New: multicast client application does not receive packets

Bugme-new Andrew Morton 1 participant 1 message Nov 23, 2009 1 message not in the archive

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Andrew Morton

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2009-11-23 22:31 UTC #1 lore raw

(switched to email. Please respond via emailed reply-to-all, not via the bugzilla web interface).

Quoted 37 lines · On Mon, 23 Nov 2009 22:00:45 GMT [email protected] wrote:

http://bugzilla.kernel.org/show_bug.cgi?id=14677
           Summary: multicast client application does not receive packets
           Product: Networking
           Version: 2.5
    Kernel Version: 2.6.31.4-2.6.32-rc8
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: IPV4
        AssignedTo: [email protected]
        ReportedBy: [email protected]
        Regression: Yes
When upgrading the kernel from 2.6.29.1 to 2.6.31.4, we discovered that packets no longer get delivered to an application that is subscribing to the multicast data.
We verified that multicast support was compiled into the kernel (CONFIG_IP_MULTICAST). A dump on the interface with tcpdump shows the multicast packets arriving on the network interface. However, they do not get delivered to the application.
/proc/net/igmp clearly showed that we were subscribed to the relevant multicast groups, and netstat showed that the application was listening.
Upgrading to 2.6.32-rc8 did not fix the problem, but downgrading to 2.6.29.1 did.
This problem was seen on two different supermicro systems: one with a single (4-core) i7 940 Intel CPU, and another one with dual X5570 Xeon CPUS. In both cases the interface was on a quad-port NIC card 82571EB gigabit ethernet controller, rev 06.