[opensuse] Linux and multicast

older
Re: [opensuse] Linux and multicast

James Knott

3 Oct 2014 3 Oct '14

15:13

As an experiment, I tried pinging 224.0.0.1, which is the all hosts multicast address, which all hosts are supposed to respond to. When I do that, I only get a response from my Yamaha A/V receiver. Other devices, including computers running Linux and Windows 7 do not respond. I get the same results if I ping the local network broadcast address, only the A/V receiver responds. Given that all devices are supposed to respond, does anyone know why Linux or other devices don't? -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org

Show replies by date

James Knott

3 Oct 3 Oct

15:23

On 10/03/2014 11:13 AM, James Knott wrote:

...

As an experiment, I tried pinging 224.0.0.1, which is the all hosts multicast address, which all hosts are supposed to respond to. When I do that, I only get a response from my Yamaha A/V receiver. Other devices, including computers running Linux and Windows 7 do not respond. I get the same results if I ping the local network broadcast address, only the A/V receiver responds. Given that all devices are supposed to respond, does anyone know why Linux or other devices don't?

The same thing also happens with ping -b 255.255.255.255. BTW, the A/V receiver runs Linux. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org

Andrei Borzenkov

15:23

В Fri, 03 Oct 2014 11:13:36 -0400 James Knott пишет:

...

As an experiment, I tried pinging 224.0.0.1, which is the all hosts multicast address, which all hosts are supposed to respond to.

Assuming they have multicast active at all. My host e.g. does not: 1: lo: mtu 65536 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever 2: eth0: mtu 1500 qdisc mq state DOWN qlen 1000 link/ether 00:1d:09:59:85:e1 brd ff:ff:ff:ff:ff:ff 3: wlan0: mtu 1500 qdisc mq state UP qlen 1000 link/ether 00:1f:3c:9c:47:ba brd ff:ff:ff:ff:ff:ff inet 192.168.1.42/24 brd 192.168.1.255 scope global wlan0 valid_lft forever preferred_lft forever

...

When I do that, I only get a response from my Yamaha A/V receiver. Other devices, including computers running Linux and Windows 7 do not respond. I get the same results if I ping the local network broadcast address, only the A/V receiver responds. Given that all devices are supposed to respond, does anyone know why Linux or other devices don't?

-- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org

James Knott

15:55

On 10/03/2014 11:23 AM, Andrei Borzenkov wrote:

...

Assuming they have multicast active at all. My host e.g. does not:

1: lo: mtu 65536 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever 2: eth0: mtu 1500 qdisc mq state DOWN qlen 1000 link/ether 00:1d:09:59:85:e1 brd ff:ff:ff:ff:ff:ff 3: wlan0: mtu 1500 qdisc mq state UP qlen 1000 link/ether 00:1f:3c:9c:47:ba brd ff:ff:ff:ff:ff:ff inet 192.168.1.42/24 brd 192.168.1.255 scope global wlan0 valid_lft forever preferred_lft forever

Then what does "MULTICAST" mean? -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org

Per Jessen

16:19

James Knott wrote:

...

On 10/03/2014 11:23 AM, Andrei Borzenkov wrote:

...
Assuming they have multicast active at all. My host e.g. does not:

1: lo: mtu 65536 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever 2: eth0: mtu 1500 qdisc mq state DOWN qlen 1000 link/ether 00:1d:09:59:85:e1 brd ff:ff:ff:ff:ff:ff 3: wlan0: mtu 1500 qdisc mq state UP qlen 1000 link/ether 00:1f:3c:9c:47:ba brd ff:ff:ff:ff:ff:ff inet 192.168.1.42/24 brd 192.168.1.255 scope global wlan0 valid_lft forever preferred_lft forever

Then what does "MULTICAST" mean?

That "subscribed" hosts will receive messages sent to that one address. (or some other group address) -- Per Jessen, Zürich (16.1°C) http://www.dns24.ch/ - your free DNS host, made in Switzerland. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org

James Knott

16:38

On 10/03/2014 12:19 PM, Per Jessen wrote:

...

...
Then what does "MULTICAST" mean? That "subscribed" hosts will receive messages sent to that one address. (or some other group address)

Yep, and that includes the all hosts multicast address. Multicast addresses can be used for a variety of things. In addition to that all hosts, there's also 244.0.0.2 for all routers .5 & .6 for OSPF routers and many more. My firewall/router is a Linux box. After allowing it to respond to broadcasts, it now responds to the all hosts address, but not the all routers. So, it appears things are not done fully according to spec. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org

Jan Ritzerfeld

19:21

Am Freitag, 3. Oktober 2014, 12:38:19 schrieb James Knott:

...

[...] So, it appears things are not done fully according to spec.

Which "spec" are you exactly talking about? As far as I know, and as Per has already pointed, all hosts must receive packets sent to 224.0.0.1, all routers to 224.0.0.2, and so on. Nevertheless, they are free to respond or not to. Gruß Jan -- I am drinking to drown my problems, but these goddamn bastards can swim! -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org

James Knott

18:13

On 10/03/2014 11:13 AM, James Knott wrote:

...

As an experiment, I tried pinging 224.0.0.1, which is the all hosts multicast address, which all hosts are supposed to respond to. When I do that, I only get a response from my Yamaha A/V receiver.

I just noticed that my Cisco DVR responds to the IPv6 all hosts ping, but not IPv4 and the Yamaha A/V receiver responds on IPv4, but not IPv6. BTW, the all hosts address is used on IPv6, in place of broadcasts, which are not allowed. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org

3497

Age (days ago)

3497

Last active (days ago)

List overview

Download

7 comments

4 participants

participants (4)

Andrei Borzenkov
James Knott
Jan Ritzerfeld
Per Jessen