Quick suggestion about enable/disable protocol

[bird21 at sensation.net.au]

Hi!

On Wed, 1 Dec 2021, Maria Matejka wrote:

>> 1. Allow enable/disable to be part of the config, so that a protocol can be 
>> disabled by default, and needs a manual poke via CLI command to enable it. 
[...]

> This is already in config, use "enabled" and "disabled" keywords.

Aha! I didn't find that previously in the docs - of course now I can see 
it. I did try "disable" as per the CLI command, but obviously that 
slightly different directive doesn't work. Perhaps a note could be added 
to the CLI docs to mention that it can be set semi-permanently in the 
config?

>> 2a. When reloading config, preserve the current state of a protocol that 
>> has been disabled. (I'm trying to debug a config, which involves disabling 
[...]

> We don't like to change what BIRD does by default as it may confuse others 
> who aren't familiar with the changes and both variants of behavior have their 
> appropriate use. Yet we may consider something like  a "keep protocol states" 
> option to explicitly disable protocol disabling/enabling on config reload.

Yes, I did intend to mean that it would be an option, rather than a 
(potentially dangerous) change in default behaviour. For now, I'll just 
try to remember to uncomment "disabled" in the block before I start 
fiddling. :)

Whilst I have your attention, there is one other thing that doesn't seem 
to be explicitly mentioned in the docs: what happens when you have 
multiple import/export filters listed for the one protocol? Does the first 
accept/reject win, and exit any further filter processing, or is there 
some other behaviour? Are the multiple filters evaluated in config order, 
or some other order?

Initially I was trying to make separate filters for 0.0.0.0/0 and 
x.x.x.0/24, for import and export via BGP respectively, and combine them 
to allow both routes to be advertised locally (without needing a third 
filter)... but it doesn't work, possibly because both filters have an 
unconditional reject at the end.

Thanks!