3com S7906E Manuel De Montage

 

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IPv6 cuts down some IPv4 header fields or move them to the IPv6 extension headers to reduce the 

length of the basic IPv6 header. IPv6 uses the basic header with a fixed length, thus making IPv6 packet 

handling simple and improving the forwarding efficiency. Although the IPv6 address size is four times 

the IPv4 address size, the basic IPv6 header size is 40 bytes and is only twice the IPv4 header size 

(excluding the Options field).  

Figure 1-1 Comparison between IPv4 packet header format and basic IPv6 packet header format 

 

 

The source and destination IPv6 addresses are both 128 bits (16 bytes) long. IPv6 can provide 3.4 x 

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 addresses to fully meet the requirements of hierarchical address division as well as allocation of 

public and private addresses. 

IPv6 adopts the hierarchical address structure to quicken route search and reduce the system sources 

occupied by the IPv6 routing table by route aggregation. 

To simplify host configuration, IPv6 supports stateful and stateless address configuration. 

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Stateful address configuration means that a host acquires an IPv6 address and related information 

from a server (for example, a DHCP server). 

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Stateless address configuration means that a host automatically generates an IPv6 address and 

related information on the basis of its own link-layer address and the prefix information advertised 

by a router. 

In addition, a host can generate a link-local address on the basis of its own link-layer address and the 

default prefix (FE80::/10) to communicate with other hosts on the same link.