Re: [Openstack-operators] Multiple floating IPs mapped to multiple vNICs (multi-homing)

[Curtis]

On Thu, Dec 1, 2016 at 8:23 AM, Paul Browne  wrote:
> On 01/12/16 14:35, Saverio Proto wrote:
>
> Your policy routing looks good.
> The problem must be somewhere else, where you do the nat maybe ?
>
> Go in the network namespace where there is the neutron router with
> address 10.0.16.1
>
> If you tcpdump there what do you see ?
>
> to be 100% sure about the policy routing just go in the network node
> where you do the nat.
>
> ip netns exec qrouter- wget -O /dev/null http://10.0.16.11/
>
> uuid is the uuid of the neutron router where you are natting
>
> I guess this will work.
>
>
> Yes, this does seem to work as expected, in both namespaces;
>
> # Determine the controller hosting the router for 10.0.0.11
> [stack@osp-director-prod ~]$ neutron l3-agent-list-hosting-router
> 5f9d983c-3b51-4411-b921-1a523652d55f
> +--+--++---+--+
> | id   | host |
> admin_state_up | alive | ha_state |
> +--+--++---+--+
> | 37051003-636f-4fb7-b6d9-1ff9d9182e9d | clc-sby4f-n3.mgt.cluster | True
> | :-)   | standby  |
> | b14fcc29-67c0-4420-8abf-433dafde980d | clc-rb15-n1.mgt.cluster  | True
> | :-)   | standby  |
> | 37518a78-4b39-463a-8387-2866989bba06 | clc-ra15-n2.mgt.cluster  | True
> | :-)   | active   |
> +--+--++---+--+
>
> # Change into the namespace and test the 10.0.0.11 web-server
> [root@clc-ra15-n2 ~]# ip netns exec
> qrouter-5f9d983c-3b51-4411-b921-1a523652d55f wget -O /tmp/test
> http://10.0.0.11/; head -n 10 /tmp/test
> --2016-12-01 14:54:09--  http://10.0.0.11/
> Connecting to 10.0.0.11:80... connected.
> HTTP request sent, awaiting response... 200 OK
> Length: 10701 (10K) [text/html]
> Saving to: ‘/tmp/test’
> 2016-12-01 14:54:09 (318 MB/s) - ‘/tmp/test’ saved [10701/10701]
>
>
>  "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd;>
> http://www.w3.org/1999/xhtml;>
>   
> 
> Apache2 Debian Default Page: It works
> 

Re: [Openstack-operators] Multiple floating IPs mapped to multiple vNICs (multi-homing)

[Saverio Proto]

Your policy routing looks good.
The problem must be somewhere else, where you do the nat maybe ?

Go in the network namespace where there is the neutron router with
address 10.0.16.1

If you tcpdump there what do you see ?

to be 100% sure about the policy routing just go in the network node
where you do the nat.

ip netns exec qrouter- wget -O /dev/null http://10.0.16.11/

uuid is the uuid of the neutron router where you are natting

I guess this will work.

Oh, did you double check the security groups ?

Saverio

2016-12-01 15:18 GMT+01:00 Paul Browne :
> Hello Saverio,
>
> Many thanks for the reply, I'll answer your queries below;
>
> On 01/12/16 12:49, Saverio Proto wrote:
>>
>> Hello,
>>
>> while the problem is in place, you should share the output of
>>
>> ip rule show
>> ip route show table 1
>>
>> It could be just a problem in your ruleset
>
>
> Of course, these are those outputs ;
>
> root@test1:~# ip rule show
> 0:  from all lookup local
> 32764:  from all to 10.0.16.11 lookup rt2
> 32765:  from 10.0.16.11 lookup rt2
> 32766:  from all lookup main
> 32767:  from all lookup default
>
> root@test1:~# ip route show table 1
> default via 10.0.16.1 dev eth1
> 10.0.16.0/24 dev eth1  scope link  src 10.0.16.11
>
>
>>
>> and, which one is your webserver ? can you tcpdump to make sure reply
>> packets get out on the NIC with src address 10.0.16.11 ?
>>
>> Saverio
>
>
> The instance has its two vNICs with source addresses 10.0.0.11 & 10.0.16.11,
> and the web-server is listening on both.
>
> The HTTP packets do seem to be getting out from 10.0.16.11 as source, but
> are stopped elsewhere upstream.
>
> I've attached two pcaps showing HTTP reply packets, one from 10.0.0.11
> (first vNIC; HTTP request and reply works to a remote client) and one from
> 10.0.16.11 (second vNIC; HTTP request is sent, reply not received by remote
> client). In the latter case, the server starts to make retransmissions to
> the remote client.
>
> Kind regards,
> Paul Browne
>
>
>
>
>>
>>
>> 2016-12-01 13:08 GMT+01:00 Paul Browne :
>>>
>>> Hello Operators,
>>>
>>> For reasons not yet amenable to persuasion otherwise, a customer of our
>>> ML2+OVS classic implemented OpenStack would like to map two floating IPs
>>> pulled from two separate external network floating IP pools, to two
>>> different vNICs on his instances.
>>>
>>> The floating IP pools correspond to one pool routable from the external
>>> Internet and another, RFC1918 pool routable from internal University
>>> networks.
>>>
>>> The tenant private networks are arranged as two RFC1918 VXLANs, each with
>>> a
>>> router to one of the two external networks.
>>>
>>> 10.0.0.0/24 -> route to -> 128.232.226.0/23
>>>
>>> 10.0.16.0/24 -> route to -> 172.24.46.0/23
>>>
>>>
>>> Mapping two floating IPs to instances isn't possible in Horizon, but is
>>> possible from command-line. This doesn't immediately work, however, as
>>> the
>>> return traffic from the instance needs to be sent back through the
>>> correct
>>> router gateway interface and not the instance default gateway.
>>>
>>> I'd initially thought this would be possible by placing a second routing
>>> table on the instances to handle the return traffic;
>>>
>>> debian@test1:/etc/iproute2$ less rt_tables
>>> #
>>> # reserved values
>>> #
>>> 255 local
>>> 254 main
>>> 253 default
>>> 0   unspec
>>> #
>>> # local
>>> #
>>> #1  inr.ruhep
>>> 1 rt2
>>>
>>> debian@test1:/etc/network$ less interfaces
>>> # The loopback network interface
>>> auto lo
>>> iface lo inet loopback
>>>
>>> # The first vNIC, eth0
>>> auto eth0
>>> iface eth0 inet dhcp
>>>
>>> # The second vNIC, eth1
>>> auto eth1
>>> iface eth1 inet static
>>>  address 10.0.16.11
>>>  netmask 255.255.255.0
>>>  post-up ip route add 10.0.16.0/24 dev eth1 src 10.0.16.11 table
>>> rt2
>>>  post-up ip route add default via 10.0.16.1 dev eth1 table rt2
>>>  post-up ip rule add from 10.0.16.11/32 table rt2
>>>  post-up ip rule add to 10.0.16.11/32 table rt2
>>>
>>> And this works well for SSH and ICMP, but curiously not for HTTP traffic.
>>>
>>>
>>> Requests to a web-server listening on all vNICs are sent but replies not
>>> received when the requests are sent to the second mapped floating IP
>>> (HTTP
>>> requests and replies work as expected when sent to the first mapped
>>> floating
>>> IP). The requests are logged in both cases however, so traffic is making
>>> it
>>> to the instance in both cases.
>>>
>>> I'd say this is clearly an unusual (and possibly un-natural) arrangement,
>>> but I was wondering whether anyone else on Operators had come across a
>>> similar situation in trying to map floating IPs from two different
>>> external
>>> networks to an instance?
>>>
>>> Kind regards,
>>>
>>> Paul Browne
>>>
>>> --
>>> ***
>>> Paul Browne
>>> Research Computing Platforms
>>> University Information Services
>>> Roger Needham Building
>>> JJ Thompson 

Re: [Openstack-operators] Multiple floating IPs mapped to multiple vNICs (multi-homing)

[Paul Browne]

Hello Saverio,

Many thanks for the reply, I'll answer your queries below;

On 01/12/16 12:49, Saverio Proto wrote:

Hello,

while the problem is in place, you should share the output of

ip rule show
ip route show table 1

It could be just a problem in your ruleset


Of course, these are those outputs ;

root@test1:~# ip rule show
0:  from all lookup local
32764:  from all to 10.0.16.11 lookup rt2
32765:  from 10.0.16.11 lookup rt2
32766:  from all lookup main
32767:  from all lookup default

root@test1:~# ip route show table 1
default via 10.0.16.1 dev eth1
10.0.16.0/24 dev eth1  scope link  src 10.0.16.11




and, which one is your webserver ? can you tcpdump to make sure reply
packets get out on the NIC with src address 10.0.16.11 ?

Saverio


The instance has its two vNICs with source addresses 10.0.0.11 & 
10.0.16.11, and the web-server is listening on both.


The HTTP packets do seem to be getting out from 10.0.16.11 as source, 
but are stopped elsewhere upstream.


I've attached two pcaps showing HTTP reply packets, one from 10.0.0.11 
(first vNIC; HTTP request and reply works to a remote client) and one 
from 10.0.16.11 (second vNIC; HTTP request is sent, reply not received 
by remote client). In the latter case, the server starts to make 
retransmissions to the remote client.


Kind regards,
Paul Browne






2016-12-01 13:08 GMT+01:00 Paul Browne :

Hello Operators,

For reasons not yet amenable to persuasion otherwise, a customer of our
ML2+OVS classic implemented OpenStack would like to map two floating IPs
pulled from two separate external network floating IP pools, to two
different vNICs on his instances.

The floating IP pools correspond to one pool routable from the external
Internet and another, RFC1918 pool routable from internal University
networks.

The tenant private networks are arranged as two RFC1918 VXLANs, each with a
router to one of the two external networks.

10.0.0.0/24 -> route to -> 128.232.226.0/23

10.0.16.0/24 -> route to -> 172.24.46.0/23


Mapping two floating IPs to instances isn't possible in Horizon, but is
possible from command-line. This doesn't immediately work, however, as the
return traffic from the instance needs to be sent back through the correct
router gateway interface and not the instance default gateway.

I'd initially thought this would be possible by placing a second routing
table on the instances to handle the return traffic;

debian@test1:/etc/iproute2$ less rt_tables
#
# reserved values
#
255 local
254 main
253 default
0   unspec
#
# local
#
#1  inr.ruhep
1 rt2

debian@test1:/etc/network$ less interfaces
# The loopback network interface
auto lo
iface lo inet loopback

# The first vNIC, eth0
auto eth0
iface eth0 inet dhcp

# The second vNIC, eth1
auto eth1
iface eth1 inet static
 address 10.0.16.11
 netmask 255.255.255.0
 post-up ip route add 10.0.16.0/24 dev eth1 src 10.0.16.11 table rt2
 post-up ip route add default via 10.0.16.1 dev eth1 table rt2
 post-up ip rule add from 10.0.16.11/32 table rt2
 post-up ip rule add to 10.0.16.11/32 table rt2

And this works well for SSH and ICMP, but curiously not for HTTP traffic.


Requests to a web-server listening on all vNICs are sent but replies not
received when the requests are sent to the second mapped floating IP (HTTP
requests and replies work as expected when sent to the first mapped floating
IP). The requests are logged in both cases however, so traffic is making it
to the instance in both cases.

I'd say this is clearly an unusual (and possibly un-natural) arrangement,
but I was wondering whether anyone else on Operators had come across a
similar situation in trying to map floating IPs from two different external
networks to an instance?

Kind regards,

Paul Browne

--
***
Paul Browne
Research Computing Platforms
University Information Services
Roger Needham Building
JJ Thompson Avenue
University of Cambridge
Cambridge
United Kingdom
E-Mail: pf...@cam.ac.uk
Tel: 0044-1223-46548
***


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--
***
Paul Browne
Research Computing Platforms
University Information Services
Roger Needham Building
JJ Thompson Avenue
University of Cambridge
Cambridge
United Kingdom
E-Mail: pf...@cam.ac.uk
Tel: 0044-1223-46548
***



eth0.pcap
Description: application/vnd.tcpdump.pcap


eth1.pcap
Description: application/vnd.tcpdump.pcap
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Re: [Openstack-operators] Multiple floating IPs mapped to multiple vNICs (multi-homing)

[Saverio Proto]

Hello,

while the problem is in place, you should share the output of

ip rule show
ip route show table 1

It could be just a problem in your ruleset

and, which one is your webserver ? can you tcpdump to make sure reply
packets get out on the NIC with src address 10.0.16.11 ?

Saverio


2016-12-01 13:08 GMT+01:00 Paul Browne :
> Hello Operators,
>
> For reasons not yet amenable to persuasion otherwise, a customer of our
> ML2+OVS classic implemented OpenStack would like to map two floating IPs
> pulled from two separate external network floating IP pools, to two
> different vNICs on his instances.
>
> The floating IP pools correspond to one pool routable from the external
> Internet and another, RFC1918 pool routable from internal University
> networks.
>
> The tenant private networks are arranged as two RFC1918 VXLANs, each with a
> router to one of the two external networks.
>
> 10.0.0.0/24 -> route to -> 128.232.226.0/23
>
> 10.0.16.0/24 -> route to -> 172.24.46.0/23
>
>
> Mapping two floating IPs to instances isn't possible in Horizon, but is
> possible from command-line. This doesn't immediately work, however, as the
> return traffic from the instance needs to be sent back through the correct
> router gateway interface and not the instance default gateway.
>
> I'd initially thought this would be possible by placing a second routing
> table on the instances to handle the return traffic;
>
> debian@test1:/etc/iproute2$ less rt_tables
> #
> # reserved values
> #
> 255 local
> 254 main
> 253 default
> 0   unspec
> #
> # local
> #
> #1  inr.ruhep
> 1 rt2
>
> debian@test1:/etc/network$ less interfaces
> # The loopback network interface
> auto lo
> iface lo inet loopback
>
> # The first vNIC, eth0
> auto eth0
> iface eth0 inet dhcp
>
> # The second vNIC, eth1
> auto eth1
> iface eth1 inet static
> address 10.0.16.11
> netmask 255.255.255.0
> post-up ip route add 10.0.16.0/24 dev eth1 src 10.0.16.11 table rt2
> post-up ip route add default via 10.0.16.1 dev eth1 table rt2
> post-up ip rule add from 10.0.16.11/32 table rt2
> post-up ip rule add to 10.0.16.11/32 table rt2
>
> And this works well for SSH and ICMP, but curiously not for HTTP traffic.
>
>
> Requests to a web-server listening on all vNICs are sent but replies not
> received when the requests are sent to the second mapped floating IP (HTTP
> requests and replies work as expected when sent to the first mapped floating
> IP). The requests are logged in both cases however, so traffic is making it
> to the instance in both cases.
>
> I'd say this is clearly an unusual (and possibly un-natural) arrangement,
> but I was wondering whether anyone else on Operators had come across a
> similar situation in trying to map floating IPs from two different external
> networks to an instance?
>
> Kind regards,
>
> Paul Browne
>
> --
> ***
> Paul Browne
> Research Computing Platforms
> University Information Services
> Roger Needham Building
> JJ Thompson Avenue
> University of Cambridge
> Cambridge
> United Kingdom
> E-Mail: pf...@cam.ac.uk
> Tel: 0044-1223-46548
> ***
>
>
> ___
> OpenStack-operators mailing list
> OpenStack-operators@lists.openstack.org
> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-operators
>

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