# Multicast Addresses

**Unicast** addresses are one-to-one.

* One source to one destination.

**Broadcast** addresses are one-to-all.

* One source to all destinations (within the subnet).

**Multicast** addresses are one-to-many.

* One source to multiple destinations (that have joined the specific *multicast group*).

IPv6 uses the range FF00::/8 for multicast. (FF00:: to FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF)

**IPv6 doesn't use broadcast** (there is no 'broadcast address' in IPv6!).

## Important addresses

| Pupose                                               | IPv6 Address | IPv4 Address |
| ---------------------------------------------------- | ------------ | ------------ |
| <p>All nodes/hosts<br>(functions like broadcast)</p> | FF02::1      | 224.0.0.1    |
| All routers                                          | FF02::2      | 224.0.0.2    |
| All OSPF routers                                     | FF02::5      | 224.0.0.5    |
| All OSPF DRs/BDRs                                    | FF02::6      | 224.0.0.6    |
| All RIP routers                                      | FF02::9      | 224.0.0.9    |
| All EIGRP routers                                    | FF02::A      | 224.0.0.10   |

## Scopes

IPv6 defines multiple multicast 'scopes' which indicate how far the packet should be forwarded.

The addresses in the previous slide all use the 'link-local' scope (FF02), which stays in the local subnet.

IPv6 multicast scopes:

* **Interface-local** (FF01): the packet doesn't leave the local device. Can be used to send traffic to a service within the local device.
* **Link-local** (FF02): The packet remains in the local subnet. Routers will not route the packet between subnets.
* **Site-local** (FF05): The packet can be forwarded by routers. Should be limited to a single physical location (not forwarded over a WAN).
* **Organization-local** (FF08): Wider in scope than site-local (an entire company/organization).
* **Global** (FF0E): No boundaries. Possible to be routed over the internet.

<figure><img src="/files/xRQ43cPiE3rFGEiTHnjI" alt=""><figcaption></figcaption></figure>

<figure><img src="/files/cgpbcBLEstiAkg70NNmp" alt=""><figcaption></figcaption></figure>


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