Subject: ARP -- Address Resolution Protocol
Author: dns
In response to: The First Layer Abstraction -- IP Address
Posted on: 07/06/2006 08:51:19 PM
The mapping between logic IP addresses and physical network addresses is resolved by Address Resolution Protocol (ARP).
Here is an example how 'HostNo1' finds the destination 'HostNo2' by resolving its IP address 192.168.0.2:
c:\ ping 192.168.0.2
-----------------------
-> 192.168.0.1 Broadcast ARP* Who has 192.168.0.2? Tell 192.168.0.1
<- 192.168.0.1 192.168.0.2 ARP 192.168.0.2 is at 00:1a:2d:4f:50:69
-> 192.168.0.1 192.168.0.2 ICMP* Echo request
<- 192.168.0.1 192.168.0.2 ICMP Echo reply
* ICMP -- Internet Control Message Protocol
* ARP -- Address Resolution Protocol
In order to know where is 192.168.0.2, the host 'HostNo1' broadcast within the Intranet with the ARP by saying "Who has 192.168.0.2? Tell 192.168.0.1"
Once 'HostNo2' gets this message, it knows the message is for him to resolve and replies by telling 'HostNo1' "192.168.0.2 is at 00:1a:2d:4f:50:69"
Once 'HostNo1' gets the destination's physical address, it can transmit any data packets though cable connection to 'HostNo2'.
>
> On 07/06/2006 08:28:48 PM
dns wrote:
The network physical address is usually encapsulated by a logic address, i.e. IP address, for the purpose of:
independence -- an abstract address based networks can hook any machines.
flexibility -- an abstract address based network architecture can be easily managed and maintained.
References:
