From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Mon Feb 07 2005 - 20:53:08 GMT-3
Tim,
Per the IPv6 standard it is technically not optional:
<RFC 2373>
2.4 Address Type Representation
<snip>
(2) The format prefixes 001 through 111, except for Multicast
Addresses (1111 1111), are all required to have to have 64-bit
interface identifiers in EUI-64 format. See section 2.5.1 for
definitions.
<snip>
2.5.1 Interface Identifiers
<snip>
In a number of the format prefixes (see section 2.4) Interface IDs
are required to be 64 bits long and to be constructed in IEEE EUI-64
format [EUI64].
</RFC 2373>
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
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> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> ccie2be
> Sent: Monday, February 07, 2005 5:05 PM
> To: Group Study
> Subject: eui-64 option - I think I got it
>
> Hey guys,
>
> I went back to my Syngress book on ipv6 to see if I could figure out
when
> I
> needed to use the eui-64 option
>
> when configuring an ipv6.
>
> Here's my conclusion:
>
> It's optional (unless the lab says otherwise).
>
> If you want - for whatever reasons - to assign all 128 of the address
you
> can
> do so.
>
> For example, below the least significant bit (bit 128) is 1.
>
> Rack1R1(config-if)#ipv6 address 2001:157:1:14::1/64
> Rack1R1(config-if)#do sh ipv6 int e0/0
> Ethernet0/0 is up, line protocol is up
> IPv6 is enabled, link-local address is FE80::2D0:58FF:FE6E:B720
> Global unicast address(es):
> 2001:157:1:14::1, subnet is 2001:157:1:14::/64 <-- unicast
address
> doesn't include mac addr
> Joined group address(es):
> FF02::1
> FF02::2
> FF02::1:FF00:1
> FF02::1:FF6E:B720
> MTU is 1500 bytes
> ICMP error messages limited to one every 100 milliseconds
> ICMP redirects are enabled
> ND DAD is enabled, number of DAD attempts: 1
> ND reachable time is 30000 milliseconds
> ND advertised reachable time is 0 milliseconds
> ND advertised retransmit interval is 0 milliseconds
> ND router advertisements are sent every 200 seconds
> ND router advertisements live for 1800 seconds
> Hosts use stateless autoconfig for addresses.
> Rack1R1(config-if)#
>
> However, if I want - for whatever reasons - to have the router assign
the
> least significant 64 bits,
> I could just add the eui-64 option to the end of the address command.
>
> Rack1R1(config-if)#no ipv6 address 2001:157:1:14::1/64 <-- remove
> previous
> address
> Rack1R1(config-if)#ipv6 address 2001:157:1:14::/64 eui-64
> Rack1R1(config-if)#do sh ipv6 int e0/0
> Ethernet0/0 is up, line protocol is up
> IPv6 is enabled, link-local address is FE80::2D0:58FF:FE6E:B720
> Global unicast address(es):
> 2001:157:1:14:2D0:58FF:FE6E:B720, subnet is 2001:157:1:14::/64
<--
> unicast
> addr includes mac addr
> Joined group address(es):
> FF02::1
> FF02::2
> FF02::1:FF6E:B720
> MTU is 1500 bytes
> ICMP error messages limited to one every 100 milliseconds
> ICMP redirects are enabled
> ND DAD is enabled, number of DAD attempts: 1
> ND reachable time is 30000 milliseconds
> ND advertised reachable time is 0 milliseconds
> ND advertised retransmit interval is 0 milliseconds
> ND router advertisements are sent every 200 seconds
> ND router advertisements live for 1800 seconds
> Hosts use stateless autoconfig for addresses.
> Rack1R1(config-if)#
>
>
> Do I have this right?
>
> Thanks for all your feedback. Tim
>
>
This archive was generated by hypermail 2.1.4 : Thu Mar 03 2005 - 08:51:18 GMT-3