{"id":17,"date":"2006-04-11T11:11:45","date_gmt":"2006-04-11T10:11:45","guid":{"rendered":"http:\/\/www.galhano.com\/blog\/?p=17"},"modified":"2006-04-11T11:11:45","modified_gmt":"2006-04-11T10:11:45","slug":"classless-inter-domain-routing-cidr","status":"publish","type":"post","link":"http:\/\/galhano.com\/blog\/?p=17","title":{"rendered":"Classless Inter-Domain Routing (CIDR)"},"content":{"rendered":"

A Better Solution: Eliminate Address Classes<\/i><\/b><\/font>
\nIt was clear that as long as there\u00c2 were only three sizes of <\/a>networks, the allocation efficiency problem\u00c2 could never be properly rectified. The solution was to get rid of the\u00c2 classes completely, in favor of a classless<\/i> allocation scheme.\u00c2 This system would solve both of the main problems with \u00e2\u20ac\u0153classful\u00e2\u20ac?\u00c2 addressing: inefficient address space use, and the exponential growth\u00c2 of routing tables.<\/font><\/p>\n

The idea behind CIDR is to adapt\u00c2 the concept of subnetting a single network to the entire internet. In\u00c2 essence, then, classless addressing means that instead of breaking a\u00c2 particular network into subnets, we can aggregate networks into larger\u00c2 \u00e2\u20ac\u0153supernets\u00e2\u20ac?. CIDR is sometimes called supernetting<\/i>\u00c2 for this reason: it applies the principles of subnetting to larger networks.\u00c2 It is this aggregation of networks into supernets that allowed CIDR\u00c2 to resolve the problem of growing Internet routing tables.<\/font><\/p>\n

Of course, if we are going to apply\u00c2 subnetting concepts to the entire internet, we need to be able to have\u00c2 subnets of different sizes. After all, that’s one of our primary goals\u00c2 in eliminating the classes. So, more accurately, CIDR is an internet-wide\u00c2 application of not regular one-level subnetting, but of <\/font>Variable\u00c2 Length Subnet Masking (VLSM)<\/font><\/a>. Just as\u00c2 VLSM lets us split a network as many times as we want to create subnets,\u00c2 \u00e2\u20ac\u0153sub-subnets\u00e2\u20ac? and \u00e2\u20ac\u0153sub-sub-subnets\u00e2\u20ac?, CIDR lets us\u00c2 do this with the entire Internet, as many times as needed.<\/font><\/p>\n

mais info<\/a><\/p>\n

Nota\u00c3\u00a7\u00c3\u00a3o standard<\/font><\/h2>\n

A nota\u00c3\u00a7\u00c3\u00a3o standard para o intervalo de\u00c2 endere\u00c3\u00a7os CIDR come\u00c3\u00a7a com o endere\u00c3\u00a7o de rede (na direita com o n\u00c3\u00bamero apropriado\u00c2 de bits com valor zero – at\u00c3\u00a9 4 octetos para IPv4, e at\u00c3\u00a9 campos hexadecimais de 8\u00c2 octetos de 16 bits para IPv6<\/a>). Isto \u00c3\u00a9 seguido por um car\u00c3\u00a1cter e comprimento de um prefixo, em bits,\u00c2 definindo o tamanho da rede em quest\u00c3\u00a3o (o prefixo \u00c3\u00a9, na verdade, o comprimento\u00c2 da m\u00c3\u00a1scara de subrede).<\/font>
\nPor exemplo:<\/font><\/p>\n