[Openstack] DHCP Replies

Mina Nagy Zaki mnzaki at gmail.com
Wed Aug 21 11:52:45 UTC 2013

I have a single node setup so far. I manually removed all the tag ovs
properties on the ports and it worked. I'm not using VLANs, so I'm not
sure why the quantum OVS plugin is adding tags.

tcpdump of br-int and dhcp tap:
I started ping from inside the dhcp namespace. I get destination
unreachable for a while, then after a few seconds the packets start
making it through.

tcpdump br-int shows me arp requests for from (dhcp tap)
the arp replies do not show up, and the ping icmp packets do not show up

tcpdump of dhcp tap captures all packets as expected (arp and icmp
echo requests and replies)

OVS plugin config:
integration_bridge = br-int
tenant_network_type = gre

enable_tunneling = True
network_vlan_ranges =
tunnel_bridge = br-tun
tunnel_id_ranges = 1:1000
local_ip = xxx.xxx.xxx.xxx

root at box1 ~ # ovs-vsctl show
    Bridge br-tun
        Port br-tun
            Interface br-tun
                type: internal
        Port "gre-1"
            Interface "gre-1"
                type: gre
                options: {in_key=flow, out_key=flow,
        Port patch-int
            Interface patch-int
                type: patch
                options: {peer=patch-tun}
    Bridge br-int
        Port "qvof0b52659-8c"
            tag: 4095
            Interface "qvof0b52659-8c"
        Port patch-tun
            Interface patch-tun
                type: patch
                options: {peer=patch-int}
        Port "qvo9a42732d-56"
            tag: 1
            Interface "qvo9a42732d-56"
        Port "qr-7f13795a-6c"
            tag: 1
            Interface "qr-7f13795a-6c"
                type: internal
        Port "tap32f910cf-c8"
            tag: 4095
            Interface "tap32f910cf-c8"
                type: internal
        Port int-br-ex
            Interface int-br-ex
        Port br-int
            Interface br-int
                type: internal
        Port "tapef814634-b1"
            tag: 1
            Interface "tapef814634-b1"
                type: internal
    Bridge br-ex
        Port "qg-22f43415-49"
            Interface "qg-22f43415-49"
                type: internal
        Port br-ex
            Interface br-ex
                type: internal
        Port "eth0"
            Interface "eth0"
    ovs_version: "1.10.1"

root at box1 ~ # ovs-ofctl show br-int
OFPT_FEATURES_REPLY (xid=0x2): dpid:0000064d98b2b243
n_tables:254, n_buffers:256
 1(qvo9a42732d-56): addr:3e:71:71:5c:08:fe
     config:     0
     state:      0
     current:    10GB-FD COPPER
     speed: 10000 Mbps now, 0 Mbps max
 2(tap32f910cf-c8): addr:5e:70:61:0d:4b:f8
     config:     0
     state:      0
     speed: 0 Mbps now, 0 Mbps max
 4(patch-tun): addr:22:f5:35:76:2a:fc
     config:     0
     state:      0
     speed: 0 Mbps now, 0 Mbps max
 10(tapef814634-b1): addr:00:00:00:00:00:00
     config:     PORT_DOWN
     state:      LINK_DOWN
     speed: 0 Mbps now, 0 Mbps max
 14(qr-7f13795a-6c): addr:00:00:00:00:00:00
     config:     PORT_DOWN
     state:      LINK_DOWN
     speed: 0 Mbps now, 0 Mbps max
 LOCAL(br-int): addr:06:4d:98:b2:b2:43
     config:     0
     state:      0
     speed: 0 Mbps now, 0 Mbps max
OFPT_GET_CONFIG_REPLY (xid=0x4): frags=normal miss_send_len=0

root at box1 ~ # ovs-ofctl dump-flows br-int
NXST_FLOW reply (xid=0x4):
 cookie=0x0, duration=2829.897s, table=0, n_packets=0, n_bytes=0,
idle_age=2829, priority=2,in_port=2 actions=drop
 cookie=0x0, duration=2896.855s, table=0, n_packets=577,
n_bytes=51006, idle_age=286, priority=1 actions=NORMAL

On Wed, Aug 21, 2013 at 10:56 AM, Sushma Korati
<sushma_korati at persistent.co.in> wrote:
> Hi Mina Nagy,
> We faced smilar issue with VLAN + Openvswitch.
> Are you using VLAN?
> Can you please paste your OVS-configuration and output of below commands in compute and quantum node.
>  tcpdump and ovs-ofctl dump-flows on dhcp tap, int-br-int, br-int
> Regards,
> Sushma Korati
> sushma_korati at persistent.co.in
> Persistent Systems Ltd. |  Partners in Innovation | www.persistentsys.com
> P Please consider your environmental responsibility: Before printing this e-mail or any other document, ask yourself whether you need a hard copy.
> ________________________________________
> From: Mina Nagy Zaki [mnzaki at gmail.com]
> Sent: Wednesday, August 21, 2013 1:37 PM
> To: openstack at lists.openstack.org
> Subject: [Openstack] DHCP Replies
> Hello,
> I have working network configuration, VMs have access to the external
> network, hosts have access to VMs. But DHCP replies are not making it
> back into the VMs.
> tcpdump and iptables tracing show me that the requests make it through
> just fine, but the replies don't make it out of the qdhcp-XXXX
> namespace (the go out the tap interface there but I'm not sure what
> happens to them next)
> How should I go about debugging this?
> Thanks!
> --
> Mina Nagy Zaki
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Mina Nagy Zaki

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