nanog mailing list archives
Re: maximum ipv4 bgp prefix length of /24 ?
From: William Herrin <bill () herrin us>
Date: Sun, 1 Oct 2023 03:48:33 -0700
On Sat, Sep 30, 2023 at 8:04 PM Owen DeLong via NANOG <nanog () nanog org> wrote:
Not sure why you think FIB compression is a risk or will be a mess. It’s a pretty straightforward task.
Hi Owen, There are multiple levels of FIB compression. The simplest version merely aggregates adjacent routes with the same next hop. Straightforward, as you say. However, there are more advanced versions of FIB compression as well. Routers have an implicit default route to a drop-and-report target. Pragmatically, though, the user doesn't really care what happens to unroutable packets: they can't reach a destination regardless. If you replace that implicit default route with a "don't care," you can roll up the entire address space into a set of "send everything to this next hop with these exceptions." And you can build on that recursively to get extraordinary FIB compression. This latter version, however, is not straightforward. Bugs that escape QC are quite a bit more likely. Will Juniper stop with the simplest version of FIB compression where not much can go wrong? Not if it works and customers like it. Regards, Bill Herrin -- William Herrin bill () herrin us https://bill.herrin.us/
Current thread:
- Re: maximum ipv4 bgp prefix length of /24 ? Saku Ytti (Oct 01)
- Re: maximum ipv4 bgp prefix length of /24 ? Matthew Petach (Oct 01)
- Re: maximum ipv4 bgp prefix length of /24 ? Seth David Schoen (Oct 01)
- Re: maximum ipv4 bgp prefix length of /24 ? Matthew Petach (Oct 01)
- Re: maximum ipv4 bgp prefix length of /24 ? Jon Lewis (Oct 01)
- Re: maximum ipv4 bgp prefix length of /24 ? Saku Ytti (Oct 02)
- Re: maximum ipv4 bgp prefix length of /24 ? Seth David Schoen (Oct 01)
- <Possible follow-ups>
- Re: maximum ipv4 bgp prefix length of /24 ? William Herrin (Oct 01)
- Re: maximum ipv4 bgp prefix length of /24 ? Jakob Heitz (jheitz) via NANOG (Oct 01)
- Re: maximum ipv4 bgp prefix length of /24 ? William Herrin (Oct 01)
- Re: maximum ipv4 bgp prefix length of /24 ? Jakob Heitz (jheitz) via NANOG (Oct 01)
- Re: maximum ipv4 bgp prefix length of /24 ? William Herrin (Oct 02)
- Re: maximum ipv4 bgp prefix length of /24 ? Nick Hilliard (Oct 02)
- Re: maximum ipv4 bgp prefix length of /24 ? William Herrin (Oct 02)
- Re: maximum ipv4 bgp prefix length of /24 ? Tom Beecher (Oct 02)
- Re: maximum ipv4 bgp prefix length of /24 ? William Herrin (Oct 02)
- Re: maximum ipv4 bgp prefix length of /24 ? Tom Beecher (Oct 02)
- Re: maximum ipv4 bgp prefix length of /24 ? William Herrin (Oct 01)
- Re: maximum ipv4 bgp prefix length of /24 ? tim () pelican org (Oct 02)
- Re: maximum ipv4 bgp prefix length of /24 ? Matthew Petach (Oct 01)