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NeedHelp44
Posts: 20
Registered: ‎05-19-2010

Filter Multicast

[ Edited ]

Modem: WRT310N Firmware: 1.0.9.0 Build 4 (Latest)

 

192.168.1.1 > Security > Firewall > Filter Multicast

 

If I want to allow Multicast traffic on my network, does this box need a "Check Mark" or does it need to be "Unchecked"

 

Thank you for your help!

 

Here is the manual's pdf text:

Filter Multicast Multicasting allows for multiple
transmissions to specific recipients at the same time. If
multicasting is permitted, then the Router will allow IP
multicast packets to be forwarded to the appropriate
computers. Select this feature to filter multicasting. This
feature is not selected by default.

 

Here is my router's internal help text:

Filter Multicast. Multicasting allows for multiple transmissions to specific recipients at the same time. If multicasting is permitted, then the Router will allow IP multicast packets to be forwarded to the appropriate computers. Select Enabled to filter multicasting, or Disabled to disable this feature.

 

WRT610N Manual:

Filter Multicast Multicasting allows for multiple
transmissions to specific recipients at the same time. If
multicasting is permitted, then the Router will allow IP
multicast packets to be forwarded to the appropriate
computers. It is selected by default. Deselect this feature
to disable it.

 

WRT54G2 Manual:

Filter Multicast Multicasting allows for multiple
transmissions to specific recipients at the same time. If
multicasting is permitted, then the Router will allow IP
multicast packets to be forwarded to the appropriate
computers. This feature is selected by default. Deselect
this feature to disable it.

brickmonkey
Posts: 2,634
Registered: ‎09-07-2006

Re: Filter Multicast

To allow Multicast traffic,you need to enable (check) the box.

NeedHelp44
Posts: 20
Registered: ‎05-19-2010

Re: Filter Multicast

[ Edited ]

Thank you for your reply. I will try this, but I do have a question.

 

Before I made this post I opened dozens of google searches on linksys, and multicast. And there seems to be a disconnect between what the router text is telling us, and what the truth is. There are a ton of these posts regarding multicast, and to me it appears the text is wrong in the help files then.

 

According to linksys text, if I enable this option, it filters out multicast (thus preventing it) however, as you and some other posters have said, the reverse is true.

 

But how do we know for certain?

 

Here's some of the other posts (Open the link then search for the word "Multicast" to jump to the interesting parts:

http://www.ciscopress.com/articles/article.asp?p=598649&seqNum=5

http://forums.sonos.com/archive/index.php?t-2607.html

http://www.broadbandreports.com/forum/remark,12064037

 

So if that's true how do we submit this typo problem to linksys to be corrected? It should probably read "Multicast Passthrough" or "Allow Multicast" and NOT "Filter Multicast" because Filter means "Prevent" that's why every other option on the linksys page says "Filter" and if you "Enable" them, they ALL "Block" that setting.

 

** Also from what I understand this controls the IGMP protocol. Is there anyway to test if its running on your router, without running another firmware like DDWRT or Tomato?

brickmonkey
Posts: 2,634
Registered: ‎09-07-2006

Re: Filter Multicast

Once you enable the "Filter Multicast",it will enable all the multiple transmissions to specific recipients at the same time.If multicasting is permitted, then the Router will allow IP multicast packets to be forwarded to the appropriate computers. Select Enabled to filter multicasting (select enable to allow transmission), or Disabled to disable this feature.

NeedHelp44
Posts: 20
Registered: ‎05-19-2010

Re: Filter Multicast

[ Edited ]

Yeah I believe you. But I just wanted to make sure I'm not reading it improperly. It is indeed grammatically incorrect right? Because if you look at the the text for:

 

Filter Internet NAT Redirection:

Select Enabled to filter Internet NAT redirection, or Disabled to disable this feature.

 

Filter IDENT (Port 113)

Select Enabled to filter port 113, or Disabled to disable this feature.

 

Filter Multicast

Select Enabled to filter multicasting, or Disabled to disable this feature.

 

It has identical text. Why do they all use the exact same grammatical structure, but multicast does the opposite of what it says? Disabling Filter NAT and Filter IDENT "Allows" traffic on those ports. However disabling multicast, "Prevents" multicast traffic. Which is opposite of the others, although they are all written identically.

 

Right? I'm not trying to be difficult or annoying, but this kind of stuff is important to be written correctly, because if it were more easily understood than these forums would have probably 25% less questions or more.

NeedHelp44
Posts: 20
Registered: ‎05-19-2010

Re: Filter Multicast

[ Edited ]

Also, is there a way to test if it is indeed working. I have tried several sites but they all say that Multicast is currently blocked, although I've tried the test with both enabled and disabled filter multicast option.

 

Here's a link, with a reply from a network administrator who says that to "Allow" multicast traffic, you must "Uncheck" the box: http://homecommunity.cisco.com/t5/Wireless-Routers/Enable-Multicast-over-Wireless-WRT150N/m-p/281298...

 

What is the correct method? How do we test?

NeedHelp44
Posts: 20
Registered: ‎05-19-2010

Re: Filter Multicast

Bump?

NeedHelp44
Posts: 20
Registered: ‎05-19-2010

Re: Filter Multicast

[ Edited ]

So i re-read some of these articles. And this is the most professional article, the most trustworthy in my opinion as it was taken straight from a textbook written by a Cisco author. However what ails me is that it is from 2006 and for a different linksys router.

 

Filter Multicast (Disabled)— This setting allows multicast traffic to be forwarded to the appropriate destination. Multicast traffic is traffic destined to multiple hosts. This allows the traffic to be sent one time, while allowing multiple registered hosts to receive it, which it more efficient than sending the traffic individually to each host (which is a process known as unicast). A host registers to receive this multicast traffic by virtue of the fact that it is running an application that is configured to listen on the corresponding multicast IP address. Multicast is frequently used for the transmission of multimedia and streaming data. Multicast traffic is frequently filtered when it is either unnecessary (for example, because no applications that utilize multicast are running on the network) or to prevent multicast-based attacks from being initiated (for example, to prevent an attack that uses multicast traffic to saturate a network with bogus traffic, thus effecting a DoS on the network). Although somewhat counterintuitive, you want to disable filtering if you want to permit multicast traffic.

 

If you read the last few lines carefully,  

1) Multicast traffic is frequently filtered when it is either unnecessary (Filter = block)

2) you want to disable filtering if you want to permit multicast traffic (Disable = Uncheck)

 

So this confirms that the manual is actually correct. If you want to "Enable" I.E. "Allow" Multicast Traffic. You must "Disable" the "Filter"

 

Basically uncheck the filter to allow

Check the filter to block (just like everything else on that page)

 

http://www.ciscopress.com/articles/article.asp?p=598649&seqNum=5

 

So if this does in fact not work, and the opposite is true. Than it is simply a bug/glitch in the firmware and it should be reported to Cisco/Linksys. However, how do we do this? Everytime I contact them, they just want to know my S/N of my router before they talk to me, and since its too old they say sorry cant help you.

 

*Edit* Here's another confirmation link from cisco on Multicast Technology:

 

http://www.cisco.com/en/US/docs/internetworking/technology/handbook/IP-Multi.html

Routers are typically configured with filters to prevent multicast traffic in this address range from flowing outside an autonomous system (AS) or any user-defined domain (Again, in this statement Filter = Block)

 

"Filter Multicast" Enabled (Checked) = Enable the Filtering (Blocking) of Multicast Traffic

"Filter Multicast" Disabled (Unchecked) = Disable the Filtering (Blocking) of Multicast Traffic

 

Which makes sense. For every other filter on that page, if you "Uncheck" them, such as "Filter Anonymous Internnet Requests" then it "Allows" your network to be pinged. But if you "Check" that box, it prevents your network from being pinged.

 

Does anyone agree/disagree?

 

stevefoobar
Posts: 1
Registered: ‎01-27-2013

Re: Filter Multicast

I felt your pain while reading this old post since you were extremely clear in your posts and were correct all along in your interpretation but some people just don't read through things before they respond. Did you ever discover if there is a way to actually test if multicast packets are getting to various computers on your network? Thanks.