MAC

[Anjaneyulu]

Hi,

I need to know why we use loopback and broadcast addresses . How to define that addresses?

[Laurent Menase · Accepted solution]

can you precise?
else with a nestat -nrv
Dest/Netmask Gateway Flags Refs Interface Pmtu
127.0.0.1/255.255.255.255 127.0.0.1 UH 0 lo0 4136
70.70.70.10/255.255.255.255 70.70.70.10 UH 0 lan0:1 4136
60.60.60.10/255.255.255.255 60.60.60.10 UH 0 lan1 4136
10.129.16.40/255.255.255.255 10.129.16.40 UH 0 lan0 4136
15.129.16.0/255.255.248.0 15.129.16.40 U 3 lan0 1500
70.70.0.0/255.255.0.0 70.70.70.10 U 3 lan0:1 1500
60.0.0.0/255.0.0.0 60.60.60.10 U 2 lan1 1500
127.0.0.0/255.0.0.0 127.0.0.1 U 0 lo0 4136
default/0.0.0.0 10.129.16.1 UG 0 lan0 1500

addresses with UH are local addresses
addresses with netmask not only with 255.255.255.255 are (sub)networks addresses

[Ganesan R]

Hi Anjaneyulu,

loopback address, by its name, to check the internal communication.

broadcast address is to communicate all the valid address on the network. When you send the data to the broadcast address of that network, all the node on that network will receive the data.

For instance when you ping particular ip, a broadcast icmp request will be sent. only the corresponding ip will reply back for the icmp request.

[Laurent Menase]

found a cool page:

http://www.comptechdoc.org/independent/networking/guide/netbroadcasting.html

[Johnson Punniyalingam]

Hi Anjaneyulu,

1. Testing - A nice simple test of network functionality.
2. Some applications work together by intersocket communication - localhost provides that address so that the elements can all work on the same PC
3. Enables you to run a web/ftp/ any other server on the same PC that you are working on without having to know the allocated IP address from a DHCP server.

Basically it just makes life a lot simpler, and prevents anyone having to worry about the complexities of the outside world if the 2 processes are on the same machine:)

You can configure loopback interface and null interface on one network device but you cannot configure more than 1 loopback interface on same network device

Thx,
Johnson