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.
---
 python/vyos/frrender.py | 8 ++++++++
 1 file changed, 8 insertions(+)

(limited to 'python')

diff --git a/python/vyos/frrender.py b/python/vyos/frrender.py
index 69bb93a96..eac03e4d3 100644
--- a/python/vyos/frrender.py
+++ b/python/vyos/frrender.py
@@ -297,6 +297,12 @@ def get_frrender_dict(conf: Config, argv=None) -> dict:
                                    no_tag_node_value_mangle=True,
                                    with_recursive_defaults=True)
         bgp['dependent_vrfs'] = {}
+        # The XML default of "parameters default local-pref" is added to the
+        # dict, the template cannot query it while rendering. Only the node
+        # "parameters default" is asked for, not the whole BGP tree.
+        tmp = conf.get_config_defaults(bgp_cli_path + ['parameters', 'default'],
+                                       key_mangling=('-', '_'), get_first_key=True)
+        bgp['xml_default_local_pref'] = tmp.get('local_pref')
         dict.update({'bgp' : bgp})
     elif conf.exists_effective(bgp_cli_path):
         dict.update({'bgp' : {'deleted' : '', 'dependent_vrfs' : {}}})
@@ -522,6 +528,8 @@ def get_frrender_dict(conf: Config, argv=None) -> dict:
                 # merge in remaining default values
                 vrf_config['protocols']['bgp'] = config_dict_merge(default_values,
                                                                    vrf_config['protocols']['bgp'])
+                vrf_config['protocols']['bgp']['xml_default_local_pref'] = dict_search(
+                    'parameters.default.local_pref', default_values)
 
                 # Add this BGP VRF instance as dependency into the default VRF
                 if 'bgp' in dict:
-- 
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