[ovs-discuss] OFPFC_DELETE and OFPFC_DELETE_STRICT commands don't delete openflow rules

Wed Jul 14 16:34:46 UTC 2021

Hello, 

We’re having trouble deleting OpenFlow rules using the OFPFC_DELETE or
OFPFC_DELETE_STRICT commands that send a Ryu controller to the OVS switch.

What you did that make the problem appear:

The Ryu controller sends OFPFC_DELETE or OFPFC_DELETE_STRICT commands to the
OVS switch in order to delete a flow rule matching certain criteria (e.g.,
outport).

What you expected to happen:

The OVS switch receives the aforementioned command and deletes the flows
that match the criteria.

What actually happened:

The matching criteria flows still appear in the OpenFlow tables. Although, I
can see that apparently a flow was removed in the OVS database.

The Open vSwitch version number: 

ovs-vswitchd (Open vSwitch) 2.15.90

The kernel version on which OVS is running: 

Linux version 4.15.0-140-generic (buildd at lgw01-amd64-054) (gcc version 7.5.0
(Ubuntu 7.5.0-3ubuntu1~18.04))

The distribution and version number of my OS: 

Ubuntu 18.04

The output of ovs-dptcl show: 

system at ovs-system:

  lookups: hit:5768706 missed:17566 lost:0

  flows: 2

  masks: hit:5955901 total:1 hit/pkt:1.03

  port 0: ovs-system (internal)

  port 1: br2 (internal)

  port 2: ens4

  port 3: ens5

  port 4: ens6

  port 5: ens7

The output of ovs-ofctl show <bridge>:

OFPT_FEATURES_REPLY (xid=0x2): dpid:0000faf67755c143

n_tables:254, n_buffers:0

capabilities: FLOW_STATS TABLE_STATS PORT_STATS QUEUE_STATS ARP_MATCH_IP

actions: output enqueue set_vlan_vid set_vlan_pcp strip_vlan mod_dl_src
mod_dl_dst mod_nw_src mod_nw_dst mod_nw_tos mod_tp_src mod_tp_dst

1(ens4): addr:fa:16:3e:8c:53:97

     config:     0

     state:      0

     speed: 0 Mbps now, 0 Mbps max

2(ens5): addr:fa:16:3e:fd:c0:1a

     config:     0

     state:      0

     speed: 0 Mbps now, 0 Mbps max

3(ens6): addr:fa:16:3e:ba:d2:c0

     config:     0

     state:      0

     speed: 0 Mbps now, 0 Mbps max

4(ens7): addr:fa:16:3e:67:bd:96

     config:     0

     state:      0

     speed: 0 Mbps now, 0 Mbps max

LOCAL(br2): addr:fa:f6:77:55:c1:43

     config:     0

     state:      0

     speed: 0 Mbps now, 0 Mbps max

OFPT_GET_CONFIG_REPLY (xid=0x4): frags=normal miss_send_len=0

A workaround is to establish an SSH connection to the host where OVS is
running and execute ovs-ofctl del-flows <bridge> <criteria>. An automatic
way to do it from the Ryu controller is using the Paramiko library to send
remotely the command.

We attach a screenshot where you can see the information in the OVS database
at the moment the controller sends OFPFC_DELETE or OFPFC_DELETE_STRICT
commands.

Thanks you very much in advance. 

Kind regards, 

Alejandro Llorens

-- 
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