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Why would an OVS bridge not forward ARP

asked 2012-09-20 23:07:13 -0500

sunil-srivastava gravatar image

Bridge "br-eth0" Port "br-eth0" Interface "br-eth0" type: internal Port "eth0" Interface "eth0" Port "phy-br-eth0" Interface "phy-br-eth0" Bridge br-int Port "tap55d1e5e8-ab" tag: 1 Interface "tap55d1e5e8-ab" type: internal Port "qr-4b50a17d-3c" tag: 1 Interface "qr-4b50a17d-3c" type: internal Port "int-br-eth0" Interface "int-br-eth0" Port "tape8d6e0a5-52" tag: 1 Interface "tape8d6e0a5-52" Port "tap6176588e-48" tag: 1 Interface "tap6176588e-48" Port br-int Interface br-int type: internal

I can see ARP packets sent from int-br-eth0 to phy-br-eth0 but not to upstream eth0.

So we cannot ping from one VM (or DHCP NetNS) on one machine to another VM on another machine.

I see the ping triggering ARPs. The Tx counter of int-br-eth0 and Rx counter of phy-br-eth0 were also corelated with ping.

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answered 2012-09-21 16:35:11 -0500

eoghank gravatar image

Original question is answered.

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answered 2012-09-26 21:55:55 -0500

sunil-srivastava gravatar image

Thanks Eoghan, that solved my question.

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answered 2012-09-21 16:11:23 -0500

gongysh gravatar image

And if your original question is answered, we should close this question. If we have new ones, we should open new one. Different questions in one thread is not helpful for others to query.

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answered 2012-09-21 16:09:31 -0500

gongysh gravatar image

Yes. But to enable the networks on multi-nodes to connect together, u need corresponding actual physical net which runs on the given VLAN id. For example, If your virtual network has | provider:segmentation_id = 1, u will have to enable your hardware switch to allow Vlan 1 to pass.

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answered 2012-09-21 15:46:51 -0500

eoghank gravatar image

I had these in the localrc before I ran stack.sh

ENABLE_TENANT_VLAN=True TENANT_VLAN_RANGE=1:1000 PHYSICAL_NETWORK=eth0

And nova.conf had vlan_interface=eth0

ovs_quantum_plugin.ini had these flags set:

bridge_mappings = eth0:br-eth0 tenant_network_type = vlan network_vlan_ranges = eth0:1:1000

Should this be sufficient for the networks to run as VLAN type?

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answered 2012-09-21 14:49:49 -0500

gongysh gravatar image

both of your networks are local type: stack@esg-dell-c4-s11:~/gitstack/devstack$ quantum net-show net1 +---------------------------+--------------------------------------+ | Field | Value | +---------------------------+--------------------------------------+ | admin_state_up | True | | id | fa8f9c5e-e41a-4f80-955c-94b3a45b9dcb | | name | net1 | | provider:network_type | local |

the flow is to drop by default. if we have Vms on the network with Vlan network_type, the port will be opened.

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answered 2012-09-21 06:43:55 -0500

Hi Sunil,

Sorry I'm not sure why you're trying to show me here. You can ping 10.0.0.2 and not 10.0.0.3, I don't know where those interfaces reside in your setup. Can you show me an ifconfig -a of this machine. Also while you are pinging a ovs-dpctl dump-flow. Also, why are you showing me a tcpdump on phy-br-eth0, you should be doing that on eth0 since you say the packets are getting there.

Thanks,

Aaron

P.S: I'll also be in #openstack-dev for a little while longer tonight.

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answered 2012-09-21 06:26:42 -0500

sunil-srivastava gravatar image

Hi Aron,

Here is the TCP Dumps.

The following output show there is no link issue between phy-br-eth0 and int-br-eth0.

(1)

root@esg-dell-c4-s11:~# ping 10.0.0.2
PING 10.0.0.2 (10.0.0.2) 56(84) bytes of data. 64 bytes from 10.0.0.2: icmp_req=1 ttl=64 time=0.056 ms 64 bytes from 10.0.0.2: icmp_req=2 ttl=64 time=0.052 ms 64 bytes from 10.0.0.2: icmp_req=3 ttl=64 time=0.032 ms 64 bytes from 10.0.0.2: icmp_req=4 ttl=64 time=0.041 ms 64 bytes from 10.0.0.2: icmp_req=5 ttl=64 time=0.048 ms --- 10.0.0.2 ping statistics --- 5 packets transmitted, 5 received, 0% packet loss, time 4006ms

The above triggers this below on int-br-eth0

stack@esg-dell-c4-s11:~/devstack$ sudo tcpdump -i int-br-eth0 arp and src 10.0.0.2 tcpdump: WARNING: int-br-eth0: no IPv4 address assigned tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on int-br-eth0, link-type EN10MB (Ethernet), capture size 65535 bytes 00:41:55.755545 ARP, Request who-has http://inenbasavbl1c.corp.emc.com tell http://usxxstephc2mbp1.corp.emc.com , length 28 00:41:56.753793 ARP, Request who-has http://inenbasavbl1c.corp.emc.com tell http://usxxstephc2mbp1.corp.emc.com , length 28 00:41:57.753782 ARP, Request who-has http://inenbasavbl1c.corp.emc.com tell http://usxxstephc2mbp1.corp.emc.com , length 28 00:41:58.771011 ARP, Request who-has http://inenbasavbl1c.corp.emc.com tell http://usxxstephc2mbp1.corp.emc.com , length 28 00:41:59.769790 ARP, Request who-has http://inenbasavbl1c.corp.emc.com tell http://usxxstephc2mbp1.corp.emc.com , length 28 00:42:00.769796 ARP, Request who-has http://inenbasavbl1c.corp.emc.com tell http://usxxstephc2mbp1.corp.emc.com , length 28

(2)

And again on phy-br-eth0.

root@esg-dell-c4-s11:~# ping 10.0.0.3 PING 10.0.0.3 (10.0.0.3) 56(84) bytes of data. From 10.0.0.2 icmp_seq=1 Destination Host Unreachable From 10.0.0.2 icmp_seq=2 Destination Host Unreachable From 10.0.0.2 icmp_seq=3 Destination Host Unreachable ^C --- 10.0.0.3 ping statistics --- 5 packets transmitted, 0 received, +3 errors, 100% packet loss, time 4024ms

stack@esg-dell-c4-s11:~/devstack$ sudo tcpdump -i phy-br-eth0 arp and src 10.0.0.2 tcpdump: WARNING: phy-br-eth0: no IPv4 address assigned tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on phy-br-eth0, link-type EN10MB (Ethernet), capture size 65535 bytes 00:43:35.871097 ARP, Request who-has http://inenbasavbl1c.corp.emc.com tell http://usxxstephc2mbp1.corp.emc.com , length 28 00:43:36.869787 ARP, Request who-has http://inenbasavbl1c.corp.emc.com tell http://usxxstephc2mbp1.corp.emc.com , length 28 00:43:37.873777 ARP, Request who-has http://inenbasavbl1c.corp.emc.com tell http://usxxstephc2mbp1.corp.emc.com , length 28 00:43:38.887008 ARP, Request who-has http://inenbasavbl1c.corp.emc.com tell http://usxxstephc2mbp1.corp.emc.com , length ... (more)

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answered 2012-09-21 06:10:35 -0500

Sunil, One last thing. If you leave the ping running and then provide the output of

ovs-dpctl dump-flows br-int ovs-dpctl dump-flows br-tun

That will show the active flow entires in the kernel. Did you try running tcpdump on eth0 to see if you see arp packets there? You never said how you know that they are not making it out eth0. You just said you were unable to ping. (The drop flow entry you provided blocks the returning replies so ping definitely will not work).

Aaron

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answered 2012-09-21 05:24:04 -0500

sunil-srivastava gravatar image

Hi Yong,

That is not the root cause. Still.

stack@esg-dell-c4-s11:~/gitstack/devstack$ quantum net-list +--------------------------------------+---------+--------------------------------------+ | id | name | subnets | +--------------------------------------+---------+--------------------------------------+ | 68f76ec1-407b-4e42-a089-d0e6553473f8 | ext_net | 09851d25-806f-492c-b708-bf03838d77b3 | | fa8f9c5e-e41a-4f80-955c-94b3a45b9dcb | net1 | 31ed889f-f3f5-4faa-bb51-1d92344c91a3 | +--------------------------------------+---------+--------------------------------------+

stack@esg-dell-c4-s11:~/gitstack/devstack$ quantum net-show net1 +---------------------------+--------------------------------------+ | Field | Value | +---------------------------+--------------------------------------+ | admin_state_up | True | | id | fa8f9c5e-e41a-4f80-955c-94b3a45b9dcb | | name | net1 | | provider:network_type | local | | provider:physical_network | | | provider:segmentation_id | | | router:external | False | | shared | False | | status | ACTIVE | | subnets | 31ed889f-f3f5-4faa-bb51-1d92344c91a3 | | tenant_id | b0d8717a0f8b4cf8bdff8d84156622af |

stack@esg-dell-c4-s11:~/gitstack/devstack$ quantum net-show ext_net +---------------------------+--------------------------------------+ | Field | Value | +---------------------------+--------------------------------------+ | admin_state_up | True | | id | 68f76ec1-407b-4e42-a089-d0e6553473f8 | | name | ext_net | | provider:network_type | local | | provider:physical_network | | | provider:segmentation_id | | | router:external | True | | shared | False | | status | ACTIVE | | subnets | 09851d25-806f-492c-b708-bf03838d77b3 | | tenant_id | 44cb33fdc72b44ad8e200a1326199895 | +---------------------------+--------------------------------------+

+---------------------------+--------------------------------------+

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Asked: 2012-09-20 23:07:13 -0500

Seen: 1,493 times

Last updated: Sep 26 '12