{"id":1490,"date":"2010-10-21T01:54:16","date_gmt":"2010-10-21T05:54:16","guid":{"rendered":"http:\/\/www.killtest.hk\/?p=1490"},"modified":"2010-10-21T01:54:16","modified_gmt":"2010-10-21T05:54:16","slug":"ccna-study","status":"publish","type":"post","link":"https:\/\/www.killtest.hk\/index.php\/cisco\/ccna-study\/","title":{"rendered":"CCNA\u5b78\u7fd2\u7b46\u8a18\uff1a\u5b50\u7db2\u5283\u5206\u8207VLSM"},"content":{"rendered":"

IP Subnetting and Variable Length Subnet Masks(VLSM)
\nSubnetting Basics<\/p>\n

CCNA(640-802)\u5b78\u7fd2<\/a>\u7b46\u8a18\u4e4b\u5b50\u7db2\u5283\u5206(subnetting)\u7684\u512a\u9ede:
\n1.\u6e1b\u5c11\u7db2\u7d61\u6d41\u91cf
\n2.\u63d0\u9ad8\u7db2\u7d61\u6027\u80fd
\n3.\u7c21\u5316\u7ba1\u7406
\n4.\u6613\u65bc\u64f4\u5927\u5730\u7406\u7bc4\u570d<\/p>\n

CCNA\u5b78\u7fd2\u7b46\u8a18\u4e4b\u5283\u5206\u5b50\u7db2?
\n\u9996\u5148\u8981\u719f\u8a182\u7684\u51aa:2\u76840\u6b21\u65b9\u52309\u6b21\u65b9\u7684\u503c\u5206\u5225\u70ba:1,2,4,8,16,32,64,128,256\u548c512.\u9084\u6709\u8981\u660e\u767d\u7684\u662f:\u5b50\u7db2\u5283\u5206\u662f\u501f\u52a9\u65bc\u53d6\u8d70\u4e3b\u6a5f\u4f4d,\u628a\u9019\u500b\u53d6\u8d70\u7684\u90e8\u5206\u4f5c\u70ba\u5b50\u7db2\u4f4d.\u56e0\u6b64\u9019\u500b\u610f\u5473\u5283\u5206\u8d8a\u591a\u7684\u5b50\u7db2,\u4e3b\u6a5f\u5c07\u8d8a\u5c11<\/p>\n

Subnet Masks
\n\u5b50\u7db2\u63a9\u78bc\u7528\u65bc\u8fa8\u5225IP\u5730\u5740\u4e2d\u54ea\u90e8\u5206\u70ba\u7db2\u7d61\u5730\u5740,\u54ea\u90e8\u5206\u70ba\u4e3b\u6a5f\u5730\u5740,\u67091\u548c0\u7d44\u6210,\u957732\u4f4d,\u5168\u70ba1\u7684\u4f4d\u4ee3\u8868\u7db2\u7d61\u865f.\u4e0d\u662f\u6240\u6709\u7684\u7db2\u7d61\u90fd\u9700\u8981\u5b50\u7db2,\u56e0\u6b64\u5c31\u5f15\u51651\u500b\u6982\u5ff5:\u9ed8\u8a8d\u5b50\u7db2\u63a9\u78bc(default subnet mask).A\u985eIP\u5730\u5740\u7684\u9ed8\u8a8d\u5b50\u7db2\u63a9\u78bc\u70ba255.0.0.0;B\u985e\u7684\u70ba255.255.0.0;C\u985e\u7684\u70ba255.255.255.0<\/p>\n

Classless Inter-Domain Routing(CIDR)
\nCIDR\u53eb\u505a\u7121\u985e\u57df\u9593\u8def\u7531,ISP\u5e38\u7528\u9019\u6a23\u7684\u65b9\u6cd5\u7d66\u5ba2\u6236\u5206\u914d\u5730\u5740,ISP\u63d0\u4f9b\u7d66\u5ba2\u62361\u500b\u584a(block size),\u985e\u4f3c\u9019\u6a23:192.168.10.32\/28,\u9019\u6392\u6578\u5b57\u544a\u8a34\u59b3\u59b3\u7684\u5b50\u7db2\u63a9\u78bc\u662f\u591a\u5c11,\/28\u4ee3\u8868\u591a\u5c11\u4f4d\u70ba1,\u6700\u5927\/32.\u4f46\u662f\u59b3\u5fc5\u9808\u77e5\u9053\u76841\u9ede\u662f:\u4e0d\u7ba1\u662fA\u985e\u9084\u662fB\u985e\u9084\u662f\u5176\u4ed6\u985e\u5730\u5740,\u6700\u5927\u53ef\u7528\u7684\u53ea\u80fd\u70ba30\/,\u5373\u4fdd\u75592\u4f4d\u7d66\u4e3b\u6a5f\u4f4d<\/p>\n

CIDR\u503c:
\n1.\u63a9\u78bc255.0.0.0:\/8(A\u985e\u5730\u5740\u9ed8\u8a8d\u63a9\u78bc)
\n2.\u63a9\u78bc255.128.0.0:\/9
\n3.\u63a9\u78bc255.192.0.0:\/10
\n4.\u63a9\u78bc255.224.0.0:\/11
\n5.\u63a9\u78bc255.240.0.0:\/12
\n6.\u63a9\u78bc255.248.0.0:\/13
\n7.\u63a9\u78bc255.252.0.0:\/14
\n8.\u63a9\u78bc255.254.0.0:\/15
\n9.\u63a9\u78bc255.255.0.0:\/16(B\u985e\u5730\u5740\u9ed8\u8a8d\u63a9\u78bc)
\n10.\u63a9\u78bc255.255.128.0:\/17
\n11.\u63a9\u78bc255.255.192.0:\/18
\n12.\u63a9\u78bc255.255.224.0:\/19
\n13.\u63a9\u78bc255.255.240.0:\/20
\n14.\u63a9\u78bc255.255.248.0:\/21
\n15.\u63a9\u78bc255.255.252.0:\/22
\n16.\u63a9\u78bc255.255.254.0:\/23
\n17.\u63a9\u78bc255.255.255.0:\/24(C\u985e\u5730\u5740\u9ed8\u8a8d\u63a9\u78bc)
\n18.\u63a9\u78bc255.255.255.128:\/25
\n19.\u63a9\u78bc255.255.255.192:\/26
\n20.\u63a9\u78bc255.255.255.224:\/27
\n21.\u63a9\u78bc255.255.255.240:\/28
\n22.\u63a9\u78bc255.255.255.248:\/29
\n23.\u63a9\u78bc255.255.255.252:\/30<\/p>\n

Subnetting Class A,B&C Address<\/p>\n

CCNA\u5b78\u7fd2\u7b46\u8a18\u4e4b\u5283\u5206\u5b50\u7db2\u7684\u5e7e\u500b\u6377\u5f91:
\n1.\u59b3\u6240\u9078\u64c7\u7684\u5b50\u7db2\u63a9\u78bc\u5c07\u6703\u7522\u751f\u591a\u5c11\u500b\u5b50\u7db2?:2\u7684x\u6b21\u65b9-2(x\u4ee3\u8868\u63a9\u78bc\u4f4d,\u53732\u9032\u5236\u70ba1\u7684\u90e8\u5206)
\n2.\u6bcf\u500b\u5b50\u7db2\u80fd\u6709\u591a\u5c11\u4e3b\u6a5f?: 2\u7684y\u6b21\u65b9-2(y\u4ee3\u8868\u4e3b\u6a5f\u4f4d,\u53732\u9032\u5236\u70ba0\u7684\u90e8\u5206)
\n3.\u6709\u6548\u5b50\u7db2\u662f?:\u6709\u6548\u5b50\u7db2\u865f=256-10\u9032\u5236\u7684\u5b50\u7db2\u63a9\u78bc(\u7d50\u679c\u53eb\u505ablock size\u6216base number)
\n4.\u6bcf\u500b\u5b50\u7db2\u7684\u5ee3\u64ad\u5730\u5740\u662f?:\u5ee3\u64ad\u5730\u5740=\u4e0b\u500b\u5b50\u7db2\u865f-1
\n5.\u6bcf\u500b\u5b50\u7db2\u7684\u6709\u6548\u4e3b\u6a5f\u5206\u5225\u662f?:\u5ffd\u7565\u5b50\u7db2\u5167\u5168\u70ba0\u548c\u5168\u70ba1\u7684\u5730\u5740\u5269\u4e0b\u7684\u5c31\u662f\u6709\u6548\u4e3b\u6a5f\u5730\u5740.\u6700\u5f8c\u6709\u65481\u500b\u4e3b\u6a5f\u5730\u5740=\u4e0b\u500b\u5b50\u7db2\u865f-2(\u5373\u5ee3\u64ad\u5730\u5740-1)<\/p>\n

CCNA\u5b78\u7fd2\u7b46\u8a18\u4e4b\u6839\u64da\u4e0a\u8ff0\u6377\u5f91\u5283\u5206\u5b50\u7db2\u7684\u5177\u9ad4\u5be6\u4f8b:
\nC\u985e\u5730\u5740\u4f8b\u5b50:\u7db2\u7d61\u5730\u5740192.168.10.0;\u5b50\u7db2\u63a9\u78bc255.255.255.192(\/26)
\n1.\u5b50\u7db2\u6578=2*2-2=2
\n2.\u4e3b\u6a5f\u6578=2\u76846\u6b21\u65b9-2=62
\n3.\u6709\u6548\u5b50\u7db2?:block size=256-192=64;\u6240\u4ee5\u7b2c\u58f9\u500b\u5b50\u7db2\u70ba192.168.10.64,\u7b2c\u4e8c\u500b\u70ba192.168.10.128
\n4.\u5ee3\u64ad\u5730\u5740:\u4e0b\u500b\u5b50\u7db2-1.\u6240\u4ee52\u500b\u5b50\u7db2\u7684\u5ee3\u64ad\u5730\u5740\u5206\u5225\u662f192.168.10.127\u548c192.168.10.191
\n5.\u6709\u6548\u4e3b\u6a5f\u7bc4\u570d\u662f:\u7b2c\u58f9\u500b\u5b50\u7db2\u7684\u4e3b\u6a5f\u5730\u5740\u662f192.168.10.65\u5230192.168.10.126;\u7b2c\u4e8c\u500b\u662f192.168.10.129\u5230192.168.10.190<\/p>\n

B\u985e\u5730\u5740\u4f8b\u5b501:\u7db2\u7d61\u5730\u5740:172.16.0.0;\u5b50\u7db2\u63a9\u78bc255.255.192.0(\/18)<\/p>\n

1.\u5b50\u7db2\u6578=2*2-2=2
\n2.\u4e3b\u6a5f\u6578=2\u768414\u6b21\u65b9-2=16382
\n3.\u6709\u6548\u5b50\u7db2?:block size=256-192=64;\u6240\u4ee5\u7b2c\u58f9\u500b\u5b50\u7db2\u70ba172.16.64.0,\u6700\u5f8c1\u500b\u70ba172.16.128.0
\n4.\u5ee3\u64ad\u5730\u5740:\u4e0b\u500b\u5b50\u7db2-1.\u6240\u4ee52\u500b\u5b50\u7db2\u7684\u5ee3\u64ad\u5730\u5740\u5206\u5225\u662f172.16.127.255\u548c172.16.191.255
\n5.\u6709\u6548\u4e3b\u6a5f\u7bc4\u570d\u662f:\u7b2c\u58f9\u500b\u5b50\u7db2\u7684\u4e3b\u6a5f\u5730\u5740\u662f172.16.64.1\u5230172.16.127.254;\u7b2c\u4e8c\u500b\u662f172.16.128.1\u5230172.16.191.254<\/p>\n

B\u985e\u5730\u5740\u4f8b\u5b502:\u7db2\u7d61\u5730\u5740:172.16.0.0;\u5b50\u7db2\u63a9\u78bc255.255.255.224(\/27)
\n1.\u5b50\u7db2\u6578=2\u768411\u6b21\u65b9-2=2046(\u56e0\u70baB\u985e\u5730\u5740\u9ed8\u8a8d\u63a9\u78bc\u662f255.255.0.0,\u6240\u4ee5\u7db2\u7d61\u4f4d\u70ba8+3=11)
\n2.\u4e3b\u6a5f\u6578=2\u76845\u6b21\u65b9-2=30
\n3.\u6709\u6548\u5b50\u7db2?:block size=256-224=32;\u6240\u4ee5\u7b2c\u58f9\u500b\u5b50\u7db2\u70ba172.16.0.32, \u6700\u5f8c1\u500b\u70ba172.16.255.192
\n4.\u5ee3\u64ad\u5730\u5740:\u4e0b\u500b\u5b50\u7db2-1.\u6240\u4ee5\u7b2c\u58f9\u500b\u5b50\u7db2\u548c\u6700\u5f8c1\u500b\u5b50\u7db2\u7684\u5ee3\u64ad\u5730\u5740\u5206\u5225\u662f172.16.0.63\u548c172.16.255.223
\n5.\u6709\u6548\u4e3b\u6a5f\u7bc4\u570d\u662f:\u7b2c\u58f9\u500b\u5b50\u7db2\u7684\u4e3b\u6a5f\u5730\u5740\u662f172.16.0.33\u5230172.16.0.62;\u6700\u5f8c1\u500b\u662f172.16.255.193\u5230172.16.255.223<\/p>\n

Variable Length Subnet Masks(VLSM)<\/p>\n

\u8b8a\u9577\u5b50\u7db2\u63a9\u78bc(VLSM)\u7684\u4f5c\u7528:\u7bc0\u7d04IP\u5730\u5740\u7a7a\u9593;\u6e1b\u5c11\u8def\u7531\u8868\u5927\u5c0f.\u4f7f\u7528VLSM\u6642,\u6240\u91c7\u7528\u7684\u8def\u7531\u5354\u8b70\u5fc5\u9808\u80fd\u5920\u652f\u6301\u5b83,\u9019\u4e9b\u8def\u7531\u5354\u8b70\u5305\u62ecRIPv2,OSPF,EIGRP\u548cBGP. \u95dc\u65bc\u66f4\u591a\u7684VLSM\u77e5\u8b58,\u53ef\u4ee5\u53bbGoogle.com\u9032\u884c\u641c\u7d22<\/p>\n

Troubleshooting IP Address<\/p>\n

CCNA\u5b78\u7fd2\u7b46\u8a18\u4e4b\u58f9\u4e9b\u7db2\u7d61\u554f\u984c\u7684\u6392\u96e3:<\/p>\n

1.\u6253\u958bWindows\u88cf\u76841\u500bDOS\u7a97\u53e3,ping\u672c\u5730\u56de\u74b0\u5730\u5740127.0.0.1,\u5982\u679c\u53cd\u994b\u4fe1\u606f\u5931\u6557,\u8aaa\u660eIP\u5354\u8b70\u68e7\u6709\u932f,\u5fc5\u9808\u91cd\u65b0\u5b89\u88ddTCP\/IP\u5354\u8b70\u3002
\n2.\u5982\u679c1\u6210\u529f,ping\u672c\u6a5fIP\u5730\u5740,\u5982\u679c\u53cd\u994b\u4fe1\u606f\u5931\u6557,\u8aaa\u660e\u59b3\u7684\u7db2\u5361\u4e0d\u80fd\u548cIP\u5354\u8b70\u68e7\u9032\u884c\u901a\u4fe1\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"

IP Subnetting and Variable Length Subnet Masks(VLSM) Su […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[272,523,3],"tags":[134,127],"class_list":["post-1490","post","type-post","status-publish","format-standard","hentry","category-640-802-cisco","category-ccna-cisco","category-cisco","tag-640-802","tag-ccna"],"_links":{"self":[{"href":"https:\/\/www.killtest.hk\/index.php\/wp-json\/wp\/v2\/posts\/1490","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.killtest.hk\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.killtest.hk\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.killtest.hk\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.killtest.hk\/index.php\/wp-json\/wp\/v2\/comments?post=1490"}],"version-history":[{"count":0,"href":"https:\/\/www.killtest.hk\/index.php\/wp-json\/wp\/v2\/posts\/1490\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.killtest.hk\/index.php\/wp-json\/wp\/v2\/media?parent=1490"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.killtest.hk\/index.php\/wp-json\/wp\/v2\/categories?post=1490"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.killtest.hk\/index.php\/wp-json\/wp\/v2\/tags?post=1490"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}