Re: BGP announcements and small providers
If the downstream customers are not multihomed, there's no reason to run BGP with them; a simple default/static will work just fine. Also, if you suballocate addresses to them from within your address space, you can aggregate them. This is generally considered a Good Thing. - paul At 08:06 AM 2/25/97 -0500, Avi Freedman wrote:
I think the general feeling is that if the customer is multi-homed, there's going to be another route announcement for them anyway - whether it's a /23, /24, or /16 or /17.
If the customer isn't multi-homed, and you're their only path, then:
a) If you BGP with them and pass it on to the global 'net, that path will flap if the line goes up or down. This is considered bad.
b) There's no point, if that route is out of your address space, in announcing the more specific if there's no extra path to them if their connection to you goes down.
Isn't it true though that some upstream providers (such as Sprint) filter out anything smaller than /19 and will not carry those routes? Therefore in this example, Sprint clients would not be able to see these smaller providers and vice versa unless he agregates them to /19 or higher and then announces the routes himself? ...David * David Papp | 4907-99 Street | Ph: +1.403.430.0811 * * Manager | Edmonton, Alberta | Fax: +1.403.436.9963 * * OA Internet Inc. | Canada, T6E 4Y1 | Email: david@oanet.com * On Tue, 25 Feb 1997, Paul Ferguson wrote:
If the downstream customers are not multihomed, there's no reason to run BGP with them; a simple default/static will work just fine. Also, if you suballocate addresses to them from within your address space, you can aggregate them.
This is generally considered a Good Thing.
- paul
Yes, Sprint and AGIS do this - and others might as well. Avi
Isn't it true though that some upstream providers (such as Sprint) filter out anything smaller than /19 and will not carry those routes? Therefore in this example, Sprint clients would not be able to see these smaller providers and vice versa unless he agregates them to /19 or higher and then announces the routes himself?
...David
* David Papp | 4907-99 Street | Ph: +1.403.430.0811 * * Manager | Edmonton, Alberta | Fax: +1.403.436.9963 * * OA Internet Inc. | Canada, T6E 4Y1 | Email: david@oanet.com *
On Tue, 25 Feb 1997, Paul Ferguson wrote:
If the downstream customers are not multihomed, there's no reason to run BGP with them; a simple default/static will work just fine. Also, if you suballocate addresses to them from within your address space, you can aggregate them.
This is generally considered a Good Thing.
- paul
On Tue, 25 Feb 1997, David Papp wrote:
Isn't it true though that some upstream providers (such as Sprint) filter out anything smaller than /19 and will not carry those routes?
Would it be possible to get a copy of the Sprint filters and the AGIS ones too, posted at http://www.nanog.org so that people can be referred to them for the precise details on what is being filtered. Michael Dillon - Internet & ISP Consulting Memra Software Inc. - Fax: +1-250-546-3049 http://www.memra.com - E-mail: michael@memra.com
participants (4)
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Avi Freedman -
David Papp -
Michael Dillon -
Paul Ferguson