3Com 4210 PWR, Configuration Manual

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46
IP
V
6 M
ANGEMENT
C
ONFIGURATION
n
■
The term "router" in this document refers to a router in a generic sense or an
Ethernet switch running a routing protocol.
■
3Com Switch 4210 Family supports IPv6 management features, but does not
support IPv6 forwarding and related features.
IPv6 Overview
Internet protocol version 6 (IPv6), also called IP next generation (IPng), was
designed by the Internet Engineering Task Force (IETF) as the successor to Internet
protocol version 4 (IPv4). The significant difference between IPv6 and IPv4 is that
IPv6 increases the IP address size from 32 bits to 128 bits.
IPv6 Features Header format simplification
IPv6 cuts down some IPv4 header fields or move them to extension headers to
reduce the load of basic IPv6 headers. IPv6 uses a fixed-length header, thus
making IPv6 packet handling simple and improving the forwarding efficiency.
Although the IPv6 address size is four times that of IPv4 addresses, the size of basic
IPv6 headers is only twice that of IPv4 headers (excluding the Options field). For
the specific IPv6 header format, see Figure 189.
Figure 189 Comparison between IPv4 header format and IPv6 header format
Adequate address space
The source IPv6 address and the destination IPv6 address are both 128 bits (16
bytes) long.IPv6 can provide 3.4 x 10
38 addresses to completely meet the
requirements of hierarchical address division as well as allocation of public and
private addresses.
Ver
Traffic
class
Flow label
Payload length
Next
header
Hop limit
Source address
128 bits
Destination address
128 bits
Ver IHL Total length
Identification F Fragment offset
TTL
Source address (32 bits)
TOS
Header checksum
Destination address (32 bits)
Protocol
IPv4 header
IPv6 header
Options Padding
0 7 15 31 0 7 15 31