From: Scott Morris (swm@emanon.com)
Date: Sat Feb 19 2005 - 01:20:52 GMT-3
They aren't the "same" from a numerical perspective. They are the "same" as
they are both host addresses.
IPv6 is no different than IPv4 at the fundamental working level (nobody go
nuts on me here)...
You have a network and a mask.
IPv6 = 2000::x/64 (2000:0000:0000:0000::x/64 as the network)
IPv4 = 200.200.200.x/24 (200.200.200.x/24 as the network)
'x' is still my host address. Based on the netmask in the IPv6 network that
host has 64 bits to define it. Based on the netmask in the IPv4 network
that host has 8 bits to describe it.
So in the IPv4 space it's kinda like asking whether host .200 and host .10
are the "same". They aren't. They are simply two different numbers. IPv4
deals with the philosophical "big ass grey area" and comes up with some
festive ways to fill out those bits.
They're still host bits though, and we can do whatever we want with them!
.200 does not represent the same thing as .10 from a physical device's
perspective, but they are both host portions of the IPvX address.
HTH,
Scott Morris, MCSE, CCDP, CCIE4 (R&S/ISP-Dial/Security/Service Provider)
#4713, JNCIP, CCNA-WAN Switching, CCSP, Cable Communications Specialist, IP
Telephony Support Specialist, IP Telephony Design Specialist, CISSP
CCSI #21903
swm@emanon.com
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of John
Matus
Sent: Friday, February 18, 2005 8:53 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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