Being assigned PI space does NOT guarantee global routability. See RFC 2050.
In the real world, prefixes shorter than /21 will probably be
globally routable. Indeed, /24 may very well be routable. Hint: do
NOT call a /24 a Class C. Registries and providers get very
suspicious of addressing plans
in which everything falls on a /24 or /16 boundary.
But the address registries -- APNIC, RIPE NCC, and ARIN -- do not
control what prefix length filters are implemented by providers. No
organization guarantees global reachability, because no organization
controls global routing.
Incidentally, the registries may differ in other policies. RIPE NCC
now requires that you must register your routing policies before
being assigned an AS.
It's not even as simple as length. Some filter policies are on the
NANOG web page. A given carrier, for example, may permit a /24 from
the 192/8 "traditional" or "swamp" space, but not permit a /24 from
more recently assigned blocks for which people are expected to know
about CIDR.
Unfortunately, a lot of this real-world global routing conventions
are not well documented. My understanding of them began with
RIPE-181, which was superceded by RPSL. That simply taught me the
language. A good working knowledge comes from daily reading of
NANOG, RIPE, and APNIC mailing lists, and, even then, I need to
discuss policies with every specific provider involved in a
particular peering situation.
There's good news, I suppose, that Cisco certifications and global
routing practice have little to do with one another.
There's bad news, I suppose, that Cisco certifications and global
routing practice have little to do with one another.
Guilherme Spolidoro wrote,
>If APNIC gave you only a single class C, yes.
>
>The bottow line is: you need to follow the APNIC rules. If they assigned a
>class C to you is because their current rules for that class C range is to
>assign on a /24 manner. Most likely they have other blocks of class C that
>they assign on CIDR mode.
>
>Does it help?
>
>From: Benny Leong (HTHK - Senior Engineer II - iServices Development,
>NNSD) [mailto:[EMAIL PROTECTED]]
>Sent: Thursday, September 28, 2000 2:19 AM
>To: 'Brian'
>
>I have PI class C address applied from APNIC. Am I globally routable ?
>
> ----------
> From: Brian [SMTP:[EMAIL PROTECTED]]
>
> On Wed, 27 Sep 2000, Benny Leong (HTHK - Senior Engineer II -
>iServices Development, NNSD) wrote: >
> > >From the ARIN, there is a statement shown below :
> >
> > *The minimum block of IP address space assigned by ARIN is a /20.
>Smaller
> > blocks obtained directly from ARIN are the least likely to be
>globally
> > routable.
> >
> > What does that mean ? Thanks.
>
> It means that if you got an allocation from arin of say a /24, /23,
> etc. That its the least likely space to be routable. Back in the
>day,
> ARIN would allocate a /24 to just about anyone on the net with a
> presense......this space is not part of any provider aggregate, and
>its
> the least likely to be routable.
>
> > ----------
> > From: Spolidoro, Guilherme
>[SMTP:[EMAIL PROTECTED]]
> > Sent: Monday, September 25, 2000 9:15 PM
>
> > You can find a lot of information about RADB on the RADB.net
>web
> > site. The
> > problem is that I never found some examples or explanations
>on how
> > large
> > ISPs use the information stored on the IRRd servers on real
>life.
> > Maybe
> > somebody with more experience could comment about that.
> >
> > Anyway, RADB runs an IRRd server that is used to store each
>ISP
> > routing
> > policy, for example: what are your AS numbers, your
>networks, what
> > networks
> > you'll accept from ISP xxx or what networks you're going to
> > advertise to ISP
> > wwww (just two simple examples). You write your policy using
>a
> > specific
> > language (like an script) that can be used to configure the
>BGP on
> > your
> > NAP/MAE routers.
> >
> > There are serveral IRRd servers and RADB.net host the
>"official" one
> > for the
> > US. RIPE has another server for Europe and some ISPs have
>their own
> > server.
> > I'm not sure why an ISP would want to have his own IRRd
>server, but
> > my guess
> > is that they probably use that information to know what are
>their
> > customers's BGP policies for them, i.e. what networks their
> > customers will
> > advertise for them so they can configure the BGP filters
>properly.
> >
> > I know of at least one ISP that won't accept any
>advertisement from
> > their
> > customers unless register on the RADB IRRd server.
> >
> > It's my opinion that since everybody can use the information
>on the
> > IRRd
> > servers as they want, it's always good to keep it up to date
>so you
> > don't
> > have somebody blocking your networks because you didn't
>register
> > your latest
> > policy there.
> >
> > Good luck.
> >
> > -----Original Message-----
> > From: Benny Leong (HTHK - Senior Engineer II - iServices
> > Development,
> > NNSD) [mailto:[EMAIL PROTECTED]]
> > Sent: Monday, September 25, 2000 2:09 AM
> > To: '[EMAIL PROTECTED]'
> > Subject: RADB - BGP routing
> >
> > What is the use of RADB ?
> > Is it a must to register AS number and the route to the RADB
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