Re: Unique Local Address (ULA) - IPv6

Whoops...means subnetted into two /8's of course : )

On Wed, Dec 16, 2009 at 12:25 AM, Joe Astorino <jastorino_at_ipexpert.com>wrote:

> It is somewhat strange.
>
> Essentially they took the FC00::/7 range and subnetted into two /7s --
> FC00::/8 and FD00::/8. Each /8 is for a different purpose. Basically we
> have two different things because different people have different views on
> how things should be done.
>
> With FC00::/8 range your site-local address is actually ASSIGNED to you by
> a registrar even though the range is NOT globally routable. This ensures
> that everything remains unique within your organization. There is actually
> accountability where there is an organization that assigns to you your
> locally used ranges
>
> With FD00::/8 it is more like RFC1918 space, where your site-ID is a
> "semi-randomly" generated number, and you have 16 bits for subnetting left
> which effectively gives you room for like 65,535 /64 subnets to play with :
> )
>
> So FC00::/8 looks something like this where the 40-bit global-id (your
> "site ID") is ASSIGNED to you
>
> [FC][Global-ID][Subnet-ID][Interface ID]
> [8 ] [40 bits ][16 bits ]]64 bits ]
>
> The FD00::/8 stuff would look essentially the same, except the 40-bit
> global-id is NOT assigned to you...it is randomly generated
>
> HTH
>
> P.S. This is not to be confused with "site-local" addressing (FEC0::/10)
> which is depricated. The reason behind this being depricated has to do with
> many many arguments over the ambiguity of what is considered a "site".
>
>
> On Tue, Dec 15, 2009 at 7:14 PM, Scott Morris <smorris_at_ine.com> wrote:
>
>> You'd configure it where the lab told you. :)
>>
>> If it said "you have been assigned an ID of ..." then I'd use FC. If it
>> said "you decided to use an ID of ...." then I'd use FD.
>>
>> HTH,
>>
>>
>>
>>
>> *Scott Morris*, CCIE/x4/ (R&S/ISP-Dial/Security/Service Provider) #4713,
>>
>> JNCIE-M #153, JNCIS-ER, CISSP, et al.
>>
>> JNCI-M, JNCI-ER
>>
>> evil_at_ine.com
>>
>>
>> Internetwork Expert, Inc.
>>
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>>
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>>
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>>
>>
>> Knowledge is power.
>>
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>>
>> Study hard and be Eeeeviiiil......
>>
>>
>>
>> Roy Waterman wrote:
>> > Hi all
>> >
>> > Would like some clarification on configuring ulas.
>> > We all know its: FC00::/7, however as per RFC4193 it mentions that the L
>> bit
>> > (the 8th bit) is set to 1 if the prefix is locally assigned, and that L
>> bit
>> > as 0 is undefined.
>> > As such in various places, Ive seen that you'd typically configure ulas
>> > starting as fd00::/8, but from a Cisco implementation perspective,
>> > does it matter whether fc00::/8 or fd00::/8 is used?
>> >
>> > >From a lab perspective, if asked to configure a ula, should ipv6
>> address
>> > fd00:... always be used (locally assigning the ipv6 address) ?
>> >
>> > Please advise.
>>
>>
>> Blogs and organic groups at http://www.ccie.net
>>
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>>
>>
>
>
> --
> Regards,
>
> Joe Astorino CCIE #24347 (R&S)
> Sr. Technical Instructor - IPexpert
> Mailto: jastorino_at_ipexpert.com
> Telephone: +1.810.326.1444
> Live Assistance, Please visit: www.ipexpert.com/chat
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>
> IPexpert is a premier provider of Classroom and Self-Study Cisco CCNA (R&S,
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>

-- 
Regards,
Joe Astorino CCIE #24347 (R&S)
Sr. Technical Instructor - IPexpert
Mailto: jastorino_at_ipexpert.com
Telephone: +1.810.326.1444
Live Assistance, Please visit: www.ipexpert.com/chat
eFax: +1.810.454.0130
IPexpert is a premier provider of Classroom and Self-Study Cisco CCNA (R&S,
Voice & Security), CCNP, CCVP, CCSP and CCIE (R&S, Voice, Security & Service
Provider) Certification Training with locations throughout the United
States, Europe and Australia. Be sure to check out our online communities at
www.ipexpert.com/communities and our public website at www.ipexpert.com
Blogs and organic groups at http://www.ccie.net