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Taikun OCP Guide

Table of Contents

Linux bridge mechanism driver

The Linux bridge mechanism driver uses only Linux bridges and
veth pairs as interconnection devices. A layer-2 agent
manages Linux bridges on each compute node and any other node that
provides layer-3 (routing), DHCP, metadata, or other network
services.

Compatibility with nftables

nftables
replaces iptables, ip6tables, arptables and ebtables, in order to
provide a single API for all Netfilter operations.
nftables provides a backwards compatibility set of tools
for those replaced binaries that present the legacy API to the user
while using the new packet classification framework. As reported in LP#1915341
and LP#1922892,
the tool ebtables-nft is not totally compatible with the
legacy API and returns some errors. To use Linux Bridge mechanism driver
in newer operating systems that use nftables by default, it
is needed to switch back to the legacy tool.

# /usr/bin/update-alternatives --set ebtables /usr/sbin/ebtables-legacy

Since LP#1922127
and LP#1922892
were fixed, Neutron Linux Bridge mechanism driver is compatible with the
nftables binaries using the legacy API.

Note

Just to unravel the possible terminology confusion, these are the
three Netfilter available framework alternatives:

  • The legacy binaries (iptables, ip6tables,
    arptables and ebtables) that use the legacy
    API.
  • The new nftables binaries that use the legacy API, to
    help in the transition to this new framework. Those binaries replicate
    the same commands as the legacy one but using the new framework. The
    binaries have the same name ended in -nft.
  • The new nftables framework using the new API. All
    Netfilter operations are executed using this new API and one single
    binary, nft.

Currently we support the first two options. The migration (total or
partial) to the new API is tracked in LP#1508155.

In order to use the nftables binaries with the legacy
API, it is needed to execute the following commands.

# /usr/bin/update-alternatives --set iptables /usr/sbin/iptables-nft
# /usr/bin/update-alternatives --set ip6tables /usr/sbin/ip6tables-nft
# /usr/bin/update-alternatives --set ebtables /usr/sbin/ebtables-nft
# /usr/bin/update-alternatives --set arptables /usr/sbin/arptables-nft

The ipset tool is not compatible with
nftables. To disable it, enable_ipset must be
set to False in the ML2 plugin configuration file
/etc/neutron/plugins/ml2/ml2_conf.ini.

[securitygroup]
# ...
enable_ipset = False

deploy-lb-provider deploy-lb-selfservice deploy-lb-ha-vrrp

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