openstack
/
openstack-ansible-openstack_hosts
Code Issues Proposed changes

Increase default value of net.ipv4.igmp_max_memberships 

The linux kernel default for igmp_max_memberships is 20 [0].

For vxlan project networks, it is possible to specify a range
of multicast addresses for use with VXLAN tunnel broadcast traffic.
In the case where a range is specified a unique multicast group
is assigned by neutron to each vxlan network, and once
igmp_max_memberships is reached for a host, vxlan interfaces will
silently fail to join the multicast group.

This results in instances being unable to DHCP or ARP, and errors
in the neutron agent log [1].

This patch increases the default value to 1024 which should be
sufficient for all but the very largest deployments.

[0] https://sysctl-explorer.net/net/ipv4/igmp_max_memberships/
[1] http://paste.openstack.org/show/796504

Change-Id: I24a0ca3001098b278d341f710ca2e4f00dc3e09a
This commit is contained in:
Jonathan Rosser 2020-08-04 17:34:20 +01:00
parent 7f26a27140
commit 7cbf51170c
1 changed files with 1 additions and 0 deletions
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1
defaults/main.yml
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@ -104,6 +104,7 @@ openstack_kernel_options:
- { key: 'net.bridge.bridge-nf-call-ip6tables', value: 1 }
- { key: 'net.bridge.bridge-nf-call-iptables', value: 1 }
- { key: 'net.bridge.bridge-nf-call-arptables', value: 1 }
- { key: 'net.ipv4.igmp_max_memberships', value: 1024 }
- { key: 'net.ipv4.neigh.default.gc_thresh1', value: "{{ set_gc_val | int // 2 }}" }
- { key: 'net.ipv4.neigh.default.gc_thresh2', value: "{{ set_gc_val | int }}" }
- { key: 'net.ipv4.neigh.default.gc_thresh3', value: "{{ set_gc_val | int * 2 }}" }