Public bug reported: High level description: When a user creates a tenant network with a very small MTU (in our case 70), neutron-dhcp-agent stops updating the dnsmasq configuration, causing DHCP issues for all networks.
Pre-conditions: Neutron is using the openvswitch, baremetal, and networking-generic-switch mechanism drivers. A physical network named `physnet1` is configured, with MTU=9000 Step-by-step reproduction steps: As an admin user, run: # Create "normal" network and subnet openstack network create --provider-network-type vlan --provider-physical-network physnet1 --mtu 1500 test-net-1500 openstack subnet create --subnet-range 10.100.10.0/24 --dhcp --network test-net-1500 test-subnet-1500 # Create "small MTU" network and subnet openstack network create --provider-network-type vlan --provider-physical-network physnet1 --mtu 70 test-net-70 openstack subnet create --subnet-range 10.100.11.0/24 --dhcp --network test-net-70 test-subnet-70 # attempt to launch an instance on the "normal" network openstack server create --image Ubuntu --flavor Baremetal --network test-net-1500 Expected output: what did you hope to see? We expected to see neutron-dhcp-agent update the dnsmasq configuration, which would then serve requests from the instances. * Actual output: did the system silently fail (in this case log traces are useful)? Openstack commands complete successfully, but instance never receives a response to its DHCP requests. Neutron-dhcp-agent logs show: https://paste.opendev.org/show/b4r0XCu5KpguM72bnh0u/ Version: ** OpenStack version "stable/xena", hash bc1dd6939d197d15799aaf252049f76442866c21 ** Linux distro, kernel. Ubuntu 20.04 ** Containers built with Kolla, and deployed via Kolla-Ansible * Environment: Single node deployment, all services (core, networking, database, etc.) on one node. All compute-nodes are baremetal via Ironic. * Perceived severity: is this a blocker for you? High, as non-admin users can trigger an DHCP outage affecting all users. ** Affects: neutron Importance: Undecided Status: New ** Tags: l3-ipam-dhcp -- You received this bug notification because you are a member of Yahoo! Engineering Team, which is subscribed to neutron. https://bugs.launchpad.net/bugs/1988069 Title: neutron-dhcp-agent fails when small tenant network mtu is set Status in neutron: New Bug description: High level description: When a user creates a tenant network with a very small MTU (in our case 70), neutron-dhcp-agent stops updating the dnsmasq configuration, causing DHCP issues for all networks. Pre-conditions: Neutron is using the openvswitch, baremetal, and networking-generic-switch mechanism drivers. A physical network named `physnet1` is configured, with MTU=9000 Step-by-step reproduction steps: As an admin user, run: # Create "normal" network and subnet openstack network create --provider-network-type vlan --provider-physical-network physnet1 --mtu 1500 test-net-1500 openstack subnet create --subnet-range 10.100.10.0/24 --dhcp --network test-net-1500 test-subnet-1500 # Create "small MTU" network and subnet openstack network create --provider-network-type vlan --provider-physical-network physnet1 --mtu 70 test-net-70 openstack subnet create --subnet-range 10.100.11.0/24 --dhcp --network test-net-70 test-subnet-70 # attempt to launch an instance on the "normal" network openstack server create --image Ubuntu --flavor Baremetal --network test-net-1500 Expected output: what did you hope to see? We expected to see neutron-dhcp-agent update the dnsmasq configuration, which would then serve requests from the instances. * Actual output: did the system silently fail (in this case log traces are useful)? Openstack commands complete successfully, but instance never receives a response to its DHCP requests. Neutron-dhcp-agent logs show: https://paste.opendev.org/show/b4r0XCu5KpguM72bnh0u/ Version: ** OpenStack version "stable/xena", hash bc1dd6939d197d15799aaf252049f76442866c21 ** Linux distro, kernel. Ubuntu 20.04 ** Containers built with Kolla, and deployed via Kolla-Ansible * Environment: Single node deployment, all services (core, networking, database, etc.) on one node. All compute-nodes are baremetal via Ironic. * Perceived severity: is this a blocker for you? High, as non-admin users can trigger an DHCP outage affecting all users. To manage notifications about this bug go to: https://bugs.launchpad.net/neutron/+bug/1988069/+subscriptions -- Mailing list: https://launchpad.net/~yahoo-eng-team Post to : [email protected] Unsubscribe : https://launchpad.net/~yahoo-eng-team More help : https://help.launchpad.net/ListHelp
