When IPv6 addresses are added to the dnsmasq host file, dnsmasq stops issuing leases

[Sean M. Collins]

When an IPv6 subnet is created, with ipv6_ra_mode not set, and ipv6_address_mode set to "slaac" - ipv6 addresses are added to the host file that dnsmasq uses, and this causes dnsmasq to cease responding to dhcp clients on the v4 side.

[Sean M. Collins (scollins)]

I will post logs and configuration information from the lab setup shortly.

[Sean M. Collins (scollins)]

Contents of the dhcp host file:

stack@osctrl-cc38-b01:/opt/stack/data/neutron/dhcp/2bc9a7db-84f8-4776-a498-ef385e1d8065$ cat host
fa:16:3e:cf:c5:59,host-10-251-2-131.openstacklocal,10.251.2.131
fa:16:3e:cf:c5:59,host-2001-db8-beef-7ac0--1.openstacklocal,[2001:db8:beef:7ac0::1]
fa:16:3e:f8:7a:12,host-10-251-2-130.openstacklocal,10.251.2.130
fa:16:3e:f8:7a:12,host-2001-db8-beef-7ac0-f816-3eff-fef8-7a12.openstacklocal,[2001:db8:beef:7ac0:f816:3eff:fef8:7a12]

[Sean M. Collins (scollins)]

console output from the guest:

[ 0.000000] Initializing cgroup subsys cpuset
[ 0.000000] Initializing cgroup subsys cpu
[ 0.000000] Linux version 3.2.0-37-virtual (buildd@allspice) (gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5) ) #58-Ubuntu SMP Thu Jan 24 15:48:03 UTC 2013 (Ubuntu 3.2.0-37.58-virtual 3.2.35)
[ 0.000000] Command line: root=/dev/vda console=tty0 console=ttyS0
[ 0.000000] KERNEL supported cpus:
[ 0.000000] Intel GenuineIntel
[ 0.000000] AMD AuthenticAMD
[ 0.000000] Centaur CentaurHauls
[ 0.000000] BIOS-provided physical RAM map:
[ 0.000000] BIOS-e820: 0000000000000000 - 000000000009fc00 (usable)
[ 0.000000] BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved)
[ 0.000000] BIOS-e820: 00000000000f0000 - 0000000000100000 (reserved)
[ 0.000000] BIOS-e820: 0000000000100000 - 0000000003ffe000 (usable)
[ 0.000000] BIOS-e820: 0000000003ffe000 - 0000000004000000 (reserved)
[ 0.000000] BIOS-e820: 00000000feffc000 - 00000000ff000000 (reserved)
[ 0.000000] BIOS-e820: 00000000fffc0000 - 0000000100000000 (reserved)
[ 0.000000] NX (Execute Disable) protection: active
[ 0.000000] DMI 2.4 present.
[ 0.000000] No AGP bridge found
[ 0.000000] last_pfn = 0x3ffe max_arch_pfn = 0x400000000
[ 0.000000] PAT not supported by CPU.
[ 0.000000] found SMP MP-table at [ffff8800000f1610] f1610
[ 0.000000] init_memory_mapping: 0000000000000000-0000000003ffe000
[ 0.000000] RAMDISK: 03c65000 - 03ff0000
[ 0.000000] ACPI: RSDP 00000000000f1470 00014 (v00 BOCHS )
[ 0.000000] ACPI: RSDT 0000000003ffe4a0 00030 (v01 BOCHS BXPCRSDT 00000001 BXPC 00000001)
[ 0.000000] ACPI: FACP 0000000003ffff80 00074 (v01 BOCHS BXPCFACP 00000001 BXPC 00000001)
[ 0.000000] ACPI: DSDT 0000000003ffe4d0 01137 (v01 BXPC BXDSDT 00000001 INTL 20100528)
[ 0.000000] ACPI: FACS 0000000003ffff40 00040
[ 0.000000] ACPI: SSDT 0000000003fff700 00838 (v01 BOCHS BXPCSSDT 00000001 BXPC 00000001)
[ 0.000000] ACPI: APIC 0000000003fff610 00078 (v01 BOCHS BXPCAPIC 00000001 BXPC 00000001)
[ 0.000000] No NUMA configuration found
[ 0.000000] Faking a node at 0000000000000000-0000000003ffe000
[ 0.000000] Initmem setup node 0 0000000000000000-0000000003ffe000
[ 0.000000] NODE_DATA [0000000003ff6000 - 0000000003ffafff]
[ 0.000000] kvm-clock: Using msrs 4b564d01 and 4b564d00
[ 0.000000] kvm-clock: cpu 0, msr 0:1cf7681, boot clock
[ 0.000000] Zone PFN ranges:
[ 0.000000] DMA 0x00000010 -> 0x00001000
[ 0.000000] DMA32 0x00001000 -> 0x00100000
[ 0.000000] Normal empty
[ 0.000000] Movable zone start PFN for each node
[ 0.000000] early_node_map[2] active PFN ranges
[ 0.000000] 0: 0x00000010 -> 0x0000009f
[ 0.000000] 0: 0x00000100 -> 0x00003ffe
[ 0.000000] ACPI: PM-Timer IO Port: 0xb008
[ 0.000000] ACPI: LAPIC (acpi_id[0x00] lapic_id[0x00] enabled)
[ 0.000000] ACPI: LAPIC_NMI (acpi_id[0xff] dfl dfl lint[0x1])
[ 0.000000] ACPI: IOAPIC (id[0x00] address[0xfec00000] gsi_base[0])
[ 0.000000] IOAPIC[0]: apic_id 0, version 17, address 0xfec00000, GSI 0-23
[ 0.000000] ACPI: INT_SRC_OVR (bus 0 bus_irq 0 global_irq 2 dfl d...

[Sean M. Collins (scollins)]

Neutron Network:

+--------------------------------------+---------+--------------------------------------------------------------+
| id | name | subnets |
+--------------------------------------+---------+--------------------------------------------------------------+
| 0574ad5f-a4c2-4e11-8941-d5eceedbcd91 | default | 09dc21a4-d46f-4e80-ab60-7a532f2bf98a 10.251.2.128/27 |
| | | 4674a928-0f7b-452c-a037-950fc1e15ba0 2001:db8:beef:7ac0::/64 |
+--------------------------------------+---------+--------------------------------------------------------------+

Neutron Subnets:

+--------------------------------------+--------------+-------------------------+-------------------------------------------------------------------------------------+
| id | name | cidr | allocation_pools |
+--------------------------------------+--------------+-------------------------+-------------------------------------------------------------------------------------+
| 09dc21a4-d46f-4e80-ab60-7a532f2bf98a | provider_net | 10.251.2.128/27 | {"start": "10.251.2.130", "end": "10.251.2.158"} |
| 4674a928-0f7b-452c-a037-950fc1e15ba0 | v6_slaac_net | 2001:db8:beef:7ac0::/64 | {"start": "2001:db8:beef:7ac0::1", "end": "2001:db8:beef:7ac0:ffff:ffff:ffff:fffe"} |
+--------------------------------------+--------------+-------------------------+-------------------------------------------------------------------------------------+

+-------------------+-------------------------------------------------------------------------------------+
| Field | Value |
+-------------------+-------------------------------------------------------------------------------------+
| allocation_pools | {"start": "2001:db8:beef:7ac0::1", "end": "2001:db8:beef:7ac0:ffff:ffff:ffff:fffe"} |
| cidr | 2001:db8:beef:7ac0::/64 |
| dns_nameservers | |
| enable_dhcp | True |
| gateway_ip | fe80::21c:73ff:fe03:11b3 |
| host_routes | |
| id | 4674a928-0f7b-452c-a037-950fc1e15ba0 |
| ip_version | 6 |
| ipv6_address_mode | slaac |
| ipv6_ra_mode | |
| name | v6_slaac_net ...

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/64578
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=1715eb7c8e1f2433df3c081e357f8c40dfe2a28a
Submitter: Jenkins
Branch: master

commit 1715eb7c8e1f2433df3c081e357f8c40dfe2a28a
Author: Sean M. Collins <email address hidden>
Date: Tue Jun 10 15:20:49 2014 -0400

    Ensure entries in dnsmasq belong to a subnet using DHCP

    In certain configurations, Neutron calculates SLAAC addresses for IPv6
    subnets and adds them to the fixed_ips field of a port. Since those
    subnets are not being managed by DHCP, do not add those fixed_ip entries
    to the host file.

    Closes-bug: #1316190
    Related-bug: #1257446

    Change-Id: I77dd55063296990c9df385f331f5de5d42402786