Merge branch 'bridge-neigh-suppression'
Ido Schimmel says: ==================== bridge: Add per-{Port, VLAN} neighbor suppression Background ========== In order to minimize the flooding of ARP and ND messages in the VXLAN network, EVPN includes provisions [1] that allow participating VTEPs to suppress such messages in case they know the MAC-IP binding and can reply on behalf of the remote host. In Linux, the above is implemented in the bridge driver using a per-port option called "neigh_suppress" that was added in kernel version 4.15 [2]. Motivation ========== Some applications use ARP messages as keepalives between the application nodes in the network. This works perfectly well when two nodes are connected to the same VTEP. When a node goes down it will stop responding to ARP requests and the other node will notice it immediately. However, when the two nodes are connected to different VTEPs and neighbor suppression is enabled, the local VTEP will reply to ARP requests even after the remote node went down, until certain timers expire and the EVPN control plane decides to withdraw the MAC/IP Advertisement route for the address. Therefore, some users would like to be able to disable neighbor suppression on VLANs where such applications reside and keep it enabled on the rest. Implementation ============== The proposed solution is to allow user space to control neighbor suppression on a per-{Port, VLAN} basis, in a similar fashion to other per-port options that gained per-{Port, VLAN} counterparts such as "mcast_router". This allows users to benefit from the operational simplicity and scalability associated with shared VXLAN devices (i.e., external / collect-metadata mode), while still allowing for per-VLAN/VNI neighbor suppression control. The user interface is extended with a new "neigh_vlan_suppress" bridge port option that allows user space to enable per-{Port, VLAN} neighbor suppression on the bridge port. When enabled, the existing "neigh_suppress" option has no effect and neighbor suppression is controlled using a new "neigh_suppress" VLAN option. Example usage: # bridge link set dev vxlan0 neigh_vlan_suppress on # bridge vlan add vid 10 dev vxlan0 # bridge vlan set vid 10 dev vxlan0 neigh_suppress on Testing ======= Tested using existing bridge selftests. Added a dedicated selftest in the last patch. Patchset overview ================= Patches #1-#5 are preparations. Patch #6 adds per-{Port, VLAN} neighbor suppression support to the bridge's data path. Patches #7-#8 add the required netlink attributes to enable the feature. Patch #9 adds a selftest. iproute2 patches can be found here [3]. Changelog ========= Since RFC [4]: No changes. [1] https://www.rfc-editor.org/rfc/rfc7432#section-10 [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a42317785c898c0ed46db45a33b0cc71b671bf29 [3] https://github.com/idosch/iproute2/tree/submit/neigh_suppress_v1 [4] https://lore.kernel.org/netdev/20230413095830.2182382-1-idosch@nvidia.com/ ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
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