Intel ER8100STUS - Express 8100 Router, Reference Manual

Page: 63 / 150

Reference.bok : Chapter08 51 Wed Apr 22 10:58:08 1998
51
IP Concept
IP Routing
Structure of a subnet
mask
The following table shows the structure of a subnet mask, where the field con-
taining a 1 is the subnet part and the field containing a 0 is the local hosts part of
the address:
Example
An example looks like this:
Address Resolution
Address resolution
The process of determining the MAC address (48-bit) from an IP address (32-bit)
is called Address Resolution (AR).
Address resolution with
ARP
The Address Resolution Protocol (ARP) is used for address resolution of hosts
which have not previously been communicated with (for example, hosts which
have just been switched on and added to the network). When the Intel Express
8100 Router receives an IP data packet which has to be transmitted to a local un-
Address (bit no.) Subnet Mask
7 6 5 4 3 2 1 0 hexadecimal decimal
0 0 0 0 0 0 0 0 0 0
1 0 0 0 0 0 0 0 80 128
1 1 0 0 0 0 0 0 C0 192
1 1 1 0 0 0 0 0 E0 224
1 1 1 1 0 0 0 0 F0 240
1 1 1 1 1 0 0 0 F8 248
1 1 1 1 1 1 0 0 FC 252
1 1 1 1 1 1 1 0 FE 254
1 1 1 1 1 1 1 1 FF 255
Class C address 193.88.251.1
Class C network 193.88.251.
Class C host .1
Divide the network by two more bits, that is set the subnet mask to
255.255.255.192 to obtain 4 subnetworks:
Subnetworks 193.88.251.0 available for hosts 1 to 62
193.88.251.64 available for hosts: 65 to 126
193.88.251.128 available for hosts: 129 to 190
193.88.251.192 available for hosts: 193 to 254