From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Fri Feb 18 2005 - 23:19:59 GMT-3
The point is that the modified EUI-64 address is derived from
the MAC address of the interface. Assuming that the 48-bit mac address
is unique (which it should be), the host address on the segment will be
too. It's just another built in mechanism for IPv6 to be as transparent
to the end user as possible. As soon as the host boots up it selects a
host address based on the EUI-64 formatting and sends a router
solicitation message using it's link-local address as the source. When
the router responds the host learns about the network prefix. It can
then go on to get additional information, such as DNS, from DHCPv6.
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
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> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> John Matus
> Sent: Friday, February 18, 2005 7:53 PM
> To: mullenm@gmail.com
> Cc: ccielab@groupstudy.com
> Subject: Re: ipv6 eui 64 address
>
> ...but how is 210:7BFF:FE35:CC72 the same as 0000:0000:0000:0001.
seems
> to
> me that they are 2 completely different host addresses. i under stand
> that
> you could use one or the other just like 10.1.1.1 or 10.1.1.2, but to
me
> they seem to represent to distinctly different addresses :-0
> am i missing something?
>
> >From: Matt Mullen <mullenm@gmail.com>
> >Reply-To: Matt Mullen <mullenm@gmail.com>
> >To: John Matus <john_matus@hotmail.com>
> >CC: ccielab@groupstudy.com
> >Subject: Re: ipv6 eui 64 address
> >Date: Fri, 18 Feb 2005 20:30:21 -0500
> >
> >The difference is in the way the host part of the address is
> >represented. Without eui-64, in your example the host ID is 1. Or
> >to be more specific it is 0000:0000:0000:0001. With eui-64, the
> >host-id gets generated based on a mac address. So in the case where I
> >enabled eui-64 the host-id is 210:7BFF:FE35:CC72. Functionally they
> >are the same. It's just two different ways of representing the host
> >portion of the IPv6 address. I can't think of any other good reason
> >to use eui-64 except for that it could help to reduce the chance of
> >duplicate IP addresses being created. Question for the group: what
> >would be some reasons to use eui-64 addresses? Personally, I would
> >rather not use eui-64 because to me an address like 2000::1 is more
> >recognizable than 2000::210:7BFF:FE35:CC72.
> >
> >
> >On Fri, 18 Feb 2005 23:01:09 +0000, John Matus
<john_matus@hotmail.com>
> >wrote:
> > > so.....i'm a bit confused. what is the functional difference
between
> an
> > > ipv6 address w/out eui-64 and one w/ eui-64?
> > >
> > > >From: Matt Mullen <mullenm@gmail.com>
> > > >Reply-To: Matt Mullen <mullenm@gmail.com>
> > > >To: John Matus <john_matus@hotmail.com>
> > > >CC: ccielab@groupstudy.com
> > > >Subject: Re: ipv6 eui 64 address
> > > >Date: Fri, 18 Feb 2005 15:46:55 -0500
> > > >
> > > >Hi John,
> > > >
> > > >It won't use eui-64 unless you tell it to:
> > > >
> > > >R2#conf t
> > > >Enter configuration commands, one per line. End with CNTL/Z.
> > > >R2(config)#int lo100
> > > >R2(config-if)#ipv6 address 2000::1/64
> > > >R2(config-if)#do sh ipv6 int brie lo100
> > > >Loopback100 [up/up]
> > > > FE80::210:7BFF:FE35:CC72
> > > > 2000::1
> > > >R2(config-if)#
> > > >
> > > >R2#conf t
> > > >Enter configuration commands, one per line. End with CNTL/Z.
> > > >R2(config)#int lo100
> > > >R2(config-if)#ipv6 address 2000::1/64 eui-64
> > > >R2(config-if)#do sh ipv6 int brie lo100
> > > >Loopback100 [up/up]
> > > > FE80::210:7BFF:FE35:CC72
> > > > 2000::210:7BFF:FE35:CC72
> > > >
> > > >HTH,
> > > >
> > > >Matt
> > > >
> > > >
> > > >On Fri, 18 Feb 2005 20:39:23 +0000, John Matus
> <john_matus@hotmail.com>
> > > >wrote:
> > > > > is eui-64 the default ipv6 address type.........meaning if i
do a:
> > > > >
> > > > > ipv6 address 2000::1/64, will that show up in the config as
> >2000::1/64
> > > > > eui-64? <i don't have a router in front of me>
> > > > >
> > > > >
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