Hi, We are integrating VPP with FRR via netlink (RTM_NEWROUTE / RTM_DELROUTE) and have observed an issue in VPP 24.10 regarding nexthop (NHID) delete handling.
Observation When FRR withdraws BGP routes, Linux sometimes emits RTM_DELNEXTHOP events (NHID delete) sometimes without corresponding RTM_DELROUTE messages. Example netlink event observed: RTNL NEXTHOP DELETE nhid=1331 family=2 proto=zebra oif=12 gw=192.168.12.21 Routes referencing this NHID (e.g.): 192.168.0.0/24 nhid 1331 encap mpls 24021 via 192.168.12.21 dev ens6.1012 proto bgp are removed from the Linux kernel, but VPP does not delete the corresponding FIB entry, since NHID delete events are currently not handled. Impact - VPP FIB can retain stale routes - Leads to state mismatch between Linux kernel and VPP - Especially visible with FRR/Zebra + MPLS + nexthop objects Expectation When RTM_DELNEXTHOP is received: - VPP (or plugins consuming netlink) should invalidate and remove all routes associated with the deleted NHID - Or at least provide a mechanism to track NHID → route mappings and act on NHID deletion Question Is the lack of RTM_DELNEXTHOP handling a known limitation? Are there plans to add native NHID tracking and cleanup in VPP, ? Any guidance or recommended approach would be appreciated. Please find ubuntu and kernel version.uname -aLinux -dev 5.15.0-101-generic #111-Ubuntu SMP Tue Mar 5 20:16:58 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux dpkg -l | grep linux-imageii linux-image-5.15.0-101-generic 5.15.0-101.111 amd64 Signed kernel image genericpi linux-image-5.15.0-97-generic 5.15.0-97.107 amd64 Signed kernel image genericcat /etc/os-releasePRETTY_NAME="Ubuntu 22.04.3 LTS"NAME="Ubuntu"VERSION_ID="22.04"VERSION="22.04.3 LTS (Jammy Jellyfish)"VERSION_CODENAME=jammyID=ubuntuID_LIKE=debianHOME_URL="https://www.ubuntu.com/"SUPPORT_URL="https://help.ubuntu.com/"BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"UBUNTU_CODENAME=jammy Thanks & regards, Manoj
-=-=-=-=-=-=-=-=-=-=-=- Links: You receive all messages sent to this group. View/Reply Online (#26675): https://lists.fd.io/g/vpp-dev/message/26675 Mute This Topic: https://lists.fd.io/mt/116902677/21656 Group Owner: [email protected] Unsubscribe: https://lists.fd.io/g/vpp-dev/leave/14379924/21656/631435203/xyzzy [[email protected]] -=-=-=-=-=-=-=-=-=-=-=-
