![]() ■ When you are thinking classfully, if the mask implies x subnet bits, then 2x possible subnets exist for that classful network, assuming the same mask is used throughout the network. This number can be used as a destination IP address to send a packet to all hosts in the subnet. ■ The other reserved IP address in the subnet is the subnet broadcast address, which by definition has binary 1s for all host bits. This number represents the subnet, and is typically seen in routing tables. ![]() This number, by definition, has binary 0s for all host bits. ■ One reserved IP address in each subnet is the subnet number itself. KEY ■ If a subnet has been defined with y host bits, there are 2y - 2 valid usable IP addresses in the POINT subnet, because two numeric values are reserved. The following list summarizes some of the common math facts about subnetting related to the format of IP addresses: Analyzing the format of an existing address, based on the mask or prefix length, allows you to determine whether enough hosts per subnet exist, or whether enough subnets exist to support the number of hosts. Every internetwork requires some number of subnets, and some number of hosts per subnet. Dissecting the Component Parts of an IP Addressįirst, deducing the size of the three parts (classful view) or two parts (classless view) of an IP address is important, because it allows you to analyze information about that subnet and other subnets. Several subsequent chapters cover the configuration details of features that require this math. This section covers the binary math briefly, with coverage of some tricks to do the math quickly without binary math. Knowing how to interpret the meaning of addresses and masks, routes and masks in the routing table, addresses and masks in ACLs, and configure route-filtering are all very important topics for the CCIE Routing and Switching written and lab exams.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |