bgpd: Ensure addpath does not withdraw selected route in some situations #19210
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Currently when configuring bgp to send up to 6 additional routes after the selected, there exists a timing window where it can decide to send a withdrawal for the selected. Thus leaving a non-selected on the sent to router. The code loops over the paths in the start of the function, skipping the best path and finding up to X additional paths to send. When this is done, it looks at the list generated compared to all the paths and sends withdrawals for all those no-longer possibly selected. Since bestpath sending is elsewhere we end up with a situation where it's possible to send a withdrawal for the selected. Modify the code in the second loop to no longer send a withdrawal in this case for the selected. Signed-off-by: Donald Sharp <sharpd@nvidia.com>
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@Mergifyio backport stable/10.4 stable/10.3 |
✅ Backports have been created
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donaldsharp
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bgpd: Ensure addpath does not withdraw selected route in some situations (backport #19210)
donaldsharp
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Jul 28, 2025
bgpd: Ensure addpath does not withdraw selected route in some situations (backport #19210)
Jafaral
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Aug 2, 2025
Bug Fixes: * bgpd: initialize local variable (backport #19233) * ospfd: Use after free cleanup of lsa (backport #19224) * vtysh: copy config from file should actually apply (backport #19242) * Revert PR #18358: BGP evpn testing and bug fixes related to non default EVPN backbone (backport #19241) * topotests: improve embedded RP test reliability (backport #19240) * lib, zebra: mark singleton nexthops inactive/active on link state changes for wecmp (backport #18947) * bgpd: LL next-hop capabilty fixes (backport #19261) * eigrp: validate hello packets and tlvs better (backport #19251) * bgpd: Fix compilation error in bgpd module: Update TP_ARGS for bgp (backport #19266) * bgpd: Ensure addpath does not withdraw selected route in some situations (backport #19210) * bgpd: [GR] fixed selectionDeferralTimer to display select_defer_time val by #19282 * bgpd: LL next-hop capabilty fixes (round 2) (backport #19277) * lib: compute link-state zapi message size (backport #19290) * zebra: Fix buffer overflows found by fuzzing. (backport #19303) Signed-off-by: Jafar Al-Gharaibeh <jafar@atcorp.com>
ton31337
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Aug 2, 2025
* bgpd: correct no form commands (backport FRRouting#18911) * bgpd: fix to show exist/non-exist-map in 'show run' properly FRRouting#18853 * redhat: make FRR RPM build to work on RedHat 10 (backport FRRouting#18920) * build: check for libunwind.h, not unwind.h (backport FRRouting#18912) * bgpd: use AS4B format for BGP loc-rib messages. (backport FRRouting#18936) * bgpd: fix for the validity and the presence of prefixes in the BGP VPN table. (backport FRRouting#17370) * bgpd: Force adj-rib-out updates if MRAI is kicked in (backport FRRouting#18959) * zebra: Provide SID value when sending SRv6 SID release notify message (backport FRRouting#18971) * bgpd: Fix crash when fetching statistics for bgp instance (backport FRRouting#19003) * nhrpd: fix crash when accessing invalid memory zone (backport FRRouting#18994) * zebra: Initialize RB tree for router tables (backport FRRouting#19049) * zebra: fix null pointer dereference in zebra_evpn_sync_neigh_del (backport FRRouting#19054) * zebra: fix stale NHG in kernel (backport FRRouting#18899) * bgpd: Fix incorrect stripping of transitive extended communities (backport FRRouting#19065) * lib: Fix no on-match goto NUM command (backport FRRouting#19108) * bgpd: Fix extended community check for IP non-transitive type (backport FRRouting#19097) * bgpd: Fix DEREF_OF_NULL.EX.COND in bgp_updgrp_packet (backport FRRouting#19126) * lib: revert addition of vtysh_flush() call in vty_out() (backport FRRouting#19109) * bgpd: Extract link bandwidth value from extcommunity before using for WCMP (backport FRRouting#19165) * Use ipv4 class E addresses (240.0.0.0/4) as connected routes by default (backport FRRouting#18095) * bfdd: Set bfd.LocalDiag when transitioning to AdminDown (backport FRRouting#18592) * zebra: clean up a json object leak (backport FRRouting#19192) * bgpd: Do not try to reuse freed route-maps (backport FRRouting#19191) * lib: fix routemap crash (backport FRRouting#19127) * bgpd: initialize local variable (backport FRRouting#19233) * ospfd: Use after free cleanup of lsa (backport FRRouting#19224) * vtysh: copy config from file should actually apply (backport FRRouting#19242) * bgpd : Fix compilation error in bgpd module: Update TP_ARGS for bgp (backport FRRouting#19266) * bgpd: Ensure addpath does not withdraw selected route in some situations (backport FRRouting#19210) * lib, zebra: mark singleton nexthops inactive/active on link state changes for wecmp (backport FRRouting#18947) * eigrp: validate hello packets and tlvs better (backport FRRouting#19251) * bgpd: [GR] fixed selectionDeferralTimer to display select_defer_time val FRRouting#19283 Signed-off-by: Donatas Abraitis <donatas@opensourcerouting.org>
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Currently when configuring bgp to send up to 6 additional routes after the selected, there exists a timing window where it can decide to send a withdrawal for the selected. Thus leaving a non-selected on the sent to router. The code loops over the paths in the start of the function, skipping the best path and finding up to X additional paths to send. When this is done, it looks at the list generated compared to all the paths and sends withdrawals for all those no-longer possibly selected. Since bestpath sending is elsewhere we end up with a situation where it's possible to send a withdrawal for the selected. Modify the code in the second loop to no longer send a withdrawal in this case for the selected.