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should physical switch ports be VLAN trunks?

asked 2013-09-04 03:06:59 -0500

MAIKA gravatar image

should physical switch ports be VLAN trunks so that VM can get IP from DHCP server? how can i check whether physical switch be capable of forwarding VLAN tagged traffic?

i am using openvswitch.

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answered 2013-09-04 06:32:27 -0500

darragh-oreilly gravatar image

Yes, when using the Open vSwitch plugin with VLAN provider networks, you must configure the physical switchports to work with host based tagging. Only the switchports that connect the NICs defined in bridge_mappings from ovs_quantum_plugin.ini need to be configured this way. These switchports need to allow the range of VLAN ids defined in network_vlan_ranges. The terms and procedures to do this vary between switch vendors, so you will need to follow your switch doc.

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Thanks! but now i have another question: when i set physical switch to be trunks model,my physical server cann't reach either internal network or external network.any suggestion to solve this problem?

MAIKA gravatar imageMAIKA ( 2013-09-04 22:33:34 -0500 )edit

Which dhcp server do you mean? A quantum dhcp server or an external ('real') dhcp server? How many servers do you have? How many nics do they have?

darragh-oreilly gravatar imagedarragh-oreilly ( 2013-09-05 04:39:29 -0500 )edit

quantum dhcp server. i have try many times,but vm still cann't get IP corrently.it shows cann't connect to 169.254.169.254,network not reachable

MAIKA gravatar imageMAIKA ( 2013-09-05 19:42:25 -0500 )edit
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answered 2013-11-12 10:33:39 -0500

riker gravatar image

updated 2013-11-12 10:34:09 -0500

I had this problem as well and my solution was to trunk the ports to which openstack was connected and create the vlans (range) on the switch itself.

interface Eth1/1 - 30

switchport mode trunk

switch port trunk allowed vlan all

vlan 100-200

This trunked the ports on the switch (physical ports 1 through 30), allowed all vlan traffic, and then let the switch know about vlans in the range 100 through 200. After that, openstack (the virtual interfaces neutron's agents create) will tag the outbound traffic for vlans 100 through 200 (allowed vlans setting in the neutron configuration options) and the switch will accept and route that traffic.

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Asked: 2013-09-04 03:06:59 -0500

Seen: 1,282 times

Last updated: Nov 12 '13