为什么在BGP中在建立EBGP对等体是要加上一条多跳的命令 bgp中为什么要bgp ipv4单播地址族
\u5728BGP\u4e2d,\u4ec0\u4e48\u65f6\u5019\u4f7f\u7528next-hope-self\uff0c\u4e3a\u4ec0\u4e48\uff1fnext-hope-self\u547d\u4ee4\u7528\u6765\u8bbe\u7f6e\u5411IBGP\u5bf9\u7b49\u4f53\uff08\u7ec4\uff09\u901a\u544a\u8def\u7531\u65f6\uff0c\u628a\u4e0b\u4e00\u8df3\u5c5e\u6027\u8bbe\u4e3a\u81ea\u8eab\u7684IP\u5730\u5740\u3002
\u7f3a\u7701\u60c5\u51b5\u4e0b\uff0cBGP\u5728\u5411EBGP\u5bf9\u7b49\u4f53\u901a\u544a\u8def\u7531\u65f6\uff0c\u5c06\u4e0b\u4e00\u8df3\u5c5e\u6027\u8bbe\u4e3a\u81ea\u8eab\u7684IP\u5730\u5740\u3002BGP\u5728\u5411IBGP\u5bf9\u7b49\u4f53\u901a\u544a\u8def\u7531\u65f6\uff0c\u4e0d\u6539\u53d8\u4e0b\u4e00\u8df3\u5c5e\u6027\u3002
\u5f53AS\u5185\u90e8\u8def\u7531\u4fe1\u606f\uff08IGP\uff09\u6ca1\u6709\u5b9e\u73b0\u540c\u6b65\u65f6\u5019\uff0c\u5219\u5728BGP\u4e2d\u9700\u8981\u4f7f\u7528next-hope-self\u3002
bgp\u901a\u5e38\u4f1a\u6709\u6570\u91cf\u5e9e\u5927\u7684\u8def\u7531\u6761\u76ee\u3002\u5b83\u6709\u5f88\u591a\u5730\u5740\u7c07\uff0c\u53ea\u6fc0\u6d3b\u4f60\u9700\u8981\u7684\u5730\u5740\u7c07\u7684\u5bf9\u7b49\u4f53\u5173\u7cfb\uff0c\u4e5f\u5c31\u53ea\u4f20\u9012\u7279\u5b9a\u7684\u8def\u7531\uff0c\u6709\u5229\u4e8e\u63a7\u5236\u548c\u7cbe\u7b80bgp\u6570\u636e\u5e93\u548c\u8def\u7531\u8868\u3002
cisco ios\u9ed8\u8ba4\u6fc0\u6d3b\u4e86ipv4 unicast\uff0c\u6240\u4ee5\u4f60\u5728\u53ea\u914d\u7f6eipv4\u5355\u64ad\u65f6\uff0c\u611f\u89c9\u662f\u4e0d\u9700\u8981\u6fc0\u6d3b\u3002
\u826f\u597d\u7684\u4e60\u60ef\u662f\uff0c\u914d\u7f6ebgp\uff0c\u5c31\u6253\u4e0ano bgp default ipv4-unicast\uff0c\u5173\u95ed\u9ed8\u8ba4\u6fc0\u6d3bipv4\u3002\u7136\u540e\u9700\u8981\u4f20\u4ec0\u4e48\u8def\u7531\uff0c\u5c31\u5355\u72ec\u6fc0\u6d3b\u3002
\u4e3e\u4e2a\u4f8b\u5b50\uff0c\u4f60\u53ea\u4f20\u9012ipv6\u8def\u7531\uff0c\u5982\u679c\u4e0d\u6253no bgp default ipv4-unicast\uff0c\u4f60\u4f1a\u53d1\u73b0ipv4\u7684\u5bf9\u7b49\u4f53\u5173\u7cfb\u4e5f\u5efa\u7acb\u4e86\uff0c\u800c\u4e14\u4e5f\u4f20\u8def\u7531\uff0c\u8fd9\u662f\u4f60\u4e0d\u9700\u8981\u7684\u3002\u6240\u4ee5\u8bf4\u6253\u4e0a\u662f\u597d\u4e60\u60ef\u3002
\u5b83\u5c5e\u4e8e\u4f18\u5316\u6027\u914d\u7f6e\u3002\u5982\u679c\u6ca1\u6709\u914d\u7f6eno bgp default ipv4-unicast\uff0c\u5168\u5c40\u4e0b\u5efa\u7acb\u90bb\u5c45\u4f1a\u76f4\u63a5UP\u3002
\u7528\u4e86no bgp default ipv4-unicast\uff0c\u5efa\u7acb\u90bb\u5c45\u662f\u4e0d\u4f1aUP\uff0c\u5fc5\u987b\u5728address family ipv4 \u4e0b\u6fc0\u6d3b\u90bb\u5c45\u624d\u4f1aUP\uff01
当EBGP使用环回口建立邻居时，数据包达到对端邻居的直连接口时因为TTL值要减去1，导致数据包的TTL=0结果被丢弃，这样就无法达到对端邻居的还回口，致使邻居状态一直处在active状态
绛旓細褰EBGP浣跨敤鐜洖鍙寤虹珛閭诲眳鏃讹紝鏁版嵁鍖呰揪鍒板绔偦灞呯殑鐩磋繛鎺ュ彛鏃跺洜涓篢TL鍊艰鍑忓幓1锛屽鑷存暟鎹寘鐨凾TL=0缁撴灉琚涪寮冿紝杩欐牱灏辨棤娉曡揪鍒板绔偦灞呯殑杩樺洖鍙ｏ紝鑷翠娇閭诲眳鐘舵佷竴鐩村鍦╝ctive鐘舵
绛旓細鍗庝负璁惧杩樻敮鎸佸preferred-value鍜孊GP鍙嶅皠鍣ㄧ瓑鐗规э紝澧炲己缃戠粶绠＄悊銆傚湪瀹為檯閰嶇疆涓紝鎴戜滑鍏虫敞濡備綍璁剧疆閭诲眳鍏崇郴锛屼緥濡侫R2涓嶢R3銆丄R5寤虹珛EBGP瀵圭瓑浣擄紝鑰孉R4閫氳繃Loopback0寮曞叆EBGP銆侫R1浣滀负OSPF鐨凴R锛孉R2鍜孉R3浣滀负鍏禝BGP瀹㈡埛绔侫R1涓嶢R2鍜孉R3鐨凚GP杩炴帴宸插缓绔嬨傛澶栵紝閰嶇疆鏃堕渶鍏虫敞璺敱浼橀夎鍒欙紝濡備涪寮冧笉鍙...
绛旓細TTL=1鐨勬姤鏂囧彂閫佺粰閭诲眳鍚庡叾鍊煎噺涓灏变笉鑳藉啀寰涓嬩竴璺冲彂閫佷簡锛屽洜姝ゅ彧鑳界粰鐩搁偦鐨勮矾鐢卞櫒鍙戦侊紝杩欐牱灏遍伩鍏嶄簡DOS鏀诲嚮銆
绛旓細BGP渚濋潬TCP鏉ヤ紶杈擄紝搴曞眰鐨凾CP浼氳瘽寤虹珛鎴愬姛鍚庯紝鎵嶈兘澶寤虹珛BGP閭诲眳鍏崇郴锛涗换浣曢敊璇簨浠堕兘灏嗗鑷撮偦灞呯姸鎬佸洖鍒癐dle锛岄噸鏂板皾璇曞缓绔婽CP浼氳瘽锛涗簩銆佸奖鍝岯GP閭诲眳寤虹珛鐨勫洜绱 1銆佸绛変綋鍦板潃涓嶅彲杈撅紱2銆佹洿鏂版簮闂锛3銆eBGP璺虫暟闂锛4銆丅GP鐗堟湰涓嶄竴鑷达紱5銆丄S鍙蜂笉涓鑷达紱6銆丷outerID鍐茬獊锛7銆丅GP璁よ瘉閿欒锛8銆乀CP 179...
绛旓細BGP鍙垎涓篒BGP锛圛nternal BGP锛夊拰EBGP锛圗xternal BGP锛夈侭GP鐨勯偦灞呭叧绯伙紙鎴栫О閫氫俊瀵圭/瀵圭瓑瀹炰綋锛夋槸閫氳繃浜哄伐閰嶇疆瀹炵幇鐨勶紝瀵圭瓑瀹炰綋涔嬮棿閫氳繃TCP浼氳瘽浜や簰鏁版嵁銆侭GP璺敱鍣ㄤ細鍛ㄦ湡鍦板彂閫19瀛楄妭鐨勪繚鎸佸瓨娲籯eep-alive娑堟伅鏉ョ淮鎶よ繛鎺ャ傚湪璺敱鍗忚涓紝鍙湁BGP浣跨敤TCP浣滀负浼犺緭灞傚崗璁
绛旓細loopback鎺ュ彛鐩稿浜庣墿鐞嗗彛鏉ヨ鏇寸ǔ瀹氾紝bgp鏄湁鍥炶瘽淇濇寔鏃堕棿鐨勶紝鍙互閬垮厤杩愯惀鍟嗙嚎璺棯鏂犳垚bgp閭诲眳闇囪崱锛涘悓鏃朵綘瀛﹁繃鏉ョ殑璺敱鏉＄洰涓嬩竴璺虫槸loop鍙ｏ紝鏇村鏄撻夎矾鎺у埗銆
绛旓細BGP Speaker</锛屽嵆杩愯BGP鍗忚鐨勮矾鐢卞櫒锛屽畠浠湪缁存姢缃戠粶杩為氭т腑鎵紨鐫杈圭晫缃戝叧鐨勮鑹层侭GP瀵圭瓑浣擄紙BGP peer</锛夊彲鍒嗕负涓ょ绫诲瀷锛氬湪鍚屼竴涓嚜娌荤郴缁燂紙AS锛夊唴閮寤虹珛鐨刬BGP</鍜岃法瓒婁笉鍚孉S鐨別BGP</銆傛帴涓嬫潵锛屾垜浠潵鎺㈣iBGP涓eBGP鐨鍖哄埆锛氱幆璺槻鑼</锛歩BGP閫氳繃閫昏緫鍏ㄨ繛鎺ラ伩鍏嶈矾鐢辩幆璺紝瑙勫畾绂佹灏嗕粠IBGP...
绛旓細1銆BGP璺敱鐨勮礋杞藉垎鎷 鍒拌揪鍚屼竴鐩殑鍦伴氬父浼氬瓨鍦ㄥ鏉℃湁鏁堣矾鐢憋紝浣嗘槸BGP鍙皢鏈浼樿矾鐢卞彂甯冪粰瀵圭瓑浣擄紱鍓11涓睘鎬у畬鍏ㄧ浉鍚岀殑鎯呭喌涓嬶紝鍙氳繃鍛戒护maximum load-balancing ebgp|ibgp閰嶇疆BGP璐熻浇鍒嗘媴鐨勬渶澶х瓑浠疯矾鐢辨潯鏁帮紝瀹炵幇涓嬪彂澶氭潯涓嶅悓涓嬩竴璺崇殑BGP璺敱鍒癐P璺敱琛ㄤ腑锛岀己鐪佸间负1锛屼笉杩涜BGP璺敱璐熻浇鍒嗘媴锛涘鏋...
绛旓細鍦ˋS鍐呴儴锛孖BGP閭诲眳鍏崇郴閫氬父鍩轰簬Loopback鎺ュ彛寤虹珛銆侲BGP閭诲眳涔嬮棿閫氬父浣跨敤鐩磋繛鎺ュ彛鐨処P鍦板潃浣滀负BGP鎶ユ枃婧愬湴鍧锛屽鑻ヤ娇鐢ㄧ幆鍥炴帴鍙寤虹珛EBGP閭诲眳鍏崇郴锛岃閰嶇疆peer ebgp-max-hop鍛戒护锛屽厑璁窫BGP閫氳繃闈炵洿杩炴柟寮忓缓绔嬮偦灞呭叧绯汇傚悓鏍锋槸涓婇潰鐨勭幆澧冿紝鎴戜滑绋嶄綔鍙樻洿锛屽湪R1鍙奟3涓婂垱寤簂oopback0锛屽湴鍧鍒嗗埆涓1.1.1.1/32鍙3.3...
绛旓細1銆丅GP 鏄敮涓涓涓敤鏉ュ鐞嗗儚鍥犵壒缃戝ぇ灏忕殑缃戠粶鍗忚锛屼篃鏄敮涓鑳藉濡ュ杽澶勭悊濂戒笉鐩稿叧璺敱鍩熼棿鐨勫璺繛鎺ュ崗璁侭GPv4鏄竴绉嶅閮ㄧ殑璺敱鍗忚锛屽彲璁や负鏄竴绉嶉珮绾х殑璺濈鍚戦噺璺敱鍗忚銆鍦˙GP缃戠粶涓紝鍙互灏嗕竴涓綉缁滃垎鎴愬涓嚜娌荤郴缁熴傝嚜娌荤郴缁熼棿浣跨敤eBGP骞挎挱璺敱锛岃嚜娌荤郴缁熷唴浣跨敤iBGP鍦ㄨ嚜宸辩殑缃戠粶鍐呭箍鎾矾鐢便2銆丅GP...
