dhcp_agent.ini 配置文件解读 路径：/etc/neutron/dhcp_agent.ini

源配置文件内容：

#
# From neutron.base.agent 

#
#设置虚拟交换机被使用的网桥的名字
# Name of Open vSwitch bridge to use (string value) 
#ovs_integration_bridge = br-int

# 设置是否支持使用veth接口。若要支持有限命名空间的内核支持（如RHEL 6.5）和路由器网关端口的速率限制则设置为True
# Uses veth for an OVS interface or not. Support kernels with limited namespace  
# support (e.g. RHEL 6.5) and rate limiting on router's gateway port so long as
# ovs_use_veth is set to True. (boolean value)
#ovs_use_veth = false

# 用于管理虚拟接口的驱动程序
# The driver used to manage the virtual interface. (string value)
#interface_driver = 
interface_driver=neutron.agent.linux.interface.OVSInterfaceDriver

#
# From neutron.dhcp.agent
#

#这部分就是设置同步时间间隔 DHCP代理将使用Neutron重新同步其状态，以从任何临时通知或RPC错误中恢复 间隔是秒数 在两次尝试之间。
# The DHCP agent will resync its state with Neutron to recover from any
# transient notification or RPC errors. The interval is number of seconds
# between attempts. (integer value)
#resync_interval = 5
resync_interval=30

#用于管理DHCP服务器的驱动程序 也就是dnsmasq
# The driver used to manage the DHCP server. (string value)
#dhcp_driver = neutron.agent.linux.dhcp.Dnsmasq

#个人理解 启动隔离网络 
# The DHCP server can assist with providing metadata support on isolated
# networks. Setting this value to True will cause the DHCP server to append
# specific host routes to the DHCP request. The metadata service will only be
# activated when the subnet does not contain any router port. The guest
# instance must be configured to request host routes via DHCP (Option 121).
# This option doesn't have any effect when force_metadata is set to True.
# (boolean value)
#enable_isolated_metadata = false
enable_isolated_metadata=False

#个人理解 通过DHCP服务器提供元数据IP信息
# In some cases the Neutron router is not present to provide the metadata IP
# but the DHCP server can be used to provide this info. Setting this value will
# force the DHCP server to append specific host routes to the DHCP request. If
# this option is set, then the metadata service will be activated for all the
# networks. (boolean value)
#force_metadata = false

# 允许服务来自专用元数据访问网络的元数据请求
# Allows for serving metadata requests coming from a dedicated metadata access
# network whose CIDR is 169.254.169.254/16 (or larger prefix), and is connected
# to a Neutron router from which the VMs send metadata:1 request. In this case
# DHCP Option 121 will not be injected in VMs, as they will be able to reach
# 169.254.169.254 through a router. This option requires
# enable_isolated_metadata = True. (boolean value)
#enable_metadata_network = false
enable_metadata_network=False

#同步过程中要使用的线程数
# Number of threads to use during sync process. Should not exceed connection
# pool size configured on server. (integer value)
#num_sync_threads = 4

#存储DHCP服务器配置文件的位置
# Location to store DHCP server config files. (string value)
#dhcp_confs = $state_path/dhcp

#使用此文件覆盖默认的dnsmasq设置。 （字符串值）
# Override the default dnsmasq settings with this file. (string value)
#dnsmasq_config_file =

#逗号分隔的DNS服务器列表，将用作转发器。
# Comma-separated list of the DNS servers which will be used as forwarders.
# (list value)
#dnsmasq_dns_servers =

#开dhco 和 dns debug记录的地方
# Base log dir for dnsmasq logging. The log contains DHCP and DNS log
# information and is useful for debugging issues with either DHCP or DNS. If
# this section is null, disable dnsmasq log. (string value)
#dnsmasq_base_log_dir = 

#使dnsmasq服务能够通过运行DHCP代理的主机上的DNS解析器为实例提供名称解析。 有效地从dnsmasq进程参数中删除“ --no-resolv”选项。 将自定义DNS解析器添加到“ dnsmasq_dns_servers”选项将禁用此功能
# Enables the dnsmasq service to provide name resolution for instances via DNS
# resolvers on the host running the DHCP agent. Effectively removes the '--no-
# resolv' option from the dnsmasq process arguments. Adding custom DNS
# resolvers to the 'dnsmasq_dns_servers' option disables this feature. (boolean
# value)
#dnsmasq_local_resolv = false

# 限制租约数量以防止拒绝服务。
# Limit number of leases to prevent a denial-of-service. (integer value)
#dnsmasq_lease_max = 16777216

# 使用广播应答
# Use broadcast in DHCP replies. (boolean value)
#dhcp_broadcast_reply = false

# DHCP更新时间T1（以秒为单位）。 如果设置为0，则默认为一半
# DHCP renewal time T1 (in seconds). If set to 0, it will default to half of
# the lease time. (integer value)
#dhcp_renewal_time = 0

# 重新绑定租约时间
# DHCP rebinding time T2 (in seconds). If set to 0, it will default to 7/8 of
# the lease time. (integer value)
#dhcp_rebinding_time = 0

#
# From oslo.log
#

# 开启debug 如果设置为true，则日志记录级别将设置为DEBUG而不是默认值
# If set to true, the logging level will be set to DEBUG instead of the default
# INFO level. (boolean value)
# Note: This option can be changed without restarting.
#debug = false
debug=False

# The name of a logging configuration file. This file is appended to any
# existing logging configuration files. For details about logging configuration
# files, see the Python logging module documentation. Note that when logging
# configuration files are used then all logging configuration is set in the
# configuration file and other logging configuration options are ignored (for
# example, logging_context_format_string). (string value)
# Note: This option can be changed without restarting.
# Deprecated group/name - [DEFAULT]/log_config
#log_config_append = 

# Defines the format string for %%(asctime)s in log records. Default:
# %(default)s . This option is ignored if log_config_append is set. (string
# value)
#log_date_format = %Y-%m-%d %H:%M:%S

# (Optional) Name of log file to send logging output to. If no default is set,
# logging will go to stderr as defined by use_stderr. This option is ignored if
# log_config_append is set. (string value)
# Deprecated group/name - [DEFAULT]/logfile
#log_file = 

# (Optional) The base directory used for relative log_file  paths. This option
# is ignored if log_config_append is set. (string value)
# Deprecated group/name - [DEFAULT]/logdir
#log_dir = 

# Uses logging handler designed to watch file system. When log file is moved or
# removed this handler will open a new log file with specified path
# instantaneously. It makes sense only if log_file option is specified and
# Linux platform is used. This option is ignored if log_config_append is set.
# (boolean value)
#watch_log_file = false

# Use syslog for logging. Existing syslog format is DEPRECATED and will be
# changed later to honor RFC5424. This option is ignored if log_config_append
# is set. (boolean value)
#use_syslog = false

# Enable journald for logging. If running in a systemd environment you may wish
# to enable journal support. Doing so will use the journal native protocol
# which includes structured metadata in addition to log messages.This option is
# ignored if log_config_append is set. (boolean value)
#use_journal = false

# Syslog facility to receive log lines. This option is ignored if
# log_config_append is set. (string value)
#syslog_log_facility = LOG_USER

# Use JSON formatting for logging. This option is ignored if log_config_append
# is set. (boolean value)
#use_json = false

# Log output to standard error. This option is ignored if log_config_append is
# set. (boolean value)
#use_stderr = false

# Format string to use for log messages with context. (string value)
#logging_context_format_string = %(asctime)s.%(msecs)03d %(process)d %(levelname)s %(name)s [%(request_id)s %(user_identity)s] %(instance)s%(message)s

# Format string to use for log messages when context is undefined. (string
# value)
#logging_default_format_string = %(asctime)s.%(msecs)03d %(process)d %(levelname)s %(name)s [-] %(instance)s%(message)s

# Additional data to append to log message when logging level for the message
# is DEBUG. (string value)
#logging_debug_format_suffix = %(funcName)s %(pathname)s:%(lineno)d

# Prefix each line of exception output with this format. (string value)
#logging_exception_prefix = %(asctime)s.%(msecs)03d %(process)d ERROR %(name)s %(instance)s

# Defines the format string for %(user_identity)s that is used in
# logging_context_format_string. (string value)
#logging_user_identity_format = %(user)s %(tenant)s %(domain)s %(user_domain)s %(project_domain)s

# List of package logging levels in logger=LEVEL pairs. This option is ignored
# if log_config_append is set. (list value)
#default_log_levels = amqp=WARN,amqplib=WARN,boto=WARN,qpid=WARN,sqlalchemy=WARN,suds=INFO,oslo.messaging=INFO,oslo_messaging=INFO,iso8601=WARN,requests.packages.urllib3.connectionpool=WARN,urllib3.connectionpool=WARN,websocket=WARN,requests.packages.urllib3.util.retry=WARN,urllib3.util.retry=WARN,keystonemiddleware=WARN,routes.middleware=WARN,stevedore=WARN,taskflow=WARN,keystoneauth=WARN,oslo.cache=INFO,dogpile.core.dogpile=INFO

#启用或禁用错误事件的发布。
# Enables or disables publication of error events. (boolean value)
#publish_errors = false

# The format for an instance that is passed with the log message. (string
# value)
#instance_format = "[instance: %(uuid)s] "

# The format for an instance UUID that is passed with the log message. (string
# value)
#instance_uuid_format = "[instance: %(uuid)s] "

# Interval, number of seconds, of log rate limiting. (integer value)
#rate_limit_interval = 0

# Maximum number of logged messages per rate_limit_interval. (integer value)
#rate_limit_burst = 0

# Log level name used by rate limiting: CRITICAL, ERROR, INFO, WARNING, DEBUG
# or empty string. Logs with level greater or equal to rate_limit_except_level
# are not filtered. An empty string means that all levels are filtered. (string
# value)
#rate_limit_except_level = CRITICAL

# Enables or disables fatal status of deprecations. (boolean value)
#fatal_deprecations = false
state_path=/var/lib/neutron
root_helper=sudo neutron-rootwrap /etc/neutron/rootwrap.conf


[agent]

#
# From neutron.az.agent
#

#该节点的可用区
# Availability zone of this node (string value)
#availability_zone = nova

#
# From neutron.base.agent
#

# Seconds between nodes reporting state to server; should be less than
# agent_down_time, best if it is half or less than agent_down_time. (floating
# point value)
#report_interval = 30

# Log agent heartbeats (boolean value)
#log_agent_heartbeats = false


[ovs]

#
# From neutron.base.agent
#

#用于与OVSDB进行交互的接口（字符串值）
# DEPRECATED: The interface for interacting with the OVSDB (string value)
# Possible values:
# vsctl - 
# native - 
# This option is deprecated for removal.
# Its value may be silently ignored in the future.
#ovsdb_interface = native

#OVSDB后端的连接字符串
# The connection string for the OVSDB backend. Will be used by ovsdb-client
# when monitoring and used for the all ovsdb commands when native
# ovsdb_interface is enabled (string value)
#ovsdb_connection = tcp:127.0.0.1:6640

#与OVSDB交互时使用的SSL私钥文件 
# The SSL private key file to use when interacting with OVSDB. Required when
# using an "ssl:" prefixed ovsdb_connection (string value)
#ssl_key_file = 

#与OVSDB交互时使用的SSL证书文件
# The SSL certificate file to use when interacting with OVSDB. Required when
# using an "ssl:" prefixed ovsdb_connection (string value)
#ssl_cert_file = 

# The Certificate Authority (CA) certificate to use when interacting with
# OVSDB.  Required when using an "ssl:" prefixed ovsdb_connection (string
# value)
#ssl_ca_cert_file = 

# Timeout in seconds for ovsdb commands. If the timeout expires, ovsdb commands
# will fail with ALARMCLOCK error. (integer value)
# Deprecated group/name - [DEFAULT]/ovs_vsctl_timeout
#ovsdb_timeout = 10

# The maximum number of MAC addresses to learn on a bridge managed by the
# Neutron OVS agent. Values outside a reasonable range (10 to 1,000,000) might
# be overridden by Open vSwitch according to the documentation. (integer value)
#bridge_mac_table_size = 50000