From e3718a611470d311a92c60d4eb535270b49a7108 Mon Sep 17 00:00:00 2001 From: Linus Lüssing Date: Wed, 17 Jun 2020 09:30:33 +0200 Subject: cfg80211/mac80211: add mesh_param "mesh_nolearn" to skip path discovery MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Currently, before being able to forward a packet between two 802.11s nodes, both a PLINK handshake is performed upon receiving a beacon and then later a PREQ/PREP exchange for path discovery is performed on demand upon receiving a data frame to forward. When running a mesh protocol on top of an 802.11s interface, like batman-adv, we do not need the multi-hop mesh routing capabilities of 802.11s and usually set mesh_fwding=0. However, even with mesh_fwding=0 the PREQ/PREP path discovery is still performed on demand. Even though in this scenario the next hop PREQ/PREP will determine is always the direct 11s neighbor node. The new mesh_nolearn parameter allows to skip the PREQ/PREP exchange in this scenario, leading to a reduced delay, reduced packet buffering and simplifies HWMP in general. mesh_nolearn is still rather conservative in that if the packet destination is not a direct 11s neighbor, it will fall back to PREQ/PREP path discovery. For normal, multi-hop 802.11s mesh routing it is usually not advisable to enable mesh_nolearn as a transmission to a direct but distant neighbor might be worse than reaching that same node via a more robust / higher throughput etc. multi-hop path. Cc: Sven Eckelmann Cc: Simon Wunderlich Signed-off-by: Linus Lüssing Link: https://lore.kernel.org/r/20200617073034.26149-1-linus.luessing@c0d3.blue [fix nl80211 policy to range 0/1 only] Signed-off-by: Johannes Berg --- include/uapi/linux/nl80211.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'include/uapi/linux/nl80211.h') diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h index f47a7a8d0216..a83d8faf88ac 100644 --- a/include/uapi/linux/nl80211.h +++ b/include/uapi/linux/nl80211.h @@ -4236,6 +4236,12 @@ enum nl80211_mesh_power_mode { * field. If left unset then the mesh formation field will only * advertise such if there is an active root mesh path. * + * @NL80211_MESHCONF_NOLEARN: Try to avoid multi-hop path discovery (e.g. + * PREQ/PREP for HWMP) if the destination is a direct neighbor. Note that + * this might not be the optimal decision as a multi-hop route might be + * better. So if using this setting you will likely also want to disable + * dot11MeshForwarding and use another mesh routing protocol on top. + * * @__NL80211_MESHCONF_ATTR_AFTER_LAST: internal use */ enum nl80211_meshconf_params { @@ -4269,6 +4275,7 @@ enum nl80211_meshconf_params { NL80211_MESHCONF_AWAKE_WINDOW, NL80211_MESHCONF_PLINK_TIMEOUT, NL80211_MESHCONF_CONNECTED_TO_GATE, + NL80211_MESHCONF_NOLEARN, /* keep last */ __NL80211_MESHCONF_ATTR_AFTER_LAST, -- cgit v1.2.3