ZyXEL Communications GS3700 Series Uživatelská příručka stáhnout pdf (Strana 393)

GS3700/XGS3700 Series User’s Guide 393

APPENDIX B

IPv6

Overview

IPv6 (Internet Protocol version 6), is designed to enhance IP address size and features. The

increase in IPv6 address size to 128 bits (from the 32-bit IPv4 address) allows up to 3.4 x 10

addresses.

IPv6 Addressing

The 128-bit IPv6 address is written as eight 16-bit hexadecimal blocks separated by colons (:). This

is an example IPv6 address 2001:0db8:1a2b:0015:0000:0000:1a2f:0000.

IPv6 addresses can be abbreviated in two ways:

• Leading zeros in a block can be omitted. So 2001:0db8:1a2b:0015:0000:0000:1a2f:0000 can

be written as 2001:db8:1a2b:15:0:0:1a2f:0.

• Any number of consecutive blocks of zeros can be replaced by a double colon. A double colon can

only appear once in an IPv6 address. So 2001:0db8:0000:0000:1a2f:0000:0000:0015 can be

written as 2001:0db8::1a2f:0000:0000:0015, 2001:0db8:0000:0000:1a2f::0015,

2001:db8::1a2f:0:0:15 or 2001:db8:0:0:1a2f::15.

Prefix and Prefix Length

Similar to an IPv4 subnet mask, IPv6 uses an address prefix to represent the network address. An

IPv6 prefix length specifies how many most significant bits (start from the left) in the address

compose the network address. The prefix length is written as “/x” where x is a number. For

example,

2001:db8:1a2b:15::1a2f:0/32

means that the first 32 bits (2001:db8) is the subnet prefix.

Link-local Address

A link-local address uniquely identifies a device on the local network (the LAN). It is similar to a

“private IP address” in IPv4. You can have the same link-local address on multiple interfaces on a

device. A link-local unicast address has a predefined prefix of fe80::/10. The link-local unicast

address format is as follows.

Table 200 Link-local Unicast Address Format

1111 1110 10 0 Interface ID

10 bits 54 bits 64 bits

1 2 ... 388 389 390 391 392 393 394 395 396 397 398 ... 415 416

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ZyXEL Communications GS3700 Series Uživatelská příručka Strana 393