1-3Figure 1-2 Subnet a Class B networkWhile allowing you to create multiple logical networks within a single Class A, B, or C network,subnetting is transparent to the rest of the Internet. All these networks still appear as one. As subnettingadds an additional level, subnet ID, to the two-level hierarchy with IP addressing, IP routing nowinvolves three steps: delivery to the site, delivery to the subnet, and delivery to the host.In the absence of subnetting, some special addresses such as the addresses with the net ID of all zerosand the addresses with the host ID of all ones, are not assignable to hosts. The same is true ofsubnetting. When designing your network, you should note that subnetting is somewhat a tradeoffbetween subnets and accommodated hosts. For example, a Class B network can accommodate 65,534(2 16 – 2. Of the two deducted Class B addresses, one with an all-ones host ID is the broadcast addressand the other with an all-zeros host ID is the network address) hosts before being subnetted. After youbreak it down into 512 (29) subnets by using the first 9 bits of the host ID for the subnet, you have only 7bits for the host ID and thus have only 126 (27 – 2) hosts in each subnet. The maximum number of hostsis thus 64,512 (512 × 126), 1022 less after the network is subnetted.Class A, B, and C networks, before being subnetted, use these default masks (also called naturalmasks): 255.0.0.0, 255.255.0.0, and 255.255.255.0 respectively.Configuring IP AddressesS5600 Series Ethernet Switches support assigning IP addresses to VLAN interfaces and loopbackinterfaces. Besides directly assigning an IP address to a VLAN interface, you may configure a VLANinterface to obtain an IP address through BOOTP or DHCP as alternatives. If you change the way aninterface obtains an IP address, from manual assignment to BOOTP for example, the IP addressobtained from BOOTP will overwrite the old one manually assigned.This chapter only covers how to assign an IP address manually. For the other two approaches to IPaddress assignment, refer to the part discussing DHCP in this manual.Follow these steps to configure an IP address to an interface:To do… Use the command… RemarksEnter system view system-view ––Enter interface view interface interface-typeinterface-number ––
