BSCI question about Multicast RFC 2365 Administratively Scoped IP Multicast

Answered Question
May 29th, 2010

Hi !

I'm currently preparing BSCI certification exam, for my studdies I read the : Authorized Self-Studdy guide BSCI.  In the chapter cover IP Multicast trafic, the author as wrote :

"

  • Limited, or administratively, scoped addresses in the range 239.0.0.0 through 239.255.255.255. As defined by Requests for Comments (RFC) 2365, Administratively Scoped IP Multicast, these addresses are reserved for use inside private domains.

"

My understanding in this text is the following : address range 239.0.0.0/8 are multicast address which will only used on private network, like it is address define by the 1918 RFC for 10.0.0.0 network as exemple.

What I"m do not understand is the following :

"The administratively scoped multicast address space includes the following scopes, per the IANA:

  • Site-local scope (239.255.0.0/16; 239.252.0.0/16, 239.253.0.0/16, and 239.254.0.0/16 are also reserved for this purpose)
  • Organization local scope (239.192.0.0 to 239.251.255.255)

The IANA has further refined these ranges, as detailed in the IANA multicast address assignment list referenced earlier."

If 239.0.0.0 is already speficied for private used, why the author wrote, the IANA as defined different range also for private used in the range already defined for private used ?

Sorry for my English, I'm a French people it's also maybe why I do not understand the explanation provide by the author here !!

Thanks a lot  !

I have this problem too.
0 votes
Correct Answer by Ganesh Hariharan about 6 years 7 months ago

Hi !

I'm currently preparing BSCI certification exam, for my studdies I read the : Authorized Self-Studdy guide BSCI.  In the chapter cover IP Multicast trafic, the author as wrote :

"

  • Limited, or administratively, scoped addresses in the range 239.0.0.0 through 239.255.255.255. As defined by Requests for Comments (RFC) 2365, Administratively Scoped IP Multicast, these addresses are reserved for use inside private domains.

"

My understanding in this text is the following : address range 239.0.0.0/8 are multicast address which will only used on private network, like it is address define by the 1918 RFC for 10.0.0.0 network as exemple.

What I"m do not understand is the following :

"The administratively scoped multicast address space includes the following scopes, per the IANA:

  • Site-local scope (239.255.0.0/16; 239.252.0.0/16, 239.253.0.0/16, and 239.254.0.0/16 are also reserved for this purpose)
  • Organization local scope (239.192.0.0 to 239.251.255.255)

The IANA has further refined these ranges, as detailed in the IANA multicast address assignment list referenced earlier."

If 239.0.0.0 is already speficied for private used, why the author wrote, the IANA as defined different range also for private used in the range already defined for private used ?

Sorry for my English, I'm a French people it's also maybe why I do not understand the explanation provide by the author here !!

Thanks a lot  !

Hi,

Check out the below link for more information about your query !!

http://conft.com/en/US/docs/app_ntwk_services/waas/acns/v52/configuration/central/guide/5645mcst.html

Hope to Help !!

Ganesh.H

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Overall Rating: 4.3 (3 ratings)
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Reza Sharifi Sat, 05/29/2010 - 13:57

Hi,

Per RFC 2365, the entire 239/8 range is administratively scoped and should not be forwarded beyond a network boundary (usually a routing domain).

HTH

Reza

Correct Answer
Ganesh Hariharan Sat, 05/29/2010 - 22:22

Hi !

I'm currently preparing BSCI certification exam, for my studdies I read the : Authorized Self-Studdy guide BSCI.  In the chapter cover IP Multicast trafic, the author as wrote :

"

  • Limited, or administratively, scoped addresses in the range 239.0.0.0 through 239.255.255.255. As defined by Requests for Comments (RFC) 2365, Administratively Scoped IP Multicast, these addresses are reserved for use inside private domains.

"

My understanding in this text is the following : address range 239.0.0.0/8 are multicast address which will only used on private network, like it is address define by the 1918 RFC for 10.0.0.0 network as exemple.

What I"m do not understand is the following :

"The administratively scoped multicast address space includes the following scopes, per the IANA:

  • Site-local scope (239.255.0.0/16; 239.252.0.0/16, 239.253.0.0/16, and 239.254.0.0/16 are also reserved for this purpose)
  • Organization local scope (239.192.0.0 to 239.251.255.255)

The IANA has further refined these ranges, as detailed in the IANA multicast address assignment list referenced earlier."

If 239.0.0.0 is already speficied for private used, why the author wrote, the IANA as defined different range also for private used in the range already defined for private used ?

Sorry for my English, I'm a French people it's also maybe why I do not understand the explanation provide by the author here !!

Thanks a lot  !

Hi,

Check out the below link for more information about your query !!

http://conft.com/en/US/docs/app_ntwk_services/waas/acns/v52/configuration/central/guide/5645mcst.html

Hope to Help !!

Ganesh.H

Remember to rate helpful post

Giuseppe Larosa Sun, 05/30/2010 - 05:16

Hello Christien,

  • Site-local scope (239.255.0.0/16; 239.252.0.0/16, 239.253.0.0/16, and 239.254.0.0/16 are also reserved for this purpose)
  • Organization local scope (239.192.0.0 to 239.251.255.255)
Simply means that inside the 239.0.0.0/8 space two subsets are introduced: the first to be used for traffic local to a single site of an intranet company and a second subset for addresses to be used in the intranet of a company company wide.
A site is a campus network in an organization with WAN links connecting to other company sites.
see
As the RFC outlines in paragraph 8, this is done also with IPv6 in mind. IPv6 multicast addresses use part of the IPv6 address to denote the scope of the address. This field is not present in IPv4 multicast.
In IPv6 site local (now unique local) and organizational local apply to unicast addresses too.
Hope to help
Giuseppe

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