From: Scott Morris (smorris@ipexpert.com)
Date: Mon Jul 30 2007 - 20:35:44 ART
Most companies don't multihome. Among those that do multihome, most do it
with a single provider in which case other protocols (including static or
running MLPPP) offer perfectly acceptable load balancing.
Larger companies may have different needs, but they likely have their own
address space already, or can afford getting some (there are fees, many,
many, evil fees).
If you are trying to influence an upstream's behavior, more often just
playing nice with their NOC staff will get you exactly what you need to have
happen without complicating everyone's life through BGP!
Nowdays, you actually have to justify WHY you need an AS number before
you'll get one. It's not just paying $500 a year for it.
Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, JNCIE
#153, CISSP, et al.
CCSI/JNCI-M/JNCI-J
VP - Technical Training - IPexpert, Inc.
IPexpert Sr. Technical Instructor
A Cisco Learning Partner - We Accept Learning Credits!
smorris@ipexpert.com
Telephone: +1.810.326.1444
Fax: +1.810.454.0130
http://www.ipexpert.com
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Gregory Gombas
Sent: Monday, July 30, 2007 5:23 PM
To: smorris@ipexpert.com
Cc: Group study
Subject: Re: Unique AS number when connecting to two different ISP's?
Thanks Scott,
Is this what smaller companies typically do?
I guess AS path prepending is out of the question considering your service
providers will remove the private AS anyway?
And finally, with millions of companie out there, I'm shocked that they
haven't run out of AS numbers already. What are all these companies doing?
On 7/29/07, Scott Morris <smorris@ipexpert.com> wrote:
> Heheheh.. In the event of your multihoming, I think your upstream may be
a
> little upset to know that you are impersonating them and only
> advertising a small set of routes (e.g. not wanting to be a transit
path!).
>
> So very often we'll have private AS's to use for purposes like this
> where you want to run BGP, but are not multihoming, or simply that you
> don't have provider independent space and even if you are multihoming
> you aren't really advertising anything.
>
> If you DO have something to advertise, then you need an AS number. I
> believe they're only on 49000 something for assignments, so there's
> still room to grow.
>
> At the same time, they're just wrapping up the 4-byte AS number
> extensions, so no fear of running out now!
>
> But with the interconnected world of BGP, if you truly have a need to
> run BGP, then you most likely will need your own AS number to do so.
> Otherwise, work with your ISP for private AS assignment, but don't
> impersonate them, they will likely not find the humor in it!
>
>
> Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713,
> JNCIE #153, CISSP, et al.
> CCSI/JNCI-M/JNCI-J
> VP - Technical Training - IPexpert, Inc.
> IPexpert Sr. Technical Instructor
>
> A Cisco Learning Partner - We Accept Learning Credits!
>
> smorris@ipexpert.com
>
> Telephone: +1.810.326.1444
> Fax: +1.810.454.0130
> http://www.ipexpert.com
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> Of Gregory Gombas
> Sent: Sunday, July 29, 2007 2:05 PM
> To: Group study
> Subject: Unique AS number when connecting to two different ISP's?
>
> 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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