Multicast Address

Hi Friends
I searched in the net but i could not understand what is
multicast Addressing
for eg consider the network having network Address 10.20.2.0 having
20 host
ranging from 10.20.2.1 to 10.20.2.20

my query is
1 . How to group the host in the Netwok Address who will do it
manually or by auto configuration
2. whether Macaddress will vary depending upon on the group,how the
system get it to know that it to accept the packet with these
MacAddress to be filled
3.How IP Address also vary

These may be idiot question for you...........
But if there is any one to give some idea means it is welcome ..and i
am very thankfull to them

if u have some other means of idea to suggest with eg also welcome

Regards
SathyaNarayanan T

On 26 Apr 2007, in the Usenet newsgroup comp.os.linux.networking, in article
<(E-Mail Removed). com>, sathya wrote:

> I searched in the net but i could not understand what is
>multicast Addressing

It's used as part of a _broadcast_ network, rather than the 'unicast'
or one-to-one networking you are used to.

>for eg consider the network having network Address 10.20.2.0 having
>20 host ranging from 10.20.2.1 to 10.20.2.20

That's nice - but not relavent to Multicast.

> my query is
>1 . How to group the host in the Netwok Address who will do it
>manually or by auto configuration

I'd bet the search engine you are posting from can find this document
if it's not on your system now.

-rw-rw-r-- 1 gferg ldp 73834 Mar 2 2000 Multicast-HOWTO

>2. whether Macaddress will vary depending upon on the group,how the
>system get it to know that it to accept the packet with these
>MacAddress to be filled

The _destination_ MAC address reflects the Multicast destination IP.

>3.How IP Address also vary

See the HOWTO above. See also RFC1301, RFC1458, RFC3171, and RFC4795.

1301 Multicast Transport Protocol. S. Armstrong, A. Freier, K.
Marzullo. February 1992. (Format: TXT=91976 bytes) (Status:
INFORMATIONAL)

1458 Requirements for Multicast Protocols. R. Braudes, S. Zabele. May
1993. (Format: TXT=48106 bytes) (Status: INFORMATIONAL)

3171 IANA Guidelines for IPv4 Multicast Address Assignments. Z.
Albanna, K. Almeroth, D. Meyer, M. Schipper. August 2001. (Format:
TXT=15389 bytes) (Also BCP0051) (Status: BEST CURRENT PRACTICE)

4795 Link-local Multicast Name Resolution (LLMNR). B. Aboba, D.
Thaler, L. Esibov. January 2007. (Format: TXT=71969 bytes) (Status:
INFORMATIONAL)

which any search engine should find instantly.

>These may be idiot question for you...........

Multicast isn't as widely used as unicast because of router issues.

Old guy