Đang chuẩn bị nút TẢI XUỐNG, xin hãy chờ
Tải xuống
Bởi vì toàn các bit 0 và tất cả 1 hạn chế bit, điều này xác định 218-2 (1-262143) mạng con hợp lệ. Phân chia này cung cấp 262.142 mạng con với tối đa là 26-2 (62) máy. Các giá trị áp dụng cho số lượng mạng con có giá trị của octet bit không có ý nghĩa thiết lập để không. Ví dụ, 01 giá trị thập lục phân trong mặt nạ mạng con này giả định một giá trị 8-bit | Because of the all bits 0 and all bits 1 restrictions this defines 218-2 from 1 to 262143 valid subnets. This split provides 262142 subnets each with a maximum of 26-2 62 hosts. The value applied to the subnet number takes the value of the full octet with non-significant bits set to zero. For example the hexadecimal value 01 in this subnet mask assumes an 8-bit value 01000000. This provides a subnet value of 64. Applying the 255.255.255.192 to the sample Class A address of 9.67.38.1 provides the following information 00001001 01000011 00100110 00000001 9.67.38.1 Class A address 11111111 11111111 11111111 11-------- 255.255.255.192 subnet mask logical_AND 00001001 01000011 00100110 00------ 9.67.38.0 subnet base address This leaves a host address of ------------------000001 1 host address IP will recognize all host addresses as being on the local network for which the logical_AND operation described earlier produces the same result. This is important for routing IP datagrams in subnet environments refer to 3.1.3 IP routing on page 77 . The subnet number is -----01000011 00100110 00------ 68760 subnet number This subnet number is a relative number. That is it is the 68760th subnet of network 9 with the given subnet mask. This number bears no resemblance to the actual IP address that this host has been assigned 9.67.38.1 . It has no meaning in terms of IP routing. The division of the original host address into subnet host is chosen by the network administrator. The values of all zeroes and all ones in the subnet field are reserved. Variable length subnetting example Consider a corporation that has been assigned the Class C network 165.214.32.0. The corporation has the requirement to split this address range into five separate networks each with the following number of hosts Subnet 1 50 hosts Subnet 2 50 hosts Subnet 3 50 hosts 76 TCP IP Tutorial and Technical Overview Subnet 4 30 hosts Subnet 5 30 hosts This cannot be achieved with static subnetting. For this example
