B.A.T.M.A.N

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Re: [pim] draft-ietf-6lo-multicast-registration-08 replacing MLD
by Linus Lüssing 13 Sep '22

13 Sep '22

On Mon, Aug 08, 2022 at 10:21:05AM -0700, Stig Venaas wrote: > Hi 6lo and draft authors > > I have some concerns about this draft replacing MLD for group registration. > > Having 2 different protocols for the same thing can be problematic. > Hosts or routers may need to support both protocols. Is it clear which > one should be used in different environments? Is there a chance that > both may be used at the same time in a network? In particular, is > there a chance that a router may need to simultaneously support both > protocols on an L3 interface? In that case it must be considered how > the two protocols interoperate. > > Also, we have been pushing the use of SSM in the IETF for a very long > time, but this draft only supports ASM since only a group address is > provided. > > It would be good to have some more info on the need to replace MLD. I > understand there are concerns about packet loss, limited resources > etc. > > Regards, > Stig Hi, Is there some good overview and/or presentation of this alternative concept available somewhere? The introduction of draft-ietf-6lo-multicast-registration-08 as is is a bit difficult to start with as its introduction references a lot of other, fairly new RFCs (which generally is fine for me, avoids duplication; just not that easy to start with as a first read :D ). I'm very interested in this topic as we too are experiencing several drawbacks with the current MLD approach in our layer 2 mesh networks based on B.A.T.M.A.N. Advanced [0]. Typically people use 802.11 based WiFi routers with fixed line power with batman-adv. At least for larger installations. While if I understand correctly this new RFC is focusing on off-grid LoRaWAN based mesh nodes, right? Might be interesting to check if for these two different radio technologies we face similar issues, but also if we might have differing requirements. To avoid that we would need a third protocol later... --- batman-adv currently makes use of MLD snooping [1]. The four main issues we are/were facing: 1) MLD overhead is high with default intervals for the mesh network sizes we are working with (> 1000 mesh nodes and > 2000 client devices) 2) MLD is too slow and unreliable with default intervals for a lossy, dynamic mesh network. -> we can't fix both 1) + 2) by tuning MLD querier parameters 3) MLD querier selection is not robust enough in a dynamic mesh network, lowest MAC addrdess for the querier is a bad criteria, we don't want a barely connected node with high packet loss at the edge of the wifi mesh network to take over such an essential roll; actually we don't want any mesh node to take over a central role, batman-adv was designed to work as a fully decentral mesh of equal nodes without any reliabilities 4) IGMPv2/MLDv1 Report suppression [2]; RFC4541 ("Considerations for Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD) Snooping Switches" is not feasible solution/workaround for us always forwarding all multicast traffic to the querier would lead to congestion On the other hand power consumption of MLD as noted in the draft is not a big issue for us right now, though it might be related to 1). The workaround for our four issues we came up with is to split the layer 2 broadcast domain per mesh node with layer 2 filtering of MLD [3]. So regarding MLD it is now behaving more like a layer 3 mesh network, where each WiFi router / mesh node is its own querier for its local Wifi clients. And between the mesh nodes we exchange listener state through the batman-adv protocol, sort of like a one-way proxy, as its more efficient for us right now. The downside is that it is one-way right now, so each batman-adv node will have the listener state which is enough for us right now to ensure that within the layer 2 broadcast domain multicast works fine. However a remote batman-adv node won't translate it back to MLD, so layer 3 multicast routers won't be informed. Also its ASM only at the moment. But I would celebrate it if we could just get rid of these workarounds by simply having a more robust, more decentral but also less costly MLDv3 (and especially no more MLDv1). --- I'll also be at the Wireless Battlemesh [4] in Rome, Italy, with several other batman-adv developers next week and we will be talking about mesh networks the whole week. Feel free to stop by if you can, it's an awesome event :-). Or would anybody be interested to exchange our experiences with MLD in mesh networks remotely during that week? I could put an official slot on the Battlemesh schedule, if people would be interested. Regards, Linus [0]: https://www.open-mesh.org/projects/batman-adv/wiki [1]: https://www.open-mesh.org/projects/batman-adv/wiki/Multicast-optimizations [2]: https://www.open-mesh.org/projects/batman-adv/wiki/Multicast-optimizations-… [3]: https://gluon.readthedocs.io/en/latest/package/gluon-mesh-batman-adv.html#m… [4]: https://www.battlemesh.org/

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[PATCH] batman-adv: Fix hang up with small MTU hard-interface
by Shigeru Yoshida 07 Sep '22

07 Sep '22

The system hangs up when batman-adv soft-interface is created on hard-interface with small MTU. For example, the following commands create batman-adv soft-interface on dummy interface with zero MTU: # ip link add name dummy0 type dummy # ip link set mtu 0 dev dummy0 # ip link set up dev dummy0 # ip link add name bat0 type batadv # ip link set dev dummy0 master bat0 These commands cause the system hang up with the following messages: [ 90.578925][ T6689] batman_adv: bat0: Adding interface: dummy0 [ 90.580884][ T6689] batman_adv: bat0: The MTU of interface dummy0 is too small (0) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1560 would solve the problem. [ 90.586264][ T6689] batman_adv: bat0: Interface activated: dummy0 [ 90.590061][ T6689] batman_adv: bat0: Forced to purge local tt entries to fit new maximum fragment MTU (-320) [ 90.595517][ T6689] batman_adv: bat0: Forced to purge local tt entries to fit new maximum fragment MTU (-320) [ 90.598499][ T6689] batman_adv: bat0: Forced to purge local tt entries to fit new maximum fragment MTU (-320) This patch fixes this issue by returning error when enabling hard-interface with small MTU size. Signed-off-by: Shigeru Yoshida <syoshida(a)redhat.com> --- net/batman-adv/hard-interface.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c index b8f8da7ee3de..dce5557800e9 100644 --- a/net/batman-adv/hard-interface.c +++ b/net/batman-adv/hard-interface.c @@ -700,6 +700,9 @@ int batadv_hardif_enable_interface(struct batadv_hard_iface *hard_iface, int max_header_len = batadv_max_header_len(); int ret; + if (hard_iface->net_dev->mtu < ETH_MIN_MTU + max_header_len) + return -EINVAL; + if (hard_iface->if_status != BATADV_IF_NOT_IN_USE) goto out; -- 2.37.2

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zero hop penalty interface?
by dan 06 Sep '22

06 Sep '22

Hi all. I'm struggling to find an answer to this specific question about path selection. I'm looking at building a prototype mesh out of the banana pi BPI-R3. That's a dual band wifi 6/6e router that runs open-wrt. 1x 2.4Ghz and 1x5-6Ghz. I would build this as a quasi-dual radio mesh. ie, I want to favor the 5-6Ghz radio and add a large hop penalty to the 2.4Ghz so that it's only used for backup. The 2.4Ghz is a fraction the speed of the 5-6Ghz. What I'm considering is that as I saturate the 'single radio mesh' that the 5-6Ghz radios is essentially making since 2.4Ghz is purposely high-cost, I may want to add a second unit starting from the main uplink out as a secondary mesh, then linking both units together via 2.5-5GbE ports on the device. The question is, can I make the hop penalty zero so the mesh treats this pair of routers basically as one? for instance data comes into node10a's 5Ghz radio, I'd like that to try to go across the 'zero cost' ethernet and exit via node10b's 5Ghz radio to make this effectively a dual radio mesh. Ultimately the same would be true of the 2.4Ghz but again, that's ideally for backup meshing as it should look like an expensive hop.

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[PATCH 5.19 1114/1157] batman-adv: tracing: Use the new __vstring() helper
by Greg Kroah-Hartman 15 Aug '22

15 Aug '22

From: Steven Rostedt (Google) <rostedt(a)goodmis.org> [ Upstream commit 9abc291812d784bd4a26c01af4ebdbf9f2dbf0bb ] Instead of open coding a __dynamic_array() with a fixed length (which defeats the purpose of the dynamic array in the first place). Use the new __vstring() helper that will use a va_list and only write enough of the string into the ring buffer that is needed. Link: https://lkml.kernel.org/r/20220724191650.236b1355@rorschach.local.home Cc: Marek Lindner <mareklindner(a)neomailbox.ch> Cc: Ingo Molnar <mingo(a)kernel.org> Cc: Andrew Morton <akpm(a)linux-foundation.org> Cc: Simon Wunderlich <sw(a)simonwunderlich.de> Cc: Antonio Quartulli <a(a)unstable.cc> Cc: "David S. Miller" <davem(a)davemloft.net> Cc: Eric Dumazet <edumazet(a)google.com> Cc: Jakub Kicinski <kuba(a)kernel.org> Cc: Paolo Abeni <pabeni(a)redhat.com> Cc: b.a.t.m.a.n(a)lists.open-mesh.org Cc: netdev(a)vger.kernel.org Acked-by: Sven Eckelmann <sven(a)narfation.org> Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org> Signed-off-by: Sasha Levin <sashal(a)kernel.org> --- net/batman-adv/trace.h | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff --git a/net/batman-adv/trace.h b/net/batman-adv/trace.h index d673ebdd0426..31c8f922651d 100644 --- a/net/batman-adv/trace.h +++ b/net/batman-adv/trace.h @@ -28,8 +28,6 @@ #endif /* CONFIG_BATMAN_ADV_TRACING */ -#define BATADV_MAX_MSG_LEN 256 - TRACE_EVENT(batadv_dbg, TP_PROTO(struct batadv_priv *bat_priv, @@ -40,16 +38,13 @@ TRACE_EVENT(batadv_dbg, TP_STRUCT__entry( __string(device, bat_priv->soft_iface->name) __string(driver, KBUILD_MODNAME) - __dynamic_array(char, msg, BATADV_MAX_MSG_LEN) + __vstring(msg, vaf->fmt, vaf->va) ), TP_fast_assign( __assign_str(device, bat_priv->soft_iface->name); __assign_str(driver, KBUILD_MODNAME); - WARN_ON_ONCE(vsnprintf(__get_dynamic_array(msg), - BATADV_MAX_MSG_LEN, - vaf->fmt, - *vaf->va) >= BATADV_MAX_MSG_LEN); + __assign_vstr(msg, vaf->fmt, vaf->va); ), TP_printk( -- 2.35.1

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[PATCH 5.18 1046/1095] batman-adv: tracing: Use the new __vstring() helper
by Greg Kroah-Hartman 15 Aug '22

15 Aug '22

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[PATCH 1/3] alfred: add missing alfred_event_notify_v0 struct documentation
by Marek Lindner 04 Aug '22

04 Aug '22

Signed-off-by: Marek Lindner <mareklindner(a)neomailbox.ch> --- packet.h | 1 + 1 file changed, 1 insertion(+) diff --git a/packet.h b/packet.h index b8d528e..c0723b8 100644 --- a/packet.h +++ b/packet.h @@ -247,6 +247,7 @@ struct alfred_event_register_v0 { * struct alfred_event_notify_v0 - event notification message * @header: TLV header describing the complete packet * @type: Type of the data triggering the event + * @source: Mac address of the original source of the data * * Sent by the daemon to client on data record update */ -- 2.36.1

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[for-next][PATCH 02/21] batman-adv: tracing: Use the new __vstring() helper
by Steven Rostedt 31 Jul '22

31 Jul '22

From: "Steven Rostedt (Google)" <rostedt(a)goodmis.org> Instead of open coding a __dynamic_array() with a fixed length (which defeats the purpose of the dynamic array in the first place). Use the new __vstring() helper that will use a va_list and only write enough of the string into the ring buffer that is needed. Link: https://lkml.kernel.org/r/20220724191650.236b1355@rorschach.local.home Cc: Marek Lindner <mareklindner(a)neomailbox.ch> Cc: Ingo Molnar <mingo(a)kernel.org> Cc: Andrew Morton <akpm(a)linux-foundation.org> Cc: Simon Wunderlich <sw(a)simonwunderlich.de> Cc: Antonio Quartulli <a(a)unstable.cc> Cc: "David S. Miller" <davem(a)davemloft.net> Cc: Eric Dumazet <edumazet(a)google.com> Cc: Jakub Kicinski <kuba(a)kernel.org> Cc: Paolo Abeni <pabeni(a)redhat.com> Cc: b.a.t.m.a.n(a)lists.open-mesh.org Cc: netdev(a)vger.kernel.org Acked-by: Sven Eckelmann <sven(a)narfation.org> Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org> --- net/batman-adv/trace.h | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff --git a/net/batman-adv/trace.h b/net/batman-adv/trace.h index d673ebdd0426..31c8f922651d 100644 --- a/net/batman-adv/trace.h +++ b/net/batman-adv/trace.h @@ -28,8 +28,6 @@ #endif /* CONFIG_BATMAN_ADV_TRACING */ -#define BATADV_MAX_MSG_LEN 256 - TRACE_EVENT(batadv_dbg, TP_PROTO(struct batadv_priv *bat_priv, @@ -40,16 +38,13 @@ TRACE_EVENT(batadv_dbg, TP_STRUCT__entry( __string(device, bat_priv->soft_iface->name) __string(driver, KBUILD_MODNAME) - __dynamic_array(char, msg, BATADV_MAX_MSG_LEN) + __vstring(msg, vaf->fmt, vaf->va) ), TP_fast_assign( __assign_str(device, bat_priv->soft_iface->name); __assign_str(driver, KBUILD_MODNAME); - WARN_ON_ONCE(vsnprintf(__get_dynamic_array(msg), - BATADV_MAX_MSG_LEN, - vaf->fmt, - *vaf->va) >= BATADV_MAX_MSG_LEN); + __assign_vstr(msg, vaf->fmt, vaf->va); ), TP_printk( -- 2.35.1

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[PATCH v2] batman-adv: tracing: Use the new __vstring() helper
by Steven Rostedt 25 Jul '22

25 Jul '22

From: "Steven Rostedt (Google)" <rostedt(a)goodmis.org> Instead of open coding a __dynamic_array() with a fixed length (which defeats the purpose of the dynamic array in the first place). Use the new __vstring() helper that will use a va_list and only write enough of the string into the ring buffer that is needed. Cc: Marek Lindner <mareklindner(a)neomailbox.ch> Cc: Ingo Molnar <mingo(a)kernel.org> Cc: Andrew Morton <akpm(a)linux-foundation.org> Cc: Simon Wunderlich <sw(a)simonwunderlich.de> Cc: Antonio Quartulli <a(a)unstable.cc> Cc: Sven Eckelmann <sven(a)narfation.org> Cc: "David S. Miller" <davem(a)davemloft.net> Cc: Eric Dumazet <edumazet(a)google.com> Cc: Jakub Kicinski <kuba(a)kernel.org> Cc: Paolo Abeni <pabeni(a)redhat.com> Cc: b.a.t.m.a.n(a)lists.open-mesh.org Cc: netdev(a)vger.kernel.org Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org> --- Changes since v1: https://lkml.kernel.org/r/20220705224751.080390002@goodmis.org - Removed no longer used BATADV_MAX_MSG_LEN net/batman-adv/trace.h | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff --git a/net/batman-adv/trace.h b/net/batman-adv/trace.h index d673ebdd0426..31c8f922651d 100644 --- a/net/batman-adv/trace.h +++ b/net/batman-adv/trace.h @@ -28,8 +28,6 @@ #endif /* CONFIG_BATMAN_ADV_TRACING */ -#define BATADV_MAX_MSG_LEN 256 - TRACE_EVENT(batadv_dbg, TP_PROTO(struct batadv_priv *bat_priv, @@ -40,16 +38,13 @@ TRACE_EVENT(batadv_dbg, TP_STRUCT__entry( __string(device, bat_priv->soft_iface->name) __string(driver, KBUILD_MODNAME) - __dynamic_array(char, msg, BATADV_MAX_MSG_LEN) + __vstring(msg, vaf->fmt, vaf->va) ), TP_fast_assign( __assign_str(device, bat_priv->soft_iface->name); __assign_str(driver, KBUILD_MODNAME); - WARN_ON_ONCE(vsnprintf(__get_dynamic_array(msg), - BATADV_MAX_MSG_LEN, - vaf->fmt, - *vaf->va) >= BATADV_MAX_MSG_LEN); + __assign_vstr(msg, vaf->fmt, vaf->va); ), TP_printk( -- 2.35.1

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[for-next][PATCH 17/23] batman-adv: tracing: Use the new __vstring() helper
by Steven Rostedt 24 Jul '22

24 Jul '22

2 2

[PATCH] batman-adv: tracing: Use the new __vstring() helper
by Sven Eckelmann 24 Jul '22

24 Jul '22

From: "Steven Rostedt (Google)" <rostedt(a)goodmis.org> Instead of open coding a __dynamic_array() with a fixed length (which defeats the purpose of the dynamic array in the first place). Use the new __vstring() helper that will use a va_list and only write enough of the string into the ring buffer that is needed. Link: https://lkml.kernel.org/r/20220705224751.080390002@goodmis.org Signed-off-by: Steven Rostedt (Google) <rostedt(a)goodmis.org> [sven(a)narfation.org: add compat code] Signed-off-by: Sven Eckelmann <sven(a)narfation.org> --- Already added to https://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git/com… compat-include/linux/tracepoint.h | 24 ++++++++++++++++++++++++ net/batman-adv/trace.h | 7 ++----- 2 files changed, 26 insertions(+), 5 deletions(-) create mode 100644 compat-include/linux/tracepoint.h diff --git a/compat-include/linux/tracepoint.h b/compat-include/linux/tracepoint.h new file mode 100644 index 00000000..61df01a3 --- /dev/null +++ b/compat-include/linux/tracepoint.h @@ -0,0 +1,24 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (C) B.A.T.M.A.N. contributors: + * + * Marek Lindner, Simon Wunderlich + * + * This file contains macros for maintaining compatibility with older versions + * of the Linux kernel. + */ + +#ifndef _NET_BATMAN_ADV_COMPAT_LINUX_TRACEPOINT_H_ +#define _NET_BATMAN_ADV_COMPAT_LINUX_TRACEPOINT_H_ + +#include <linux/version.h> +#include_next <linux/tracepoint.h> + +#if LINUX_VERSION_IS_LESS(5, 19, 0) + +#define __vstring(item, fmt, ap) __dynamic_array(char, item, 256) +#define __assign_vstr(dst, fmt, va) \ + WARN_ON_ONCE(vsnprintf(__get_dynamic_array(dst), 256, fmt, *va) >= 256) + +#endif /* LINUX_VERSION_IS_LESS(5, 19, 0) */ + +#endif /* _NET_BATMAN_ADV_COMPAT_LINUX_TRACEPOINT_H_ */ diff --git a/net/batman-adv/trace.h b/net/batman-adv/trace.h index d673ebdd..67d2a8a0 100644 --- a/net/batman-adv/trace.h +++ b/net/batman-adv/trace.h @@ -40,16 +40,13 @@ TRACE_EVENT(batadv_dbg, TP_STRUCT__entry( __string(device, bat_priv->soft_iface->name) __string(driver, KBUILD_MODNAME) - __dynamic_array(char, msg, BATADV_MAX_MSG_LEN) + __vstring(msg, vaf->fmt, vaf->va) ), TP_fast_assign( __assign_str(device, bat_priv->soft_iface->name); __assign_str(driver, KBUILD_MODNAME); - WARN_ON_ONCE(vsnprintf(__get_dynamic_array(msg), - BATADV_MAX_MSG_LEN, - vaf->fmt, - *vaf->va) >= BATADV_MAX_MSG_LEN); + __assign_vstr(msg, vaf->fmt, vaf->va); ), TP_printk( -- 2.30.2

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