Re: any dangers of filtering every /24 on full internet table to preserve FIB space ?

[Jakob Heitz (jheitz) via NANOG]

Here is a reason you might want to keep that /24.

Suppose you are a small ISP and I am your customer.
I also have another larger provider.
That larger provider is also your provider.
I own a /21 and advertise it to my larger provider.
You get that /21 from my larger provider.
I advertise a /24 subset of the /21 to you.
If you ignore my /24, then traffic for it goes
to the larger provider and I pay him for the traffic, not you.

Regards,
Jakob.

Re: any dangers of filtering every /24 on full internet table to preserve FIB space ?

[Jon Lewis]

On Wed, 12 Oct 2022, Andrey Kostin wrote:


Matthew Petach писал(а) 2022-10-11 20:33:


 My point is that it's not a feature of BGP, it's a purely human
 convention,
 arrived at through the intersection of pain and laziness.
 There's nothing inherently "right" or "wrong" about where the line was

 drawn, so for networks to decide that /24 is causing too much pain,
 and moving the line to /23 is no more "right" or "wong" than drawing
 the line at /24.  A network that *counts* on its non-connected sites
 being reachable because they're over a mythical /24 limit is no more
 right than a customer upset that their /25 announcements aren't being
 listened to.


IMO this line wasn't arbitrary, it was (and it still is) a smallest possible 
network size allocated by RIRs. So it's just a common sense to receive 
everything down to /24 to have the complete data about all Internet 
participants.


Nope.  I first did some work on this topic in early 2008 and remembered 
writing a blog entry about it.


https://web.archive.org/web/20060926140659/https://www.ripe.net/ripe/docs/ripe-ncc-managed-address-space.html

RIPE, at least back in 2008, would allocate as long as /29 from several 
/8s.  I have no idea how many sub-/24 allocations they did or what the 
recipients tried doing with the space.  Even then, despite RIPE saying 
"we'll allocate as long as /29", I set the filter cut-off [arbitrarily] at 
/24 and made sure we had defaults pointing at ISPs that had "fuller" 
tables.


And just for the record, despite having been bitten by it more than 
once, I'm very much in the camp of "if you advertise a covering 
aggregate, you're offering to get packets there, regardless of whether or 
not more specifics exist."  You have no business demanding what routes 
someone else's network receives/accepts.  All you can reasonably control 
is what you advertise and what you accept.


--
 Jon Lewis, MCP :)   |  I route
 StackPath, Sr. Neteng   |  therefore you are
_ http://www.lewis.org/~jlewis/pgp for PGP public key_

Re: any dangers of filtering every /24 on full internet table to preserve FIB space ?

[David Conrad]

Andrey,

On Oct 12, 2022, at 7:54 AM, Andrey Kostin  wrote:
>> My point is that it's not a feature of BGP, it's a purely human convention, 
>> arrived at through the intersection of pain and laziness. There's nothing 
>> inherently "right" or "wrong" about where the line was drawn, so for 
>> networks to decide that /24 is causing too much pain, and moving the line to 
>> /23 is no more "right" or "wong" than drawing the line at /24.  A network 
>> that *counts* on its non-connected sites being reachable because they're 
>> over a mythical /24 limit is no more right than a customer upset that their 
>> /25 announcements aren't being listened to.
> 
> IMO this line wasn't arbitrary, it was (and it still is) a smallest possible 
> network size allocated by RIRs.

There was a period in the mid- to late-90s where some of RIRs allocated longer 
than /24s, i.e., to match the amount of address space justified by the 
requester, even if that meant (say) a /29. This didn’t last very long as one of 
the (at the time) 800 lb gorillas (Sprint) decided to start filtering at /19 
(which IIRC was the default prefix length RIPE-NCC chose to allocate to LIRs) 
to keep their routers from falling over.

In this context, any prefix length, including /24, is arbitrary. Today, 
filtering on /24 will probably drop some number of perfectly valid and perhaps 
better routes to specific destinations (I’m too lazy to look to see). That’s 
fine as long as there is some covering route that allows the traffic to get 
from here to there. It feels to me like the responsibility should be on the 
announcer to ensure there is some covering less-specific for stuff that has "a 
good chance" of being filtered.

> So it's just a common sense to receive everything down to /24 to have the 
> complete data about all Internet participants.


Given infinite resources, sure. However, I believe the issue here, as it was in 
the mid- to late-90s, is hardware limitations. Having a partial view with 
(potentially) non-optimal less specifics is better than having your routers 
fall over.

Regards,
-drc



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Re: any dangers of filtering every /24 on full internet table to preserve FIB space ?

[William Herrin]

On Wed, Oct 12, 2022 at 7:54 AM Andrey Kostin  wrote:
> IMO this line wasn't arbitrary, it was (and it still is) a smallest
> possible network size allocated by RIRs. So it's just a common sense to
> receive everything down to /24 to have the complete data about all
> Internet participants.

Hi Andrey,

Filtering routes longer than /24 route filtering came first and is the
cause here while the RIR minimum assignment is an effect. The RIRs
stay at /24 because it would be implicitly wasteful to assign
addresses in units smaller than can be routed on the public Internet.
Of the things that would have to change to make longer prefixes
routeable on the Internet, the RIR policies are the easiest.

The /24 boundary is simply a holdover from pre-CIDR times when the
smallest routing unit was a "class C." Folks wanted to make sure CIDR
didn't make their routing woes worse, so they filtered and it stuck.

Regards,
Bill Herrin




-- 
For hire. https://bill.herrin.us/resume/

Re: any dangers of filtering every /24 on full internet table to preserve FIB space ?

[Andrey Kostin]

Matthew Petach писал(а) 2022-10-11 20:33:


My point is that it's not a feature of BGP, it's a purely human
convention,
arrived at through the intersection of pain and laziness.
There's nothing inherently "right" or "wrong" about where the line was

drawn, so for networks to decide that /24 is causing too much pain,
and moving the line to /23 is no more "right" or "wong" than drawing
the line at /24.  A network that *counts* on its non-connected sites
being reachable because they're over a mythical /24 limit is no more
right than a customer upset that their /25 announcements aren't being
listened to.


IMO this line wasn't arbitrary, it was (and it still is) a smallest 
possible network size allocated by RIRs. So it's just a common sense to 
receive everything down to /24 to have the complete data about all 
Internet participants.



--
Kind regards,
Andrey

Re: CLEC lawfirm recommendations?

[Josh Luthman]

Tom Forte should still be able to help you get started (he's contracted
sales now).

thefor...@hotmail.com theforty...@gmail.com

I saw him in Vegas last week, I didn't think to get his new email address.

On Tue, Oct 11, 2022 at 2:22 PM Glenn Kelley 
wrote:

> The team @ Inteserra are amazing.
>
> Reach out to TOM  tfo...@inteserra.com
> They have some nice programs to help spread the cost out as well
>
>
>
>
> *Glenn S. Kelley, *I am a Connectivity.Engineer
> Text and Voice Direct:  740-206-9624
>
>
> a Division of CreatingNet.Works 
> IMPORTANT: The contents of this email and any attachments are
> confidential. They are intended for the named recipient(s) only. If you
> have received this email by mistake, please notify Glenn Kelley, the
> sender, immediately and do not disclose the contents to anyone or make
> copies thereof.
>
>
> On Tue, Oct 11, 2022 at 11:21 AM Tim Utschig  wrote:
>
>> Hello NANOG'ers,
>>
>> I hope this isn't too far off-topic:
>>
>> I'm wondering, does anyone have any recommendations for a lawfirm
>> that will help a newbie through the process of becoming a CLEC? I
>> understand that it can take years, and am prepared for that.
>>
>> Specifically in San Jose, California.
>>
>> I'm trying to determine (by trial and error) the theoretical
>> minimum cost of running a tiny neighborhood FTTH +
>> very-short-range fixed-point wireless ISP for residences that
>> don't have fiber for no good reason at all.
>>
>> https://mplink.llc/img/mplink-v0.1-pencil.jpg
>>
>> Have gear, some funds, conflict-of-interest exception, and a
>> smidge of clue. Even have the first run of fiber already pulled
>> (via quickly-cancelled AT Dedicated Internet). Just need
>> https://clec.att.com/ access and somewhere to put my gear on the
>> other end of the line. I think.
>>
>> Cheers.
>>
>> --
>> Tim Utschig 
>> 408-644-3861 (mobile)
>>
>