AS number assignment criteria
Just a quick one about assigning AS numbers. The reasons for ASN requests we get can be categorised as follows: 1 - "Because the router manual says we need one." Needs no further explanation, does it? 2 - "To identify routing processes for internal routing." Some isolated networks run multiple IGPs and seek unique numbers to identify them. 3 - "To identify single-homed ASes." They connect to a service provider or to another enterprise and use external routing. The other end tells them they need an ASN. Strictly speaking they do not need one, because they can only have one external policy. 4 - "To identify multi-homed ASes." These really need one because they have a unique external policy. So far we have never assigned ASNs to categories 1 and 2. I see no reason why we should either. We have assigned ASNs to some in category 3 because their service provider required it for their management purposes. We have always assigned ASNs to category 4. The question now is: Should we assign ASNs to those in category 3 who request it because their ISP requires it? This is a potentially large number. Opinions? Daniel
* 3 - "To identify single-homed ASes." * They connect to a service provider or to another enterprise and * use external routing. The other end tells them they need an ASN. * Strictly speaking they do not need one, because they can only have * one external policy. * The question now is: Should we assign ASNs to those in category 3 * who request it because their ISP requires it? * This is a potentially large number. * * Opinions? Potentially the ISP can request an AS because it can enforce a stricter policy on its client than on its own AS. It can for instance say that the customer AS will not be announced to XX where the AS of the provider itself could be announced to XX. Unlikely, but a different policy possibly needing an AS...... -Marten
Marten Terpstra <Marten.Terpstra@ripe.net> writes:
* 3 - "To identify single-homed ASes." * They connect to a service provider or to another enterprise and * use external routing. The other end tells them they need an ASN. * Strictly speaking they do not need one, because they can only have * one external policy.
* The question now is: Should we assign ASNs to those in category 3 * who request it because their ISP requires it? * This is a potentially large number. * * Opinions?
Potentially the ISP can request an AS because it can enforce a stricter policy on its client than on its own AS. It can for instance say that the customer AS will not be announced to XX where the AS of the provider itself could be announced to XX. Unlikely, but a different policy possibly needing an AS......
Right.
In <9407190931.AA00436@rijp.ripe.net>, <Marten.Terpstra@ripe.net> wrote:
* 3 - "To identify single-homed ASes." * They connect to a service provider or to another enterprise and * use external routing. The other end tells them they need an ASN. * Strictly speaking they do not need one, because they can only have * one external policy.
* The question now is: Should we assign ASNs to those in category 3 * who request it because their ISP requires it? * This is a potentially large number. * * Opinions?
Potentially the ISP can request an AS because it can enforce a stricter policy on its client than on its own AS. It can for instance say that the customer AS will not be announced to XX where the AS of the provider itself could be announced to XX. Unlikely, but a different policy possibly needing an AS......
I tend to agree with Marten here. We have a number of down-stream providers who buy transit from us, and find it virtually essential to be able to distinguish their routes from ours using AS number, to provide a clean adminstrative boundary. An example of Marten's principle (to pick a hot topic :-), is where the downstream provider is not a CIX member, but the upstream one is. I think therefore the rule is that category 3 sites can receive an AS number if they are a re-seller of some kind, rather than just a retail customer. In practice, a resale provider might well be expected to set up peerings with other providers on their own in the future, so putting an AS number in now also helps future-proof things. Of course, it can often be hard to define "re-seller" or "provider"in some circumstances, I suppose an alternative rule could be that they need to have some minimum number of aggregates to qualify, it is clearly worthless to set all this up if they only have one. Keith Mitchell Network Manager Public IP Exchange keith@pipex.net 216 The Science Park keith@unipalm.co.uk Cambridge, UK Phone: +44 223-250120 Fax: +44 223-250121 PIPEX is a subsidiary of Unipalm Group PLC
participants (3)
-
Daniel Karrenberg -
keith＠pipex.net -
Marten Terpstra