v\u2026 th\u00ec n\u00f3 \u0111\u1ec3 thu\u1ed9c t\u00ednh l\u00e0: \u201c?\u201d.C\u00f2n sau \u0111\u00f3 c\u00e1c m\u1ea1ng n\u00e0y \u0111\u01b0\u1ee3c qu\u1ea3ng b\u00e1 t\u1edbi c\u00e1c EGP router l\u00e1ng gi\u1ec1ng th\u00ec thu\u1ed9c t\u00ednh n\u00e0y \u0111\u01b0\u1ee3c \u0111\u1ed5i th\u00e0nh e v\u00ec router m\u1edbi h\u1ecdc \u0111\u01b0\u1ee3c c\u00e1c tuy\u1ebfn \u0111\u01b0\u1eddng n\u00e0y nh\u1edd EGP. Thu\u1ed9c t\u00ednh origin kh\u00f4ng thay \u0111\u1ed5i qua giao th\u1ee9c EBGP m\u00e0 v\u1eabn gi\u1eef nguy\u00ean. Thu\u1ed9c t\u00ednh origin l\u00e0 e khi tuy\u1ebfn \u0111\u01b0\u1ee3c h\u1ecdc t\u1eeb giao th\u1ee9c EGP (\u0111\u00e2y l\u00e0 giao th\u1ee9c \u0111\u1ecbnh tuy\u1ebfn gi\u1eefa c\u00e1c AS, \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng nhi\u1ec1u tr\u00ean Internet khi BGP ch\u01b0a ra \u0111\u1eddi nh\u01b0ng hi\u1ec7n nay h\u1ea7u nh\u01b0 kh\u00f4ng c\u00f2n \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng)<\/p>\n

Next-Hop attribute:<\/p>\n

Trong eBGP, gi\u00e1 tr\u1ecb next-hop l\u00e0 \u0111\u1ecba ch\u1ec9 IP c\u1ee7a router t\u1eeb b\u00ean ngo\u00e0i c\u1ee7a v\u00f9ng t\u1ef1 tr\u1ecb AS qu\u1ea3ng b\u00e1 v\u00e0o b\u00ean trong AS. \u0110\u1ecba ch\u1ec9 IP \u0111\u01b0\u1ee3c ch\u1ec9 ra b\u1edfi l\u1ec7nh neighbor. Tuy nhi\u00ean trong m\u00f4i tr\u01b0\u1eddng multiaccess, n\u1ebfu m\u1ed9t route \u0111\u1ebfn t\u1eeb m\u1ed9t router, s\u1ebd l\u00e0 kh\u00f4ng kh\u00f4n ngoan n\u1ebfu m\u1ed9t router qu\u1ea3ng b\u00e1 \u0111\u1ecba ch\u1ec9 c\u1ee7a n\u00f3 nh\u01b0 l\u00e0 \u0111\u1ecba ch\u1ec9 ngu\u1ed3n v\u00ec \u0111i\u1ec1u n\u00e0y s\u1ebd d\u1eabn \u0111\u1ebfn vi\u1ec7c c\u00e1c packets b\u1ecb g\u1eedi \u0111\u1ebfn v\u00e0i router tr\u00ean m\u1ea1ng multiacess tr\u01b0\u1edbc khi c\u00f3 th\u1ec3 t\u00ecm ra \u0111\u01b0\u1ee3c ngu\u1ed3n g\u1ed1c xu\u1ea5t ph\u00e1t th\u1eadt s\u1ef1. V\u00ec v\u1eady, c\u00f3 m\u1ed9t lu\u1eadt r\u1eb1ng, \u0111\u1ecba ch\u1ec9 c\u1ee7a router xu\u1ea5t ph\u00e1t g\u00f3i tin BGP s\u1ebd v\u1eabn gi\u1eef nh\u01b0 \u0111\u1ecba ch\u1ec9 ngu\u1ed3n.<\/p>\n

Khi BGP khai b\u00e1o m\u1ed9t m\u1ea1ng, router t\u1ef1 \u0111\u1ecbnh r\u00f5 b\u1ea3n th\u00e2n router \u0111\u00f3 nh\u01b0 l\u00e0 Next Hop. Tuy nhi\u00ean, n\u1ebfu router \u0111\u00f3 g\u1edfi th\u00f4ng \u0111i\u1ec7p update cho m\u1ed9t router l\u00e1ng gi\u1ec1ng kh\u00e1c trong c\u00f9ng m\u1ed9t AS th\u00ec n\u00f3 l\u1ea1i ti\u1ebfp t\u1ee5c d\u00f9ng router ngo\u00e0i AS l\u00e0m Next hop. Do \u0111\u00f3 ta ph\u1ea3i c\u1ea5u h\u00ecnh cho c\u00e1c router c\u00f2n l\u1ea1i trong AS bi\u1ebft \u0111\u01b0\u1ee3c ch\u00ednh router \u1edf bi\u00ean c\u00f9ng AS v\u1edbi n\u00f3 l\u00e0 router Next Hop ch\u1ee9 kh\u00f4ng ph\u1ea3i l\u00e0 router kh\u00e1c AS.<\/p>\n

\"\"
\nB\u01b0\u1edbc 1: Router A g\u1eedi c\u1eadp nh\u1eadt v\u1ec1 m\u1ea1ng 192.33.33.0<\/p>\n

B\u01b0\u1edbc 2: Router D nh\u1eadn update v\u00e0 truy\u1ec1n. Tuy nhi\u00ean n\u1ebfu routerD thay \u0111\u1ed5i \u0111\u1ecba ch\u1ec9 source-address th\u00e0nh \u0111\u1ecba ch\u1ec9 \u0111\u1ecba ch\u1ec9 c\u1ee7a ch\u00ednh n\u00f3, s\u1ebd c\u00f3 m\u1ed9t s\u1ef1 nh\u1ea7m l\u1eabn x\u1ea3y ra v\u00ec trong m\u00f4i tr\u01b0\u1eddng multiaccess, m\u1ecdi router s\u1ebd c\u00f4ng b\u1ed1 n\u00f3 l\u00e0 next-hop. \u0110\u1ec3 tr\u00e1nh t\u00ecnh hu\u1ed1ng n\u00e0y, \u0111\u1ecba ch\u1ec9 ngu\u1ed3n c\u1ee7a update kh\u00f4ng thay \u0111\u1ed5i.<\/p>\n

B\u01b0\u1edbc 3: Router B bi\u1ebft routerA l\u00e0 next-hop c\u1ee7a m\u1ea1ng 192.33.33.0<\/p>\n

The Next-Hop Attribute and a Nonbroadcast Multiaccess Network<\/p>\n

C\u0169ng gi\u1ed1ng nh\u01b0 trong m\u00f4i tr\u01b0\u1eddng multiaccess, m\u1ed9t m\u1ea1ng NBMS c\u0169ng tu\u00e2n theo c\u00f9ng m\u1ed9t qui lu\u1eadt. Tuy nhi\u00ean s\u1ebd c\u00f3 ti\u1ec1m \u1ea9n m\u1ed9t v\u1ea5n \u0111\u1ec1 v\u00ec c\u00e1c router kh\u00e1c s\u1ebd kh\u00f4ng c\u00f3 kh\u1ea3 n\u0103ng k\u1ebft n\u1ed1i tr\u1ef1c ti\u1ebfp v\u1edbi router ngu\u1ed3n n\u1ebfu \u0111\u00e1m m\u00e2y NBMA c\u00f3 c\u1ea5u h\u00ecnh hub-and-spoke.<\/p>\n

\"\"
\nThu\u1ed9c t\u00ednh Nexthopself trong BGP<\/p>\n

150.10.0.0 (AS 100)
\nRouterA\u2014\u2014\u2013(150.10.3.1)\u2014IBGP\u2014\u2014\u2013RouterB\u2014|
\n|(170.10.20.1)
\n|
\n| (170.10.20.2)
\nRouterC
\n|_ 170.10.0.0 (AS 300)<\/p>\n

Thu\u1ed9c t\u00ednh BGP nexthop l\u00e0 m\u1ed9t \u0111\u1ecba ch\u1ec9 next hop IP m\u00e0 n\u00f3 s\u1ebd \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ec3 \u0111i \u0111\u1ebfn m\u1ed9t s\u1ed1 m\u1ea1ng \u0111\u00edch. \u0110\u1ed1i v\u1edbi EBGP, next hop lu\u00f4n lu\u00f4n l\u00e0 \u0111\u1ecba ch\u1ec9 IP c\u1ee7a router l\u00e1ng gi\u1ec1ng \u0111\u00e3 \u0111\u01b0\u1ee3c khai b\u00e1o trong c\u00e2u l\u1ec7nh neighbor. Theo v\u00ed d\u1ee5 tr\u00ean, RouterC s\u1ebd qu\u1ea3ng c\u00e1o network 170.10.0.0 cho RouterA v\u1edbi m\u1ed9t next hop l\u00e0 170.10.20.2 v\u00e0 ng\u01b0\u1ee3c l\u1ea1i RouterA s\u1ebd qu\u1ea3ng c\u00e1o l\u1ea1i 150.10.0.0 cho RouterC v\u1edbi m\u1ed9t next hop l\u00e0 170.10.20.1. \u0110\u1ed1i v\u1edbi IBGP, c\u00f3 m\u1ed9t nguy\u00ean t\u1eafc l\u00e0: \u201cthe next hop advertised by EBGP should be carried into IBGP\u201d. Ch\u00ednh v\u00ec quy lu\u1eadt n\u00e0y, n\u00ean Router A s\u1ebd qu\u1ea3ng c\u00e1o l\u1ea1i 170.10.0.0 cho c\u00e1c IBGP peer c\u1ee7a n\u00f3, trong tr\u01b0\u1eddng h\u1ee3p n\u00e0y l\u00e0 RouterB v\u1edbi m\u1ed9t next hop l\u00e0 170.10.20.2. V\u00ec th\u1ebf, l\u00fac n\u00e0y RouterB s\u1ebd c\u00f3 next hop \u0111\u1ec3 \u0111i \u0111\u1ebfn network 170.10.0.0 s\u1ebd l\u00e0 170.10.20.2 ch\u1ee9 KH\u00d4NG ph\u1ea3i l\u00e0 150.10.30.1
\nL\u00fac n\u00e0y th\u00ec b\u1ea1n ph\u1ea3i \u0111\u1ea3m b\u1ea3o r\u1eb1ng RouterB c\u00f3 th\u1ec3 reach 170.10.20.2 th\u00f4ng qua IGP, n\u1ebfu kh\u00f4ng RouterB s\u1ebd drop nh\u1eefng packet c\u00f3 dest. l\u00e0 170.10.0.0 v\u00ec l\u00fac n\u00e0y \u0111\u1ecba ch\u1ec9 next hop address tr\u1edf n\u00ean inaccessible. \u0110\u1ebfn \u0111\u00e2y th\u00ec b\u1ea1n h\u00e3y h\u00ecnh dung n\u1ebfu nh\u01b0 trong m\u00f4i tr\u01b0\u1eddng NBMA, v\u00e0 c\u00f3 th\u00eam m\u1ed9t RouterD (network 180.20.0.0) \u0111\u01b0\u1ee3c th\u00eam v\u00e0o trong AS 300, m\u00e0 RouterA kh\u00f4ng c\u00f3 PVC k\u1ebft n\u1ed1i tr\u1ef1c ti\u1ebfp \u0111\u1ebfn RouterD th\u00ec l\u00fac n\u00e0y nexthop c\u1ee7a RouterD qu\u00e3ng c\u00e1o cho RouterA m\u00e0 RouterA s\u1ebd kh\u00f4ng reach \u0111\u01b0\u1ee3c. L\u00fac n\u00e0y routing s\u1ebd fail. \u0110\u1ec3 kh\u1eafc ph\u1ee5c t\u00ecnh tr\u1ea1ng n\u00e0y th\u00ec NEXT-HOPE-SELF \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng.<\/p>\n

neighbor {ip-address| peer-group-name1 } next-hop-self<\/p>\n

C\u00e2u l\u1ec7nh n\u00e0y s\u1ebd cho ph\u00e9p \u00e1p \u0111\u1eb7t BGP d\u00f9ng \u0111\u1ecba ch\u1ec9 m\u00ecnh khai b\u00e1o th\u00e0nh next hop thay v\u00ec \u0111\u1ec3 BGP t\u1ef1 ch\u1ecdn next hop.<\/p>\n

RouterC#
\nrouter bgp 300
\nneighbor 170.10.20.1 remote-as 100
\nneighbor 170.10.20.1 next-hop-self<\/p>\n

RouterC s\u1ebd q\u1ee7ang c\u00e1o 180.20.0.0 v\u1edbi NextHop = 170.10.20.2. Next-hop-self ch\u1ec9 c\u00f3 l\u1ee3i trong m\u00f4i tr\u01b0\u1eddng nonmeshed.<\/p>\n

Local-Preference attribute: \u0110\u00e2y l\u00e0 thu\u1ed9c t\u00ednh kh\u00f4ng b\u1eaft bu\u1ed9c (t\u1ee9c l\u00e0 kh\u00f4ng c\u1ea7n ph\u1ea3i xu\u1ea5t hi\u1ec7n trong th\u00f4ng \u0111i\u1ec7p Update), ch\u1ec9 mang \u00fd ngh\u0129a c\u1ee5c b\u1ed9 trong ph\u1ea1m vi AS m\u00e0 kh\u00f4ng bao gi\u1edd g\u1edfi ra kh\u1ecfi AS \u0111\u00f3. N\u00f3 \u0111\u01b0\u1ee3c truy\u1ec1n \u0111\u1ebfn c\u00e1c local BGP neighbors. Thu\u1ed9c t\u00ednh Local-Preference cho ph\u00e9p ch\u00fang ta ch\u1ecdn con \u0111\u01b0\u1eddng mong mu\u1ed1n nh\u1ea5t ra kh\u1ecfi m\u1ed9t AS.<\/p>\n

Weight attribute: \u0110\u00e2y c\u0169ng l\u00e0 thu\u1ed9c t\u00ednh kh\u00f4ng b\u1eaft bu\u1ed9c, c\u00e1c nh\u00e0 cung c\u1ea5p kh\u00f4ng c\u1ea7n ph\u1ea3i h\u1ed7 tr\u1ee3 cho n\u00f3. Th\u1ef1c t\u1ebf thu\u1ed9c t\u00ednh ch\u1ec9 \u0111\u01b0\u1ee3c cung c\u1ea5p cho m\u1ed9t b\u1ed9 \u0111\u1ecbnh tuy\u1ebfn \u0111\u01a1n v\u00e0 kh\u00f4ng g\u1edfi trong b\u1ea5t k\u1ef3 th\u00f4ng \u0111i\u1ec7p Update n\u00e0o. Thu\u1ed9c t\u00ednh Weight \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ec3 \u0111i\u1ec1u khi\u1ec3n h\u01b0\u1edbng truy\u1ec1n c\u00e1c local packet \u0111\u1ebfn router khi router \u0111\u00f3 c\u00f3 hai route kh\u00e1c nhau ra kh\u1ecfi AS(multihomed).<\/p>\n

Thu\u1ed9c t\u00ednh MULTI_EXIT_DISC (MED)<\/p>\n

\u0110\u00e2y l\u00e0 thu\u1ed9c t\u00ednh \u0111\u01b0\u1ee3c AS d\u00f9ng \u0111\u1ec3 tham chi\u1ebfu cho vi\u1ec7c n\u00ean ch\u1ecdn router n\u00e0o \u0111\u1ec3 \u0111i \u0111\u1ebfn c\u00f9ng m\u1ed9t \u0111\u00edch trong m\u1ed9t AS. Trong BGP c\u0169ng c\u00f3 m\u1ed9t ATTRIBUTE \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 metric, \u0111\u00f3 l\u00e0 MED (Multiexit Discrimination). Tuy nhi\u00ean MED n\u00e0y c\u00f3 \u00fd ngh\u0129a h\u01a1i kh\u00e1c so v\u1edbi metric trong c\u00e1c IGP. BGP d\u00f9ng MED (metric) \u0111\u1ec3 h\u01b0\u1edbng d\u1eabn cho c\u00e1c router l\u00e1ng gi\u1ec1ng l\u1ef1a ch\u1ecdn \u0111\u01b0\u1eddng \u0111i t\u1ed1t nh\u1ea5t. MED(multiple-exit-discriminator) l\u00e0 1 attribute c\u1ee7a BGP, n\u00f3 gi\u1edbi thi\u1ec7u v\u1ec1 nh\u1eefng router l\u00e1ng gi\u1ec1ng b\u00ean ngo\u00e0i v\u1ec1 1 m\u1ea1ng \u0111\u01b0\u1ee3c ch\u1ecdn v\u00e0o 1 AS c\u00f3 nhi\u1ec1u exit point, c\u00e1i n\u00e0o c\u00f3 MED th\u1ea5p h\u01a1n s\u1ebd \u0111\u01b0\u1ee3c ch\u1ecdn (do \u0111\u00f3 c\u00f3 l\u1ebd n\u00f3 gi\u1ed1ng v\u1edbi metric), kh\u00f4ng gi\u1ed1ng nh\u01b0 Local Preference, MED \u0111\u01b0\u1ee3c trao \u0111\u1ed5i gi\u1eefa c\u00e1c AS nh\u01b0ng n\u00f3 s\u1ebd kh\u00f4ng ra kh\u1ecfi AS \u0111\u00f3 n\u1ebfu n\u00f3 \u0111\u00e3 v\u00e0o (khi 1 th\u00f4ng tin c\u1eadp nh\u1eadt \u0111\u1ecbnh tuy\u1ebfn v\u00e0o 1 AS v\u1edbi gi\u00e1 tr\u1ecb MEd x\u00e1c \u0111\u1ecbnh th\u00ec n\u00f3 s\u1ebd \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 th\u1ef1c hi\u1ec7n quy\u1ebft \u0111\u1ecbnh trong n\u1ed9i b\u1ed9 AS \u0111\u00f3 .N\u1ebfu 1 route xu\u1ea5t ph\u00e1t t\u1eeb ch\u00ednh AS th\u00ec MED s\u1ebd \u0111\u01b0\u1ee3c t\u00ednh theo metric c\u1ee7a IBGP. MED l\u00e0 m\u1ed9t attribute y\u1ebfu (trong th\u1ee9 t\u1ef1 route-selection c\u1ee7a BGP), n\u00ean \u0111\u1ec3 control \u0111\u01b0\u1ee3c n\u00f3 c\u1ea7n ph\u1ea3i care \u0111\u01b0\u1ee3c c\u00e1c thu\u1ed9c t\u00ednh c\u00f3 m\u1ee9c \u01b0u ti\u00ean cao h\u01a1n (weight-localpreference-originate-ASpath-origin code). H\u01a1n n\u1eefa, originated AS kh\u00f4ng th\u1ec3 \u0111i\u1ec1u khi\u1ec3n qu\u00e1 tr\u00ecnh \u0111\u1eb7t MED tr\u00ean c\u00e1c originating AS (neighbor AS), ho\u1eb7c ng\u01b0\u1ee3c l\u1ea1i, n\u00ean hi\u1ebfm khi \u0111\u01b0\u1ee3c d\u00f9ng trong th\u1ef1c t\u1ebf. Ngo\u00e0i ra, v\u1edbi nhi\u1ec1u Customer v\u1edbi c\u00e1c y\u00eau c\u1ea7u ch\u00ednh s\u00e1ch ch\u1ecdn outgoing traffic kh\u00e1c nhau, MED kh\u00f4ng hi\u1ec7u qu\u1ea3. Ng\u01b0\u1eddi ta hay s\u1eed d\u1ee5ng community attribute \u0111\u1ec3 gi\u1ea3i quy\u1ebft v\u1ea5n \u0111\u1ec1 ch\u1ecdn incomming traffic thay cho as-path prepending ho\u1eb7c MED.<\/p>\n

Communtity attribute:<\/p>\n

\u0110\u00e2y l\u00e0 m\u1ed9t thu\u1ed9c t\u00ednh kh\u00f4ng b\u1eaft bu\u1ed9c. Thu\u1ed9c t\u00ednh n\u00e0y \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ec3 cung c\u1ea5p ch\u00ednh s\u00e1ch cho m\u1ed9t nh\u00f3m c\u00e1c router \u0111i qua c\u00e1c AS. Do \u0111\u00f3 c\u00e1c router n\u00e0y c\u00f3 c\u00f9ng m\u1ed9t t\u00ednh ch\u1ea5t v\u00e0 c\u00f3 chung ch\u00ednh s\u00e1ch. N\u1ebfu m\u1ed9t router nh\u1eadn \u0111\u01b0\u1ee3c m\u1ed9t th\u00f4ng \u0111i\u1ec7p Th\u00f4ng tin c\u1eadp nh\u1eadt \u0111\u1ecbnh tuy\u1ebfn v\u1edbi thu\u1ed9c t\u00ednh Community \u0111\u01b0\u1ee3c thi\u1ebft l\u1eadp,n\u00f3 s\u1ebd x\u1eed l\u00fd th\u00f4ng \u0111i\u1ec7p n\u00e0y m\u1ed9t c\u00e1ch h\u1ee3p l\u00ed. N\u1ebfu n\u00f3 kh\u00f4ng hi\u1ec3u th\u00f4ng \u0111i\u1ec7p n\u00e0y th\u00ec s\u1ebd g\u1eedi thu\u1ed9c t\u00ednh \u0111\u00f3 cho router l\u00e1ng gi\u1ec1ng router x\u1eed l\u00fd. (Tuy nhi\u00ean, n\u1ebfu n\u00f3 hi\u1ec3u th\u00ec s\u1ebd kh\u00f4ng bao gi\u1edd g\u1eedi thu\u1ed9c t\u00ednh \u0111\u00f3 cho l\u00e1ng gi\u1ec1ng router tr\u1eeb khi \u0111\u01b0\u1ee3c ch\u1ec9 \u0111\u1ecbnh l\u00e0m th\u00eam \u0111i\u1ec1u g\u00ec \u0111\u00f3).<\/p>\n

T\u1ed5ng quan ho\u1ea1t \u0111\u1ed9ng c\u1ee7a BGP<\/p>\n

BGP l\u00e0 m\u1ed9t giao th\u1ee9c h\u01b0\u1edbng k\u1ebft n\u1ed1i. Khi thi\u1ebft l\u1eadp m\u1ed9t quan h\u1ec7 neighbor, m\u1ed9t phi\u00ean l\u00e0m vi\u1ec7c TCP s\u1ebd \u0111\u01b0\u1ee3c thi\u1ebft l\u1eadp v\u00e0 duy tr\u00ec. BGP s\u1ebd g\u1eedi ra c\u00e1c th\u00f4ng \u0111i\u1ec7p keepalive \u0111\u1ec3 ki\u1ec3m tra \u0111\u01b0\u1eddng truy\u1ec1n v\u00e0 duy tr\u00ec phi\u00ean l\u00e0m vi\u1ec7c TCP n\u00e0y. C\u00e1c th\u00f4ng \u0111i\u1ec7p keepalive n\u00e0y ch\u1ec9 l\u00e0 nh\u1eefng header c\u00f3 gi\u00e1 tr\u1ecb 19-bytes. Sau \u0111\u00f3 c\u00e1c router s\u1ebd g\u1eedi c\u00e1c c\u1eadp nh\u1eadt \u0111\u1ecbnh k\u1ef3 ch\u1ec9 khi c\u00f3 thay \u0111\u1ed5i x\u1ea3y ra. Sau khi \u0111\u00e3 \u0111i\u1ec1u ch\u1ec9nh b\u1ea3ng BGP, qu\u00e1 tr\u00ecnh BGP s\u1ebd truy\u1ec1n \u0111\u1ebfn t\u1ea5t c\u1ea3 c\u00e1c l\u00e1ng gi\u1ec1ng c\u00e1c thay \u0111\u1ed5i.<\/p>\n

C\u00f3 4 ki\u1ec3u th\u00f4ng \u0111i\u1ec7p \u0111\u01b0\u1ee3c d\u00f9ng trong BGP:<\/p>\n

Th\u00f4ng \u0111i\u1ec7p Open: \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ec3 thi\u1ebft l\u1eadp k\u1ebft n\u1ed1i v\u1edbi c\u00e1c router BGP kh\u00e1c.<\/p>\n

Th\u00f4ng \u0111i\u1ec7p keepalive: \u0111\u01b0\u1ee3c g\u1eedi \u0111\u1ecbnh k\u1ef3 gi\u1eefa c\u00e1c BGP peers \u0111\u1ec3 duy tr\u00ec k\u1ebft n\u1ed1I v\u00e0 \u0111\u1ec3 ki\u1ec3m tra \u0111\u01b0\u1eddng \u0111i. C\u00e1c th\u00f4ng \u0111i\u1ec7p keepalive n\u00e0y \u0111\u01b0\u1ee3c g\u1eedi theo c\u01a1 ch\u1ebf kh\u00f4ng tin c\u1eady. N\u1ebfu kho\u1ea3ng th\u1eddi gian \u0111\u1ecbnh k\u1ef3 \u0111\u01b0\u1ee3c g\u00e1n v\u1ec1 b\u1eb1ng 0, s\u1ebd kh\u00f4ng c\u00f3 th\u00f4ng \u0111i\u1ec7p keepalive n\u00e0o \u0111\u01b0\u1ee3c g\u1eedi.<\/p>\n

Th\u00f4ng \u0111i\u1ec7p c\u1eadp nh\u1eadt: ch\u1ee9a c\u00e1c \u0111\u01b0\u1eddng \u0111i v\u1ec1 c\u00e1c \u0111\u1ecba ch\u1ec9 \u0111\u00edch v\u00e0 c\u00e1c thu\u1ed9c t\u00ednh c\u1ee7a \u0111\u01b0\u1eddng \u0111i. C\u00e1c c\u1eadp nh\u1eadt bao g\u1ed3m c\u00e1c route kh\u00f4ng c\u00f2n t\u1ed3n t\u1ea1i. Th\u00f4ng tin ch\u1ee9a trong c\u00e1c c\u1eadp nh\u1eadt bao g\u1ed3m c\u00e1c thu\u1ed9c t\u00ednh v\u1ec1 \u0111\u01b0\u1eddng d\u1eabn, bao g\u1ed3m thu\u1ed9c t\u00ednh origin, AS_PATH, neighbor.<\/p>\n

Th\u00f4ng \u0111i\u1ec7p Notification: \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ec3 th\u00f4ng b\u00e1o cho c\u00e1c router kh\u00e1c v\u1ec1 nh\u1eefng nguy\u00ean nh\u00e2n g\u00e2y ra k\u1ebft n\u1ed1i b\u1ecb ng\u1eaft.<\/p>\n

CIDR v\u00e0 Route Aggregation<\/p>\n

BGP c\u1ea7n ph\u1ea3i truy\u1ec1n m\u1ed9t s\u1ed1 th\u00f4ng tin gi\u1eefa c\u00e1c AS nh\u01b0ng c\u00f3 l\u1ebd kh\u00f4ng ph\u1ea3i t\u1ea5t c\u1ea3 c\u00e1c th\u00f4ng tin l\u00e0 c\u1ea7n thi\u1ebft. N\u1ebfu h\u1ec7 th\u1ed1ng m\u1ea1ng \u0111\u01b0\u1ee3c thi\u1ebft k\u1ebf \u0111\u1ec3 h\u1ed7 tr\u1ee3 qu\u00e1 tr\u00ecnh summarization, t\u1ed5ng s\u1ed1 t\u00e0i nguy\u00ean m\u1ea1ng s\u1ebd \u0111\u01b0\u1ee3c gi\u1ea3m \u0111i b\u1edfi v\u00ec c\u00f3 r\u1ea5t \u00edt b\u1ed9 nh\u1edb, b\u0103ng th\u00f4ng v\u00e0 CPU \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ec3 g\u1eedi b\u1ea3ng \u0111\u1ecbnh tuy\u1ebfn. Th\u1eadt ra, b\u1eb1ng c\u00e1ch t\u00f3m t\u1eaft c\u00e1c l\u1edbp \u0111\u1ecba ch\u1ec9 IANA, m\u1ea1ng Internet s\u1ebd tr\u1edf th\u00e0nh m\u1ed9t m\u1ed9t m\u00f4i tr\u01b0\u1eddng nhanh h\u01a1n v\u00e0 tin c\u1eady h\u01a1n. C\u00e1ch d\u00f9ng CIDR l\u00e0 m\u1ed9t trong nh\u1eefng gi\u1ea3i ph\u00e1p \u0111\u01b0\u1ee3c d\u00f9ng nhi\u1ec1u trong nh\u1eefng n\u0103m g\u1ea7n \u0111\u00e2y. C\u00e1c \u0111\u1ecba ch\u1ec9 s\u1ebd \u0111\u01b0\u1ee3c h\u1ee3p nh\u1ea5t l\u1ea1i th\u00e0nh m\u1ed9t s\u1ed1 \u0111\u1ecba ch\u1ec9 d\u1ea1ng summary. Thay v\u00ec m\u1ed9t \u0111\u1ecba ch\u1ec9 c\u00f3 m\u1ed9t gi\u00e1 tr\u1ecb netmask \u0111\u1ec3 nh\u1eadn ra ph\u1ea7n \u0111\u1ecba ch\u1ec9 network, n\u00f3 s\u1ebd c\u00f3 m\u1ed9t gi\u00e1 tr\u1ecb prefix mask. Gi\u00e1 tr\u1ecb n\u00e0y \u0111\u01a1n gi\u1ea3n l\u00e0 m\u1ed9t con s\u1ed1 ch\u1ec9 ra s\u1ed1 bit \u0111\u00e3 d\u00e0nh cho ph\u1ea7n network. Qu\u00e1 tr\u00ecnh summarization s\u1ebd gi\u1ea3m thi\u1ec3u s\u1ed1 prefix. N\u1ebfu m\u1ed9t m\u1ea1ng \u0111\u01b0\u1ee3c c\u1ea5p t\u00e1m \u0111\u1ecba ch\u1ec9 l\u1edbp C, n\u00f3 c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c qu\u1ea3ng b\u00e1 nh\u01b0 m\u1ed9t network.<\/p>\n

BGP s\u1ebd truy\u1ec1n c\u00e1c prefix v\u00e0 c\u00e1c prefix mask. M\u1ed9t router c\u00f3 th\u1ec3 truy\u1ec1n route \u0111\u00e3 \u0111\u01b0\u1ee3c t\u00f3m t\u1eaft, c\u00e1c route ri\u00eang l\u1ebd ch\u01b0a \u0111\u01b0\u1ee3c summarize ho\u1eb7c truy\u1ec1n c\u1ea3 hai.<\/p>\n

\"\"
\nC\u01a1 ch\u1ebf ho\u1ea1t \u0111\u1ed9ng c\u1ee7a IBGP<\/p>\n

IBGP kh\u00f4ng thay \u0111\u1ed5i thu\u1ed9c t\u00ednh AS-PATH c\u1ee7a m\u1ed9t tuy\u1ebfn do \u0111\u00f3 \u0111\u1ec3 ch\u1ed1ng loop, s\u1eed d\u1ee5ng qui lu\u1eadt split-horizon: m\u1ed9t BGP peer s\u1ebd kh\u00f4ng g\u1edfi c\u00e1c tuy\u1ebfn \u0111\u01b0\u1ee3c h\u1ecdc t\u1eeb IBGP \u0111\u1ebfn m\u1ed9t BGP peer kh\u00e1c. Nh\u01b0 v\u1eady, \u0111\u1ec3 c\u00f3 th\u1ec3 forward d\u1eef li\u1ec7u cho c\u00e1c AS kh\u00e1c, c\u00e1c router c\u1ee7a transit AS ph\u1ea3i th\u1ef1c hi\u1ec7n:
\n\u2013 Gi\u1ea3i ph\u00e1p th\u1ee9 nh\u1ea5t: ph\u00e2n ph\u1ed1i l\u1ea1i c\u00e1c tuy\u1ebfn BGP v\u00e0o IGP \u0111\u1ec3 th\u1ecfa m\u00e3n qui lu\u1eadt \u0111\u1ed3ng b\u1ed9, nh\u01b0ng ph\u01b0\u01a1ng ph\u00e1p n\u00e0y kh\u00f4ng n\u00ean s\u1eed d\u1ee5ng trong c\u00e1c m\u1ea1ng core c\u1ee7a ISP do s\u1ed1 tuy\u1ebfn tr\u00ean Internet r\u1ea5t l\u1edbn, c\u00e1c IGP \u0111\u01b0\u1ee3c thi\u1ebft k\u1ebf kh\u00f4ng ph\u1ea3i \u0111\u1ec3 c\u00f3 th\u1ec3 qu\u1ea3n l\u00fd s\u1ed1 tuy\u1ebfn qu\u00e1 l\u1edbn nh\u01b0 v\u00e2y, ngo\u00e0i ra, n\u1ebfu d\u00f9ng ph\u01b0\u01a1ng ph\u00e1p n\u00e0y th\u00ec khi c\u00f3 s\u1ef1 thay \u0111\u1ed5i v\u1ec1 1 tuy\u1ebfn tr\u00ean Internet s\u1ebd l\u00e0m c\u00e1c IGP ph\u1ea3i th\u1ef1c hi\u1ec7n gi\u1ea3i thu\u1eadt t\u00ecm \u0111\u01b0\u1eddng -> chi\u1ebfm nhi\u1ec1u CPU v\u00e0 b\u1ed9 nh\u1edb g\u00e2y m\u1ea5t \u1ed5n \u0111\u1ecbnh.<\/p>\n

\u2013 Gi\u1ea3i ph\u00e1p th\u1ee9 hai: c\u00e1c BGP peer \u0111\u01b0\u1ee3c full-mesh \u0111\u1ec3 \u0111\u1ea3m b\u1ea3o c\u00e1c router \u0111\u1ec1u c\u00f3 \u0111\u1ee7 th\u00f4ng tin \u0111\u1ecbnh tuy\u1ebfn \u0111\u1ec3 forward packet. Khi n\u00e0y c\u00f3 th\u1ec3 t\u1eaft ch\u1ee9c n\u0103ng \u0111\u1ed3ng b\u1ed9 c\u1ee7a IBGP. Nh\u01b0ng full-mesh d\u1eabn \u0111\u1ebfn vi\u1ec7c kh\u00f3 qu\u1ea3n l\u00fd, t\u1ed1n b\u0103ng th\u00f4ng \u0111\u1ec3 c\u1eadp nh\u1eadt \u0111\u1ecbnh tuy\u1ebfn, t\u1ed1n CPU,mem. C\u00f3 2 c\u00e1ch \u0111\u1ec3 gi\u1ea3i quy\u1ebft v\u1ea7n \u0111\u1ec1 n\u00e0y. S\u1eed d\u1ee5ng Route Reflector: thay \u0111\u1ed5i qui lu\u1eadt split-horizon c\u1ee7a IBGP. C\u00e1c RR c\u00f3 th\u1ec3 g\u1edfi c\u00e1c tuy\u1ebfn IBGP \u0111\u1ebfn c\u00e1c BGP peer kh\u00e1c. \u0110\u1ec3 ch\u1ed1ng l\u1eb7p v\u00f2ng, c\u00e1c RR th\u00eam v\u00e0o c\u00e1c thu\u1ed9c t\u00ednh: cluster-id v\u00e0 originator. S\u1eed d\u1ee5ng Confederation: thay \u0111\u1ed5i c\u00e1ch x\u1eed l\u00fd AS-PATH c\u1ee7a IBGP: Chia m\u1ed9t AS th\u00e0nh nhi\u1ec1u member-AS. BGP gi\u1eefa c\u00e1c BGP peer thu\u1ed9c c\u00e1c member-AS kh\u00e1c nhau s\u1ebd l\u00e0 EBGP (t\u1ee9c l\u00e0 s\u1ebd th\u00eam member-AS v\u00e0o AS-PATH \u0111\u1ec3 ch\u1ed1ng loop) nh\u01b0ng c\u00e1c thu\u1ed9c t\u00ednh kh\u00e1c nh\u01b0 Local Preference, MED, Next-hop s\u1ebd kh\u00f4ng thay \u0111\u1ed5i. \u01afu \u0111i\u1ec3m c\u1ee7a gi\u1ea3i ph\u00e1p n\u00e0y l\u00e0 c\u00e1c member-AS c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c qu\u1ea3n l\u00fd \u0111\u1ed9c l\u1eadp, t\u0103ng kh\u1ea3 n\u0103ng ch\u00ednh s\u00e1ch \u0111\u1ecbnh tuy\u1ebfn routing. C\u00e1c member-AS c\u00f3 th\u1ec3 s\u1eed d\u1ee5ng c\u00e1c IGP kh\u00e1c nhau. Nh\u01b0ng qu\u1ea3n l\u00fd m\u1ed9t Confederation th\u00ec c\u00f3 th\u1ec3 s\u1ebd r\u1ea5t ph\u1ee9c t\u1ea1p do \u0111\u00f3 n\u00f3 ch\u1ec9 th\u00edch h\u1ee3p cho c\u00e1c ISP c\u1ef1c l\u1edbn (c\u00e1c ISP k\u1ebft n\u1ed1i tr\u1ef1c ti\u1ebfp v\u00e0o c\u00e1c \u0111i\u1ec3m trung chuy\u1ec3n qu\u1ed1c t\u1ebf nh\u01b0 NAP,\u2026) ho\u1eb7c c\u00e1c c\u00f4ng ty \u0111a qu\u1ed1c gia c\u1ea7n c\u00f3 s\u1ef1 linh \u0111\u1ed9ng v\u00e0 \u0111\u1ed9c l\u1eadp gi\u1eefa c\u00e1c th\u00e0nh ph\u1ea7n c\u1ee7a h\u1ec7 th\u1ed1ng. \u0110\u1ec3 l\u1ef1a ch\u1ecdn tuy\u1ebfn cho c\u00e1c Incoming traffic, c\u00f3 th\u1ec3 s\u1eed d\u1ee5ng c\u00e1c c\u00e1ch sau. S\u1eed d\u1ee5ng thu\u1ed9c t\u00ednh MED: c\u00e1ch n\u00e0y \u00edt s\u1eed d\u1ee5ng do MED l\u00e0 m\u1ed9t thu\u1ed9c t\u00ednh y\u1ebfu v\u00e0 non-transitive. S\u1eed d\u1ee5ng community: ph\u01b0\u01a1ng ph\u00e1p n\u00e0y \u0111\u00f2i h\u1ecfi ph\u1ea3i \u0111\u01b0\u1ee3c upstream ISP h\u1ed7 tr\u1ee3, ch\u1ec9 \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn ISP tr\u1ef1c ti\u1ebfp, trong nhi\u1ec1u tr\u01b0\u1eddng h\u1ee3p kh\u00f4ng l\u00e0m vi\u1ec7c t\u1ed1t. S\u1eed d\u1ee5ng AS-Prepend: ph\u01b0\u01a1ng ph\u00e1p n\u00e0y \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng th\u00f4ng d\u1ee5ng h\u01a1n do c\u00f3 th\u1ec3 l\u00e0m vi\u1ec7c t\u1ed1t trong t\u1ea5t c\u1ea3 c\u00e1c m\u00f4 h\u00ecnh. Nh\u01b0ng m\u1ed9t \u0111i\u1ec1u c\u1ea7n ph\u1ea3i nh\u1edb, quy\u1ebft \u0111\u1ecbnh tuy\u1ebfn cho Incoming traffic r\u1ea5t kh\u00f3 th\u1ef1c hi\u1ec7n ch\u00ednh x\u00e1c do c\u00e1c AS kh\u00e1c c\u00f3 th\u1ec3 thay \u0111\u1ed5i c\u00e1c attribute.<\/p>\n

\u0110\u1ec3 set metric, b\u1ea1n c\u00f3 th\u1ec3 d\u00f9ng l\u1ec7nh default-metric<\/p>\n

Router(config-router)#default-metric number<\/p>\n

ho\u1eb7c c\u00f3 th\u1ec3 d\u00f9ng route-map:<\/p>\n

router bgp 100
\nneighbor 1.1.1.1 route-map freddy out
\n!
\nip as-path access-list 1 permit ^690_
\nip as-path access-list 2 permit .*
\n!
\nroute-map freddy permit 10
\nmatch as-path 1
\nset metric 127
\n!
\nroute-map freddy permit 20
\nmatch as-path 2<\/p>\n

trong v\u00ed d\u1ee5 tr\u00ean, c\u00e1c route \u1edf as 690 s\u1ebd \u0111\u01b0\u1ee3c set metric l\u00e0 127.<\/p>\n

T\u00f3m t\u1eaft gi\u1ea3i thu\u1eadt t\u00ecm \u0111\u01b0\u1eddng \u0111i t\u1ed1t nh\u1ea5t c\u1ee7a BGP.<\/p>\n

BGP s\u1ebd g\u00e1n \u0111\u01b0\u1eddng \u0111i h\u1ee3p l\u1ec7 \u0111\u1ea7u ti\u00ean nh\u01b0 l\u00e0 \u0111\u01b0\u1eddng \u0111i t\u1ed1t nh\u1ea5t hi\u1ec7n c\u00f3. Sau \u0111\u00f3 BGP s\u1ebd so s\u00e1nh \u0111\u01b0\u1eddng \u0111i t\u1ed1t nh\u1ea5t n\u00e0y v\u1edbI \u0111\u01b0\u1eddng \u0111i k\u1ebf ti\u1ebfp trong danh s\u00e1ch cho \u0111\u1ebfn khi n\u00e0o ho\u00e0n t\u1ea5t t\u1ea5t c\u1ea3 c\u00e1c \u0111\u01b0\u1eddng trong danh s\u00e1ch c\u00e1c \u0111\u01b0\u1eddng \u0111i h\u1ee3p l\u1ec7. D\u01b0\u1edbI \u0111\u00e2y l\u00e0 danh s\u00e1ch c\u00e1c lu\u1eadt \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ec3 x\u00e1c \u0111\u1ecbnh \u0111\u01b0\u1eddng \u0111i t\u1ed1t nh\u1ea5t.<\/p>\n

* \u01afu ti\u00ean \u0111\u01b0\u1eddng \u0111i c\u00f3 tr\u1ecdng s\u1ed1 WEIGHT cao nh\u1ea5t. WEIGHT l\u00e0 m\u1ed9t th\u00f4ng s\u1ed1 do Cisco \u0111\u01b0a ra. Th\u00f4ng s\u1ed1 n\u00e0y ch\u1ec9 c\u00f3 \u1ea3nh h\u01b0\u1edfng trong ph\u1ea1m vi n\u1ed9i b\u1ed9 c\u1ee7a router \u0111\u01b0\u1ee3c c\u1ea5u h\u00ecnh d\u00f9ng th\u00f4ng s\u1ed1 n\u00e0y.<\/p>\n

* \u01afu ti\u00ean \u0111\u01b0\u1eddng \u0111i c\u00f3 LOCAL_PREF cao nh\u1ea5t. Nh\u1eefng \u0111\u01b0\u1eddng \u0111i kh\u00f4ng c\u00f3 thu\u1ed9c t\u00ednh LOCAL_PREF s\u1ebd c\u00f3 gi\u00e1 tr\u1ecb m\u1eb7c \u0111\u1ecbnh l\u00e0 100.<\/p>\n

* \u01afu ti\u00ean nh\u1eefng \u0111\u01b0\u1eddng \u0111i c\u00f3 ngu\u1ed3n g\u1ed1c t\u1eeb l\u1ec7nh network ho\u1eb7c l\u1ec7nh aggregate ho\u1eb7c th\u00f4ng qua qu\u00e1 tr\u00ecnh redistribution t\u1eeb m\u1ed9t IGP. C\u00e1c \u0111\u01b0\u1eddng \u0111i c\u00f3 ngu\u1ed3n g\u1ed1c t\u1eeb l\u1ec7nh network ho\u1eb7c l\u1ec7nh redistribution \u0111\u01b0\u1ee3c \u01b0u ti\u00ean h\u01a1n nh\u1eefng \u0111\u01b0\u1eddng \u0111i c\u00f3 ngu\u1ed3n g\u1ed1c t\u1eeb l\u1ec7nh aggregate.<\/p>\n

* \u01afu ti\u00ean nh\u1eefng \u0111\u01b0\u1eddng \u0111i c\u00f3 thu\u1ed9c t\u00ednh AS_PATH ng\u1eafn nh\u1ea5t. B\u01b0\u1edbc n\u00e0y s\u1ebd b\u1ecb b\u1ecf qua n\u1ebfu bi\u1ebfn bgp bestpath as-path \u0111\u01b0\u1ee3c c\u1ea5u h\u00ecnh. M\u1ed9t t\u1eadp h\u1ee3p AS_SET s\u1ebd \u0111\u01b0\u1ee3c \u0111\u1ebfm t\u1eeb 1, b\u1ea5t ch\u1ea5p c\u00f3 bao nhi\u00eau AS b\u00ean trong t\u1eadp h\u1ee3p. C\u00e1c bi\u1ebfn AS_CONFED_SEQUENCE v\u00e0 AS_CONFED_SET s\u1ebd kh\u00f4ng bao g\u1ed3m trong AS_PATH.<\/p>\n

* \u01afu ti\u00ean c\u00e1c \u0111\u01b0\u1eddng \u0111i c\u00f3 ngu\u1ed3n g\u1ed1c th\u1ea5p nh\u1ea5t. IGP th\u00ec th\u1ea5p h\u01a1p EGP v\u00e0 EGP th\u00ec th\u1ea5p h\u01a1n INCOMPLETE.<\/p>\n

* \u01afu ti\u1ebfn nh\u1eefng \u0111\u01b0\u1eddng \u0111i c\u00f3 gi\u00e1 tr\u1ecb MED nh\u1ecf nh\u1ea5t. S\u1ef1 so s\u00e1nh n\u00e0y ch\u1ec9 \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n n\u1ebfu AS \u0111\u1ea7u ti\u00ean l\u00e0 gi\u1ed1ng nhau cho c\u1ea3 hai \u0111\u01b0\u1eddng \u0111i. B\u1ea5t c\u1ee9 m\u1ed9t AS con n\u00e0o c\u1ee7a confederation s\u1ebd b\u1ecb b\u1ecf qua. N\u00f3i c\u00e1ch kh\u00e1c, MED \u0111\u01b0\u1ee3c so s\u00e1nh ch\u1ec9 n\u1ebfu gi\u00e1 tr\u1ecb AS \u0111\u1ea7u ti\u00ean trong AS_SEQUENCE l\u00e0 gi\u1ed1ng nhau. N\u1ebfu l\u1ec7nh bgp always-compare-med \u0111\u01b0\u1ee3c c\u1ea5u h\u00ecnh, MED \u0111\u01b0\u1ee3c so s\u00e1nh cho t\u1ea5t c\u1ea3 c\u00e1c \u0111\u01b0\u1eddng \u0111i c\u00f3 th\u1ec3. N\u1ebfu d\u00f9ng ch\u1ecdn l\u1ef1a n\u00e0y, t\u1ea5t c\u1ea3 c\u00e1c router trong AS ph\u1ea3I \u0111\u01b0\u1ee3c c\u1ea5u h\u00ecnh v\u1edbI ch\u1ecdn l\u1ef1a bgp always-compare-med, n\u1ebfu kh\u00f4ng routing loop s\u1ebd x\u1ea3y ra. N\u1ebfu th\u00f4ng s\u1ed1 bgp bestpath med-confed \u0111\u01b0\u1ee3c c\u1ea5u h\u00ecnh, MED s\u1ebd \u0111\u01b0\u1ee3c so s\u00e1nh tr\u00ean t\u1ea5t c\u1ea3 c\u00e1c \u0111\u01b0\u1eddng \u0111i m\u00e0 ch\u1ec9 ch\u1ee9a bi\u1ebfn AS_CONFED_SEQUENCE ( l\u00e0 nh\u1eefng \u0111\u01b0\u1eddng \u0111i xu\u1ea5t ph\u00e1t t\u1eeb local confederation). Nh\u1eefng \u0111\u01b0\u1eddng \u0111i \u0111\u01b0\u1ee3c nh\u1eadn t\u1eeb m\u1ed9t router l\u00e1ng gi\u1ec1ng c\u00f3 gi\u00e1 tr\u1ecb MED l\u00e0 4,294,967,295 s\u1ebd c\u00f3 gi\u00e1 tr\u1ecb MED thay \u0111\u1ed5I \u0111\u1ebfn 4,294,967,294 tr\u01b0\u1edbc khi \u0111\u01b0\u1ee3c ch\u00e8n v\u00e0o b\u1ea3ng BGP. Nh\u1eefng \u0111\u01b0\u1eddng \u0111i \u0111\u01b0\u1ee3c nh\u1eadn m\u00e0 kh\u00f4ng c\u00f3 MED \u0111\u01b0\u1ee3c c\u1ea5u h\u00ecnh s\u1ebd \u0111\u01b0\u1ee3c g\u00e1n gi\u00e1 tr\u1ecb MED b\u1eb1ng 0.<\/p>\n

* \u01afu ti\u00ean nh\u1eefng \u0111\u01b0\u1eddng \u0111i eBGP so v\u1edbI iBGP. N\u1ebfu \u0111\u01b0\u1eddng \u0111i t\u1ed1t nh\u1ea5t \u0111\u01b0\u1ee3c ch\u1ecdn l\u1ef1a, qua b\u01b0\u1edbc 9.<\/p>\n

* \u01afu ti\u00ean nh\u1eefng \u0111\u01b0\u1eddng \u0111i c\u00f3 IGP metric th\u1ea5p nh\u1ea5t \u0111\u1ebfn BGP next-hop.<\/p>\n

* Ki\u1ec3m tra xem c\u00f3 nhi\u1ec1u \u0111\u01b0\u1eddng \u0111i d\u1ef1 ph\u00f2ng c\u1ea7n ph\u1ea3i c\u00e0i \u0111\u1eb7t v\u00e0o b\u1ea3ng routing hay kh\u00f4ng. N\u1ebfu c\u1ea3 hai \u0111\u01b0\u1eddng \u0111i l\u00e0 t\u1eeb b\u00ean ngo\u00e0i, \u01b0u ti\u00ean \u0111\u01b0\u1eddng \u0111i \u0111\u01b0\u1ee3c nh\u1eadn tr\u01b0\u1edbc (\u0111\u01b0\u1eddng \u0111i c\u0169 nh\u1ea5t). B\u01b0\u1edbc n\u00e0y s\u1ebd b\u1ecb b\u1ecf qua n\u1ebfu<\/p>\n

-L\u1ec7nh bgp best path compare-routerid \u0111\u01b0\u1ee3c d\u00f9ng<\/p>\n

-RouterID l\u00e0 gi\u1ed1ng nhau cho nhi\u1ec1u \u0111\u01b0\u1eddng \u0111i v\u00ec c\u00e1c routes \u0111\u01b0\u1ee3c nh\u1eadn t\u1eeb c\u00f9ng 1 router.<\/p>\n

-Hi\u1ec7n t\u1ea1i kh\u00f4ng c\u00f3 m\u1ed9t \u0111\u01b0\u1eddng \u0111i t\u1ed1t nh\u1ea5t.<\/p>\n

* \u01afu ti\u00ean nh\u1eefng \u0111\u01b0\u1eddng \u0111i \u0111\u1ebfn t\u1eeb BGP router c\u00f3 routerID nh\u1ecf nh\u1ea5t. Gi\u00e1 tr\u1ecb routerID l\u00e0 \u0111\u1ecba ch\u1ec9 IP cao nh\u1ea5t tr\u00ean router. Gi\u00e1 tr\u1ecb n\u00e0y c\u0169ng c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c g\u00e1n b\u1eb1ng l\u1ec7nh bgp router-id. N\u1ebfu m\u1ed9t \u0111\u01b0\u1eddng \u0111i ch\u1ee9a 1 route-reflector, thu\u1ed9c t\u00ednh Originator ID c\u1ee7a Route-Reflector s\u1ebd thay th\u1ebf cho routerID.<\/p>\n

* N\u1ebfu RouterID l\u00e0 gi\u1ed1ng nhau cho nhi\u1ec1u \u0111\u01b0\u1eddng \u0111i, \u01b0u ti\u00ean \u0111\u01b0\u1eddng \u0111i c\u00f3 s\u1ed1 cluster l\u00e0 \u00edt nh\u1ea5t. \u0110i\u1ec1u n\u00e0y ch\u1ec9 \u0111\u00fang trong m\u00f4i tr\u01b0\u1eddng BGP route-reflector. N\u00f3 cho ph\u00e9p nh\u1eefng th\u00e0nh vi\u00ean trong Route-Reflector thi\u1ebft l\u1eadp quan h\u1ec7 peer v\u1edbI c\u00e1c th\u00e0nh vi\u00ean trong c\u00e1c RR kh\u00e1c.<\/p>\n

* \u01afu ti\u00ean nh\u1eefng \u0111\u01b0\u1eddng \u0111i \u0111\u1ebfn t\u1eeb nh\u1eefng l\u00e1ng gi\u1ec1ng c\u00f3 \u0111\u1ecba ch\u1ec9 th\u1ea5p nh\u1ea5t. \u0110\u1ecba ch\u1ec9 n\u00e0y l\u00e0 \u0111\u1ecba ch\u1ec9 \u0111\u01b0\u1ee3c d\u00f9ng trong l\u1ec7nh neighbor.<\/p>\n

\n

S\u01a0 L\u01af\u1ee2C V\u1ec0 GIAO TH\u1ee8C \u0110\u1ecaNH TUY\u1ebeN BGP<\/h2>\n

Nh\u01b0 ch\u00fang ta th\u1ea5y th\u1ebf gi\u1edb c\u00f4ng ngh\u1ec7 ng\u00e0y c\u00e0ng ph\u00e1t tri\u1ec3n, Internet ra \u0111\u1eddi \u0111\u00e3 v\u00e0 \u0111ang l\u00e0 m\u1ed9t b\u01b0\u1edbc ti\u1ebfn nh\u1ea3y v\u1ecdt c\u1ee7a c\u00f4ng ngh\u1ec7 th\u00f4ng tin. V\u1eady th\u1ef1c ch\u1ea5t internet l\u00e0 s\u1ef1 k\u1ebft n\u1ed1i c\u1ee7a nhi\u1ec1u AS (Automatic System) v\u1edbi nhau \u0111\u1ec3 trao \u0111\u1ed5i th\u00f4ng tin gi\u1eefa ch\u00fang. V\u00e0 BGP cung c\u1ea5p \u0111\u1ecbnh tuy\u1ebfn c\u00e1c AS n\u00e0y.<\/p>\n

N\u1ebfu ch\u1ec9 1 k\u1ebft n\u1ed1i \u0111\u1ebfn ISP th\u00ec kh\u00f4ng c\u1ea7n d\u00f9ng BGP, nh\u01b0ng n\u1ebfu nhi\u1ec1u k\u1ebft n\u1ed1i \u0111\u1ebfn 1 ISP th\u00ec BGP l\u00e0 1 l\u1ef1a ch\u1ecdn ph\u00f9 h\u1ee3p. M\u1ed9t c\u00e1ch ph\u00e2n lo\u1ea1i giao th\u1ee9c \u0111\u1ecbnh tuy\u1ebfn \u0111\u00f3 l\u00e0 li\u1ec7u ch\u00fang l\u00e0 Interio hay l\u00e0 Exterio +IGP (Interio Gateway Protocol) l\u00e0 giao th\u1ee9c \u0111\u1ecbnh tuy\u1ebfn b\u00ean trong 1 AS nh\u01b0 (RIP, IGRP, EIGRP, OSPF…). +EGP (Exterio Gateway Protocol) l\u00e0 giao th\u1ee9c trao \u0111\u1ed5i th\u00f4ng tin gi\u1eefa c\u00e1c AS kh\u00e1c nhau.<\/p>\n

\"Border<\/a><\/p>\n

Border Gateway Protocol<\/em><\/p>\n

Khi BGP ch\u1ea1y tr\u00ean nh\u1eefng AS kh\u00e1c nhau th\u00ec n\u00f3 \u0111c g\u1ecdi l\u00e0 Exteral BGP \u2013 EBGP, ch\u1ea1y trong c\u00f9ng 1 AS th\u00ec g\u1ecdi l\u00e0 Internal BGP-IBGP<\/p>\n

S\u01a1 l\u01b0\u1ee3c v\u1ec1 BGP:<\/strong><\/p>\n

+ C\u00e1c kh\u00e1i ni\u1ec7m li\u00ean quan \u0111\u1ebfn BGP<\/strong><\/em><\/p>\n

– Gi\u00e1 tr\u1ecb AD c\u1ee7a EBGP l\u00e0 20. Gi\u00e1 tr\u1ecb AD c\u1ee7a IBGP l\u00e0 200.<\/p>\n

– C\u00e1c BGP l\u00e1ng gi\u1ec1ng \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 c\u00e1c peers ph\u1ea3i \u0111\u01b0\u1ee3c c\u1ea5u h\u00ecnh tr\u1ef1c ti\u1ebfp theo ki\u1ec3u t\u0129nh.<\/p>\n

– BGP s\u1eed d\u1ee5ng TCP port 179. C\u00e1c BGP peers s\u1ebd trao \u0111\u1ed5i c\u00e1c th\u00f4ng tin nh\u01b0 th\u00f4ng tin c\u1eadp nh\u1eadt, g\u00f3i tin keepalive…<\/p>\n

– C\u00e1c Routers ch\u1ec9 c\u00f3 th\u1ec3 ch\u1ea1y m\u1ed9t BGP t\u1ea1i m\u1ed9t th\u1eddi \u0111i\u1ec3m<\/p>\n

– BGP l\u00e0 m\u1ed9t giao th\u1ee9c ki\u1ec3u path-vector. \u0110\u01b0\u1eddng \u0111i c\u1ee7a n\u00f3 \u0111\u1ebfn m\u1ed9t m\u1ea1ng bao g\u1ed3m m\u1ed9t danh s\u00e1ch c\u00e1c AS.<\/p>\n

– C\u01a1 ch\u1ebf ch\u1ed1ng loop l\u00e0 m\u1ed9t ASN- AS number. Khi m\u1ed9t c\u1eadp nh\u1eadt v\u1ec1 m\u1ed9t m\u1ea1ng \u0111i ra kh\u1ecfi 1 AS, ASN c\u1ee7a AS \u0111\u00f3 \u0111\u01b0\u1ee3c \u0111\u00ednh k\u00e8m v\u00e0o b\u1ea3n c\u1eadp nh\u1eadt. Khi m\u1ed9t AS nh\u1eadn m\u1ed9t c\u1eadp nh\u1eadt, n\u00f3 s\u1ebd xem trong AS list. N\u1ebfu nh\u1eadn ra ASN c\u1ee7a ch\u00ednh n\u00f3, c\u1eadp nh\u1eadt s\u1ebd b\u1ecb lo\u1ea1i b\u1ecf.<\/p>\n

+ BGP Database:<\/strong><\/em>\u00a0BGP d\u00f9ng 3 lo\u1ea1i database, 2 lo\u1ea1i d\u00f9ng ri\u00eang cho giao th\u1ee9c, 1 lo\u1ea1i d\u00f9ng cho to\u00e0n b\u1ed9 qu\u00e1 tr\u00ecnh routing tr\u00ean router<\/p>\n

– Neighbor database: m\u1ed9t danh c\u00e1ch t\u1ea5t c\u1ea3 c\u00e1c BGP l\u00e1ng gi\u1ec1ng \u0111\u01b0\u1ee3c c\u1ea5u h\u00ecnh.<\/p>\n

– BGP database, hay c\u00f2n g\u1ecdi RIB (Routing Information Base): m\u1ed9t danh s\u00e1ch c\u00e1c m\u1ea1ng m\u00e0 BGP bi\u1ebft, k\u00e8m theo l\u00e0 paths (\u0111\u01b0\u1eddng \u0111i) v\u00e0 attributes.<\/p>\n

\"BGP<\/a><\/p>\n

BGP s\u1eed d\u1ee5ng Route l\u00e0 c\u00e1c AS<\/em><\/p>\n

Routing table: danh s\u00e1ch c\u00e1c paths \u0111\u1ebfn m\u1ed1i m\u1ea1ng \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng b\u1edfi Router v\u00e0 next hop cho m\u1ed7i m\u1ea1ng.<\/p>\n

+ C\u00e1c ki\u1ec3u th\u00f4ng \u0111i\u1ec7p BGP: C\u00f3 4 ki\u1ec3u th\u00f4ng \u0111i\u1ec7p<\/strong><\/em><\/p>\n

– Open:<\/em>\u00a0sau khi m\u1ed9t l\u00e1ng gi\u1ec1ng \u0111\u01b0\u1ee3c c\u1ea5u h\u00ecnh, BGP g\u1eedi m\u1ed9t th\u00f4ng \u0111i\u1ec7p open \u0111\u1ec3 c\u1ed1 g\u1eafng k\u1ebft n\u1ed1i v\u1edbi l\u00e1ng gi\u1ec1ng \u0111\u00f3. Bao g\u1ed3m th\u00f4ng tin nh\u01b0 ASN, RIB, v\u00e0 hold time.<\/p>\n

– Update:<\/em>\u00a0th\u00f4ng \u0111i\u1ec7p n\u00e0y \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 trao \u0111\u1ed5i th\u00f4ng tin \u0111\u1ecbnh tuy\u1ebfn gi\u1eefa c\u00e1c peers. Ch\u1ee9a c\u00e1 th\u00f4ng v\u1ec1 c\u00e1c route m\u1edbi, c\u00e1c routes b\u1ecb down, v\u00e0 c\u00e1c thu\u1ed9c t\u00ednh c\u1ee7a \u0111\u01b0\u1eddng (path attributes).<\/p>\n

– Keepalive:<\/em>\u00a0m\u1eb7c \u0111\u1ecbnh, c\u00e1c BGP peers trao \u0111\u1ed5i th\u00f4ng \u0111i\u1ec7p n\u00e0y sau m\u1ed7i 60 gi\u00e2y. Ch\u00fang s\u1ebd gi\u1eef phi\u00ean l\u00e0m vi\u1ec7c gi\u1eefa c\u00e1c peer \u0111\u01b0\u1ee3c active .<\/p>\n

– Notification:<\/em>\u00a0khi x\u1ea3y ra 1 v\u1ea5n \u0111\u1ec1 l\u00e0m cho Router ph\u1ea3i k\u1ebft th\u00fac phi\u00ean l\u00e0m vi\u1ec7c BGP, m\u1ed9t th\u00f4ng \u0111i\u1ec7p notification s\u1ebd \u0111\u01b0\u1ee3c g\u1eedi \u0111\u1ebfn BGP neighbor v\u00e0 vi\u1ec7c k\u1ebft n\u1ed1i s\u1ebd ch\u1ea5m d\u1ee9t.<\/p>\n

\n

Ngo\u00e0i ra b\u1ea1n c\u00f3 th\u1ec3 tham kh\u1ea3o b\u00e0i post sau<\/p>\n

Th\u1ea5y a\/e trong di\u1ec5n \u0111\u00e0n nhi\u1ec1u ng\u01b0\u1eddi h\u1ecfi v\u00e0 th\u1eafc m\u1eafc v\u1ec1 giao th\u1ee9c BGP – Border Gateway Protocol
\nH\u00f4m nay m\u00ecnh xin ph\u00e9p n\u00f3i c\u00f4 \u0111\u1ecdng, ng\u1eafn g\u1ecdn v\u1ec1 giao th\u1ee9c n\u00e0y cho m\u1ecdi ng\u01b0\u1eddi d\u1ec5 h\u00ecnh dung, ko b\u1ecb hoang mang v\u00e0 nh\u1eabm l\u1eabn v\u1edbi c\u00e1c giao th\u1ee9c kh\u00e1c.
\n1. BGP c\u00e1c b\u1ea1n n\u00e0o l\u00e0m ISP th\u00ec hay ph\u1ea3i l\u00e0m vi\u1ec7c c\u00f9ng, ch\u1ee9 c\u00e1c b\u1ea1n qu\u1ea3n tr\u1ecb h\u1ec7 th\u1ed1ng doanh nghi\u1ec7p ho\u1eb7c c\u00e1c h\u1ec7 th\u1ed1ng network nh\u1ecf, ko c\u1ea7n bi\u1ebft \u0111\u1ebfn c\u00e1i n\u00e0y l\u00e0m g\u00ec nha\u2026Doanh nghi\u1ec7p m\u00e0 c\u00f3 c\u1ea5u h\u00ecnh k\u1ebft n\u1ed1i Internet – BGP th\u00ec ISP c\u0169ng sang t\u1eadn n\u01a1i l\u00e0m cho b\u1ea1n, config 1 l\u1ea7n c\u1ea3 \u0111\u1eddi ch\u1ea3 \u0111\u1ed5i\u00a0:<\/span><\/span>) n\u00ean kh\u1ecfi ph\u1ea3i m\u00f3 v\u00e0o n\u1eefa l\u00e0m g\u00ec.
\n2. Bi\u1ebft bao nhi\u00eau giao th\u1ee9c route, sao ph\u1ea3i h\u1ecdc BGP? \u0110\u1ecbnh tuy\u1ebfn \u0111\u1ed9ng h\u1ebft m\u00e0? sao ko d\u00f9ng RIP, EIGRP, OSPF? Ph\u1ee9c t\u1ea1p th\u00eam giao th\u1ee9c BGP n\u1eefa chi v\u1eady?
\n\u2043 C\u00e1c giao th\u1ee9c kia c\u00e1c b\u1ea1n nh\u1edb l\u00e0 ch\u1ec9 d\u00f9ng \u0111\u1ec3 d\u00e0nh cho c\u00e1c m\u1ea1ng doanh nghi\u1ec7p, ho\u1eb7c t\u1eeb doanh nghi\u1ec7p n\u00e0y t\u1edbi doanh nghi\u1ec7p kh\u00e1c th\u00f4i, ko c\u00f3 d\u00f9ng cho c\u00e1c ISP ( internet services provider) \u0111c nh\u00e9.
\n\u2043 v\u00e0i route , v\u00e0i ch\u1ee5c route, d\u00f9ng c\u00e1c \u0111\u1ecbnh tuy\u1ebfn tr\u00ean \u0111\u01b0\u1ee3c. Ch\u1ee9 t\u1ea7m ISP r\u1ed3i ph\u1ea3i c\u00f3 t\u1edbi h\u00e0ng ngh\u00ecn, v\u00e0i ch\u1ee5c ngh\u00ecn v\u00e0i tr\u0103m ngh\u00ecn route, l\u00e0m sao m\u00e0 \u0111\u1ecbnh tuy\u1ebfn n\u1ed5i n\u1eefa ==>\u0110\u00d3 L\u00c0 L\u00dd DO BGP RA \u0110\u1edcI.
\n3. BGP ph\u1ee5c v\u1ee5 khi c\u1ea5u h\u00ecnh router gi\u1eefa c\u00e1c nh\u00e0 m\u1ea1ng ISP v\u1edbi nhau ho\u1eb7c t\u1eeb doanh nghi\u1ec7p t\u1edbi nh\u00e0 m\u1ea1ng khi c\u00f3 2 hay nhi\u1ec1u \u0111\u01b0\u1eddng thu\u00ea bao t\u1edbi 2 hay nhi\u1ec1u nh\u00e0 m\u1ea1ng kh\u00e1c nhau tr\u1edf l\u00ean.
\n4. Mu\u1ed1n n\u1eafm \u0111c BGP ph\u1ea3i hi\u1ec3u \u0111\u01b0\u1ee3c kh\u00e1i ni\u1ec7m AS ( Autonomous System) hay c\u00f2n g\u1ecdi l\u00e0 \u2018\u2019h\u1ec7 th\u1ed1ng t\u1ef1 tr\u1ecb\u201d. C\u00e1i n\u00e0y d\u1ec5 hi\u1ec3u th\u00f4i nh\u00e9, m\u1ed7i nh\u00e0 m\u1ea1ng ISP n\u00f3 c\u00f3 m\u1ed9t d\u1ea3i m\u1ea1ng vd Viettel 203.x.x.x, FPT 118.x.x.x th\u00ec c\u00e1i range n\u00e0y s\u1ebd n\u1eb1m trong range d\u1ea3i ip c\u1ee7a nh\u00e0 cung c\u1ea5p. Th\u1ebf th\u00ec \u0111\u00e2u l\u00e0 \u0111\u1ec3 nh\u1eadn bi\u1ebft \u0111\u01b0\u1ee3c \u0111\u00e2u l\u00e0 d\u1ea3i m\u1ea1ng c\u1ee7a ISP n\u00e0o??? Ta d\u1ef1a v\u00e0o c\u00e1i s\u1ed1 AS \u0111\u00f3, m\u1ed7i nh\u00e0 m\u1ea1ng coi nh\u01b0 l\u00e0 1 KHU T\u1ef0 TR\u1eca ri\u00eang v\u00e0 n\u00f3 \u0111\u01b0\u1ee3c g\u00e1n s\u1ed1 cho KHU T\u1ef0 TR\u1eca \u0111\u00f3 ==> c\u00e1i s\u1ed1 \u0111\u00f3 g\u1ecdi l\u00e0 AS Number \u0111\u00f3.
\n5. C\u00f3 r\u1ea5t nhi\u1ec1u thu\u1ed9c t\u00ednh \u0111\u1ec3 l\u1ef1a ch\u1ecdn \u0111\u01b0\u1eddng \u0111i trong \u0111\u1ecbnh tuy\u1ebfn BGP ch\u1ee9 ko nh\u01b0 c\u00e1c \u0111\u1ecbnh tuy\u1ebfn kh\u00e1c, ch\u1ec9 d\u1ef1a v\u00e0o s\u1ed1 metric cost m\u00e0 l\u1ef1a ch\u1ecdn \u0111\u01b0\u1eddng \u0111i, \u1edf BGP c\u00f3 t\u1edbi m\u01b0\u1eddi m\u1ea5y thu\u1ed9c t\u00ednh \u0111c \u0111\u01b0a v\u00e0o \u0111\u1ec3 t\u00ednh to\u00e1n \u0111\u01b0\u1eddng \u0111i t\u1ed1i \u01b0u t\u1eeb isp n\u00e0y t\u1edbi isp kh\u00e1c
\n6. C\u00e1c router \u0111\u1ecbnh tuy\u1ebfn AS-by-AS ch\u1ee9 ko c\u00f2n l\u00e0 Hop-by-hop nh\u01b0 c\u00e1c giao th\u1ee9c \u0111\u1ecbnh tuy\u1ebfn kh\u00e1c
\n7. BGP tin c\u1eady h\u01a1n ospf hay c\u00e1c giao th\u1ee9c \u0111\u1ecbnh tuy\u1ebfn kh\u00e1c do ch\u1ea1y tr\u00ean n\u1ec1n TCP ch\u1ee9 ko ph\u1ea3i IP nh\u01b0 c\u00e1c giao th\u1ee9c kia.
\n8. Khi c\u00f3 thay \u0111\u1ed5i \u0111\u1ecbnh tuy\u1ebfn, l\u1eadp t\u1ee9c thay \u0111\u1ed5i v\u00e0 update ch\u1ee9 ko c\u00f3 th\u1eddi gian \u0111\u1ecbnh k\u1ef3 update. Ch\u1ec9 update thay \u0111\u1ed5i ch\u1ee9 ko update l\u1ea1i c\u1ea3 b\u1ea3ng \u0111\u1ecbnh tuy\u1ebfn
\nM\u1ecdi ng\u01b0\u1eddi c\u00f3 c\u00e2u h\u1ecfi hay \u00fd ki\u1ebfn \u0111\u00f3ng g\u00f3p comment th\u00eam cho a\/e r\u00f5 th\u00eam nh\u00e9<\/span><\/p>\n

https:\/\/www.facebook.com\/allen.peter.54379\/posts\/119810262245241<\/p>\n","protected":false},"excerpt":{"rendered":"

S\u1ef1 c\u1ea7n thi\u1ebft c\u1ee7a BGP BGP l\u00e0 m\u1ed9t giao th\u1ee9c kh\u00e1 ph\u1ee9c t\u1ea1p \u0111\u01b0\u1ee3c d\u00f9ng nhi\u1ec1u tr\u00ean Internet v\u00e0 trong […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[29,31,27,28,21,6],"tags":[36],"class_list":["post-505","post","type-post","status-publish","format-standard","hentry","category-ccie-rs","category-ccnp-route","category-jncie","category-jncip","category-juniper","category-networking","tag-bgp"],"_links":{"self":[{"href":"https:\/\/kb.lagonet.vn\/index.php?rest_route=\/wp\/v2\/posts\/505","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kb.lagonet.vn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kb.lagonet.vn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kb.lagonet.vn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/kb.lagonet.vn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=505"}],"version-history":[{"count":0,"href":"https:\/\/kb.lagonet.vn\/index.php?rest_route=\/wp\/v2\/posts\/505\/revisions"}],"wp:attachment":[{"href":"https:\/\/kb.lagonet.vn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=505"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kb.lagonet.vn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=505"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kb.lagonet.vn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=505"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}