[Openstack] [Quantum] Metadata service route from a VM

Sylvain Bauza sylvain.bauza at digimind.com
Tue Feb 26 08:20:01 UTC 2013


Hi Dan,

Thanks for your clear answer. I do confirm, the 169.254.0.0/16 route was 
working with my nova-network setup (FlatDHCP).

When mentioning Grizzly pushing a route to VMs, I guess it would be 
possible to backport it to Folsom.
Do you have any idea on which changes to do for that feature ?
I'll take a look at dnsmasq and see if I can hardcode this.

-Sylvain

Le 26/02/2013 06:37, Dan Wendlandt a écrit :
> Hi Sylvain,
>
> The answer here is that "it depends".
>
> If you are using Folsom + Quantum, the only supported mechanism is 
> reaching the metadata server is via your default gateway, so VMs 
> should not have specific routes to reach the metadata subnet (I 
> believe this is also the case for nova-network, so I'm a bit surprised 
> by your original comments in this thread about using the direct route 
> with nova-network).
>
> In Grizzly, Quantum will support two different mechanisms of reaching 
> metadata.  One via the router (as before) and another via the DHCP 
> server IP (with a route for 169.254.169.254/32 
> <http://169.254.169.254/32> injected into the VM via DHCP).  The 
> latter supports metadata on networks that do not have a router 
> provided by Quantum.
>
> Dan
>
> On Mon, Feb 25, 2013 at 8:36 AM, Sylvain Bauza 
> <sylvain.bauza at digimind.com <mailto:sylvain.bauza at digimind.com>> wrote:
>
>     Yet no reply ?
>
>     I did the hack, I removed the 169.254.0.0/16
>     <http://169.254.0.0/16> route from my images, but this is quite a
>     ugly hack.
>     Could someone with OpenVswitch/GRE setup please confirm that there
>     is no route to create for metadata ?
>
>     Thanks,
>     -Sylvain
>
>     Le 21/02/2013 11:33, Sylvain Bauza a écrit :
>
>         Anyone ?
>         I found the reason why a 'quantum-dhcp-agent restart' is
>         fixing the route, this is because the lease is DHCPNACK'd at
>         next client refresh and the VM is getting a fresh new
>         configuration excluding 169.254.0.0/16 <http://169.254.0.0/16>
>         route.
>
>         Community, I beg you to confirm the 169.254.0.0/16
>         <http://169.254.0.0/16> route should *not* be pushed to VMs,
>         and 169.254.169.254/32 <http://169.254.169.254/32> should be
>         sent thru the default route (ie. provider router internal IP).
>         If it's the case, I'll update all my images to remove that
>         route. If not, something is wrong with my Quantum setup that I
>         should fix.
>
>         Thanks,
>         -Sylvain
>
>         Le 20/02/2013 15:55, Sylvain Bauza a écrit :
>
>             Hi,
>
>             Previously using nova-network, all my VMs were having :
>              # route -n
>             Table de routage IP du noyau
>             Destination     Passerelle      Genmask Indic Metric Ref
>             Use Iface
>             10.0.0.0        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   1002 0
>                    0 eth0
>             0.0.0.0         10.0.0.1        0.0.0.0         UG  0 0 0 eth0
>
>             Now, this setup seems incorrect with Quantum, as the ARP
>             query goes directly from the network node trying to
>             resolve 169.254.169.254 :
>             [root at toto ~]# curl http://169.254.169.254/
>             curl: (7) couldn't connect to host
>
>             sylvain at folsom02:~$ sudo tcpdump -i qr-f76e4668-fa -nn not
>             ip6 and not udp and host 169.254.169.254 -e
>             tcpdump: verbose output suppressed, use -v or -vv for full
>             protocol decode
>             listening on qr-f76e4668-fa, link-type EN10MB (Ethernet),
>             capture size 65535 bytes
>             15:47:46.009548 fa:16:3e:bf:0b:f6 > ff:ff:ff:ff:ff:ff,
>             ethertype ARP (0x0806), length 42: Request who-has
>             169.254.169.254 tell 10.0.0.5, length 28
>             15:47:47.009076 fa:16:3e:bf:0b:f6 > ff:ff:ff:ff:ff:ff,
>             ethertype ARP (0x0806), length 42: Request who-has
>             169.254.169.254 tell 10.0.0.5, length 28
>
>             The only way for me to fix it is to remove the
>             169.254.0.0/16 <http://169.254.0.0/16> route on the VM (or
>             for some reason I doesn't understand, by restarting
>             quantum-dhcp-agent on the network node) and then L3
>             routing is working correctly :
>
>             [root at toto ~]# route del -net 169.254.0.0/16
>             <http://169.254.0.0/16>
>             [root at toto ~]# curl http://169.254.169.254/
>             1.0
>             2007-01-19
>             2007-03-01
>             2007-08-29
>             2007-10-10
>             2007-12-15
>             2008-02-01
>             2008-09-01
>             2009-04-04
>
>             sylvain at folsom02:~$ sudo tcpdump -i qg-f2397006-20 -nn not
>             ip6 and not udp and host 10.0.0.5 and not port 22 -e
>             tcpdump: verbose output suppressed, use -v or -vv for full
>             protocol decode
>             listening on qg-f2397006-20, link-type EN10MB (Ethernet),
>             capture size 65535 bytes
>             15:52:58.479234 fa:16:3e:e1:95:20 > e0:46:9a:2c:f4:7d,
>             ethertype IPv4 (0x0800), length 74: 10.0.0.5.55428 >
>             192.168.1.71.8775: Flags [S], seq 3032859044, win 14600,
>             options [mss 1460,sackOK,TS val 2548891 ecr 0,nop,wscale
>             5], length 0
>             15:52:58.480987 e0:46:9a:2c:f4:7d > fa:16:3e:e1:95:20,
>             ethertype IPv4 (0x0800), length 74: 192.168.1.71.8775 >
>             10.0.0.5.55428: Flags [S.], seq 3888257357, ack
>             3032859045, win 14480, options [mss 1460,sackOK,TS val
>             16404712 ecr 2548891,nop,wscale 7], length 0
>             15:52:58.482211 fa:16:3e:e1:95:20 > e0:46:9a:2c:f4:7d,
>             ethertype IPv4 (0x0800), length 66: 10.0.0.5.55428 >
>             192.168.1.71.8775: Flags [.], ack 1, win 457, options
>             [nop,nop,TS val 2548895 ecr 16404712], length 0
>
>
>             I can't understand what's wrong with my setup. Could you
>             help me ? I would have to undergo a post-up statement for
>             all my images... :(
>
>             Thanks,
>             -Sylvain
>
>
>
>
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> -- 
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Dan Wendlandt
> Nicira, Inc: www.nicira.com <http://www.nicira.com>
> twitter: danwendlandt
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~

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