Can't make multicast work

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jitterFreak
Posts: 3
Joined: 2010/12/10 17:10:36

Can't make multicast work

Post by jitterFreak » 2010/12/13 22:54:34

I have an application in which several hosts on a LAN communicate with one another by UDP broadcasts. I would like to change it to use multicasting, because of administrative policies at some sites that discourage or forbid the use of IP broadcasting on the LAN. I have found a number of different example programs on the web, but I can't get any of them to work on my development net.

Here's one example:

http://webcache.googleusercontent.com/search?q=cache:QWvKjRpsxFcJ:www.hyfr.org/lj/LJ/0065/3041l1.html+multicast+%22column+width,+it+wraps%22&cd=1&hl=en&ct=clnk&gl=us

This program is interesting because forks off a child process, and then attempts to send mulitcast packets from the parent to the child process. When I run it, I can ping the multicast address, and the host will respond; and when I stop the program, the host stops responding to pings, but the child process never seems to receive any of the packets sent by the parent.

I've been trying IPv4 multicast addresses in the range 239.255.xxx.xxx, and port numbers > 1024. I've tried running as root, and I've tried running as an ordinary user. I have tried compiling other demo programs that I've found on the web, all with more or less the same result. I've also tried running the sender and the receiver on different hosts (more like my intended application anyway) and still, the same result.

Here is what getinfo says about my development box:

Information for network problems.
[code]
== BEGIN uname -rmi ==
2.6.9-89.0.20.EL i686 i386
== END uname -rmi ==

== BEGIN rpm -q centos-release ==
centos-release-4-8
== END rpm -q centos-release ==

== BEGIN cat /etc/redhat-release ==
CentOS release 4.8 (Final)
== END cat /etc/redhat-release ==

== BEGIN getenforce ==
Disabled
== END getenforce ==

== BEGIN lspci ==
00:00.0 Host bridge: Intel Corporation 5000V Chipset Memory Controller Hub (rev 92)
00:02.0 PCI bridge: Intel Corporation 5000 Series Chipset PCI Express x8 Port 2-3 (rev 92)
00:08.0 System peripheral: Intel Corporation 5000 Series Chipset DMA Engine (rev 92)
00:10.0 Host bridge: Intel Corporation 5000 Series Chipset FSB Registers (rev 92)
00:10.1 Host bridge: Intel Corporation 5000 Series Chipset FSB Registers (rev 92)
00:10.2 Host bridge: Intel Corporation 5000 Series Chipset FSB Registers (rev 92)
00:11.0 Host bridge: Intel Corporation 5000 Series Chipset Reserved Registers (rev 92)
00:13.0 Host bridge: Intel Corporation 5000 Series Chipset Reserved Registers (rev 92)
00:15.0 Host bridge: Intel Corporation 5000 Series Chipset FBD Registers (rev 92)
00:16.0 Host bridge: Intel Corporation 5000 Series Chipset FBD Registers (rev 92)
00:1c.0 PCI bridge: Intel Corporation 631xESB/632xESB/3100 Chipset PCI Express Root Port 1 (rev 09)
00:1d.0 USB Controller: Intel Corporation 631xESB/632xESB/3100 Chipset UHCI USB Controller #1 (rev 09)
00:1d.1 USB Controller: Intel Corporation 631xESB/632xESB/3100 Chipset UHCI USB Controller #2 (rev 09)
00:1d.2 USB Controller: Intel Corporation 631xESB/632xESB/3100 Chipset UHCI USB Controller #3 (rev 09)
00:1d.3 USB Controller: Intel Corporation 631xESB/632xESB/3100 Chipset UHCI USB Controller #4 (rev 09)
00:1d.7 USB Controller: Intel Corporation 631xESB/632xESB/3100 Chipset EHCI USB2 Controller (rev 09)
00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev d9)
00:1f.0 ISA bridge: Intel Corporation 631xESB/632xESB/3100 Chipset LPC Interface Controller (rev 09)
00:1f.1 IDE interface: Intel Corporation 631xESB/632xESB IDE Controller (rev 09)
00:1f.2 RAID bus controller: Intel Corporation 631xESB/632xESB SATA RAID Controller (rev 09)
00:1f.3 SMBus: Intel Corporation 631xESB/632xESB/3100 Chipset SMBus Controller (rev 09)
01:00.0 PCI bridge: Intel Corporation 6311ESB/6321ESB PCI Express Upstream Port (rev 01)
01:00.3 PCI bridge: Intel Corporation 6311ESB/6321ESB PCI Express to PCI-X Bridge (rev 01)
02:00.0 PCI bridge: Intel Corporation 6311ESB/6321ESB PCI Express Downstream Port E1 (rev 01)
02:02.0 PCI bridge: Intel Corporation 6311ESB/6321ESB PCI Express Downstream Port E3 (rev 01)
04:00.0 Ethernet controller: Intel Corporation 80003ES2LAN Gigabit Ethernet Controller (Copper) (rev 01)
04:00.1 Ethernet controller: Intel Corporation 80003ES2LAN Gigabit Ethernet Controller (Copper) (rev 01)
07:01.0 VGA compatible controller: ATI Technologies Inc ES1000 (rev 02)
== END lspci ==

== BEGIN lspci -n ==
00:00.0 Class 0600: 8086:25d4 (rev 92)
00:02.0 Class 0604: 8086:25f7 (rev 92)
00:08.0 Class 0880: 8086:1a38 (rev 92)
00:10.0 Class 0600: 8086:25f0 (rev 92)
00:10.1 Class 0600: 8086:25f0 (rev 92)
00:10.2 Class 0600: 8086:25f0 (rev 92)
00:11.0 Class 0600: 8086:25f1 (rev 92)
00:13.0 Class 0600: 8086:25f3 (rev 92)
00:15.0 Class 0600: 8086:25f5 (rev 92)
00:16.0 Class 0600: 8086:25f6 (rev 92)
00:1c.0 Class 0604: 8086:2690 (rev 09)
00:1d.0 Class 0c03: 8086:2688 (rev 09)
00:1d.1 Class 0c03: 8086:2689 (rev 09)
00:1d.2 Class 0c03: 8086:268a (rev 09)
00:1d.3 Class 0c03: 8086:268b (rev 09)
00:1d.7 Class 0c03: 8086:268c (rev 09)
00:1e.0 Class 0604: 8086:244e (rev d9)
00:1f.0 Class 0601: 8086:2670 (rev 09)
00:1f.1 Class 0101: 8086:269e (rev 09)
00:1f.2 Class 0104: 8086:2682 (rev 09)
00:1f.3 Class 0c05: 8086:269b (rev 09)
01:00.0 Class 0604: 8086:3500 (rev 01)
01:00.3 Class 0604: 8086:350c (rev 01)
02:00.0 Class 0604: 8086:3510 (rev 01)
02:02.0 Class 0604: 8086:3518 (rev 01)
04:00.0 Class 0200: 8086:1096 (rev 01)
04:00.1 Class 0200: 8086:1096 (rev 01)
07:01.0 Class 0300: 1002:515e (rev 02)
== END lspci -n ==

== BEGIN ifconfig -a ==
eth0 Link encap:Ethernet HWaddr 00:30:48:89:0A:B0
inet addr:xxx.xxx.xxx.151 Bcast:xxx.xxx.xxx.255 Mask:255.255.255.0
inet6 addr: xxxx::xxx:xxxx:xxxx:ab0/64 Scope:Link
UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1
RX packets:330643016 errors:0 dropped:0 overruns:0 frame:0
TX packets:293351176 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:494386313 (471.4 MiB) TX bytes:172830852 (164.8 MiB)

eth1 Link encap:Ethernet HWaddr 00:30:48:89:0A:B1
BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:4239625 errors:0 dropped:0 overruns:0 frame:0
TX packets:4239625 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:454269699 (433.2 MiB) TX bytes:454269699 (433.2 MiB)

sit0 Link encap:IPv6-in-IPv4
NOARP MTU:1480 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)

== END ifconfig -a ==

== BEGIN route -n ==
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
xxx.xxx.xxx.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0
224.0.0.0 0.0.0.0 240.0.0.0 U 0 0 0 eth0
0.0.0.0 xxx.xxx.xxx.1 0.0.0.0 UG 0 0 0 eth0
== END route -n ==

== BEGIN cat /etc/resolv.conf ==
search xxxxxxxxxx.com
nameserver xxx.xxx.xxx.2
nameserver 66.207.132.2
== END cat /etc/resolv.conf ==

== BEGIN grep net /etc/nsswitch.conf ==
#networks: ldap [NOTFOUND=return] files
netmasks: files
networks: files
netgroup: files
== END grep net /etc/nsswitch.conf ==

== BEGIN chkconfig --list | grep -Ei 'network|wpa' ==
NetworkManager 0:off 1:off 2:off 3:off 4:off 5:off 6:off
network 0:off 1:off 2:on 3:on 4:on 5:on 6:off
== END chkconfig --list | grep -Ei 'network|wpa' ==

[/code]

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AlanBartlett
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Can't make multicast work

Post by AlanBartlett » 2010/12/14 01:24:32

Welcome to the [i]CentOS[/i] fora.

You have clearly done your reading of the [url=https://www.centos.org/modules/newbb/viewforum.php?forum=47]FAQ & Readme First[/url]. :-)

Unfortunately the URL you have quoted is seriously garbled and, hence, the link can not be viewed.

As your choice of forum was incorrect, this thread has now been moved to the appropriate [i]CentOS 4[/i] forum.

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AlanBartlett
Forum Moderator
Posts: 9319
Joined: 2007/10/22 11:30:09
Location: ~/Earth/UK/England/Suffolk
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Re: Can't make multicast work

Post by AlanBartlett » 2010/12/14 22:40:16

This duplicate thread is now locked.

Any assistance to the [url=https://www.centos.org/modules/newbb/viewtopic.php?topic_id=29306&forum=30]other thread[/url], please.

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