Re: [B.A.T.M.A.N.] [OpenWrt-Devel] [PATCH netifd] bridge: allow enabling or disabling the multicast querier independently of IGMP snooping
Reading this mail seems that who installa batman-adv nodes should do this setting manually, doesn't batman-adv know/(can estimate) who is the goode node were to put the querier?
What happen if we have the querier on every node?
Thanks!
On Tuesday, January 27, 2015 03:49:52 AM Matthias Schiffer wrote:
In larger networks, especially big batman-adv meshes, it may be desirable to enable IGMP snooping on every bridge without enabling the multicast querier to specifically put the querier on a well-connected node.
This patch adds a new UCI option 'multicast_querier' for bridges which allows this. The default is still the value of the 'igmp_snooping' option to maintain backwards compatiblity.
Signed-off-by: Matthias Schiffer mschiffer@universe-factory.net
bridge.c | 8 +++++++- system-linux.c | 2 +- system.h | 1 + 3 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/bridge.c b/bridge.c index f8478ad..f7dbf61 100644 --- a/bridge.c +++ b/bridge.c @@ -32,6 +32,7 @@ enum { BRIDGE_ATTR_HELLO_TIME, BRIDGE_ATTR_MAX_AGE, BRIDGE_ATTR_BRIDGE_EMPTY,
- BRIDGE_ATTR_MULTICAST_QUERIER, __BRIDGE_ATTR_MAX
};
@@ -45,6 +46,7 @@ static const struct blobmsg_policy bridge_attrs[__BRIDGE_ATTR_MAX] = { [BRIDGE_ATTR_MAX_AGE] = { "max_age", BLOBMSG_TYPE_INT32 }, [BRIDGE_ATTR_IGMP_SNOOP] = { "igmp_snooping", BLOBMSG_TYPE_BOOL }, [BRIDGE_ATTR_BRIDGE_EMPTY] = { "bridge_empty", BLOBMSG_TYPE_BOOL },
- [BRIDGE_ATTR_MULTICAST_QUERIER] = { "multicast_querier", BLOBMSG_TYPE_BOOL
}, };
static const struct uci_blob_param_info bridge_attr_info[__BRIDGE_ATTR_MAX] = { @@ -547,6 +549,7 @@ bridge_apply_settings(struct bridge_state *bst, struct blob_attr **tb) cfg->stp = false; cfg->forward_delay = 2; cfg->igmp_snoop = true;
- cfg->multicast_querier = true; cfg->bridge_empty = false; cfg->priority = 0x7FFF;
@@ -560,7 +563,10 @@ bridge_apply_settings(struct bridge_state *bst, struct blob_attr **tb) cfg->priority = blobmsg_get_u32(cur);
if ((cur = tb[BRIDGE_ATTR_IGMP_SNOOP]))
cfg->igmp_snoop = blobmsg_get_bool(cur);
cfg->multicast_querier = cfg->igmp_snoop = blobmsg_get_bool(cur);if ((cur = tb[BRIDGE_ATTR_MULTICAST_QUERIER]))
cfg->multicast_querier = blobmsg_get_bool(cur);if ((cur = tb[BRIDGE_ATTR_AGEING_TIME])) { cfg->ageing_time = blobmsg_get_u32(cur);
diff --git a/system-linux.c b/system-linux.c index 4737fa6..ef90880 100644 --- a/system-linux.c +++ b/system-linux.c @@ -772,7 +772,7 @@ int system_bridge_addbr(struct device *bridge, struct bridge_config *cfg) bridge->ifname, cfg->igmp_snoop ? "1" : "0");
system_set_dev_sysctl("/sys/devices/virtual/net/%s/bridge/multicast_querie
r", - bridge->ifname, cfg->igmp_snoop ? "1" : "0");
bridge->ifname, cfg->multicast_querier ? "1" : "0");args[0] = BRCTL_SET_BRIDGE_PRIORITY; args[1] = cfg->priority;
diff --git a/system.h b/system.h index 9a2326b..94e0dd9 100644 --- a/system.h +++ b/system.h @@ -50,6 +50,7 @@ struct bridge_config { enum bridge_opt flags; bool stp; bool igmp_snoop;
- bool multicast_querier; unsigned short priority; int forward_delay; bool bridge_empty;
Regarding IGMP/MLD, batman-adv will just provide an overlay ethernet layer, on which the normal rules of RFC2710 / RFC3376 will be used to elect the querier: the router with the lowest IP address that has the querier feature enabled becomes the querier.
Linus Lüssing, who developled the multicast optimization feature for batman-adv, suggested to only enable IGMP/MLD snooping, but not the querier, on normal mesh nodes, which is why I wrote this patch.
On 01/27/2015 11:48 AM, Gioacchino Mazzurco wrote:
Reading this mail seems that who installa batman-adv nodes should do this setting manually, doesn't batman-adv know/(can estimate) who is the goode node were to put the querier?
What happen if we have the querier on every node?
Thanks!
On Tuesday, January 27, 2015 03:49:52 AM Matthias Schiffer wrote:
In larger networks, especially big batman-adv meshes, it may be desirable to enable IGMP snooping on every bridge without enabling the multicast querier to specifically put the querier on a well-connected node.
This patch adds a new UCI option 'multicast_querier' for bridges which allows this. The default is still the value of the 'igmp_snooping' option to maintain backwards compatiblity.
Signed-off-by: Matthias Schiffer mschiffer@universe-factory.net
bridge.c | 8 +++++++- system-linux.c | 2 +- system.h | 1 + 3 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/bridge.c b/bridge.c index f8478ad..f7dbf61 100644 --- a/bridge.c +++ b/bridge.c @@ -32,6 +32,7 @@ enum { BRIDGE_ATTR_HELLO_TIME, BRIDGE_ATTR_MAX_AGE, BRIDGE_ATTR_BRIDGE_EMPTY,
- BRIDGE_ATTR_MULTICAST_QUERIER, __BRIDGE_ATTR_MAX
};
@@ -45,6 +46,7 @@ static const struct blobmsg_policy bridge_attrs[__BRIDGE_ATTR_MAX] = { [BRIDGE_ATTR_MAX_AGE] = { "max_age", BLOBMSG_TYPE_INT32 }, [BRIDGE_ATTR_IGMP_SNOOP] = { "igmp_snooping", BLOBMSG_TYPE_BOOL }, [BRIDGE_ATTR_BRIDGE_EMPTY] = { "bridge_empty", BLOBMSG_TYPE_BOOL },
- [BRIDGE_ATTR_MULTICAST_QUERIER] = { "multicast_querier", BLOBMSG_TYPE_BOOL
}, };
static const struct uci_blob_param_info bridge_attr_info[__BRIDGE_ATTR_MAX] = { @@ -547,6 +549,7 @@ bridge_apply_settings(struct bridge_state *bst, struct blob_attr **tb) cfg->stp = false; cfg->forward_delay = 2; cfg->igmp_snoop = true;
- cfg->multicast_querier = true; cfg->bridge_empty = false; cfg->priority = 0x7FFF;
@@ -560,7 +563,10 @@ bridge_apply_settings(struct bridge_state *bst, struct blob_attr **tb) cfg->priority = blobmsg_get_u32(cur);
if ((cur = tb[BRIDGE_ATTR_IGMP_SNOOP]))
cfg->igmp_snoop = blobmsg_get_bool(cur);
cfg->multicast_querier = cfg->igmp_snoop = blobmsg_get_bool(cur);if ((cur = tb[BRIDGE_ATTR_MULTICAST_QUERIER]))
cfg->multicast_querier = blobmsg_get_bool(cur);if ((cur = tb[BRIDGE_ATTR_AGEING_TIME])) { cfg->ageing_time = blobmsg_get_u32(cur);
diff --git a/system-linux.c b/system-linux.c index 4737fa6..ef90880 100644 --- a/system-linux.c +++ b/system-linux.c @@ -772,7 +772,7 @@ int system_bridge_addbr(struct device *bridge, struct bridge_config *cfg) bridge->ifname, cfg->igmp_snoop ? "1" : "0");
system_set_dev_sysctl("/sys/devices/virtual/net/%s/bridge/multicast_querie
r", - bridge->ifname, cfg->igmp_snoop ? "1" : "0");
bridge->ifname, cfg->multicast_querier ? "1" : "0");args[0] = BRCTL_SET_BRIDGE_PRIORITY; args[1] = cfg->priority;
diff --git a/system.h b/system.h index 9a2326b..94e0dd9 100644 --- a/system.h +++ b/system.h @@ -50,6 +50,7 @@ struct bridge_config { enum bridge_opt flags; bool stp; bool igmp_snoop;
- bool multicast_querier; unsigned short priority; int forward_delay; bool bridge_empty;
On Tue, Jan 27, 2015 at 11:48:09AM +0100, Gioacchino Mazzurco wrote:
Reading this mail seems that who installa batman-adv nodes should do this setting manually, doesn't batman-adv know/(can estimate) who is the goode node were to put the querier?
Like Matthias said, the selection process is an "upper layer thing" (from the batman-adv point of view). The querier with the lowest IP address will become the selected querier as specified by the IGMP/MLD RFCs.
What happen if we have the querier on every node?
To be honest, I'm not 100% sure. For what is implemented so far, it might actually work out with no downsides. If the node/querier with the lowest IP happens to be behind a bad, lossy wifi link and two consecutive IGMP/MLD query messages from this selected querier get lost then one of the other potential queriers should take over within a five seconds window.
This should work out well if you have a planned, structured mesh network with a few dozen nodes where you made sure that each node is well connected to the rest of the mesh.
If you're having a mesh network with some hundreds of nodes with potentially many behind bad wifi links, I'd get a little nervous... it'd be like running your IPv6 network (IPv6 relies on multicast) on a large, wobbly jelly.
My general suggestion at the moment is, to only have queriers enabled on a few well- and redundantly connected nodes close to the center of the mesh if you want to use the bridge multicast snooping feature in your mesh network).
Cheers, Linus
PS: batman-adv has no multicast optimizations for bridges or traffic other than link-local yet, btw. Still, queriers behind unreliable wifi links could be an issue even with multicast optimzations disabled in batman-adv and multicast snooping enabled in the bridge.
PPS: Have spent some time thinking about implementing an IGMP/MLD proxy in the bridge and/or batman-adv lately. It's just that so many complicated workarounds have piled up thanks to the old (and in my opinion broken...) MLDv1/IGMPv1/IGMPv2 (MLDv2+IGMPv3 are cool though) which we didn't all notice before implementing and testing things. Now I'd happily trade that for some "layer violations". And enterprise switches are doing just that, too, afaik (aggregating IGMP/MLD reports and stuff like that for instance).
Thanks for the info :)
b.a.t.m.a.n@lists.open-mesh.org
-
Gioacchino Mazzurco -
Linus Lüssing -
Matthias Schiffer