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The Second Layer Abstraction -- NetBIOS Name And Domain Name |
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Subject: The Second Layer Abstraction -- NetBIOS Name And Domain Name
Author: dns
In response to: ARP -- Address Resolution Protocol
Posted on: 07/06/2006 09:25:39 PM
The logic IP address is usually further encapsulated by a NetBIOS name or domain name, for the purpose of:
readability -- an abstract name based networks is more readable and memorized.
portability -- an abstract name based application can run on any machine with different IP address.
scaleability -- an abstract name based network architecture can hook more than one computers (IPs) to serve a single well-known domain name by diversifying the network traffic.
For example, few people know what '66.94.230.41' is because it is hard for human beings to memorize such a long meaningless digits. But most people know what 'www.yahoo.com' is.
In terms of portability, the domain 'www.yahoo.com' can run on any IP address like '66.94.230.41' or '66.94.234.13'
For scaleability, 'www.yahoo.com' can hook a cluster of machines running on different geographical locations to tackle local traffic for fast turn out.
>
> On 07/06/2006 08:51:19 PM dns wrote:
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
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-> 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'.
References:
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