nanog mailing list archives
Re: Setting sensible max-prefix limits
From: "Dale W. Carder" <dwcarder () es net>
Date: Wed, 18 Aug 2021 10:49:42 -0500
Thus spake Chriztoffer Hansen (ch () ntrv dk) on Wed, Aug 18, 2021 at 12:03:51PM +0200:
On Wed, 18 Aug 2021 at 11:33, Lars Prehn <lprehn () mpi-inf mpg de> wrote:I guess for long standing peers one could just eyeball it, e.g., current prefix count + some safety margin. How does that work for new peers?
sadly, this is the state of the art.
If you have automation in place. Another approach is to count the received prefix. Store the counted value in a database. Based on the avg prefix count over X (time period). Add e.g. 10 - 25 % headroom over the avg prefix count and use the calculated value as the max-prefix limit? PeeringDB data (sometimes or often?) be somewhat misleading (in contrast to actual avg prefix count) in the sense 'some' networks will input a value with headroom percentages already included.
Our code tries all 3: a) using the max values in peeringdb b) expand all the routes in the IRR record from peeringdb b.1) if no object is specified, try to guess if it's named ASnnnnn c) count the currently received prefixes Many times the values in peeringdb can be off, or increasingly this is a good warning not to peer with a negligent operator. For some peers 'b' can expand to a huge, unrealistic set (not always their fault), so if it's substantially larger than 'a' we throw it out. (c) has proven the most reliable. The count chosen then fits in the appropriate sized bin and given 30% headroom. The code compares all this and gives the user a warning that in proactive gets ignored for option 'c'. (For example we can override 'b' with a more appropriate object record in our provisioning db) Dale
Current thread:
- Re: PeerinDB refuses to register certain networks [was: Setting sensible max-prefix limits], (continued)
- Re: PeerinDB refuses to register certain networks [was: Setting sensible max-prefix limits] Ross Tajvar (Aug 19)
- Re: PeerinDB refuses to register certain networks [was: Setting sensible max-prefix limits] Brielle (Aug 19)
- Re: PeerinDB refuses to register certain networks [was: Setting sensible max-prefix limits] Seth Mattinen (Aug 19)
- Re: PeerinDB refuses to register certain networks [was: Setting sensible max-prefix limits] Stefan Funke (Aug 20)
- Re: Setting sensible max-prefix limits Lukas Tribus (Aug 18)
- Re: Setting sensible max-prefix limits Hank Nussbacher (Aug 18)
- Re: Setting sensible max-prefix limits Dale W. Carder (Aug 18)
- Re: Setting sensible max-prefix limits Lars Prehn (Aug 18)
- Re: Setting sensible max-prefix limits tim () pelican org (Aug 18)
- Re: Setting sensible max-prefix limits Tom Beecher (Aug 18)
- Re: Setting sensible max-prefix limits Jared Mauch (Aug 18)
- Re: Setting sensible max-prefix limits Jon Lewis (Aug 18)