Broadcom hardware IGMP snooping

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deydey0
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Joined: 25 Jul 2018
Posts: 6

PostPosted: Tue Feb 05, 2019 15:29    Post subject: Broadcom hardware IGMP snooping Reply with quote
Hi,

On Qualcomm Atheros switches, we can toggle IGMP snooping thanks to swconfig command :
swconfig dev switch0 set igmp_snooping 1

What about Broadcom switches (for example BCM4709) ?
Do they support IGMP snooping ?
Can we toggle it ? How ?
Or is it enabled by default ?
I did not manage to find a datasheet explaining this.

Many thanks !
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danielwritesback
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Joined: 29 Aug 2011
Posts: 219

PostPosted: Tue Feb 05, 2019 17:53    Post subject: Reply with quote
There's a spot in the menu to turn on IGMP snooping for Broadcom. Setup > Networking, bridging, IGMP snooping (click on), save.

I hadn't used it until recently, when I couldn't get some multimedia networking features working. It worked!


Last edited by danielwritesback on Wed Feb 06, 2019 13:26; edited 1 time in total
deydey0
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Joined: 25 Jul 2018
Posts: 6

PostPosted: Tue Feb 05, 2019 18:49    Post subject: Reply with quote
This option enables "IGMP snooping" at the bridge level only.
This will restrict the multicast flows to only one interface of the bridge (for example the vlan containing the ethernet switch ports), preventing the flows from reaching the other interfaces (the WiFi interfaces for example).

The option is then totally different than the hardware IGMP snooping capability of the ethernet switch (which will restrict the multicast flow to the concerned port only).
nolimitz
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Joined: 26 Nov 2010
Posts: 495

PostPosted: Wed Feb 06, 2019 8:55    Post subject: Reply with quote
deydey0 wrote:
This option enables "IGMP snooping" at the bridge level only.
This will restrict the multicast flows to only one interface of the bridge (for example the vlan containing the ethernet switch ports), preventing the flows from reaching the other interfaces (the WiFi interfaces for example).

The option is then totally different than the hardware IGMP snooping capability of the ethernet switch (which will restrict the multicast flow to the concerned port only).


let me know if you find a way, i use the web gui option and my IPTV box gets stuck randomly.
<Kong>
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Joined: 15 Dec 2010
Posts: 4354
Location: Germany

PostPosted: Wed Feb 06, 2019 10:59    Post subject: Reply with quote
nolimitz wrote:
deydey0 wrote:
This option enables "IGMP snooping" at the bridge level only.
This will restrict the multicast flows to only one interface of the bridge (for example the vlan containing the ethernet switch ports), preventing the flows from reaching the other interfaces (the WiFi interfaces for example).

The option is then totally different than the hardware IGMP snooping capability of the ethernet switch (which will restrict the multicast flow to the concerned port only).


let me know if you find a way, i use the web gui option and my IPTV box gets stuck randomly.


Did you enable "Optimize Multicast Traffic" under Wireless settings?

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nolimitz
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Joined: 26 Nov 2010
Posts: 495

PostPosted: Wed Feb 06, 2019 11:22    Post subject: Reply with quote
<Kong> wrote:
nolimitz wrote:
deydey0 wrote:
This option enables "IGMP snooping" at the bridge level only.
This will restrict the multicast flows to only one interface of the bridge (for example the vlan containing the ethernet switch ports), preventing the flows from reaching the other interfaces (the WiFi interfaces for example).

The option is then totally different than the hardware IGMP snooping capability of the ethernet switch (which will restrict the multicast flow to the concerned port only).


let me know if you find a way, i use the web gui option and my IPTV box gets stuck randomly.


Did you enable "Optimize Multicast Traffic" under Wireless settings?


thanks for the reply <Kong>,

yes, i have optimize multicast traffic enabled on both radios of R7000P. without enabling those the router will get stuck with massive wireless errors.

so what i did:
- enable "optimize multicast traffic" for both radios
- enable IGMP snooping (choose yes)

then apply and reboot.

channels on iptv would run then stop, randomly, the iptv box would say can't find media source. router is configured as AP, modem is a Huawei Gateway / Fiber.
deydey0
DD-WRT Novice


Joined: 25 Jul 2018
Posts: 6

PostPosted: Wed Feb 06, 2019 11:52    Post subject: Reply with quote
<Kong> wrote:
Did you enable "Optimize Multicast Traffic" under Wireless settings?

Hi <Kong>,
Do you mean "Optimize Multicast Traffic" under Wireless settings could have an impact on the IGMP snooping feature of the Ethernet switch itself ?!
<Kong>
DD-WRT Guru


Joined: 15 Dec 2010
Posts: 4354
Location: Germany

PostPosted: Wed Feb 06, 2019 12:50    Post subject: Reply with quote
nolimitz wrote:
<Kong> wrote:
nolimitz wrote:
deydey0 wrote:
This option enables "IGMP snooping" at the bridge level only.
This will restrict the multicast flows to only one interface of the bridge (for example the vlan containing the ethernet switch ports), preventing the flows from reaching the other interfaces (the WiFi interfaces for example).

The option is then totally different than the hardware IGMP snooping capability of the ethernet switch (which will restrict the multicast flow to the concerned port only).


let me know if you find a way, i use the web gui option and my IPTV box gets stuck randomly.


Did you enable "Optimize Multicast Traffic" under Wireless settings?


thanks for the reply <Kong>,

yes, i have optimize multicast traffic enabled on both radios of R7000P. without enabling those the router will get stuck with massive wireless errors.

so what i did:
- enable "optimize multicast traffic" for both radios
- enable IGMP snooping (choose yes)

then apply and reboot.

channels on iptv would run then stop, randomly, the iptv box would say can't find media source. router is configured as AP, modem is a Huawei Gateway / Fiber.


That should do.

But R7000P might be the problem, have you tried same config on a non dhd unit. Not sure if it is implemented for DHD units.

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egc
DD-WRT Guru


Joined: 18 Mar 2014
Posts: 4220
Location: Netherlands

PostPosted: Wed Feb 06, 2019 13:14    Post subject: Reply with quote
dhd: probably Broadcom Dongle Host Driver?

Used with the wireless in certain Broadcom
routers?

Do not ask me which ones Smile

But maybe a kernel module and should list with lsmod?
(not present on my R6400v1)

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Routers:Netgear R7800, Netgear R6400v1, Netgear R6400v2, Linksys EA6900 (XvortexCFE), Linksys E2000 (converted WRT320N), WRT54GS v1.
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nolimitz
DD-WRT User


Joined: 26 Nov 2010
Posts: 495

PostPosted: Wed Feb 06, 2019 13:29    Post subject: Reply with quote
<Kong> wrote:
nolimitz wrote:
<Kong> wrote:
nolimitz wrote:
deydey0 wrote:
This option enables "IGMP snooping" at the bridge level only.
This will restrict the multicast flows to only one interface of the bridge (for example the vlan containing the ethernet switch ports), preventing the flows from reaching the other interfaces (the WiFi interfaces for example).

The option is then totally different than the hardware IGMP snooping capability of the ethernet switch (which will restrict the multicast flow to the concerned port only).


let me know if you find a way, i use the web gui option and my IPTV box gets stuck randomly.


Did you enable "Optimize Multicast Traffic" under Wireless settings?


thanks for the reply <Kong>,

yes, i have optimize multicast traffic enabled on both radios of R7000P. without enabling those the router will get stuck with massive wireless errors.

so what i did:
- enable "optimize multicast traffic" for both radios
- enable IGMP snooping (choose yes)

then apply and reboot.

channels on iptv would run then stop, randomly, the iptv box would say can't find media source. router is configured as AP, modem is a Huawei Gateway / Fiber.


That should do.

But R7000P might be the problem, have you tried same config on a non dhd unit. Not sure if it is implemented for DHD units.


i do not think R7000P is the problem, at another location (family's) we have R7000 and R6300v2, exactly same behavior.
deydey0
DD-WRT Novice


Joined: 25 Jul 2018
Posts: 6

PostPosted: Wed Feb 06, 2019 16:08    Post subject: Re: Broadcom hardware IGMP snooping Reply with quote
deydey0 wrote:
What about Broadcom switches (for example BCM4709) ?
Do they support IGMP snooping ?
Can we toggle it ? How ?
Or is it enabled by default ?


I found this (2014-10-01):
https://dev.archive.openwrt.org/ticket/17954
Broadcom switches do not implement full MLD/IGMP snooping in hardware but are only able to redirect these packets to linux with additional information, which would then require a special driver to update the switch internal forwarding tables to match the joins/leaves/membership reports.

I'm however not sure it's still relevant...
<Kong>
DD-WRT Guru


Joined: 15 Dec 2010
Posts: 4354
Location: Germany

PostPosted: Wed Feb 06, 2019 17:10    Post subject: Re: Broadcom hardware IGMP snooping Reply with quote
deydey0 wrote:
deydey0 wrote:
What about Broadcom switches (for example BCM4709) ?
Do they support IGMP snooping ?
Can we toggle it ? How ?
Or is it enabled by default ?


I found this (2014-10-01):
https://dev.archive.openwrt.org/ticket/17954
Broadcom switches do not implement full MLD/IGMP snooping in hardware but are only able to redirect these packets to linux with additional information, which would then require a special driver to update the switch internal forwarding tables to match the joins/leaves/membership reports.

I'm however not sure it's still relevant...


And that is exactly how it is done on our firmware it uses broadcom igs module, if you do an lsmod you will see igs module loaded and you can check status with igs command line util.

E.g.:

root@DD-WRT:~# igs show stats br0
IgmpPkts IgmpQueries IgmpReports IgmpV2Reports IgmpLeaves
1 0 0 0 0
IgmpNotHandled McastGroups McastMembers MemTimeouts
1 0 0 0

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deydey0
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Joined: 25 Jul 2018
Posts: 6

PostPosted: Thu Feb 07, 2019 7:36    Post subject: Reply with quote
Really interesting, thank you <Kong>.

Last edited by deydey0 on Fri Feb 15, 2019 7:36; edited 1 time in total
nolimitz
DD-WRT User


Joined: 26 Nov 2010
Posts: 495

PostPosted: Sun Feb 10, 2019 7:11    Post subject: Reply with quote
<Kong> wrote:

Did you enable "Optimize Multicast Traffic" under Wireless settings?


so i think i found the problem. as i noted earlier, my router is set up as an AP. i enabled "assign WAN port to switch" too.

Fiber Gateway Lan port is connected to R7000P WAN Port (which is assigned to switch).

connecting the Fiber Gateway lan port to R7000P lan port solved the issue. its been only few hours but it looks fine, so it seems the driver cannot do IGMP snooping properly through WAN port even if it is assigned to the switch.


there is also a difference of traffic going through the vlans as well with the configurations noted above. screenshots attached.

i think we need to update the wiki article about multicast to simply talk about optimize multicast in wireless settings and enabling IGMP + a note for the switch ports as using the WAN port in an AP config will not allow IGMP snooping to function.


egc wrote:
dhd: probably Broadcom Dongle Host Driver?

Used with the wireless in certain Broadcom
routers?

Do not ask me which ones Smile

But maybe a kernel module and should list with lsmod?
(not present on my R6400v1)


can you help with updating the wiki? otherwise who can? it would really save people good amount of time.

thanks KONG, BS and everyone here.



WAN PORT Assigned to switchR.png
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WAN PORT Assigned to switchR.png



LAN PORTR.png
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LAN PORTR.png


egc
DD-WRT Guru


Joined: 18 Mar 2014
Posts: 4220
Location: Netherlands

PostPosted: Sun Feb 10, 2019 9:33    Post subject: Reply with quote
I am not a moderator, so I can not help with editing the wiki.

I know ian5142 and Malachi can and are active, you can PM them and ask. Ian is editing wiki's actively, and I occasionally ask Malachi to alter things.

One note about the assign WAN to switch, I once did speed testing, I think with my EA6900 and when the WAN port was assigned to the switch the throughput was about 500 Mb/s in contrast to the regular ports which were 900 Mb/s.
From then on I never used it again and never advised it.

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Routers:Netgear R7800, Netgear R6400v1, Netgear R6400v2, Linksys EA6900 (XvortexCFE), Linksys E2000 (converted WRT320N), WRT54GS v1.
Install guide Linksys EA6900: http://www.dd-wrt.com/phpBB2/viewtopic.php?t=291230
OpenVPN Policy Based Routing guide: https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=321686
Install guide R6400v2:http://forum.dd-wrt.com/phpBB2/viewtopic.php?t=316399
OpenVPN Server Setup:https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=318795
Install guide R7800: https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=320614
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