
一。bgp配制中的属性
* F% e6 B7 S! y1 S! t: P' e『19.0.0.0/8-RTa-ospf-RTb』- ebgp-2.2.2.23 @8 B( w5 o! g4 `5 h3 `
!!!!!!控制出站路由!!!!!!!!!!!!!!!!!!!!!!!!!!!
v5 L& R7 r5 ^7 E" Z7 y+ R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)
0 G! |9 h$ _) M. [ Aaccess-list 1 deny 181.194.33.0 0.0.0.2559 z+ R B0 t, ~9 t. ~
access-list 1 permit any& z N0 ]$ J+ Z2 `8 ?* w
- D2 g8 N8 I/ k6 [, _router bgp 1
& y' W5 O1 J2 A1 H. F" E" Fnei 1.1.1.1 remote-as 23 j7 u2 l. |5 g
nei 1.1.1.1 router-map deny181 out2 V( m0 m( t7 G! Y8 W
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route-map deny181 permit 104 T4 P. o: s3 L3 X
match ip address 1
# C' Y0 A0 L: @' T& M2 G0 A% e: L!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! j+ _1 w W3 m
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
# d3 G/ ]* H6 o7 ^local-prefernce实例: C0 G! J% A4 X, h O) s0 H4 B% O6 Q
【AS2】 【AS3】( y+ g! s! j2 X1 I- n; x
、 ’
& _; f0 ^* b$ ?$ W2 I7 Q6 C 【AS1】
2 ~. G% o3 H% U' Z: H: v. u x+ OAS1有两个出站策略时候
% R g; X9 d: t0 _6 W8 p- {7 bAcces-list 1 permit any
6 V+ {( S: P; [% \5 o2 I8 k! Vrouter bgp 1+ U" i0 z- q2 e! `
nei 2.2.2.2 remote-as 2
/ d4 c3 \4 I* F! Z& ]nei 2.2.2.2 router-map set_local in$ _$ A4 O" U5 w1 V6 P# P
nei 3.3.3.3 remote-as 38 M6 h7 S5 S5 z/ V
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route-map set_local permit 108 d" Q, S7 n; |3 x! L
match ip add address 1
* d5 s* s& T# S& B t! f5 j& Yset local-preference 200; D, p0 t7 F9 [# r V+ [
local preference 的缺省值是100 值越大优先级越高
0 |! j/ A( _+ l: ]6 U( B" G!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
9 ?5 H# Y% V. ]& W- w! KMED实例% f5 `! X- S# v \. P
3 X& V5 J# }, R* |2 f1 y' b6 B『AS200【A】【B】』! l8 ~2 }# F2 R6 r5 S- g* d
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[] []8 b- o+ Y2 [: g- p) M9 f. w* \
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[]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 ^4 Y. w+ g5 i2 d
ip as-path access-list 10 permit ^$, c" C- d5 Z; [% j
ip as-path access-list 10 deny *0 j: m; S0 C t8 ^
router bgp 10 G1 a+ p# u3 E' U
nei 2.2.2.2 remote-as 2
% D7 q; R& a6 F$ O* Z5 i* N; c2 }( x$ Snei 2.2.2.2 route-map my_med out
$ H; u, T7 q) ^' w( F# Prouter-map my_med permit 20
0 G& Y `* ]% _) ]3 u9 W9 Qmatch as-path 10
4 J# L6 L* v/ ]- i+ [, Bset metric 2000
, W! M/ l0 r( J4 X* D. ^med缺省值是0 值越小越优$ X) |: T9 ~- _+ W p
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!: G# ~0 u6 D; u- k) z
AS path实例
S/ u! U* E1 I- z# U' Q2 M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( E) J/ ~' _5 p& |
Ip as-path access-list deny _400$! @0 ~+ l4 a; b& y u+ e3 `9 e
ip as-path access-list 1 permit any$ o! A4 |) h% K% D0 S
router bgp 1
1 N+ x2 `6 o3 r' nnei 2.2.2.2 remote-as 2 阿富汉自治系统邻居配4 L- @3 T; n B! L8 E# q y# g9 q
nei 2.2.2.2 router-map deny_usa in
# T7 _. r$ e) p5 rroute-map deny_usa permit 10( }, D6 m& l# Y% e l, w* B
match as-path 1
# z, D0 _' Q S' [2 A!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
6 J& F2 z+ A% s: x: |. o: w( [community属性的实际应用
& x r( ?& P' k6 k. R7 |一群路由的团体而不是路由器的团体。& K) F5 h3 \5 x4 v
已知中国移动互联网中,每个省都有一台路由器运行BGP03 z8 l8 G1 C0 P+ y
, A. D! J& E: s+ O1 S) H想知道某些网段来自哪个省。5 U4 r/ K w) w( _
access-list 1 permit any j: U7 A$ ^9 Q% U6 L
router bgp 65000& }, N7 V$ o. k% d$ r: |# C i
net 202.24.0.0 255.255.0.0 route-map set-comm out
4 u, M1 ?+ o2 o; J7 D1 M/ [) Onei 2.2.2.2 remote-as 65000国际出口路由" E- z$ [6 N6 x- [3 V
nei 2.2.2.2 send-community* x/ y4 M- ]6 W1 U) l
router-map set_comm permit 10' D0 k) J2 z" g" `
match ip add 1
: t' N+ D) [8 l9 W. wset community 65000:24 additive4 Y3 K& d, }* A2 o4 k
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' A5 r4 a: J+ h6 u2 d为了防止破坏或者是防
$ F9 i2 c) @" c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
9 _0 \( o& y& Q# J% ?ACces-list 1 deny 03 q I; a1 w+ V* I3 L# m: z. F$ a
access-list 1 permit any! y; L; p5 r# Z/ I5 E
router bgp 1
3 @6 X8 `% u/ P) ~. P; ~$ v7 Vdistribute-list 1 in* f5 N5 S. d- Y. e7 l
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+ w8 S- c% M% `( B" U \. Y
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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