Re: [p2pi] ALTO Information Export Service

If you say "prefer this ASN" (since you are implicitly or explicitly for
that matter) assuming that prefix 1.1.1/24 is hosted in that ASN but is
actually not, then is misleading, yes?

On 10/29/08 9:47 AM, "Laird Popkin" <laird@pando.com> wrote:

> I agree with your analysis, up until the last paragraph.
> 
> I don't understand why you say that "policy stated in ASNs is actively
> misleading" though. Keep in mind that ALTO helps p2p networks find good
> endpoints, not good routes - that's done by BGP, OSPF, etc., when actually
> exchanging data. That is, a p2p network knows that it can exchange data
> between a addresses within (to make up an example) AT&T NYC and Verizon NYC,
> but it can't control the actual route that the data flows through. Of course,
> selecting endpoints that have cheap routes between them makes it likely that
> those cheap routes are actually used, but that's more a matter of the lower
> layers working properly than anything ALTO allows ISPs to directly express.
> 
> - Laird Popkin, CTO, Pando Networks
>   mobile: 646/465-0570
> 
> ----- Original Message -----
> From: "John Leslie" <john@jlc.net>
> To: "Laird Popkin" <laird@pando.com>
> Cc: p2pi@ietf.org
> Sent: Wednesday, October 29, 2008 11:47:44 AM (GMT-0500) America/New_York
> Subject: Re: [p2pi] ALTO Information Export Service
> 
> Laird Popkin <laird@pando.com> wrote:
>> 
>> Keep in mind that ASNs are just an option in ALTO (as we're discussing
>> it so far), so even if the P2P network uses a public IP to ASN mapping
>> database, the ISP can provide their own IP prefix guidance without
>> referencing ASNs if they care to.
> 
>    Indeed they can -- (by omitting any ASN guidance at all).
> 
>    But then, why include the option?
> 
>    The advantage of including an ASN option, IMHO, is that a policy can
> be stated in a reasonably static manner using ASNs -- provided that the
> meaning of those ASNs is clearly "where my routers will forward packets".
> 
>    This avoids having to frequently update policy as routing tables change
> and having to state policy for hundreds of thousands of CIDR blocks.
> 
>    A downside is that ALTO clients may lack up-to-the-minute routing
> information when mapping IPs to ASNs. That, IMHO, is something to work
> on when the ALTO WG is formed. Several "good-enough" approaches suggest
> themselves...
> 
>    But if clients are encouraged to use mapping quite unrelated to the
> actual routing, then policy stated in ASNs is actively misleading. I
> would much prefer not to _design_ misleading policy into ALTO.
> 
> --
> John Leslie <john@jlc.net>
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> p2pi@ietf.org
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