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Re: idea for work in ovsdb netvirt L3: icmp responder

Marcelo Amaral <marcelo.amaral@...>
 

Hi Flavio,

I managed to extend ovs to accept icmp packets configuration.

I am trying to create the OF rule to replay ping from the gateway, for instance:
sudo ovs-ofctl add-flow -OOpenFlow13 br-int
"table=20, dl_type=0x0800, nw_proto=1, icmp_code=0, ip_dst=10.1.0.1,
actions=move:NXM_OF_ETH_SRC[]->NXM_OF_ETH_DST[], mod_dl_src:fa:16:3e:13:b5:f0,
load:0x00->NXM_OF_ICMP_TYPE[], load:0x00->NXM_OF_ICMP_CODE[],
move:NXM_OF_IP_SRC[]->NXM_OF_IP_DST[], load:0x10101->NXM_OF_IP_SRC[],
in_port"

But It is not working yet. Do you have any clue about what is missing?

Best,
Marcelo Amaral

On 12/08/15 05:26, Flavio Fernandes wrote:
[cc: ovsdb-dev]

Hi Marcelo,

It was really nice meting at the Summit! Sorry for not having a lot of extra time to mingle.

You mentioned you were looking for some work on ovsdb L3 and I thought of a very specific task that would have
a great impact in the L3 work; which may be within the time you have left to work on your internship.

While doing the demo [demo], Tim Rozet pointed out how tenant vms cannot get a response when pinging their default
gateway. As explained in the "Final thoughts” of my blog [1], this is the case because there is no ip stack to
handle any packets destined to the neutron router.

A solution to this would be to extend the arp responder table (20) to have rules that match on a specific icmp query
packets, move things around to turn it into a ping response and send the packet out of the in_port. the arp
handling code [2] can be a guide in how that gets accomplished. A way of prototyping this would be to create the
rule ‘manually’ [3] after doing the demo [demo] and coming up with what it would look like; similar to how Dave Tucker
and I started off when doing L3 [4].

@Tim: did you ever open the bug on this? If not, please do.
@Marcelo: would this be something you would be interested to work on?

Thanks,

— flavio

[demo]: https://youtu.be/2axNKHvt5MY?t=29m46s
[1]: http://www.flaviof.com/blog/work/how-to-odl-with-openstack-part2.html
[2]: https://github.com/opendaylight/ovsdb/blob/master/openstack/net-virt/src/main/java/org/opendaylight/ovsdb/openstack/netvirt/api/ArpProvider.java#L18
[3]: sh ovs-ofctl add-flow -OOpenFlow13 br-int “table=20, dl_type=0x800,nw_proto=1,icmp_code=..."
[4]: http://dtucker.co.uk/hack/building-a-router-with-openvswitch.html
--
Marcelo Amaral, PhD Candidate
BSC Associate Researcher
Dept. d'Arquitectura de Computadors, Univ. Politecnica de Catalunya
UPC Campus Nord - Modul D6-112, Jordi Girona 1-3, Barcelona 08034, SPAIN
http://people.ac.upc.edu/mamaral
http://www.bsc.es/autonomic


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