IPv6 Configuration Guide K/KA/KB.15.15

Example 37 Configuring multiple station access
Table 5 (page 64) shows an example in which a mask that authorizes switch access to four
management stations is applied to the IPv6 address:
2001:DB8:0000:0000:244:17FF:FEB6:D37D.
The mask is: FFFF:FFFF:FFFF:FFF8:FFFF:FFFF:FFFF:FFFC.
Table 5 Mask for configuring a single authorized IPv6 manager station
Manager- or operator-level
access
8th
block
7th
block
6th
block
5th
block
4th
block
3rd
block
2nd
block
1st
block
The "F" value in the first 124
bits of the mask specifies that
FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFIPv6 mask
D37DFEB617FF24400000000DB82001
IPv6
address
only the exact value of each
corresponding bit in an
authorized IPv6 address is
allowed. However, the "C"
value in the last four bits of the
mask allows four possible
combinations (D37C, D37D,
D37E, and D37F) in the last
block of an authorized IPv6
address.
As shown in Table 6 (page 64), if you use a mask of
FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFC with an IPv6 address, you can authorize
four IPv6-based stations to access the switch. In this mask, all bits except the last two are set to 1
(“on”); the binary equivalent of hexadecimal C is 1100.
Table 6 How a mask determines four authorized IPv6 manager addresses
Last block in mask: FFFC
Last block in IPv6 address: D37D
BitBitBitBitBitBitBitBitBitBitBitBitBitBitBitBitBit numbers
0123456789101112131415
CFFFBit value
0011111111111111
FFFC: Last block
in mask
1011110110010011
D37D:Last block
in IPv6 address
0 = Off1 = OnBit setting:
Therefore, this mask requires the first corresponding 126 bits in an authorized IPv6 address to be
the same as in the specified IPv6 address: 2001:DB8:0000:0000:244:17FF:FEB6:D37C. However,
the last two bits are set to 0 ("off") and allow the corresponding bits in an authorized IPv6 address
to be either "on" or "off". As a result, only the four IPv6 addresses shown in Table 7 (page 64)
are allowed access.
Table 7 Mask for configuring a single authorized IPv6 manager station
8th
block
7th
block
6th
block
5th
block
4th
block
3rd
block
2nd
block
1st
block
FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFIPv6 mask
D37DFEB617FF24400000000DB82001
IPv6 address entered with the ipv6
authorized-managers
command
64 IPv6 Management Security Features