BGP實驗之操縱BGP路徑選擇---localpreference屬性案例(配圖+詳細驗證過程)作者：JACKSON參考：CISCO中文社區(qū)感謝JACKSON支持原創(chuàng)I■艸.】R4l.nO-44-4^191.[,[J撲R3AS1()0I■艸.】R4l.nO-44-4^191.[,[J撲R3AS1()0AS200/>4IINip.C0M193.1.I..1本地優(yōu)先級(localpref)屬性是分配給路由的一種優(yōu)先級度量，用于和到同一目的地的其他路由相比較。這是BGP路由處理中的第二優(yōu)先屬性(WEIGHT是第一優(yōu)先屬性)。LocalPref屬性只在本AS內(nèi)部有效，不會被傳送到EBGP鄰居上。本地優(yōu)先級越高，路由優(yōu)先級越高。以上案例中，我們通過對R3的配置，設(shè)置從R1學(xué)到的1.0.0.0的本地優(yōu)先級(Localpref)設(shè)置為200，由于缺省的值為100，AS200中所有的路由器都會選擇R3到達1.0.0.0。////r1////intf2/0ipad192.1.1.1255.255.255.0intf3/0ipad193.1.1.1255.255.255.0intlo0ipad1.1.1.1255.255.255.0intlo1ipad2.2.2.2255.255.255.0routerbgp100nosynneighbor192.1.1.2remote-as200neighbor193.1.1.3remote-as200network1.0.0.0network1.0.0.0////r2////intf2/0ipad192.1.1.2255.255.255.0intf4/0ipad194.1.1.2255.255.255.0routeros1netw0.0.0.0255.255.255.255a0passive-interfacef2/0routerbgp200nosynneighbor192.1.1.1remote-as100neighbor194.1.1.4remote-as200neighbor195.1.1.3remote-as200neighbor194.1.1.4next-hop-self////r3////intf3/0ipad193.1.1.3255.255.255.0intf5/0ipad195.1.1.3255.255.255.0routeros1netw0.0.0.0255.255.255.255a0passive-interfacef3/0routerbgp200nosynneighbor193.1.1.1remote-as100neighbor195.1.1.4remote-as200neighbor195.1.1.4next-hop-selfneighbor194.1.1.2remote-as200neighbor193.1.1.1route-maplocalprefinaccess-list1permit1.0.0.00.255.255.255route-maplocalprefpermit10matchipad1setlocal-pref200route-maplocalprefpermit20setlocal-pref100////r4////intf4/0ipad194.1.1.4255.255.255.0intf5/0ipad195.1.1.4255.255.255.0intlo0ipad4.4.4.4255.255.255.0routeros1netw0.0.0.0255.255.255.255a0routerbgp200nosynneighbor194.1.1.2remote-as200neighbor195.1.1.3remote-as200netw4.0.0.0驗證：////r4////r4#shipbgpNetworkNextHopMetricLocPrfWeightPath*>i1.0.0.0195.1.1.302000100i*i2.0.0.0195.1.1.301000100i*>i194.1.1.201000100i*>4.0.0.00.0.0.0032768ir4#shiproB1.0.0.0/8[200/0]via195.1.1.3,00:02:20B2.0.0.0/8[200/0]via194.1.1.2,00:02:244.0.0.0/24issubnetted,1subnetsC4.4.4.0isdirectlyconnected,Loopback0O193.1.1.0/24[110/128]via195.1.1.3,00:04:35,Serial5/0O192.1.1.0/24[110/128]via194.1.1.2,00:04:35,Serial4/0C195.1.1.0/24isdirectlyconnected,Serial5/0C194.1.1.0/24isdirectlyconnected,Serial4/0r2#shipbgpNetworkNextHopMetricLocPrfWeightPath*>i1.0.0.0193.1.1.102000100i*192.1.1.100100i*i2.0.0.0193.1.1.101000100i*>192.1.1.100100i*>i4.0.0.0194.1.1.401000ir2#shiproB1.0.0.0/8[200/0]via193.1.1.1,00:06:00B2.0.0.0/8[20/0]via192.1.1.1,00:06:044.0.0.0/8isvariablysubnetted,2subnets,2masksO4.4.4.4/32[110/65]via194.1.1.4,00:08:20,Serial4/0B4.0.0.0/8[200/0]via194.1.1.4,00:06:55O193.1.1.0/24[110/192]via194.1.1.4,00:08:20,Serial4/0C192.