Hi guys,

I'm having trouble figuring out why a Cirros test VM on my compute node is not obtaining a DHCP address from my controller node, over a Neutron/OVS/VLAN arrangement. So, the scenario in more detail...

2x DELL PowerEdge R420s, running stock Ubuntu 13.10 Saucy (OpenStack Havana). 2x NetGear GS724 switches

Primary switch is for 192.168.1.0/24 traffic, with gateway router at 1.1. Both DELLs connected via their primary (em0) interface.

Secondary switch is for 10.0.0.0/24 traffic, with no gateway. Both DELLs connected via their secondary (em1) interface.

First DELL is called 'controller1'. Second DELL is called 'compute1'. I'll focus on the compute node's configuration for now, as I'm having trouble tracing where the DHCP request packet goes within this domain.

First, the underlying /etc/network/interfaces network config...

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto em1
iface em1 inet static
    address 0.0.0.0

# The primary network interface
auto br-ex
iface br-ex inet static
    address 192.168.1.11
    netmask 255.255.255.0
    gateway 192.168.1.1
    dns-nameservers 192.168.1.1

auto em2
iface em2 inet static
    address 0.0.0.0

auto br-int
iface br-int inet static
    address 10.0.0.11
    netmask 255.255.255.0

OVS bridges configured as per 'ovs-vsctl show'...

b8840243-e3a1-43de-badb-cfbe0ce1405c
    Bridge br-int
        Port int-br-ex
            Interface int-br-ex
        Port "em2"
            Interface "em2"
        Port phy-br-int
            Interface phy-br-int
        Port br-int
            Interface br-int
                type: internal
        Port "tapc015b393-e7"
            tag: 3
            Interface "tapc015b393-e7"
        Port int-br-int
            Interface int-br-int
    Bridge br-ex
        Port phy-br-ex
            Interface phy-br-ex
        Port "em1"
            Interface "em1"
        Port br-ex
            Interface br-ex
                type: internal
    ovs_version: "1.10.2"

The tap interface belongs to my 'test1' Cirros guest, and I can see DHCP request packets on it if I tcpdump it as the VM boots.

I have the OpenVSwitch (OVS) plugin configured as follows:

[ovs]
tenant_network_type = vlan
network_vlan_ranges = physnet2:1000:2999
local_ip = 10.0.0.11
bridge_mappings = physnet2:br-int

[agent]

[securitygroup]
firewall_driver = neutron.agent.linux.iptables_firewall.OVSHybridIptablesFirewallDriver

[database]
connection=(snipped)

FTR, the controller node is the same, with the local_ip being 10.0.0.11

On Neutron, there is a virtual 'testnet':

+---------------------------+--------------------------------------+
| Field                     | Value                                |
+---------------------------+--------------------------------------+
| admin_state_up            | True                                 |
| id                        | c7497b77-a716-4ad6-8d44-3fa9b2dcfaf0 |
| name                      | testnet                              |
| provider:network_type     | vlan                                 |
| provider:physical_network | physnet2                             |
| provider:segmentation_id  | 1001                                 |
| router:external           | False                                |
| shared                    | False                                |
| status                    | ACTIVE                               |
| subnets                   | 8821440b-839b-4e91-85ca-1f2651ed6896 |
| tenant_id                 | 83b3ca4a4ec94070904d5112aeb1baab     |
+---------------------------+--------------------------------------+

And a virtual 'testsubnet':

+------------------+--------------------------------------------------+
| Field            | Value                                            |
+------------------+--------------------------------------------------+
| allocation_pools | {"start": "192.168.9.2", "end": "192.168.9.254"} |
| cidr             | 192.168.9.0/24                                   |
| dns_nameservers  | 8.8.8.8                                          |
| enable_dhcp      | True                                             |
| gateway_ip       | 192.168.9.1                                      |
| host_routes      |                                                  |
| id               | 8821440b-839b-4e91-85ca-1f2651ed6896             |
| ip_version       | 4                                                |
| name             | testsubnet                                       |
| network_id       | c7497b77-a716-4ad6-8d44-3fa9b2dcfaf0             |
| tenant_id        | 83b3ca4a4ec94070904d5112aeb1baab                 |
+------------------+--------------------------------------------------+

My confusion seems to arise from not being quite clear about where the VLAN id is being set and what to exactly, so I can trace the packet beyond the tap interface.

It seems I am not quite grokking the relationship between the 'provider:segmentation_id', and the OVS 'tag id'. The segmentation_id seems to have been correctly taken from ... (more)