frrcfgd: does not push 'ip protocol bgp route-map', resulting in incorrect default source address selection #14195
Comments
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In case it's intentional that by default this is not configured, here's a patch that adds support for configuring it manually through the config DB: genesiscloud@c2ec9bf |
Is there any chance of pushing the above proposal upstream? |
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@lukasstockner @matofeder Can you create a pull request for review? |
I'm on it |
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Here's a PR: #20332 Who should I add as reviewers? |
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I added this commit that should add ipv6 support for the The main differences from #20332 are:
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For what it is worth, I ended up adding the following workaround on my switches. Posting it here in case it is of use to anyone else. /usr/local/bin/set-default-source-ip#!/bin/bash -x
# Set the default source address for BGP routes to the Loopback0 address.
# Assumes there is only a single IPv4 address configured on Loopback0.
# Workaround for https://github.com/sonic-net/sonic-buildimage/issues/14195
# [email protected] 2025
SRCIP=$(sonic-db-cli CONFIG_DB KEYS 'LOOPBACK_INTERFACE|Loopback0|*')
SRCIP=${SRCIP#LOOPBACK_INTERFACE|Loopback0|}
SRCIP=${SRCIP%/32}
if test -z "$SRCIP"; then
echo "ERROR: unable to determine Loopback0 IP address"
exit 1
fi
/usr/bin/vtysh \
--echo \
--command 'configure' \
--command 'route-map RM_SET_SRC permit 10' \
--command "set src ${SRCIP}" \
--command 'exit' \
--command 'ip protocol bgp route-map RM_SET_SRC'/etc/systemd/system/set-default-source-ip.service[Unit]
Description=Set default source IP for BGP routes
Requires=bgp.service
After=bgp.service
[Service]
ExecStart=/usr/local/bin/set-default-source-ip
Restart=on-failure
RestartSec=5
RemainAfterExit=true
[Install]
WantedBy=bgp.service
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Description
When using the FRR configuration management framework, the route-map that ensures that locally originated traffic (e.g., ICMP errors) are sourced from the
Loopback0address is no longer included in the FRR configuration by default, nor does it seem possible to manually create it from entries in ConfigDB.This results in 240.127.1.1 (assigned to
docker0) inappropriately being used as the default source address for locally originated traffic that are routed to interfaces without IPv4 addresses assigned, which is the case for routes learned from unnumbered BGP neighbours, for example.Steps to reproduce the issue:
bgpcontainer:Describe the results you received:
The
ip protocol bgp route-mapconfiguration is missing:It is possible to take it one step further and establish some unnumbered BGP peerings where some routes are being learned. Observing the routing table with
ip routewill then reveal that thesrcattribute is missing. Attempting, e.g.,ping <remote-ip-learned-from-unnumberd-BGP>will use 240.127.1.1 as the source address and will therefore not receive any replies.Describe the results you expected:
A
ip protocol bgp route-mapshould have been created to set the default source address to the one assigned toLoopback0, this should have been visible in the output fromip route, andping <remote-ip-learned-from-unnumberd-BGP>should have used theLoopback0address and should have received responses.Alternatively, the current behaviour could have been acceptable as the default, but only if there was some other way for the user to manually instruct
frrcfgdto create the necessary FRR configuration from ConfigDB keys. However, after reading through the documentation and the templates I have come to the conclusion that this is currently not possible.Output of
show version:Output of
show techsupport:sonic_dump_sonic_20230310_092339.tar.gz
Additional information you deem important (e.g. issue happens only occasionally):
This is the template that renders the necessary FRR configuration when the FRR configuration management framework is not in use: zebra.set_src.conf.j2.
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