From: sheherezada@gmail.com
Date: Thu Aug 02 2007 - 11:07:18 ART
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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