From df22720c7af9fab801f2f7b3b69afd05e6e511e9 Mon Sep 17 00:00:00 2001
From: Alex Kudentsov <43482574+alexk37@users.noreply.github.com>
Date: Tue, 6 Oct 2026 13:25:22 +0700
Subject: bgp: T9404: do not render "bgp default local-preference" when the
 value is 100

FRR does not print "bgp default local-preference 100" in show
running-config because 100 is its default, so frr-reload never finds the
line in the running config and sends it again on every reload. The
command handler calls bgp_clear_star_soft_in() whether or not the value
changed, so every reload ran "clear bgp * soft in" (once in pass 0 and
twice in pass 1), a full inbound re-evaluation of every peer.

Add the default (100) to the XML definition of parameters default
local-pref. Templates cannot query the XML definition while rendering,
so frrender takes the value from the config defaults of "parameters
default" (conf.get_config_defaults) and adds it to the BGP dict as the
key xml_default_local_pref, for the global instance and for every VRF
instance. bgpd.frr.j2 renders the line only when the configured value
differs from xml_default_local_pref, so the value 100 is not hardcoded
in the template. A real value change (100 to 200, or 200 to 100) is
still sent: frr-reload sees the difference between the rendered file and
the running config.
---
 data/templates/frr/bgpd.frr.j2 | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

(limited to 'data')

diff --git a/data/templates/frr/bgpd.frr.j2 b/data/templates/frr/bgpd.frr.j2
index e2def6e6f..7671576d1 100644
--- a/data/templates/frr/bgpd.frr.j2
+++ b/data/templates/frr/bgpd.frr.j2
@@ -619,7 +619,8 @@ router bgp {{ system_as }} {{ 'vrf ' ~ vrf if vrf is vyos_defined }} {{ 'as-nota
 {# Doesn't work in current FRR configuration; vtysh (bgp dampening 16 751 2001 61) #}
  bgp dampening {{ parameters.dampening.half_life }} {{ parameters.dampening.re_use if parameters.dampening.re_use is vyos_defined }} {{ parameters.dampening.start_suppress_time if parameters.dampening.start_suppress_time is vyos_defined }} {{ parameters.dampening.max_suppress_time if parameters.dampening.max_suppress_time is vyos_defined }}
 {% endif %}
-{% if parameters.default.local_pref is vyos_defined %}
+{# xml_default_local_pref is the XML default of parameters default local-pref, added to the dict by frrender #}
+{% if parameters.default.local_pref is vyos_defined and parameters.default.local_pref != xml_default_local_pref %}
  bgp default local-preference {{ parameters.default.local_pref }}
 {% endif %}
 {% if parameters.deterministic_med is vyos_defined %}
-- 
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