nanog mailing list archives
Re: any dangers of filtering every /24 on full internet table to preserve FIB space ?
From: William Herrin <bill () herrin us>
Date: Tue, 11 Oct 2022 19:02:32 -0700
On Tue, Oct 11, 2022 at 5:32 PM Matthew Petach <mpetach () netflight com> 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.
Hi Matthew, If you defy convention in a manner which causes things that normally work to break, your implementation is "wrong" for a fairly important definition of "wrong."
Let BGP work as it's supposed to work. If there's a covering prefix being announced, according to BGP, it's a valid pathway to reach all the prefixes contained within it. If that's not how your network is constructed, don't send out your announcements that way. Only announce prefixes for which you *do* have actual reachability.
All TCP/IP routing is more-specific route first. That is the expected behavior. I honestly don't fathom your view that BGP is or should be different from that norm. If the origin of a covering route has no problem sinking the traffic when the more-specific is offline, I don't see the problem. You shouldn't be taking them offline with route filtering. Regards, Bill Herrin -- For hire. https://bill.herrin.us/resume/
Current thread:
- Re: any dangers of filtering every /24 on full internet table to preserve FIB space ?, (continued)
- Re: any dangers of filtering every /24 on full internet table to preserve FIB space ? Mark Tinka (Oct 10)
- Re: any dangers of filtering every /24 on full internet table to preserve FIB space ? Matthew Petach (Oct 10)
- Re: any dangers of filtering every /24 on full internet table to preserve FIB space ? Ryan Rawdon (Oct 10)
- Re: any dangers of filtering every /24 on full internet table to preserve FIB space ? Jeff Tantsura (Oct 10)
- Re: any dangers of filtering every /24 on full internet table to preserve FIB space ? Mark Tinka (Oct 10)
- Re: any dangers of filtering every /24 on full internet table to preserve FIB space ? William Herrin (Oct 11)
- Re: any dangers of filtering every /24 on full internet table to preserve FIB space ? Matthew Petach (Oct 11)
- Re: any dangers of filtering every /24 on full internet table to preserve FIB space ? William Herrin (Oct 11)
- Re: any dangers of filtering every /24 on full internet table to preserve FIB space ? Richard Golodner (Oct 11)
- Re: any dangers of filtering every /24 on full internet table to preserve FIB space ? Matthew Petach (Oct 11)
- Re: any dangers of filtering every /24 on full internet table to preserve FIB space ? William Herrin (Oct 11)
- Re: any dangers of filtering every /24 on full internet table to preserve FIB space ? Matthew Petach (Oct 16)
- Re: any dangers of filtering every /24 on full internet table to preserve FIB space ? William Herrin (Oct 16)
- Re: any dangers of filtering every /24 on full internet table to preserve FIB space ? Owen DeLong via NANOG (Oct 16)
- Re: any dangers of filtering every /24 on full internet table to preserve FIB space ? Matthew Petach (Oct 10)
- Re: any dangers of filtering every /24 on full internet table to preserve FIB space ? Mark Tinka (Oct 10)
- Re: any dangers of filtering every /24 on full internet table to preserve FIB space ? Andrey Kostin (Oct 12)
- Re: any dangers of filtering every /24 on full internet table to preserve FIB space ? William Herrin (Oct 12)
- Re: any dangers of filtering every /24 on full internet table to preserve FIB space ? David Conrad (Oct 12)
- Re: any dangers of filtering every /24 on full internet table to preserve FIB space ? Andrey Kostin (Oct 14)
- Re: any dangers of filtering every /24 on full internet table to preserve FIB space ? Jon Lewis (Oct 12)
- Re: any dangers of filtering every /24 on full internet table to preserve FIB space ? Joe Provo (Oct 15)