Subject: Re: [babel] AD review of draft-ietf-babel-information-model

From: Juliusz Chroboczek <[email-masked]>
Date: Fri, 09 Oct 2020 16:02:56 +0200

Hi Barbara,

Sorry for the delay, but we've been very busy organising teaching in a way
that respects the current restrictions while still being of reasonable
quality.  It's a lot of stress, but also a lot of fun.

> In contemplating your unnatural silence, I realized you weren't on any
> of the lists included in this thread.  The basic question is whether we
> need config parameters for source-specific routing.

It is my opinion that no such parameter is needed.

1. Source-specific has no effect unless a source-specific route is
   redistributed into the network.  If no such route has been
   redistributed, then source-specific has no effect.  If such a route has
   been distrbuted, then it has probably been redistributed for a reason.

   I see source-specific as analogous to IPv4: there is no knob to
   disable IPv4, since IPv4 routing will only happen if IPv4 routes are
   redistributed into the network.

2. Should the need arise, source-specific can be disabled by defining the
   right filtering rules.  For example, in babeld you can say

       in src-ge 1 deny

   and all source-specific routes will be dropped.  This, again, is
   analogous to IPv4:

      in ip 0.0.0.0/0 deny

   will effectively disable IPv4 routing.

-- Juliusz