openstack/kolla-ansible
Code Issues Proposed changes

[neutron] Adjust neighbour table thresholds

Browse Source 
When clouds have a large number of hosts, the default size of the ARP
cache is too small. The cache can overflow, which means that the system
has no way to reach some IP addresses.

Increasing threshold limits addresses the situation, in a reasonably
safe way (the maximum impact is 5MB or so of additional RAM used).

More context on this issue:

* http://man7.org/linux/man-pages/man7/arp.7.html
* https://bugs.launchpad.net/charm-nova-compute/+bug/1780348
* https://bugs.launchpad.net/fuel/+bug/1488938
* https://bugs.launchpad.net/tripleo/+bug/1690087
* 0583a0c949
* 3dd21ea62a
* 1651a1805a

Change-Id: I60c871e8eb9f2c086818ff077987f2390930800c
Closes-Bug: #1844349
This commit is contained in:
Pierre Riteau 2019-11-27 16:32:47 +01:00
parent 692d176cd5
commit 4234cc4b5b
2 changed files with 12 additions and 0 deletions
ansible/roles/neutron
defaults
main.yml
tasks
config.yml

6
ansible/roles/neutron/defaults/main.yml

@ -348,6 +348,12 @@ neutron_logging_debug: "{{ openstack_logging_debug }}"
openstack_neutron_auth: "{{ openstack_auth }}"
neutron_l3_agent_host_rp_filter_mode: 0
neutron_l3_agent_host_ipv4_neigh_gc_thresh1: 128
neutron_l3_agent_host_ipv4_neigh_gc_thresh2: 28672
neutron_l3_agent_host_ipv4_neigh_gc_thresh3: 32768
neutron_l3_agent_host_ipv6_neigh_gc_thresh1: "{{ neutron_l3_agent_host_ipv4_neigh_gc_thresh1 }}"
neutron_l3_agent_host_ipv6_neigh_gc_thresh2: "{{ neutron_l3_agent_host_ipv4_neigh_gc_thresh2 }}"
neutron_l3_agent_host_ipv6_neigh_gc_thresh3: "{{ neutron_l3_agent_host_ipv4_neigh_gc_thresh3 }}"
####################
# Extension drivers

6
ansible/roles/neutron/tasks/config.yml

@ -8,6 +8,12 @@
- { name: "net.ipv4.ip_forward", value: 1}
- { name: "net.ipv4.conf.all.rp_filter", value: "{{ neutron_l3_agent_host_rp_filter_mode }}"}
- { name: "net.ipv4.conf.default.rp_filter", value: "{{ neutron_l3_agent_host_rp_filter_mode }}"}
- { name: "net.ipv4.neigh.default.gc_thresh1", value: "{{ neutron_l3_agent_host_ipv4_neigh_gc_thresh1 }}"}
- { name: "net.ipv4.neigh.default.gc_thresh2", value: "{{ neutron_l3_agent_host_ipv4_neigh_gc_thresh2 }}"}
- { name: "net.ipv4.neigh.default.gc_thresh3", value: "{{ neutron_l3_agent_host_ipv4_neigh_gc_thresh3 }}"}
- { name: "net.ipv6.neigh.default.gc_thresh1", value: "{{ neutron_l3_agent_host_ipv6_neigh_gc_thresh1 }}"}
- { name: "net.ipv6.neigh.default.gc_thresh2", value: "{{ neutron_l3_agent_host_ipv6_neigh_gc_thresh2 }}"}
- { name: "net.ipv6.neigh.default.gc_thresh3", value: "{{ neutron_l3_agent_host_ipv6_neigh_gc_thresh3 }}"}
when:
- set_sysctl | bool
- (neutron_l3_agent.enabled | bool and neutron_l3_agent.host_in_groups | bool)