Red Hat Bugzilla – Bug 158173
MLDv2 uses wrong ICMP type: IPv6 multicast receiving broken
Last modified: 2007-11-30 17:07:07 EST
Description of problem:
MLDv2 code uses wrong ICMP type, and in consequence, multicast receiving does
not work because the routers ignore the wrong type. This has since then been
fixed in the later kernel releases, but apparently not in RHEL.
Version-Release number of selected component (if applicable):
1) run 'tcpdump -n -vvv -s0 icmp6'
2) start a v6 multicast application, for example 'ttcp -r ff1e::1'
3) observe that the ff1e::1 group shows in 'netstat -g -n' but the generated
MLDv2 report uses a bogus ICMP type #206, instead of #143
Steps to Reproduce:
Created attachment 114561 [details]
Trivial patch to fix the problem.
Minor correction: the MLD report doesn't show with 'tcpdump icmp6' because
there's a hop-by-hop option; you must use 'tcpdump -XXXX ip6' instead.
Additional observation after running with locally patched kernel for a while:
the MLDv2 implementation is severely broken, it doesn't seem to refresh the MLD
memberships, so the router forgets about the MLD reports for applications which
run for more than 5 minutes.
Thus, it might be beneficial to update the whole MLDv2 code from a newer 2.4
kernel, which is hopefully works a lot better, but just fixing the ICMP type
helps a bit as well.
Any progress on this....?
This bug is filed against RHEL 3, which is in maintenance phase.
During the maintenance phase, only security errata and select mission
critical bug fixes will be released for enterprise products. Since
this bug does not meet that criteria, it is now being closed.
For more information of the RHEL errata support policy, please visit:
If you feel this bug is indeed mission critical, please contact your
support representative. You may be asked to provide detailed
information on how this bug is affecting you.