The problem is definitely solved disabling ipv6 at boot time by passing this
command to the kernel at boot time (arg passed into the bootloader):
"disable.ipv6=1"
And by disabling it via sysctl :
Into /etc/sysctl.conf :
net.ipv6.conf.all.disable_ipv6=1
And there the problem is definitely solved.
Some kernel are set with build-in IPv6 driver and so, trying to disable it into
modprobe.d/blacklist is inefficient because there is no IPv6 modules.
And for whom who do not want to reboot it's a pitty because the sysctl command
is not enough.
For some guy's it'll be only a workaround because disabling IPv6 is not always
what we want.
Finally, I'll be interested in how to sharply disable the multicast ICMPv6
announcement.
-----Message d'origine-----
De : Thomas Halinka [mailto:lists@xxxxxxxxx]
Envoyé : jeudi 15 avril 2010 12:46
À : Guillaume S
Objet : Re: [Xen-users] Packets droped by Dom0
Am Donnerstag, den 15.04.2010, 12:22 +0200 schrieb Guillaume S:
> Dear,
>
>
>
> I got a real strange problem with my Xen installation.
>
> When I setup a DomU with an interface with a public IP, packets are
> droped by dom0 …
>
>
>
> I got a bridged configuration with VLANs :
>
>
>
> # brctl show
>
> bridge name bridge id STP enabled interfaces
>
> tmpbridge 8000.000000000000 no
>
> xlan.20 8000.feffffffffff no eth1.20
>
> xlan.30 8000.feffffffffff no GEV1lan
>
> NSlan
>
> OmegaBlog1lan
>
> RMlan
>
> SFlan
>
> eth1.30
>
> xwan 8000.0026b9835a88 no peth0
>
> testWan
>
>
>
>
>
> # ip add sh dev xwan
>
> 6: xwan: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue
> state UNKNOWN
>
> link/ether 00:26:b9:83:5a:88 brd ff:ff:ff:ff:ff:ff
>
> inet 78.24.xx.yy/26 brd 78.24.xx.yy scope global xwan
>
> inet6 fe80::226:b9ff:fe83:5a88/64 scope link
>
> valid_lft forever preferred_lft forever
>
>
>
> -When I try to ping my domU I get huge amount of packet loss:
>
> # ping 78.24.xx.zz
>
> PING 78.24.xx.zz (78.24.xx.zz) 56(84) bytes of data.
>
> 64 bytes from 78.24.xx.zz: icmp_seq=1 ttl=128 time=5.69 ms
>
> ^C
>
> --- 78.24.xx.zz ping statistics ---
>
> 5 packets transmitted, 1 received, 80% packet loss, time 4026ms
>
> rtt min/avg/max/mdev = 5.690/5.690/5.690/0.000 ms
>
>
>
>
>
> Monitoring the xwan bridge :
>
> # tcpdump -n -e -ttt -i xwan icmp
>
> tcpdump: verbose output suppressed, use -v or -vv for full protocol
> decode
>
> listening on xwan, link-type EN10MB (Ethernet), capture size 96 bytes
>
> …
>
>
>
> 00:00:01.006698 00:26:b9:83:5a:88 > 00:16:3e:52:89:d2, ethertype IPv4
> (0x0800), length 98: 78.24.130.200 > 78.24.130.204: ICMP echo request,
> id 60001, seq 304, length 64
>
> 00:00:01.000464 00:26:b9:83:5a:88 > 00:16:3e:52:89:d2, ethertype IPv4
> (0x0800), length 98: 78.24.130.200 > 78.24.130.204: ICMP echo request,
> id 60001, seq 305, length 64
>
> 00:00:01.008578 00:26:b9:83:5a:88 > 00:16:3e:52:89:d2, ethertype IPv4
> (0x0800), length 98: 78.24.130.200 > 78.24.130.204: ICMP echo request,
> id 60001, seq 306, length 64
>
> 00:00:01.008262 00:26:b9:83:5a:88 > 00:16:3e:52:89:d2, ethertype IPv4
> (0x0800), length 98: 78.24.130.200 > 78.24.130.204: ICMP echo request,
> id 60001, seq 307, length 64
>
> 00:00:01.009170 00:26:b9:83:5a:88 > 00:16:3e:52:89:d2, ethertype IPv4
> (0x0800), length 98: 78.24.130.200 > 78.24.130.204: ICMP echo request,
> id 60001, seq 308, length 64
>
> 00:00:00.000642 00:16:3e:52:89:d2 > 00:26:b9:83:5a:88, ethertype IPv4
> (0x0800), length 98: 78.24.130.204 > 78.24.130.200: ICMP echo reply,
> id 60001, seq 308, length 64ß Sometime an echo reply …
>
> 00:00:00.999149 00:26:b9:83:5a:88 > 00:16:3e:52:89:d2, ethertype IPv4
> (0x0800), length 98: 78.24.130.200 > 78.24.130.204: ICMP echo request,
> id 60001, seq 309, length 64
>
> 00:00:01.000767 00:26:b9:83:5a:88 > 00:16:3e:52:89:d2, ethertype IPv4
> (0x0800), length 98: 78.24.130.200 > 78.24.130.204: ICMP echo request,
> id 60001, seq 310, length 64
>
> 00:00:01.000895 00:26:b9:83:5a:88 > 00:16:3e:52:89:d2, ethertype IPv4
> (0x0800), length 98: 78.24.130.200 > 78.24.130.204: ICMP echo request,
> id 60001, seq 311, length 64
>
> 00:00:00.999157 00:26:b9:83:5a:88 > 00:16:3e:52:89:d2, ethertype IPv4
> (0x0800), length 98: 78.24.130.200 > 78.24.130.204: ICMP echo request,
> id 60001, seq 312, length 64
>
>
>
>
>
> - Iptables settings looks fine :
>
>
>
> # iptables -L
>
......
>
>
>
> I did notice something weird : Lots of multicast ICMPv6 packets sent :
>
>
>
> # tcpdump -n -e -ttt -i BurdaWan
>
> tcpdump: WARNING: BurdaWan: no IPv4 address assigned
>
> tcpdump: verbose output suppressed, use -v or -vv for full protocol
> decode
>
> listening on BurdaWan, link-type EN10MB (Ethernet), capture size 96
> bytes
>
.......
> …
>
>
>
>
>
> If someone could help me on this it would be MUCH appreciated !
Is IPv6 enabled?
# lsmod | grep v6
ipv6 289352 38
Blacklist the Module
# echo "blacklist ipv6" >> /etc/modprobe.d/blacklist
and unload or reboot...
>
>
>
> Thanks by advance,
>
>
>
> Guillaume S.
>
cu,
thomas
>
>
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