From: Scott Morris (swm@emanon.com)
Date: Thu Aug 02 2007 - 12:12:29 ART
You make it sound like there's something wrong with having your own AS and
PI space. ;)
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
sheherezada@gmail.com
Sent: Thursday, August 02, 2007 10:07 AM
To: Hyunseog Ryu
Cc: Gregory Gombas; Herbert Maosa; Group study
Subject: Re: Unique AS number when connecting to two different ISP's?
Not really necessary. You can use a private ASN even when multihoming with
two different providers and even if announcing some [provider independent]
prefixes. They will just strip your private ASN when announcing your
prefixes to the outside world.
You need your public AS number only if you want to express a particular
routing policy, i.e. you do have a particular preference as to which of the
upstream providers should be used for incoming traffic. Otherwise, there is
absolutely no problem for the outside world to see that the prefix appears
to be originated from different ASs.
Mihai Dumitru
CCIE #16616
P.S. And I know a person who had a public ASN and PI address space for his
own personal use - it's not me :)
On 7/29/07, Hyunseog Ryu <r.hyunseog@ieee.org> wrote:
> Upstream providers will remove private AS number when they readvertise
> to other ISPs.
> So natually if you have multi-homed to multiple ISPs, the route will
> be appeared as inconsistent ORIGIN AS, which will not appeared as
> valid route from RFC viewpoint.
> According to RFC - I don't remember which -, it should be originated
> from single AS number.
> Also, customer who uses Private ASN with multiple upstream providers
> can NOT implement consistent routing policy for that matter.
> So multihomed customer with private ASN is not recommended for
> multiple providers upstream connection.
> If customer have multiple connections with SAME providers, they may
> use private ASN for load sharing purpose.
>
> Hyun
>
>
> Gregory Gombas wrote:
> > What are you losing by using a private ASN? You can still advertise
> > your own dedicated IP address space via both providers can't you?
> > Your ISP's simply needs to remove that private AS when passing the
> > update to other ISP's...
> >
> > Am I missing something here?
> >
> > On 7/29/07, Herbert Maosa <asawilunda@googlemail.com> wrote:
> >
> >> If you dont have your own ASN, you will most likely have to use a
> >> private ASN to connect to the two ISPs. Remember that if you use
> >> the ISPs ASN then you are an extension of that ISP. Using the
> >> private ASN in this case will permit you to be totally provider
independent.
> >>
> >> regards,
> >>
> >> Herbert.
> >>
> >>
> >> On 7/29/07, Gregory Gombas <ggombas@gmail.com> wrote:
> >>
> >>> When connecting to the internet via two different ISP's, why is it
> >>> necessary to have a unique AS?
> >>>
> >>> What if you simply configured your BGP router with the same AS
> >>> number as one of your ISP's?
> >>>
> >>> Considering there are only 64511 unique AS numbers, I assume that
> >>> most if not all the AS numbers are already taken. What do
> >>> companies do in the case they cannot get their own AS number and need
to multihome?
> >>>
> >>> Thanks,
> >>> Greg
> >>>
> >>>
> >>>
> >> ___________________________________________________________________
> >> ____
> >>
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> >>>
> >>
> >> --
> >> Kindest regards,
> >> hm
> >>
> >
> > ____________________________________________________________________
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>
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