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Old 08-11-2012, 12:50 AM
Stephen Harris
 
Default IPv6 on Centos 6

On Fri, Aug 10, 2012 at 05:24:12PM -0700, Alan Batie wrote:
> IPV6_DEFROUTE=yes

Not sure where you get that from. Instead try adding
IPV6_DEFAULTDEV=eth0
to /etc/sysconfig/network

FWIW you can see the current routing table with "ip -6 route".

--

rgds
Stephen
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Old 08-11-2012, 12:59 AM
Alan Batie
 
Default IPv6 on Centos 6

On 8/10/12 5:50 PM, Stephen Harris wrote:
> On Fri, Aug 10, 2012 at 05:24:12PM -0700, Alan Batie wrote:
>> IPV6_DEFROUTE=yes
>
> Not sure where you get that from.

That's not something normally in our configs, I think it was in the
default config the centos 6 installer created, and I only stripped out
some of the excess... stuff like that I left in in case it mattered in 6
for some reason... The config on the working centos 5 systems (which is
what we use on the centos 6 systems also) is much simpler:

<ns6.peak.org> [113] # cat /etc/sysconfig/network
NETWORKING=yes
NETWORKING_IPV6=yes
HOSTNAME=ns6.peak.org
GATEWAY=207.55.16.1
<ns6.peak.org> [114] # cat /etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE=eth0
BOOTPROTO=static
BROADCAST=207.55.19.255
IPADDR=207.55.16.53
NETMASK=255.255.252.0
ONBOOT=yes
TYPE=Ethernet

IPV6INIT=yes
IPV6ADDR=2607:f678::56
IPV6_DEFAULTGW=2607:f678::1


> FWIW you can see the current routing table with "ip -6 route".

netstat is the one I usually use:

<centos666.peak.org> [39] # ip -6 router
Object "router" is unknown, try "ip help".
<centos666.peak.org> [40] # netstat -rn -A inet6
Kernel IPv6 routing table
Destination Next Hop
Flags Metric Ref Use Iface
2607:f678::/64 ::
U 256 1 0 eth0
fe80::/64 ::
U 256 0 0 eth0
::/0 2607:f678::1
UG 1 5 0 eth0
::1/128 ::
U 0 1 1 lo
2607:f678::16:66/128 ::
U 0 58 1 lo
fe80::250:56ff:fe98:708b/128 ::
U 0 0 1 lo
ff00::/8 ::
U 256 0 0 eth0

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Old 08-11-2012, 09:17 AM
James Hogarth
 
Default IPv6 on Centos 6

On Aug 11, 2012 2:00 AM, "Alan Batie" <alan@peak.org> wrote:
>
> On 8/10/12 5:50 PM, Stephen Harris wrote:
> > On Fri, Aug 10, 2012 at 05:24:12PM -0700, Alan Batie wrote:
> >> IPV6_DEFROUTE=yes
> >
> > Not sure where you get that from.
>
> That's not something normally in our configs, I think it was in the
> default config the centos 6 installer created, and I only stripped out
> some of the excess... stuff like that I left in in case it mattered in 6
> for some reason... The config on the working centos 5 systems (which is
> what we use on the centos 6 systems also) is much simpler:
>
> <ns6.peak.org> [113] # cat /etc/sysconfig/network
> NETWORKING=yes
> NETWORKING_IPV6=yes
> HOSTNAME=ns6.peak.org
> GATEWAY=207.55.16.1
> <ns6.peak.org> [114] # cat /etc/sysconfig/network-scripts/ifcfg-eth0
> DEVICE=eth0
> BOOTPROTO=static
> BROADCAST=207.55.19.255
> IPADDR=207.55.16.53
> NETMASK=255.255.252.0
> ONBOOT=yes
> TYPE=Ethernet

>
> netstat is the one I usually use:
>
> <centos666.peak.org> [39] # ip -6 router
> Object "router" is unknown, try "ip help".
> <centos666.peak.org> [40] # netstat -rn -A inet6

With ipv6 in the picture stop using net-tools - they were deprecated a long
time ago and there's multiple edge cases and bugs where they don't work
properly or lack features... learn to use the iproute2 toolset - ip, ss and
tc being the key ones.

And it's ip -6 route not ip -6 router... or ip -6 r s in short ;-)
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Old 08-11-2012, 04:36 PM
Emmanuel Noobadmin
 
Default IPv6 on Centos 6

On 8/11/12, Alan Batie <alan@peak.org> wrote:
> We've been running ipv6 for a year or so now, but some of our newer
> instances (all on an ESX cluster) are not working. It looks like it's
> all of our Centos 6 instances. I'm hoping someone can point me in the
> right direction...

> <centos666.peak.org> [27] # cat ifcfg-eth0
> DEVICE="eth0"
> NM_CONTROLLED="no"
> ONBOOT="yes"
> TYPE=Ethernet
> BOOTPROTO=none
> IPADDR=207.55.16.66
> PREFIX=22
> GATEWAY=207.55.16.1

Not sure if this is related/relevant but I remember reading this bug
about problems if PREFIX is used instead of NETMASK.

http://bugs.centos.org/view.php?id=5391
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Old 08-13-2012, 06:05 PM
Alan Batie
 
Default IPv6 on Centos 6

On 8/11/12 2:17 AM, James Hogarth wrote:

> With ipv6 in the picture stop using net-tools - they were deprecated a long
> time ago and there's multiple edge cases and bugs where they don't work
> properly or lack features... learn to use the iproute2 toolset - ip, ss and
> tc being the key ones.

Love gratuitous changes to long standard toolsets... sigh...

> And it's ip -6 route not ip -6 router... or ip -6 r s in short ;-)

You're right, sorry, it was late on Friday ;-)

<centos666.peak.org> [50] # ip -6 r
unreachable ::/96 dev lo metric 1024 error -101 mtu 16436 advmss 16376
hoplimit 4294967295
unreachable ::ffff:0.0.0.0/96 dev lo metric 1024 error -101 mtu 16436
advmss 16376 hoplimit 4294967295
unreachable 2002:a00::/24 dev lo metric 1024 error -101 mtu 16436
advmss 16376 hoplimit 4294967295
unreachable 2002:7f00::/24 dev lo metric 1024 error -101 mtu 16436
advmss 16376 hoplimit 4294967295
unreachable 2002:a9fe::/32 dev lo metric 1024 error -101 mtu 16436
advmss 16376 hoplimit 4294967295
unreachable 2002:ac10::/28 dev lo metric 1024 error -101 mtu 16436
advmss 16376 hoplimit 4294967295
unreachable 2002:c0a8::/32 dev lo metric 1024 error -101 mtu 16436
advmss 16376 hoplimit 4294967295
unreachable 2002:e000::/19 dev lo metric 1024 error -101 mtu 16436
advmss 16376 hoplimit 4294967295
2607:f678::/64 dev eth0 proto kernel metric 256 mtu 1500 advmss 1440
hoplimit 4294967295
unreachable 3ffe:ffff::/32 dev lo metric 1024 error -101 mtu 16436
advmss 16376 hoplimit 4294967295
fe80::/64 dev eth0 proto kernel metric 256 mtu 1500 advmss 1440
hoplimit 4294967295
default via 2607:f678::1 dev eth0 metric 1 mtu 1500 advmss 1440
hoplimit 4294967295

Also love quality error messages "-101" is *sooo* informative ;-)

But the last line should be the important one and shows the proper
default route in place, though the even more important one is the route
to the local net (2607:f678::/64) which also looks right. It's not a
routing issue, it's a neighbor discovery issue:

<centos666.peak.org> [55] # ip neigh show
2607:f678::1 dev eth0 FAILED
207.55.16.1 dev eth0 lladdr 00:26:88:f2:9e:80 REACHABLE

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Old 08-13-2012, 07:00 PM
James Hogarth
 
Default IPv6 on Centos 6

>
> Love gratuitous changes to long standard toolsets... sigh...
>

It's not a recent change and is far from gratuitous....

http://lists.debian.org/debian-devel/2009/03/msg00780.html

Features such as traffic shaping, policy routing and multiple IPs on
an interface (not virtual interfaces) either are impossible with
net-tools or just don't work very well...


> Also love quality error messages "-101" is *sooo* informative ;-)
>
> But the last line should be the important one and shows the proper
> default route in place, though the even more important one is the route
> to the local net (2607:f678::/64) which also looks right. It's not a
> routing issue, it's a neighbor discovery issue:
>
> <centos666.peak.org> [55] # ip neigh show
> 2607:f678::1 dev eth0 FAILED
> 207.55.16.1 dev eth0 lladdr 00:26:88:f2:9e:80 REACHABLE
>

Are you allowing ICMPv6? I don't just mean echo and echo-reply (the
pings above) but most of the rest of it too?

IPv6 relies on ICMPv6 heavily for path MTU discovery, neighbour
discovery and a whole lot more...
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Old 08-13-2012, 07:16 PM
Alan Batie
 
Default IPv6 on Centos 6

On 8/13/12 12:00 PM, James Hogarth wrote:

> Are you allowing ICMPv6? I don't just mean echo and echo-reply (the
> pings above) but most of the rest of it too?

Yes, the test system has the default ip6tables, but we always permit icmp:

# Firewall configuration written by system-config-firewall
# Manual customization of this file is not recommended.
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
-A INPUT -p ipv6-icmp -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT
-A INPUT -j REJECT --reject-with icmp6-adm-prohibited
-A FORWARD -j REJECT --reject-with icmp6-adm-prohibited
COMMIT

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Old 08-13-2012, 07:35 PM
James Hogarth
 
Default IPv6 on Centos 6

>
> Yes, the test system has the default ip6tables, but we always permit icmp:
>

Hmm this is especially weird given the 5.8 systems are working -
otherwise I'd have moved the troubleshooting up to vmware or the
switch next...

Without access to the machines/switches to traffic dump and check in
wireshark you've got me stumped at this point I'm afraid...
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Old 08-13-2012, 07:37 PM
Alan Batie
 
Default IPv6 on Centos 6

I found another CentOS 6 system that not only is talking ipv6 properly,
but the test system that can't even talk to the router can talk to it.
That indicates it's probably something wonky with the network itself...

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Old 08-13-2012, 07:45 PM
James Hogarth
 
Default IPv6 on Centos 6

On 13 August 2012 20:37, Alan Batie <alan@peak.org> wrote:
> I found another CentOS 6 system that not only is talking ipv6 properly,
> but the test system that can't even talk to the router can talk to it.
> That indicates it's probably something wonky with the network itself...
>

Hmm...


I don't have a C6 ipv6 machine but I do have a F17 which might not be
too far off in behaviour...

The general recommendation though is that next hop should always be
via the local link FE80:: addresses (I notice your public address for
gateway there)...

Don't worry about the error -101 - the actual error is the unreachable
bit and just says that those networks can't be reached over the lo
device - which is understandable...

Here's a look at my F17 server for comparison:


ip -6 r s
2001:0:4137:9e76:24f8:3b1a:2598:7928 via fe80::e291:f5ff:fecc:7919 dev
em1 metric 0
cache
2001:0:9d38:953c:2805:3e4f:484e:6234 via fe80::e291:f5ff:fecc:7919 dev
em1 metric 0
cache
2001:0:9d38:953c:344a:332e:37f7:24f7 via fe80::e291:f5ff:fecc:7919 dev
em1 metric 0
cache
2001:470:97df:1::/64 dev em1 proto kernel metric 256 expires 85879sec
unreachable fe80::/64 dev lo proto kernel metric 256 error -101
fe80::/64 dev em1 proto kernel metric 256
default via fe80::e291:f5ff:fecc:7919 dev em1 proto kernel metric
1024 expires 1305sec

I'm using radvd on my network ... but things shouldn't be too far off
for static settings...

Is the other C6 system that *is* working on the same vmware server,
bare metal or on another virtualization server?
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