Difference between revisions of "IP Multicast"
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*Used by financial applications and networks. Other uses include resource discovery, data collection, auctions, and polling. | *Used by financial applications and networks. Other uses include resource discovery, data collection, auctions, and polling. | ||
== IP multicast Addresses == | == IP multicast Addresses == | ||
| + | IP Multicast addresses ranging from from 224.0.0.0 to 239.255.255.255 are divided into three multicast address groups. | ||
| + | {|border=1 | ||
| + | |+ IPv4 Multicast Address groups | ||
| + | |- bgcolor=lightgrey | ||
| + | ! From !! to !! Range | ||
| + | |- | ||
| + | |224.0.0.0 || 224.0.0.255 || Reserved link, Local addresses | ||
| + | |- | ||
| + | |224.0.1.0 || 238.255.255.255 || Globally scoped addresses | ||
| + | |- | ||
| + | |239.0.0.0 || 239.255.255.255 || Limited Scope addresses | ||
| + | |- | ||
| + | |} | ||
| + | |||
=== Locally scoped (reserved link local) addresses === | === Locally scoped (reserved link local) addresses === | ||
*Reserved by the Internet Assigned Numbers Authority (IANA) for network protocol use. | *Reserved by the Internet Assigned Numbers Authority (IANA) for network protocol use. | ||
| Line 51: | Line 65: | ||
*Organization-local scope (239.192.0.0 to 239.251.255.255) | *Organization-local scope (239.192.0.0 to 239.251.255.255) | ||
*Site-local scope (239.255.0.0/16, with 239.252.0.0/16, 239.253.0.0/16, and 239.254.0.0/16 also reserved) | *Site-local scope (239.255.0.0/16, with 239.252.0.0/16, 239.253.0.0/16, and 239.254.0.0/16 also reserved) | ||
| − | [[Category:Network]] | + | == Layer 2 Multicast addressing == |
| + | === IP Multicast MAC address mapping on Ethernet === | ||
| + | On Ethernet the IP multicast address is converted to a Ethernet Multicast address. | ||
| + | *IPv4 addresses are 32 bits wide. | ||
| + | *Ethernet MAC Addresses are 48 bits wide. | ||
| + | Because the IP address are shorter than the MAC address a direct conversion is not possible. | ||
| + | |||
| + | [[Category:Network]][[Category:Cisco]] | ||
Revision as of 22:57, 26 February 2009
Multicast Applications
One-to-Many
where one sender sends data to many receivers.
- This type of application may be used for audio or video distribution, push media, announcements, monitoring, and so on.
- If a one-to-many application needs feedback from receivers, it becomes a many-to-many application
Many-to-Many =
where a host can be a sender and a receiver simultaneously or where two or more receivers also act as senders.
- Receiving data from several sources increases the complexity of applications and creates different management challenges.
- Using a many-to-many multicast concept as a foundation, a whole new range of applications may be built (for example, collaboration, concurrent processing, and distributed interactive simulations).
Many-to-One
where many receivers are sending data back to one sender.
- Used by financial applications and networks. Other uses include resource discovery, data collection, auctions, and polling.
IP multicast Addresses
IP Multicast addresses ranging from from 224.0.0.0 to 239.255.255.255 are divided into three multicast address groups.
| From | to | Range |
|---|---|---|
| 224.0.0.0 | 224.0.0.255 | Reserved link, Local addresses |
| 224.0.1.0 | 238.255.255.255 | Globally scoped addresses |
| 239.0.0.0 | 239.255.255.255 | Limited Scope addresses |
Locally scoped (reserved link local) addresses
- Reserved by the Internet Assigned Numbers Authority (IANA) for network protocol use.
- Address range is from 224.0.0.0 through 224.0.0.255.
- Multicasts in this range are never forwarded off the local network, regardless of Time to Live (TTL). Usually, the TTL is set to 1.
| Address | Meaning |
|---|---|
| 224.0.0.1 | All multicast Systems on a subnet |
| 224.0.0.2 | All multicast Routers on a subnet |
| 224.0.0.4 | All Distant vector multicast routing protocol routers |
| 224.0.0.5 | All OSPF Routers |
| 224.0.0.6 | All OSPF designated Routers |
| 224.0.0.9 | All RIPv2 Routers |
| 224.0.0.10 | All EIGRP Routers |
| 224.0.0.13 | All PIMv2 Routers |
Globally scoped addresses
- Allocated dynamically throughout the Internet.
- Address range is from 224.0.1.0 through 238.255.255.255.
- The 224.2.X.X range is used in Multicast Backbone (Mbone) applications. Established by the Internet Engineering Task Force (IETF) to multicast audio and video meetings, Mbone is a collection of Internet routers that support IP multicasting on which various public and private audio and video programs are sent.
Limited (administratively) scoped addresses
- Reserved for use inside private domains. Similar to the private IP address space that is used within the boundaries of a single organization, limited or administratively scoped addresses are constrained to a local group or organization.
- Address range is from 239.0.0.0 through 239.255.255.255.
- Organizations can use limited scope addresses to have local multicast applications that will not be forwarded over the Internet.
- Within an autonomous system or domain, the limited scope address range can be further subdivided so that local multicast boundaries can be defined. This subdivision is called address scoping and allows for address reuse between smaller domains. The administratively scoped multicast address space is divided into the following scopes:
- Organization-local scope (239.192.0.0 to 239.251.255.255)
- Site-local scope (239.255.0.0/16, with 239.252.0.0/16, 239.253.0.0/16, and 239.254.0.0/16 also reserved)
Layer 2 Multicast addressing
IP Multicast MAC address mapping on Ethernet
On Ethernet the IP multicast address is converted to a Ethernet Multicast address.
- IPv4 addresses are 32 bits wide.
- Ethernet MAC Addresses are 48 bits wide.
Because the IP address are shorter than the MAC address a direct conversion is not possible.