
一。bgp配制中的属性
7 [. y: s* }8 [1 S0 A『19.0.0.0/8-RTa-ospf-RTb』- ebgp-2.2.2.2
; `6 j2 @$ t; z$ `!!!!!!控制出站路由!!!!!!!!!!!!!!!!!!!!!!!!!!!1 E" k) \2 a6 Y
已知某国政府官方网站只希望本国公民访问,不希望国外流量访问。该国的官方网站集中在181.194.33.0、24 网段内(在RTA与RTB间的AS里)
+ l& W9 o) w+ O: u4 zaccess-list 1 deny 181.194.33.0 0.0.0.255% k" ^# y" H' x( }3 n
access-list 1 permit any7 M- d6 U9 }: h# {
5 i, B. E" B2 h2 Lrouter bgp 1
* f" z6 L5 r ~nei 1.1.1.1 remote-as 2. \) m& }8 ^0 s) n( _
nei 1.1.1.1 router-map deny181 out
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route-map deny181 permit 107 @8 I8 o; a0 {. f
match ip address 1
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!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
, Q9 a l8 Z# I* `# k5 h4 @5 elocal-prefernce实例
* ?2 e7 N& O, Y+ T3 \& z【AS2】 【AS3】1 A$ ]. F: q8 y
、 ’
3 w e- Z' X" f1 Z! n7 T 【AS1】 R @- l. [" q! b& p) w1 g
AS1有两个出站策略时候- p5 V7 ~* [# }% \7 c
Acces-list 1 permit any! I# S: `8 K4 i, |& N
router bgp 1
3 X1 K2 ~; J: }$ wnei 2.2.2.2 remote-as 2
2 w3 y Q% K; \8 Q" p$ w6 q1 v1 hnei 2.2.2.2 router-map set_local in8 B0 c9 j3 n, e; o7 J( D
nei 3.3.3.3 remote-as 3
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$ ]8 X9 z& y6 _' u) L Y1 {' uroute-map set_local permit 107 n$ ^+ y1 U8 j& \1 A
match ip add address 1% y5 _8 F- B7 ]- C. W7 P
set local-preference 200- ^. _6 }) N4 O6 i' k
local preference 的缺省值是100 值越大优先级越高
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" u" n P c' @8 R6 y; Q/ J# L!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
6 M, w( ?" ] y" X: K3 PMED实例
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『AS200【A】【B】』
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/ R8 c" S. X- ~ I[]网通两个国际出口,希望出流量负载均衡,入流量只通过右下的[]进来9 t( W. T2 R7 ]3 I
ip as-path access-list 10 permit ^$' d# R+ I: S1 U* X& F2 ]
ip as-path access-list 10 deny *
% x* r% |! i. ~- F3 p' Frouter bgp 1
% F [5 a$ Z( i) _4 X2 dnei 2.2.2.2 remote-as 23 c* e3 c4 X, P" A3 Q% H! v
nei 2.2.2.2 route-map my_med out- M- I+ n x( O$ e
router-map my_med permit 20
+ J0 [5 z0 a' N' C/ Zmatch as-path 10+ D$ K1 y; O- L' l. v3 H* W
set metric 20002 F3 d4 S5 q3 W; J) W5 p, z0 y
med缺省值是0 值越小越优
# M6 y+ S1 c+ n. @1 C% T2 e!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
- |" N- H% M7 U8 G& sAS path实例
3 G4 ]2 X+ \2 P9 B某国政府不希望民众访问美国的站点,已经知道美国的AS是400
. a: t4 E0 R7 S' {9 dIp as-path access-list deny _400$
5 U. h2 k; r* w7 w. M5 f, d* g+ H/ Cip as-path access-list 1 permit any2 Q( z9 ]2 B: h4 G2 p# K
router bgp 1
, B9 L/ [9 W" A+ U; \2 Snei 2.2.2.2 remote-as 2 阿富汉自治系统邻居配
% m- v2 ^# B4 A" o" f# \, q Q% Tnei 2.2.2.2 router-map deny_usa in
2 s' \9 c+ e+ p* L" D, Lroute-map deny_usa permit 10
. C' d0 F B) E/ z% Rmatch as-path 14 n" n0 p5 q) Y, v- @8 w
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
2 ~+ j) l' F' T% n7 a8 I2 Icommunity属性的实际应用+ E& k( j1 w1 m+ p9 E7 \- Y$ S/ X
一群路由的团体而不是路由器的团体。 b% h/ M) T% V# X+ T
已知中国移动互联网中,每个省都有一台路由器运行BGP0
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想知道某些网段来自哪个省。
1 E1 S2 O" q, L" M& S7 d3 v) faccess-list 1 permit any! T3 v# C- ~$ R+ T4 q
router bgp 65000
& A' O7 N+ w% xnet 202.24.0.0 255.255.0.0 route-map set-comm out$ K9 j, n/ r7 J4 d8 K- J
nei 2.2.2.2 remote-as 65000国际出口路由
i) B- w8 S _7 U' lnei 2.2.2.2 send-community* m$ }. | R. F: f
router-map set_comm permit 10
. s7 G; f4 q4 l) g8 \0 Gmatch ip add 1
% o6 X; Z5 h$ U% A/ y! x% Jset community 65000:24 additive1 M/ c8 E3 K# y/ i
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# S$ H: @1 \4 a q4 _& e f. N" S为了防止破坏或者是防2 o# J, I; E! h- b B A' M3 t& q
止一些工程师错误配置对自己的影响我们访问列表拒绝掉从BGP学来的默认8 k& f4 E# _% ?0 k, h! G/ V9 v! N
ACces-list 1 deny 0
" X) M N1 W9 w5 m. haccess-list 1 permit any
# [# G6 M/ X! E6 e- X. \" Krouter bgp 1% b6 X* j5 L# ~& ?
distribute-list 1 in# z: G m- s3 }% U5 [
每台运行EBGP的路由器上一定不会有一条指向其他EBGP邻居的缺省路由; q* L7 ~6 J$ t# E$ v8 q
不将无效的流量指向他人,是一台BGP路由器应尽到的义务 |
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