3com 4210 PWR 9-Port 3CR17341-91-ME User Manual

C

HAPTER

 46: IP

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6 M

ANGEMENT

 C

ONFIGURATION

There are several forms of unicast address assignment in IPv6, including global 
unicast address, link-local address, and site-local address.

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The global unicast address, equivalent to an IPv4 public address, is used for 
aggregatable links and provided for network service providers. This type of 
address allows efficient routing aggregation to restrict the number of global 
routing entries.

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The link-local address is used for the neighbor discovery protocol as well as 
communication between link-local nodes in stateless autoconfiguration. 
Routers must not forward any packets with link-local source or destination 
addresses to other links.

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IPv6 unicast site-local addresses are similar to private IPv4 addresses. Routers 
must not forward any packets with site-local source or destination addresses 
outside of the site (equivalent to a private network).

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Loopback address: The unicast address 0:0:0:0:0:0:0:1 (represented in shorter 
format as ::1) is called the loopback address and may never be assigned to any 
physical interface. Like the loopback address in IPv4, it may be used by a node 
to send an IPv6 packet to itself.

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Unassigned address: The unicast address :: is called the unassigned address and 
may not be assigned to any node. Before acquiring a valid IPv6 address, a node 
may fill this address in the source address field of an IPv6 packet, but may not 
use it as a destination IPv6 address.

Multicast addresses listed in Table 384 are reserved for special purpose.

Besides, there is another type of multicast address: solicited-node address. The 
solicited-node multicast address is used to acquire the link-layer addresses of 
neighbor nodes on the same link and is also used for duplicate address detection. 
Each IPv6 unicast or anycast address has one corresponding solicited-node 
address. The format of a solicited-node multicast address is as follows:

FF02:0:0:0:0:1:FFXX:XXXX

Anycast address

Anycast addresses are taken from unicast address space 
and are not syntactically distinguishable from unicast 
addresses.

Table 384   Reserved IPv6 multicast addresses

FF01::1 

Node-local scope all-nodes multicast address 

FF02::1 

Link-local scope all-nodes multicast address 

FF01::2 

Node-local scope all-routers multicast address 

FF02::2 

Link-local scope all-routers multicast address 

FF05::2 

Site-local scope all-routers multicast address

Table 383   Mapping between address types and format prefixes