[afnog] Help Please - is my ISP Stripping my prepends?

[Alex Rhys-Hurn]

Dear Patrick,

Thank you for the insight. I am trying this now.

Alex

----- Original Message -----
> From: "Patrick Okui" <pokui at psg.com>
> To: "Alex Rhys-Hurn" <alex at itworx.co.ke>, afnog at afnog.org
> Sent: Friday, 30 May, 2014 11:30:32 AM
> Subject: Re: [afnog] Help Please - is my ISP Stripping my prepends?
> 
> Hi Alex,
> 
> Firstly .. you can not predict how many ASes someone is from you. So
> getting prepends to work is going to be tough.
> 
> If you're willing to live with traffic to a particular /24 coming only
> over a particular link then I'd suggest the following alternative:
> 
> On  30-May-2014 11:16:35 (+0300), Alex Rhys-hurn wrote:
> > My prefixes are:
> > 194.9.64.0/23
> > 194.9.64.0/24
> > 194.9.65.0/24
> > 
> > Announced as:
> > 194.9.65.0/24 via Access Kenya with no prepend
> 
> I assume you want traffic to this /24 on access Kenya ... leave this as is.
> 
> > 194.9.64.0/24 via ISP1 prepended 3x
> 
> Remove this announcement on your link to Access Kenya (see below)
> 
> > 194.9.0.0/23 via Access Kenya with no prepend
> 
> Announce this prefix to Access Kenya so that if your link via Safaricom
> goes down 194.9.64.0/24 is still reachable.
> 
> > 
> > and
> > 
> > 194.9.64.0/24 via Safaricom with no prepend
> 
> Keep this (traffic to this /24 will only be on this link unless it goes
> down)
> 
> > 194.9.65.0/24 via Safaricom prepended 3x
> 
> Remove this prefix from your advertisement to Safaricom
> 
> > 194.9.0.0/23 via Safaricom prepended 3x
> 
> Prepending on the /23 does nothing really. As long as a /24 route exists
> for a particular route the /23 won't be used. If the /24s from Access
> Kenya disappear, it's likely the /23 from there will to.
> 
> SO ... keep this announcement but _remove_ the prepends. This will only
> be used if your link to Access Kenya goes down (to reach 194.9.65.0/24.)
> 
> Remember rule 1 of routing. The longest match wins.
> 
> --
> patrick
> 
> 

-- 
Alex Rhys-Hur n | ITworX Limited 
P.O. Box 1649, 00502, Karen, Kenya 
Tel: +254 (0) 20 2444824 | Cell: +254 (0) 724 972541 
Web: www.itworx.co.ke