I understand that the subnet mask when combined with an IP is
used to define the range of IPs that the router is responsible for
routing. e.g. a router with 192.168.3.1 subnet 255.255.254.0, will route
192.168.2.1 to 192.168.3.255 through its LAN port, all other will be
forwarded to its WAN/gateway. (sanity check please)
What is the subnet mask (as shown on ipconfig /all) for a client computer used for? Does the subnet mask of the client have to be same as its gateway?
What is the subnet mask (as shown on ipconfig /all) for a client computer used for? Does the subnet mask of the client have to be same as its gateway?
A:
It's for precisely the same reason. The client computer needs to know
which destinations it should try to reach directly and which it should
try to reach through a router.
For IP addresses inside the subnet, the client computer uses ARP to locate the Ethernet hardware address of the destination machine's interface in the subnet. For IP addresses outside the subnet, Ethernet traffic is sent to the router's Ethernet hardware address in the subnet.
While a typical SoHo "WiFi router" has layer 2 (bridging, switching) and layer 3 (routing, NAT) functions combined, the client computer still acts precisely the same as it would if the switching and routing functions on the network were entirely separate like they typically used to be.
For IP addresses inside the subnet, the client computer uses ARP to locate the Ethernet hardware address of the destination machine's interface in the subnet. For IP addresses outside the subnet, Ethernet traffic is sent to the router's Ethernet hardware address in the subnet.
While a typical SoHo "WiFi router" has layer 2 (bridging, switching) and layer 3 (routing, NAT) functions combined, the client computer still acts precisely the same as it would if the switching and routing functions on the network were entirely separate like they typically used to be.
Calculate IP Subnet from netmask. (Link)
| Address (Host or Network) | Netmask (i.e. 24) | Netmask for sub/supernet (optional) |
| / | move to: | |
Address: 192.168.123.124 11000000.10101000.011110 11.01111100 Netmask: 255.255.252.0 = 22 11111111.11111111.111111 00.00000000 Wildcard: 0.0.3.255 00000000.00000000.000000 11.11111111 => Network: 192.168.120.0/22 11000000.10101000.011110 00.00000000 (Class C) Broadcast: 192.168.123.255 11000000.10101000.011110 11.11111111 HostMin: 192.168.120.1 11000000.10101000.011110 00.00000001 HostMax: 192.168.123.254 11000000.10101000.011110 11.11111110 Hosts/Net: 1022 (Private Internet)
沒有留言:
張貼留言