1-3subnetting. 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-zero 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.Protocols and Standardsz RFC 1366, Guidelines for Management of IP Address Spacez RFC 1367, Schedule for IP Address Space Management GuidelinesConfiguring IP AddressesS4200G Series Ethernet Switches support assigning IP addresses to loopback interfaces and VLANinterfaces.A loopback interface is a virtual interface. The physical layer state and link layer protocols of a loopbackinterface are always up unless the loopback interface is manually shut down. A loopback interface canbe configured with an IP address, so routing protocols can be enabled on a loopback interface, and aloopback interface is capable of sending and receiving routing protocol packets.Each VLAN needs an IP address so that it can be addressed. For more information about VLANinterfaces, refer to VLAN Operation in this manual.Besides directly assigning an IP address to a VLAN interface, you may configure a VLAN interface toobtain an IP address through BOOTP or DHCP as alternatives. If you change the way an interfaceobtains an IP address, from manual assignment to BOOTP for example, the IP address obtained fromBOOTP will overwrite the old one manually assigned.This chapter only covers how to assign an IP address manually. For the other two approaches, refer tothe part discussing DHCP.Follow these steps to configure an IP address for an interface:To do… Use the command… RemarksEnter system view system-view ––Enter interface view interface interface-typeinterface-number ––Assign an IP address to theInterfaceip address ip-address { mask |mask-length }RequiredNo IP address is assigned bydefault.
