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FS#3266 - Multicast does not work over bridge with AP/VLAN interfaces #8135

openwrt-bot opened this issue Aug 3, 2020 · 3 comments


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MikroTik RouterBOARD wAP G-5HacT2HnD with OpenWRT r13630-635f111148
EnGenius EAP1300 with OpenWRT r14017-c90db26e05

I have a wifi setup with EAP and dynamic vlan assigment from a radius server.
Clients can connect and both unicast and broadcast (DHCP) works fine, but multicast does not, so IPv6 SLAAC does not work for example.
On the APs I can see the multicast packets being sent out on the the AP/VLAN interfaces (tcpdump -n -i wlan1.10 multicast), but none of the three clients (linux laptop and two iOS devices) receives them.
I have tried enabling multicast_to_unicast, multicast_snooping and hairpin_mode by hand in sysfs, doesn't make any difference, also tried disabling multicast_router.
It sometimes works on the MikroTik device, but mostly does not.

My wireless config (it's the same on both devices for both radios):
config wifi-iface 'myssid_5'
option mode 'ap'
option ssid 'myssid'
option hidden '1'
option encryption 'wpa3-mixed'
option auth_server 'authserver'
option auth_secret 'secret'
option dynamic_vlan '2'
option vlan_tagged_interface 'eth0'
option max_inactivity '1800'
option device 'radio0'
option mobility_domain 'f1f1'
option nasid 'mynasid'
option pmk_r1_push '1'
option ieee80211r '1'
option rsn_preauth '0'
option isolate '1'
option vlan_bridge 'br-vlan'
option vlan_naming '0'
option ieee80211w '1'
list r0kh '....'
list r0kh '....'
list r0kh '....'
list r0kh '....'
list r1kh '....'
list r1kh '....'
list r1kh '....'
list r1kh '....'

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russoisraeli commented Mar 3, 2023

Similar issue on GL-B1300 (GL.iNet).

Device is configured as an AP with multiple bridged VLANs.
The observed behaviour (via tcpdump) is that when SLAAC is used, the wireless client sends a Router Solicitation, it never gets from the bridge interface ( ath* -> br* -> eth0.* ) to the ethernet (VLAN) interface (and then never comes to the wired server).
The server eventually sends the (periodic) Router Advertisement, which actually gets through the other way ( eth0.* -> br* -> ath* ), and the client gets autoconfigured.

root@GL-B1300-Living:~# cat /etc/openwrt_release
DISTRIB_DESCRIPTION='OpenWrt Chaos Calmer 15.05.1'

root@GL-B1300-Living:~# cat /etc/openwrt_version

In the screenshots attached, ath* are the wifi virtual interfaces, eth0.* are the VLAN interfaces on eth0.
Behaviour is consistently observed over br-Wireless as well as br-WiFi_v6.

Please let me know if you need any other information.

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Screen Shot 2023-03-03 at 9 31 50 AM

Screen Shot 2023-03-03 at 9 32 35 AM

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nbd168 commented Mar 3, 2023

This sounds very much like an issue in the Linux bridge layer which got fixed years ago. Feel free to open up a new ticket, or reopen if it's still reproducible with a recent version of OpenWrt.

@nbd168 nbd168 closed this as completed Mar 3, 2023
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3 participants