I would like to ask question more specifically. I know most of tier1 providers accept their customer prefixes smaller than /24. it means smaller than /24 routes always routable in that Tier1 provider. What about between Tier1 and another Tier1 ? Do they exchange their full customer's routes without any limitation of prefixes length ? or do they refer to some DB information like Regional Internet Registry and apply another filter on neighbor configuration with another Tier1 ? Chiyoung ============================================= Chi-Young Joung SAMSUNG NETWORKS Inc. Email: lionair@samsung.com Tel +82 70 7015 0623, Mobile +82 17 520 9193 Fax +82 70 7016 0031 ============================================= ------- Original Message ------- Sender : Nathan Ward<nanog@daork.net> Date : 2008-12-23 10:44 (GMT+09:00) Title : Re: What is the most standard subnet length on internet On 23/12/2008, at 2:39 PM, Joe Provo wrote:

On Tue, Dec 23, 2008 at 02:34:39PM +1300, Nathan Ward wrote: [snip]

...

Let me rephrase; Are there people who are filtering /24s received from eBGP peers who do not have a default route?

of course.

Curiously, it was really meant as a rhetorical question where the answer was "no". Why are people doing this? Are they lacking clue, or, is there some reasonable purpose? -- Nathan Ward